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Tinsley SL, Shelley RA, Mall GK, Chianis ERD, Dhiman A, Baral G, Kothandaraman H, Thoma MC, Daniel CJ, Lanman NA, di Magliano MP, Narla G, Solorio L, Dykhuizen EC, Sears RC, Allen-Petersen BL. KRAS-mediated upregulation of CIP2A promotes suppression of PP2A-B56α to initiate pancreatic cancer development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.01.547283. [PMID: 38826439 PMCID: PMC11142131 DOI: 10.1101/2023.07.01.547283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Oncogenic mutations in KRAS are present in approximately 95% of patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) and are considered the initiating event of pancreatic intraepithelial neoplasia (PanIN) precursor lesions. While it is well established that KRAS mutations drive the activation of oncogenic kinase cascades during pancreatic oncogenesis, the effects of oncogenic KRAS signaling on regulation of phosphatases during this process is not fully appreciated. Protein Phosphatase 2A (PP2A) has been implicated in suppressing KRAS-driven cellular transformation. However, low PP2A activity is observed in PDAC cells compared to non-transformed cells, suggesting that suppression of PP2A activity is an important step in the overall development of PDAC. In the current study, we demonstrate that KRASG12D induces the expression of both an endogenous inhibitor of PP2A activity, Cancerous Inhibitor of PP2A (CIP2A), and the PP2A substrate, c-MYC. Consistent with these findings, KRASG12D sequestered the specific PP2A subunit responsible for c-MYC degradation, B56α, away from the active PP2A holoenzyme in a CIP2A-dependent manner. During PDAC initiation in vivo, knockout of B56α promoted KRASG12D tumorigenesis by accelerating acinar-to-ductal metaplasia (ADM) and the formation of PanIN lesions. The process of ADM was attenuated ex vivo in response to pharmacological re-activation of PP2A utilizing direct small molecule activators of PP2A (SMAPs). Together, our results suggest that suppression of PP2A-B56α through KRAS signaling can promote the MYC-driven initiation of pancreatic tumorigenesis.
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Affiliation(s)
- Samantha L. Tinsley
- Purdue University Interdisciplinary Life Sciences Program (PULSe), Purdue University, West Lafayette, IN, USA
- Department of Biological Sciences, Purdue University, West Lafayette, IN USA
| | - Rebecca A. Shelley
- Department of Biological Sciences, Purdue University, West Lafayette, IN USA
| | - Gaganpreet K. Mall
- Department of Biological Sciences, Purdue University, West Lafayette, IN USA
| | | | - Alisha Dhiman
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, USA
| | - Garima Baral
- Department of Biological Sciences, Purdue University, West Lafayette, IN USA
| | - Harish Kothandaraman
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN, USA
| | - Mary C. Thoma
- Department of Molecular Medicine and Genetics, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Colin J. Daniel
- Department of Molecular Medicine and Genetics, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Nadia Atallah Lanman
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN, USA
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, USA
| | | | - Goutham Narla
- University of Michigan School of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Luis Solorio
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Emily C. Dykhuizen
- Purdue University Interdisciplinary Life Sciences Program (PULSe), Purdue University, West Lafayette, IN, USA
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN, USA
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Rosalie C. Sears
- Department of Molecular Medicine and Genetics, Oregon Health and Sciences University, Portland, Oregon, USA
- Brenden-Colson Center for Pancreatic Care, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Brittany L. Allen-Petersen
- Purdue University Interdisciplinary Life Sciences Program (PULSe), Purdue University, West Lafayette, IN, USA
- Department of Biological Sciences, Purdue University, West Lafayette, IN USA
- Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN, USA
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Avelar RA, Gupta R, Carvette G, da Veiga Leprevost F, Colina J, Teitel J, Nesvizhskii AI, O’Connor CM, Hatzoglou M, Shenolikar S, Arvan P, Narla G, DiFeo A. Integrated stress response plasticity governs normal cell adaptation to chronic stress via the PP2A-TFE3-ATF4 pathway. RESEARCH SQUARE 2024:rs.3.rs-4013396. [PMID: 38585734 PMCID: PMC10996823 DOI: 10.21203/rs.3.rs-4013396/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
The integrated stress response (ISR) regulates cell fate during conditions of stress by leveraging the cell's capacity to endure sustainable and efficient adaptive stress responses. Protein phosphatase 2A (PP2A) activity modulation has been shown to be successful in achieving both therapeutic efficacy and safety across various cancer models; however, the molecular mechanisms driving its selective antitumor effects remain unclear. Here, we show for the first time that ISR plasticity relies on PP2A activation to regulate drug response and dictate cellular fate under conditions of chronic stress. We demonstrate that genetic and chemical modulation of the PP2A leads to chronic proteolytic stress and triggers an ISR to dictate cell fate. More specifically, we uncovered that the PP2A-TFE3-ATF4 pathway governs ISR cell plasticity during endoplasmic reticular and cellular stress independent of the unfolded protein response. We further show that normal cells reprogram their genetic signatures to undergo ISR-mediated adaptation and homeostatic recovery thereby successfully avoiding toxicity following PP2A-mediated stress. Conversely, oncogenic specific cytotoxicity induced by chemical modulation of PP2A is achieved by activating chronic and irreversible ISR in cancer cells. Our findings propose that a differential response to chemical modulation of PP2A is determined by intrinsic ISR plasticity, providing a novel biological vulnerability to selectively induce cancer cell death and improve targeted therapeutic efficacy.
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Affiliation(s)
- Rita A. Avelar
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Riya Gupta
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Gracie Carvette
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, The University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Jose Colina
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Jessica Teitel
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Alexey I. Nesvizhskii
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Caitlin M. O’Connor
- Rogel Cancer Center, The University of Michigan, Ann Arbor, MI 48109, USA
- Department of Internal Medicine, Division of Genetic Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Maria Hatzoglou
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Shirish Shenolikar
- Emeritus Professor, Duke-NUS Medical School, Singapore
- Professor Emeritus, Duke University School of Medicine, USA
| | - Peter Arvan
- Division of Metabolism Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
| | - Goutham Narla
- Rogel Cancer Center, The University of Michigan, Ann Arbor, MI 48109, USA
- Department of Internal Medicine, Division of Genetic Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Analisa DiFeo
- Department of Pathology, The University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, The University of Michigan, Ann Arbor, MI 48109, USA
- Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MI 48109, USA
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Zhou X, Xu Q, Li W, Dong N, Stomberski C, Narla G, Lin Z. Protein Phosphatase 2A Activation Promotes Heart Transplant Acceptance in Mice. Transplantation 2024; 108:e36-e48. [PMID: 38126420 PMCID: PMC10922415 DOI: 10.1097/tp.0000000000004832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
BACKGROUND Although heart transplantation is the definitive treatment for heart failure in eligible patients, both acute and chronic transplant rejection frequently occur. Protein phosphatase 2A (PP2A) activity is critical in maintaining tissue and organ homeostasis. In this study, we evaluated the effect of a novel class of small molecule activators of PP2A (SMAPs) on allograft rejection in a mouse heterotopic heart transplantation model. METHODS Recipient mice were administered with DT-061 (a pharmaceutically optimized SMAP) or vehicle by oral gavage beginning 1 d after transplantation. Histological and immunofluorescence analyses were performed to examine allograft rejection. Regulatory T cells (Treg) from recipient spleens were subjected to flow cytometry and RNA sequencing analysis. Finally, the effect of DT-061 on smooth muscle cells (SMCs) migration and proliferation was assessed. RESULTS DT-061 treatment prolonged cardiac allograft survival. SMAPs effectively suppressed the inflammatory immune response while increasing Treg population in the allografts, findings corroborated by functional analysis of RNA sequencing data derived from Treg of treated splenic tissues. Importantly, SMAPs extended immunosuppressive agent cytotoxic T lymphocyte-associated antigen-4-Ig-induced cardiac transplantation tolerance and allograft survival. SMAPs also strongly mitigated cardiac allograft vasculopathy as evidenced by a marked reduction of neointimal hyperplasia and SMC proliferation. Finally, our in vitro studies implicate suppression of MEK/ERK pathways as a unifying mechanism for the effect of PP2A modulation in Treg and SMCs. CONCLUSIONS PP2A activation prevents cardiac rejection and prolongs allograft survival in a murine model. Our findings highlight the potential of PP2A activation in improving alloengraftment in heart transplantation.
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Affiliation(s)
- Xianming Zhou
- Cardiology Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qian Xu
- Cardiology Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
- Department of Cardiovascular Surgery, Xiangya Hospital of Central South University, Changsha, China
| | - Wangzi Li
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Nianguo Dong
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Colin Stomberski
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Zhiyong Lin
- Cardiology Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
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Runa F, Ortiz-Soto G, de Barros NR, Kelber JA. Targeting SMAD-Dependent Signaling: Considerations in Epithelial and Mesenchymal Solid Tumors. Pharmaceuticals (Basel) 2024; 17:326. [PMID: 38543112 PMCID: PMC10975212 DOI: 10.3390/ph17030326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 02/19/2024] [Accepted: 02/23/2024] [Indexed: 04/01/2024] Open
Abstract
SMADs are the canonical intracellular effector proteins of the TGF-β (transforming growth factor-β). SMADs translocate from plasma membrane receptors to the nucleus regulated by many SMAD-interacting proteins through phosphorylation and other post-translational modifications that govern their nucleocytoplasmic shuttling and subsequent transcriptional activity. The signaling pathway of TGF-β/SMAD exhibits both tumor-suppressing and tumor-promoting phenotypes in epithelial-derived solid tumors. Collectively, the pleiotropic nature of TGF-β/SMAD signaling presents significant challenges for the development of effective cancer therapies. Here, we review preclinical studies that evaluate the efficacy of inhibitors targeting major SMAD-regulating and/or -interacting proteins, particularly enzymes that may play important roles in epithelial or mesenchymal compartments within solid tumors.
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Affiliation(s)
- Farhana Runa
- Department of Biology, California State University Northridge, Northridge, CA 91330, USA
| | | | | | - Jonathan A Kelber
- Department of Biology, California State University Northridge, Northridge, CA 91330, USA
- Department of Biology, Baylor University, Waco, TX 76706, USA
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Wang J, Chen Y, Li S, Liu W, Zhou XA, Luo Y, Xu Z, Xiong Y, Cheng K, Ruan M, Yu W, Li X, Wang W, Wang J. PP2A inhibition causes synthetic lethality in BRCA2-mutated prostate cancer models via spindle assembly checkpoint reactivation. J Clin Invest 2024; 134:e172137. [PMID: 37934606 PMCID: PMC10760972 DOI: 10.1172/jci172137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 10/31/2023] [Indexed: 11/09/2023] Open
Abstract
Mutations in the BRCA2 tumor suppressor gene have been associated with an increased risk of developing prostate cancer. One of the paradoxes concerning BRCA2 is the fact that its inactivation affects genetic stability and is deleterious for cellular and organismal survival, while BRCA2-mutated cancer cells adapt to this detriment and malignantly proliferate. Therapeutic strategies for tumors arising from BRCA2 mutations may be discovered by understanding these adaptive mechanisms. In this study, we conducted forward genetic synthetic viability screenings in Caenorhabditis elegans brc-2 (Cebrc-2) mutants and found that Ceubxn-2 inactivation rescued the viability of Cebrc-2 mutants. Moreover, loss of NSFL1C, the mammalian ortholog of CeUBXN-2, suppressed the spindle assembly checkpoint (SAC) activation and promoted the survival of BRCA2-deficient cells. Mechanistically, NSFL1C recruited USP9X to inhibit the polyubiquitination of AURKB and reduce the removal of AURKB from the centromeres by VCP, which is essential for SAC activation. SAC inactivation is common in BRCA2-deficient prostate cancer patients, but PP2A inhibitors could reactivate the SAC and achieve BRCA2-deficient prostate tumor synthetic lethality. Our research reveals the survival adaptation mechanism of BRCA2-deficient prostate tumor cells and provides different angles for exploring synthetic lethal inhibitors in addition to targeting DNA damage repair pathways.
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Affiliation(s)
- Jian Wang
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Yuke Chen
- Department of Urology, Peking University First Hospital, Beijing, China
| | - Shiwei Li
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Wanchang Liu
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Xiao Albert Zhou
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Yefei Luo
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Zhanzhan Xu
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Yundong Xiong
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Kaiqi Cheng
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Mingjian Ruan
- Department of Urology, Peking University First Hospital, Beijing, China
| | - Wei Yu
- Department of Urology, Peking University First Hospital, Beijing, China
| | - Xiaoman Li
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Weibin Wang
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
| | - Jiadong Wang
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University International Cancer Institute, Beijing Key Laboratory of Tumor Systems Biology, Peking University Health Science Center, Beijing, China
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Denisova OV, Merisaari J, Huhtaniemi R, Qiao X, Yetukuri L, Jumppanen M, Kaur A, Pääkkönen M, von Schantz‐Fant С, Ohlmeyer M, Wennerberg K, Kauko O, Koch R, Aittokallio T, Taipale M, Westermarck J. PP2A-based triple-strike therapy overcomes mitochondrial apoptosis resistance in brain cancer cells. Mol Oncol 2023; 17:1803-1820. [PMID: 37458534 PMCID: PMC10483611 DOI: 10.1002/1878-0261.13488] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 05/08/2023] [Accepted: 07/13/2023] [Indexed: 07/27/2023] Open
Abstract
Mitochondrial glycolysis and hyperactivity of the phosphatidylinositol 3-kinase-protein kinase B (AKT) pathway are hallmarks of malignant brain tumors. However, kinase inhibitors targeting AKT (AKTi) or the glycolysis master regulator pyruvate dehydrogenase kinase (PDKi) have failed to provide clinical benefits for brain tumor patients. Here, we demonstrate that heterogeneous glioblastoma (GB) and medulloblastoma (MB) cell lines display only cytostatic responses to combined AKT and PDK targeting. Biochemically, the combined AKT and PDK inhibition resulted in the shutdown of both target pathways and priming to mitochondrial apoptosis but failed to induce apoptosis. In contrast, all tested brain tumor cell models were sensitive to a triplet therapy, in which AKT and PDK inhibition was combined with the pharmacological reactivation of protein phosphatase 2A (PP2A) by NZ-8-061 (also known as DT-061), DBK-1154, and DBK-1160. We also provide proof-of-principle evidence for in vivo efficacy in the intracranial GB and MB models by the brain-penetrant triplet therapy (AKTi + PDKi + PP2A reactivator). Mechanistically, PP2A reactivation converted the cytostatic AKTi + PDKi response to cytotoxic apoptosis, through PP2A-elicited shutdown of compensatory mitochondrial oxidative phosphorylation and by increased proton leakage. These results encourage the development of triple-strike strategies targeting mitochondrial metabolism to overcome therapy tolerance in brain tumors.
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Affiliation(s)
- Oxana V. Denisova
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
| | - Joni Merisaari
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
- Institute of BiomedicineUniversity of TurkuFinland
| | - Riikka Huhtaniemi
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
| | - Xi Qiao
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
| | - Laxman Yetukuri
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
- Institute for Molecular Medicine Finland (FIMM), HiLIFEUniversity of HelsinkiFinland
- Centre for Biostatistics and Epidemiology (OCBE)University of OsloNorway
| | - Mikael Jumppanen
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
| | - Amanpreet Kaur
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
| | - Mirva Pääkkönen
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
| | | | - Michael Ohlmeyer
- Icahn School of Medicine at Mount SinaiNew YorkNYUSA
- Atux Iskay LLCPlainsboroNJUSA
| | - Krister Wennerberg
- Institute for Molecular Medicine Finland (FIMM), HiLIFEUniversity of HelsinkiFinland
- Biotech Research & Innovation CentreUniversity of CopenhagenDenmark
| | - Otto Kauko
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
| | | | - Tero Aittokallio
- Institute for Molecular Medicine Finland (FIMM), HiLIFEUniversity of HelsinkiFinland
- Centre for Biostatistics and Epidemiology (OCBE)University of OsloNorway
- Institute for Cancer ResearchOslo University HospitalNorway
| | - Mikko Taipale
- Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoCanada
| | - Jukka Westermarck
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityFinland
- Institute of BiomedicineUniversity of TurkuFinland
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Peris I, Romero-Murillo S, Vicente C, Narla G, Odero MD. Regulation and role of the PP2A-B56 holoenzyme family in cancer. Biochim Biophys Acta Rev Cancer 2023; 1878:188953. [PMID: 37437699 DOI: 10.1016/j.bbcan.2023.188953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/07/2023] [Accepted: 07/08/2023] [Indexed: 07/14/2023]
Abstract
Protein phosphatase 2A (PP2A) inactivation is common in cancer, leading to sustained activation of pro-survival and growth-promoting pathways. PP2A consists of a scaffolding A-subunit, a catalytic C-subunit, and a regulatory B-subunit. The functional complexity of PP2A holoenzymes arises mainly through the vast repertoire of regulatory B-subunits, which determine both their substrate specificity and their subcellular localization. Therefore, a major challenge for developing more effective therapeutic strategies for cancer is to identify the specific PP2A complexes to be targeted. Of note, the development of small molecules specifically directed at PP2A-B56α has opened new therapeutic avenues in both solid and hematological tumors. Here, we focus on the B56/PR61 family of PP2A regulatory subunits, which have a central role in directing PP2A tumor suppressor activity. We provide an overview of the mechanisms controlling the formation and regulation of these complexes, the pathways they control, and the mechanisms underlying their deregulation in cancer.
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Affiliation(s)
- Irene Peris
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.
| | - Silvia Romero-Murillo
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain
| | - Carmen Vicente
- Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, The University of Michigan Medical School, Ann Arbor, MI, USA
| | - Maria D Odero
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain; CIBERONC, Instituto de Salud Carlos III, Madrid, Spain.
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van Pelt J, Meeusen B, Derua R, Guffens L, Van Cutsem E, Janssens V, Verslype C. Human pancreatic cancer patients with Epithelial-to-Mesenchymal Transition and an aggressive phenotype show a disturbed balance in Protein Phosphatase Type 2A expression and functionality. J Transl Med 2023; 21:317. [PMID: 37170215 PMCID: PMC10176933 DOI: 10.1186/s12967-023-04145-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 04/20/2023] [Indexed: 05/13/2023] Open
Abstract
BACKGROUND Pancreatic ductal adenocarcinoma (PDAC) has a low survival, its incidence is rising and little therapeutic improvements are expected in the near future. It has been observed that Epithelial-to-Mesenchymal transition (EMT) contributes (including in PDAC) to a more aggressive cancer phenotype. Additionally, largely unexplored, studies indicate a mechanistic interplay between Protein Phosphatase Type 2A (PP2A) enzymes and EMT that could offer treatment opportunities. The aim was to investigate the relation of a PP2A expression signature (encompassing all PP2A subunits, endogenous inhibitors and activators) with EMT and aggressive pancreatic cancer, and to discuss possible implications. METHODS We retrieved different PDAC expression datasets from NCBI to capture the variation in patients, and analyzed these using datamining, survival analysis, differential gene and protein expression. We determined genes highly associated with aggressive PDAC. For in vitro evaluation, Panc-1 cells were treated with the pharmacologic PP2A inhibitor Okadaic Acid (OA). Additionally, two OA-resistant Panc-1 clones were developed and characterized. RESULTS In patients, there is a strong correlation between EMT and aggressive PDAC, and between aggressive PDAC and PP2A, with a significant upregulation of PP2A inhibitor genes. Several PP2A genes significantly correlated with decreased survival. In vitro, short-term exposure to OA induced EMT in Panc-1 cells. This shift towards EMT was further pronounced in the OA-resistant Panc-1 clones, morphologically and by pathway analysis. Proteomic analysis and gene sequencing showed that the advanced OA-resistant model most resembles the clinical PDAC presentation (with EMT signature, and with several specific PP2A genes upregulated, and others downregulated). CONCLUSIONS We demonstrated a strong association between EMT, altered PP2A expression and aggressive PDAC in patients. Also, in vitro, PP2A inhibition induces EMT. Overall, statistics suggests the mechanistic importance of PP2A dysregulation for PDAC progression. Translationally, our observations indicate that pharmacologic restoration of PP2A activity could be an attractive therapeutic strategy to block or reverse progression.
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Affiliation(s)
- Jos van Pelt
- Laboratory of Digestive Oncology, Department of Oncology, KU Leuven & University Hospitals Leuven, Geb. Onderwijs & Navorsing 4, Room 07.465, Herestraat 49, Bus 603, B3000, Leuven, Belgium.
- KU Leuven Cancer Institute (LKI), Herestraat 49, B3000, Leuven, Belgium.
| | - Bob Meeusen
- Laboratory of Protein Phosphorylation & Proteomics, Dept. of Cellular & Molecular Medicine, O&N1, University of Leuven (KU Leuven), Herestraat 49, Bus 901, B3000, Leuven, Belgium
| | - Rita Derua
- Laboratory of Protein Phosphorylation & Proteomics, Dept. of Cellular & Molecular Medicine, O&N1, University of Leuven (KU Leuven), Herestraat 49, Bus 901, B3000, Leuven, Belgium
- SyBioMa (KU Leuven), Herestraat 49, B3000, Leuven, Belgium
| | - Liesbeth Guffens
- KU Leuven Cancer Institute (LKI), Herestraat 49, B3000, Leuven, Belgium
- Laboratory of Protein Phosphorylation & Proteomics, Dept. of Cellular & Molecular Medicine, O&N1, University of Leuven (KU Leuven), Herestraat 49, Bus 901, B3000, Leuven, Belgium
| | - Eric Van Cutsem
- Laboratory of Digestive Oncology, Department of Oncology, KU Leuven & University Hospitals Leuven, Geb. Onderwijs & Navorsing 4, Room 07.465, Herestraat 49, Bus 603, B3000, Leuven, Belgium
- KU Leuven Cancer Institute (LKI), Herestraat 49, B3000, Leuven, Belgium
| | - Veerle Janssens
- KU Leuven Cancer Institute (LKI), Herestraat 49, B3000, Leuven, Belgium.
- Laboratory of Protein Phosphorylation & Proteomics, Dept. of Cellular & Molecular Medicine, O&N1, University of Leuven (KU Leuven), Herestraat 49, Bus 901, B3000, Leuven, Belgium.
| | - Chris Verslype
- Laboratory of Digestive Oncology, Department of Oncology, KU Leuven & University Hospitals Leuven, Geb. Onderwijs & Navorsing 4, Room 07.465, Herestraat 49, Bus 603, B3000, Leuven, Belgium
- KU Leuven Cancer Institute (LKI), Herestraat 49, B3000, Leuven, Belgium
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9
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Avelar RA, Armstrong AJ, Carvette G, Gupta R, Puleo N, Colina JA, Joseph P, Sobeck AM, O'Connor CM, Raines B, Gandhi A, Dziubinski ML, Ma DS, Resnick K, Singh S, Zanotti K, Nagel C, Waggoner S, Thomas DG, Skala SL, Zhang J, Narla G, DiFeo A. Small-Molecule-Mediated Stabilization of PP2A Modulates the Homologous Recombination Pathway and Potentiates DNA Damage-Induced Cell Death. Mol Cancer Ther 2023; 22:599-615. [PMID: 36788429 PMCID: PMC10157366 DOI: 10.1158/1535-7163.mct-21-0880] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 05/17/2022] [Accepted: 02/09/2023] [Indexed: 02/16/2023]
Abstract
High-grade serous carcinoma (HGSC) is the most common and lethal ovarian cancer subtype. PARP inhibitors (PARPi) have become the mainstay of HGSC-targeted therapy, given that these tumors are driven by a high degree of genomic instability (GI) and homologous recombination (HR) defects. Nonetheless, approximately 30% of patients initially respond to treatment, ultimately relapsing with resistant disease. Thus, despite recent advances in drug development and an increased understanding of genetic alterations driving HGSC progression, mortality has not declined, highlighting the need for novel therapies. Using a small-molecule activator of protein phosphatase 2A (PP2A; SMAP-061), we investigated the mechanism by which PP2A stabilization induces apoptosis in patient-derived HGSC cells and xenograft (PDX) models alone or in combination with PARPi. We uncovered that PP2A genes essential for cellular transformation (B56α, B56γ, and PR72) and basal phosphatase activity (PP2A-A and -C) are heterozygously lost in the majority of HGSC. Moreover, loss of these PP2A genes correlates with worse overall patient survival. We show that SMAP-061-induced stabilization of PP2A inhibits the HR output by targeting RAD51, leading to chronic accumulation of DNA damage and ultimately apoptosis. Furthermore, combination of SMAP-061 and PARPi leads to enhanced apoptosis in both HR-proficient and HR-deficient HGSC cells and PDX models. Our studies identify PP2A as a novel regulator of HR and indicate PP2A modulators as a therapeutic therapy for HGSC. In summary, our findings further emphasize the potential of PP2A modulators to overcome PARPi insensitivity, given that targeting RAD51 presents benefits in overcoming PARPi resistance driven by BRCA1/2 mutation reversions.
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Affiliation(s)
- Rita A. Avelar
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
| | | | - Gracie Carvette
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
| | - Riya Gupta
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
| | - Noah Puleo
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
| | - Jose A. Colina
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
| | - Peronne Joseph
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio
| | - Alexander M. Sobeck
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
| | - Caitlin M. O'Connor
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
- Department of Internal Medicine, Genetic Medicine, University of Michigan, Ann Arbor, Michigan
| | - Brynne Raines
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
- Department of Internal Medicine, Genetic Medicine, University of Michigan, Ann Arbor, Michigan
| | - Agharnan Gandhi
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
| | - Michele L. Dziubinski
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
| | - Daniel S. Ma
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio
| | | | | | | | | | | | - Daffyd G. Thomas
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
| | | | - Junran Zhang
- Department of Radiation Oncology, Ohio State University, Columbus, Ohio
| | - Goutham Narla
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
- Department of Internal Medicine, Genetic Medicine, University of Michigan, Ann Arbor, Michigan
| | - Analisa DiFeo
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- The Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
- Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan
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10
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Clausse V, Fang Y, Tao D, Tagad HD, Sun H, Wang Y, Karavadhi S, Lane K, Shi ZD, Vasalatiy O, LeClair CA, Eells R, Shen M, Patnaik S, Appella E, Coussens NP, Hall MD, Appella DH. Discovery of Novel Small-Molecule Scaffolds for the Inhibition and Activation of WIP1 Phosphatase from a RapidFire Mass Spectrometry High-Throughput Screen. ACS Pharmacol Transl Sci 2022; 5:993-1006. [PMID: 36268125 PMCID: PMC9578142 DOI: 10.1021/acsptsci.2c00147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Indexed: 11/28/2022]
Abstract
Wild-type P53-induced phosphatase 1 (WIP1), also known as PPM1D or PP2Cδ, is a serine/threonine protein phosphatase induced by P53 after genotoxic stress. WIP1 inhibition has been proposed as a therapeutic strategy for P53 wild-type cancers in which it is overexpressed, but this approach would be ineffective in P53-negative cancers. Furthermore, there are several cancers with mutated P53 where WIP1 acts as a tumor suppressor. Therefore, activating WIP1 phosphatase might also be a therapeutic strategy, depending on the P53 status. To date, no specific, potent WIP1 inhibitors with appropriate pharmacokinetic properties have been reported, nor have WIP1-specific activators. Here, we report the discovery of new WIP1 modulators from a high-throughput screen (HTS) using previously described orthogonal biochemical assays suitable for identifying both inhibitors and activators. The primary HTS was performed against a library of 102 277 compounds at a single concentration using a RapidFire mass spectrometry assay. Hits were further evaluated over a range of 11 concentrations with both the RapidFire MS assay and an orthogonal fluorescence-based assay. Further biophysical, biochemical, and cell-based studies of confirmed hits revealed a WIP1 activator and two inhibitors, one competitive and one uncompetitive. These new scaffolds are prime candidates for optimization which might enable inhibitors with improved pharmacokinetics and a first-in-class WIP1 activator.
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Affiliation(s)
- Victor Clausse
- Synthetic
Bioactive Molecules Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Yuhong Fang
- National
Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Dingyin Tao
- National
Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Harichandra D. Tagad
- Laboratory
of Cell Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Hongmao Sun
- National
Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Yuhong Wang
- National
Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Surendra Karavadhi
- National
Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Kelly Lane
- Chemistry
and Synthesis Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Zhen-Dan Shi
- Chemistry
and Synthesis Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Olga Vasalatiy
- Chemistry
and Synthesis Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Christopher A. LeClair
- National
Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Rebecca Eells
- Reaction
Biology Corporation, 1 Great Valley Parkway, Suite 2, Malvern, Pennsylvania 19355, United States
| | - Min Shen
- National
Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Samarjit Patnaik
- National
Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Ettore Appella
- Laboratory
of Cell Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Nathan P. Coussens
- Molecular
Pharmacology Laboratories, Applied and Developmental Research Directorate, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
| | - Matthew D. Hall
- National
Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Daniel H. Appella
- Synthetic
Bioactive Molecules Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, United States
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11
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Chuang HW, Pan JH, Cai YX, Rupa D, Huang TS, Kuo TC, Lin CW, Chen CW, Lin CC, Lee HS, Yuan TC. Reciprocal regulation of CIP2A and AR expression in prostate cancer cells. Discov Oncol 2022; 13:87. [PMID: 36098827 PMCID: PMC9470804 DOI: 10.1007/s12672-022-00552-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/30/2022] [Indexed: 11/17/2022] Open
Abstract
Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein overexpressed in human malignancies, including prostate cancer (PCa). In this study, we aimed to explore the oncogenic function of CIP2A in PCa cells and its underlying mechanism. We showed that 63.3% (38/60 cases) of PCa tissues exhibited a high CIP2A immunostaining, compared to 25% (3/12 cases) of BPH samples (p = 0.023). Furthermore, the protein level of CIP2A was positively correlated with patients' short survival time and nuclear AR levels in PCa tissues. Compared to PZ-HPV-7, an immortalized prostate cell line, androgen-sensitive LNCaP C-33, androgen-independent LNCaP C-81, or 22Rv1 cells exhibited a high CIP2A level, associated with high protein and phosphorylation levels of AR. While AR expression and activity modulated CIP2A expression, manipulating CIP2A expression in PCa cells regulated their AR protein levels and proliferation. The reduction of CIP2A expression also enhanced the sensitivity of PCa cells toward Enzalutamide treatment. Our data further showed that depletion of polo-kinase 1 (PLK1) expression or activity in C-81 or 22Rv1 cells caused reduced protein levels of c-Myc and AR. Notably, inhibition of PLK1 activity could abolish CIP2A-promoted expressions in c-Myc, AR, and prostate-specific antigen (PSA) in C-33 cells under an androgen-deprived condition, suggesting the role of PLK1 activity in CIP2A-promoted AR expression. In summary, our data showed the existence of a novel regulation between CIP2A and AR protein levels, which is critical for promoting PCa malignancy. Thus, CIP2A could serve as a therapeutic target for PCa.
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Affiliation(s)
- Hao-Wen Chuang
- Department of Pathology and Laboratory Medicine, Kaohsiung Veterans General Hospital, No. 386, Dazhong 1st Rd, Zuoying Dist, Kaohsiung, 813414, Taiwan, ROC
| | - Jian-Hua Pan
- Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301, Taiwan, ROC
| | - Yi-Xuan Cai
- Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301, Taiwan, ROC
| | - Darius Rupa
- Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301, Taiwan, ROC
| | - Ting-Syuan Huang
- Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301, Taiwan, ROC
| | - Tzu-Chien Kuo
- Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301, Taiwan, ROC
| | - Chiao-Wen Lin
- Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301, Taiwan, ROC
| | - Chi-Wei Chen
- Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301, Taiwan, ROC
| | - Chia-Chin Lin
- Department of Pathology and Laboratory Medicine, Kaohsiung Veterans General Hospital, No. 386, Dazhong 1st Rd, Zuoying Dist, Kaohsiung, 813414, Taiwan, ROC
| | - Herng-Sheng Lee
- Department of Pathology and Laboratory Medicine, Kaohsiung Veterans General Hospital, No. 386, Dazhong 1st Rd, Zuoying Dist, Kaohsiung, 813414, Taiwan, ROC
| | - Ta-Chun Yuan
- Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301, Taiwan, ROC.
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12
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Narayan S, Raza A, Mahmud I, Koo N, Garrett TJ, Law ME, Law BK, Sharma AK. Sensitization of FOLFOX-resistant colorectal cancer cells via the modulation of a novel pathway involving protein phosphatase 2A. iScience 2022; 25:104518. [PMID: 35754740 PMCID: PMC9218363 DOI: 10.1016/j.isci.2022.104518] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 05/16/2022] [Accepted: 05/30/2022] [Indexed: 12/04/2022] Open
Abstract
The treatment of colorectal cancer (CRC) with FOLFOX shows some efficacy, but these tumors quickly develop resistance to this treatment. We have observed increased phosphorylation of AKT1/mTOR/4EBP1 and levels of p21 in FOLFOX-resistant CRC cells. We have identified a small molecule, NSC49L, that stimulates protein phosphatase 2A (PP2A) activity, downregulates the AKT1/mTOR/4EBP1-axis, and inhibits p21 translation. We have provided evidence that NSC49L- and TRAIL-mediated sensitization is synergistically induced in p21-knockdown CRC cells, which is reversed in p21-overexpressing cells. p21 binds with procaspase 3 and prevents the activation of caspase 3. We have shown that TRAIL induces apoptosis through the activation of caspase 3 by NSC49L-mediated downregulation of p21 translation, and thereby cleavage of procaspase 3 into caspase 3. NSC49L does not affect global protein synthesis. These studies provide a mechanistic understanding of NSC49L as a PP2A agonist, and how its combination with TRAIL sensitizes FOLFOX-resistant CRC cells.
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Affiliation(s)
- Satya Narayan
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
| | - Asif Raza
- Department of Pharmacology, Penn State University College of Medicine, Penn State Cancer Institute, Hershey, PA 17033, USA
| | - Iqbal Mahmud
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Nayeong Koo
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
| | - Timothy J. Garrett
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Mary E. Law
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA
| | - Brian K. Law
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA
| | - Arun K. Sharma
- Department of Pharmacology, Penn State University College of Medicine, Penn State Cancer Institute, Hershey, PA 17033, USA
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13
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Tinsley SL, Allen-Petersen BL. PP2A and cancer epigenetics: a therapeutic opportunity waiting to happen. NAR Cancer 2022; 4:zcac002. [PMID: 35118387 PMCID: PMC8807117 DOI: 10.1093/narcan/zcac002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 12/08/2021] [Accepted: 01/10/2022] [Indexed: 12/13/2022] Open
Abstract
The epigenetic state of chromatin is altered by regulators which influence gene expression in response to environmental stimuli. While several post-translational modifications contribute to chromatin accessibility and transcriptional programs, our understanding of the role that specific phosphorylation sites play is limited. In cancer, kinases and phosphatases are commonly deregulated resulting in increased oncogenic signaling and loss of epigenetic regulation. Aberrant epigenetic states are known to promote cellular plasticity and the development of therapeutic resistance in many cancer types, highlighting the importance of these mechanisms to cancer cell phenotypes. Protein Phosphatase 2A (PP2A) is a heterotrimeric holoenzyme that targets a diverse array of cellular proteins. The composition of the PP2A complex influences its cellular targets and activity. For this reason, PP2A can be tumor suppressive or oncogenic depending on cellular context. Understanding the nuances of PP2A regulation and its effect on epigenetic alterations can lead to new therapeutic avenues that afford more specificity and contribute to the growth of personalized medicine in the oncology field. In this review, we summarize the known PP2A-regulated substrates and potential phosphorylation sites that contribute to cancer cell epigenetics and possible strategies to therapeutically leverage this phosphatase to suppress tumor growth.
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Affiliation(s)
- Samantha L Tinsley
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
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14
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Yin S, Chen Y, Tong H, Li T, Qin Z, Zhu J, He W. PP2A promotes apoptosis and facilitates docetaxel sensitivity via the PP2A/p‑eIF4B/XIAP signaling pathway in prostate cancer. Oncol Lett 2022; 23:101. [PMID: 35154432 PMCID: PMC8822497 DOI: 10.3892/ol.2022.13221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 11/10/2021] [Indexed: 11/16/2022] Open
Abstract
Serine/threonine protein phosphatase 2A (PP2A) is a protein that has a wide range of biological functions. As prostate cancer progresses from hormone-sensitive prostate cancer to castration-resistant prostate cancer (CRPC), the expression level of PP2A has been found to decrease. The present study aimed to determine the roles that PP2A may play in prostate cancer and its association with the downstream factor, X-linked inhibitor of apoptosis (XIAP). First, the mRNA and protein expression levels of PP2A in LNCaP, DU145 and PC-3 prostate cancer cell lines were measured. Next, the population of PP2A heterodimers was increased using a PP2A agonist, DT061, in the DU145 and PC-3 cell lines. PP2A expression was then knocked down in the LNCaP cell line. Western blot analysis was performed to determine the association between PP2A, phosphorylated (p)-eukaryotic initiation factor 4B (eIF4B) and XIAP. The results revealed that following the increase in PP2A expression, the DU145 and PC-3 cell lines were more sensitive to docetaxel according to Cell Counting Kit-8 assays and had an increased apoptotic rate as assessed by flow cytometry. Conversely, following the transfection of small interfering (si)PP2A into the LNCaP cell line, the sensitivity to docetaxel decreased, as well as the apoptotic rate. In addition, following treatment with the PP2A agonist, DT061, PP2A expression was found to be significantly upregulated, while p-eIF4B and XIAP protein expression levels were significantly downregulated. By contrast, following the transfection of siPP2A into the LNCaP cell line, PP2A protein expression levels were found to be downregulated, while p-eIF4B and XIAP expression levels were significantly upregulated. In conclusion, by affecting the downstream factor XIAP, PP2A may play a key role in promoting apoptosis and facilitating docetaxel sensitivity in prostate cancer cell lines.
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Affiliation(s)
- Siwen Yin
- Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Yong Chen
- Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Hang Tong
- Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Tinghao Li
- Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Zijia Qin
- Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Junlong Zhu
- Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Weiyang He
- Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
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15
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Sergienko NM, Donner DG, Delbridge LMD, McMullen JR, Weeks KL. Protein phosphatase 2A in the healthy and failing heart: New insights and therapeutic opportunities. Cell Signal 2021; 91:110213. [PMID: 34902541 DOI: 10.1016/j.cellsig.2021.110213] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 12/02/2021] [Accepted: 12/07/2021] [Indexed: 02/06/2023]
Abstract
Protein phosphatases have emerged as critical regulators of phosphoprotein homeostasis in settings of health and disease. Protein phosphatase 2A (PP2A) encompasses a large subfamily of enzymes that remove phosphate groups from serine/threonine residues within phosphoproteins. The heterogeneity in PP2A structure, which arises from the grouping of different catalytic, scaffolding and regulatory subunit isoforms, creates distinct populations of catalytically active enzymes (i.e. holoenzymes) that localise to different parts of the cell. This structural complexity, combined with other regulatory mechanisms, such as interaction of PP2A heterotrimers with accessory proteins and post-translational modification of the catalytic and/or regulatory subunits, enables PP2A holoenzymes to target phosphoprotein substrates in a highly specific manner. In this review, we summarise the roles of PP2A in cardiac physiology and disease. PP2A modulates numerous processes that are vital for heart function including calcium handling, contractility, β-adrenergic signalling, metabolism and transcription. Dysregulation of PP2A has been observed in human cardiac disease settings, including heart failure and atrial fibrillation. Efforts are underway, particularly in the cancer field, to develop therapeutics targeting PP2A activity. The development of small molecule activators of PP2A (SMAPs) and other compounds that selectively target specific PP2A holoenzymes (e.g. PP2A/B56α and PP2A/B56ε) will improve understanding of the function of different PP2A species in the heart, and may lead to the development of therapeutics for normalising aberrant protein phosphorylation in settings of cardiac remodelling and dysfunction.
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Affiliation(s)
- Nicola M Sergienko
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Central Clinical School, Monash University, Clayton VIC 3800, Australia
| | - Daniel G Donner
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia
| | - Lea M D Delbridge
- Department of Anatomy and Physiology, The University of Melbourne, Parkville VIC 3010, Australia
| | - Julie R McMullen
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia; Department of Physiology and Department of Medicine Alfred Hospital, Monash University, Clayton VIC 3800, Australia; Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora VIC 3086, Australia; Department of Diabetes, Central Clinical School, Monash University, Clayton VIC 3800, Australia.
| | - Kate L Weeks
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Department of Anatomy and Physiology, The University of Melbourne, Parkville VIC 3010, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia; Department of Diabetes, Central Clinical School, Monash University, Clayton VIC 3800, Australia.
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16
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Hollenstein DM, Gérecová G, Romanov N, Ferrari J, Veis J, Janschitz M, Beyer R, Schüller C, Ogris E, Hartl M, Ammerer G, Reiter W. A phosphatase-centric mechanism drives stress signaling response. EMBO Rep 2021; 22:e52476. [PMID: 34558777 PMCID: PMC8567219 DOI: 10.15252/embr.202152476] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 08/27/2021] [Accepted: 09/03/2021] [Indexed: 12/14/2022] Open
Abstract
Changing environmental cues lead to the adjustment of cellular physiology by phosphorylation signaling networks that typically center around kinases as active effectors and phosphatases as antagonistic elements. Here, we report a signaling mechanism that reverses this principle. Using the hyperosmotic stress response in Saccharomyces cerevisiae as a model system, we find that a phosphatase-driven mechanism causes induction of phosphorylation. The key activating step that triggers this phospho-proteomic response is the Endosulfine-mediated inhibition of protein phosphatase 2A-Cdc55 (PP2ACdc55 ), while we do not observe concurrent kinase activation. In fact, many of the stress-induced phosphorylation sites appear to be direct substrates of the phosphatase, rendering PP2ACdc55 the main downstream effector of a signaling response that operates in parallel and independent of the well-established kinase-centric stress signaling pathways. This response affects multiple cellular processes and is required for stress survival. Our results demonstrate how a phosphatase can assume the role of active downstream effectors during signaling and allow re-evaluating the impact of phosphatases on shaping the phosphorylome.
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Affiliation(s)
- David Maria Hollenstein
- Department of Biochemistry and Cell BiologyMax Perutz LabsVienna BioCenter (VBC)University of ViennaViennaAustria
| | - Gabriela Gérecová
- Department of Biochemistry and Cell BiologyMax Perutz LabsVienna BioCenter (VBC)University of ViennaViennaAustria
| | | | - Jessica Ferrari
- Department of Biochemistry and Cell BiologyMax Perutz LabsVienna BioCenter (VBC)University of ViennaViennaAustria
| | - Jiri Veis
- Department of Biochemistry and Cell BiologyMax Perutz LabsVienna BioCenter (VBC)University of ViennaViennaAustria
- Center for Medical BiochemistryMax Perutz Labs, Vienna BioCenterMedical University of ViennaViennaAustria
| | - Marion Janschitz
- Department of Biochemistry and Cell BiologyMax Perutz LabsVienna BioCenter (VBC)University of ViennaViennaAustria
| | - Reinhard Beyer
- Department of Applied Genetics and Cell Biology (DAGZ)University of Natural Resources and Life Sciences (BOKU)ViennaAustria
- Research Platform Bioactive Microbial Metabolites (BiMM)Tulln a.d. DonauAustria
| | - Christoph Schüller
- Department of Applied Genetics and Cell Biology (DAGZ)University of Natural Resources and Life Sciences (BOKU)ViennaAustria
- Research Platform Bioactive Microbial Metabolites (BiMM)Tulln a.d. DonauAustria
| | - Egon Ogris
- Center for Medical BiochemistryMax Perutz Labs, Vienna BioCenterMedical University of ViennaViennaAustria
| | - Markus Hartl
- Department of Biochemistry and Cell BiologyMax Perutz LabsVienna BioCenter (VBC)University of ViennaViennaAustria
- Mass Spectrometry FacilityMax Perutz Labs, Vienna BioCenterUniversity of ViennaViennaAustria
| | - Gustav Ammerer
- Department of Biochemistry and Cell BiologyMax Perutz LabsVienna BioCenter (VBC)University of ViennaViennaAustria
| | - Wolfgang Reiter
- Department of Biochemistry and Cell BiologyMax Perutz LabsVienna BioCenter (VBC)University of ViennaViennaAustria
- Mass Spectrometry FacilityMax Perutz Labs, Vienna BioCenterUniversity of ViennaViennaAustria
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17
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Allosteric activation of PP2A inhibits experimental abdominal aortic aneurysm. Clin Sci (Lond) 2021; 135:2085-2097. [PMID: 34402501 DOI: 10.1042/cs20210315] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 08/06/2021] [Accepted: 08/17/2021] [Indexed: 12/22/2022]
Abstract
Although extremely important, the molecular mechanisms that govern aortic aneurysm (AA) formation and progression are still poorly understood. This deficit represents a critical roadblock toward the development of effective pharmaceutical therapies for the treatment of AA. While dysregulation of protein phosphatase 2A (PP2A) is thought to play a role in cardiovascular disease, its role in aortic aneurysm is unknown. The objective of the present study is to test the hypothesis that PP2A regulates abdominal aortic aneurysm (AAA) progression in a murine model. In an angiotensin II-induced AAA murine model, the PP2A inhibitor, LB-100, markedly accelerated AAA progression as demonstrated by increased abdominal aortic dilation and mortality. AAA progression was associated with elevated inflammation and extracellular matrix fragmentation, concomitant with increases in both metalloproteinase activity and reactive oxygen species production. Conversely, administration of a novel class of small molecule activators of PP2A (SMAPs) resulted in an antithetical effect. SMAPs effectively reduced AAA incidence along with the corresponding pathologies that were increased with LB-100 treatment. Mechanistically, modulation of PP2A activities in vivo functioned in part via alteration of the ERK1/2 and NFκB signaling pathways, known regulators of AAA progression. These studies, for the first time, demonstrate a role of PP2A in AAA etiology and demonstrate that PP2A activation may represent a novel strategy for the treatment of abdominal aortic aneurysms.
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18
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Chen C, Huang FW, Huang SS, Huang JS. IGFBP-3 and TGF-β inhibit growth in epithelial cells by stimulating type V TGF-β receptor (TβR-V)-mediated tumor suppressor signaling. FASEB Bioadv 2021; 3:709-729. [PMID: 34485840 PMCID: PMC8409558 DOI: 10.1096/fba.2021-00016] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/06/2021] [Accepted: 04/23/2021] [Indexed: 12/13/2022] Open
Abstract
The TGF-β type V receptor (TβR-V) mediates growth inhibition by IGFBP-3 and TGF-β in epithelial cells and loss of TβR-V expression in these cells leads to development of carcinoma. The mechanisms by which TβR-V mediates growth inhibition (tumor suppressor) signaling remain elusive. Previous studies revealed that IGFBP-3 and TGF-β inhibit growth in epithelial cells by stimulating TβR-V-mediated IRS-1/2-dependent activation and cytoplasm-to-nucleus translocation of IGFBP-3- or TGF-β-stimulated protein phosphatase (PPase), resulting in dephosphorylation of pRb-related proteins (p107, p130) or pRb, and growth arrest. To define the signaling, we characterized/identified the IGFBP-3- and TGF-β-stimulated PPases in cell lysates and nucleus fractions in Mv1Lu cells treated with IGFBP-3 and TGF-β, using a cell-free assay with 32P-labeled casein as a substrate. Both IGFBP-3- and TGF-β-stimulated PPase activities in cell lysates are abolished when cells are co-treated with TGF-β/IGFBP-3 antagonist or RAP (LRP-1/TβR-V antagonist). However, the IGFBP-3-stimulated PPase activity, but not TGF-β-stimulated PPase activity, is sensitive to inhibition by okadaic acid (OA). In addition, OA or PP2Ac siRNA reverses IGFBP-3 growth inhibition, but not TGF-β growth inhibition, in Mv1Lu and 32D cells. These suggest that IGFBP-3- and TGF-β-stimulated PPases are identical to PP2A and PP1, respectively. By Western blot/phosphorimager/immunofluorescence-microscopy analyses, IGFBP-3 and TGF-β stimulate TβR-V-mediated IRS-2-dependent activation and cytoplasm-to-nucleus translocation of PP2Ac and PP1c, resulting in dephosphorylation of p130/p107 and pRb, respectively, and growth arrest. Small molecule TGF-β enhancers, which potentiate TGF-β growth inhibition by enhancing TβR-I-TβR-II-mediated canonical signaling and thus activating TβR-V-mediated tumor suppressor signaling cascade (TβR-V/IRS-2/PP1/pRb), could be used to prevent and treat carcinoma.
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Affiliation(s)
- Chun‐Lin Chen
- Department of Biological ScienceNational Sun Yat‐sen UniversityKaohsiungTaiwan
- Departments of Biochemistry and Molecular BiologySaint Louis University School of MedicineSt. LouisMOUSA
| | - Franklin W. Huang
- Division of Hematology and OncologyDepartment of MedicineUniversity of CaliforniaSan FranciscoCAUSA
| | | | - Jung San Huang
- Departments of Biochemistry and Molecular BiologySaint Louis University School of MedicineSt. LouisMOUSA
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19
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Targeting protein phosphatase PP2A for cancer therapy: development of allosteric pharmaceutical agents. Clin Sci (Lond) 2021; 135:1545-1556. [PMID: 34192314 DOI: 10.1042/cs20201367] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/15/2021] [Accepted: 07/16/2021] [Indexed: 01/26/2023]
Abstract
Tumor initiation is driven by oncogenes that activate signaling networks for cell proliferation and survival involving protein phosphorylation. Protein kinases in these pathways have proven to be effective targets for pharmaceutical inhibitors that have progressed to the clinic to treat various cancers. Here, we offer a narrative about the development of small molecule modulators of the protein Ser/Thr phosphatase 2A (PP2A) to reduce the activation of cell proliferation and survival pathways. These novel drugs promote the assembly of select heterotrimeric forms of PP2A that act to limit cell proliferation. We discuss the potential for the near-term translation of this approach to the clinic for cancer and other human diseases.
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20
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Yang H, Khan S, Sun A, Bai Q, Cheng H, Akhtari K. Enhancement of interferon gamma stability as an anticancer therapeutic protein against hepatocellular carcinoma upon interaction with calycosin. Int J Biol Macromol 2021; 185:813-820. [PMID: 34186122 DOI: 10.1016/j.ijbiomac.2021.06.159] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 06/13/2021] [Accepted: 06/24/2021] [Indexed: 11/30/2022]
Abstract
The stability of IFN-γ as a therapeutic protein can play a key role on its anticancer effects. Herein, we explored the thermodynamic parameters and conformational stability of IFN-γ in the presence of calycosin, the main active compound of Radix astragali, by different biophysical and theoretical analysis. Afterwards, the improved anticancer effects of IFN-γ-calycosin interaction relative to IFN-γ alone were assessed on hepatocellular carcinoma (HepG2) cell line by MTT and caspase assays. ITC data indicated that upon interaction of calycosin with IFN-γ the binding and thermodynamic parameters were as follows: Kd = 1.9 μM, ΔG° = -32.45 kJ/mol, ΔH° = -11.91 kJ/mol, and TΔS° = 20.54 kJ/mol. ANS/synchronous fluorescence, CD and UV-Vis spectroscopy studies indicated that the interaction between calycosin and IFN-γ caused the folding of the IFN-γ backbone in to a more packed structure with enhanced α-helix content and higher melting temperature (Tm) value. The spectroscopic outcomes were then verified by molecular docking and molecular dynamic analysis. It was also shown that after incubation of the IFN-γ samples at 50 °C for 60 min in the presence of calycosin (5 μM), the IFN-γ-calycosin system showed a significant antiproliferative effects against hepatocellular carcinoma (HepG2) cells through caspase-9/3 activation and this anticancer effect was more pronounced than free IFN-γ. This data may provide useful information about the development of IFN-γ-based therapeutic platforms.
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Affiliation(s)
- Huiyu Yang
- Department of Gastroenterology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, PR China.
| | - Suliman Khan
- Department of Cerebrovascular Diseases, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, PR China
| | - Aimin Sun
- Henan Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, PR China
| | - Qian Bai
- Department of Anesthesiology, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, PR China.
| | - Haowei Cheng
- Henan Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, PR China
| | - Keivan Akhtari
- Department of Physics, University of Kurdistan, Sanandaj, Iran
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21
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Scarpa M, Singh P, Bailey CM, Lee JK, Kapoor S, Lapidus RG, Niyongere S, Sangodkar J, Wang Y, Perrotti D, Narla G, Baer MR. PP2A-activating Drugs Enhance FLT3 Inhibitor Efficacy through AKT Inhibition-Dependent GSK-3β-Mediated c-Myc and Pim-1 Proteasomal Degradation. Mol Cancer Ther 2021; 20:676-690. [PMID: 33568357 PMCID: PMC8027945 DOI: 10.1158/1535-7163.mct-20-0663] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/26/2020] [Indexed: 11/16/2022]
Abstract
Fms-like tyrosine-like kinase 3 internal tandem duplication (FLT3-ITD) is present in acute myeloid leukemia (AML) in 30% of patients and is associated with short disease-free survival. FLT3 inhibitor efficacy is limited and transient but may be enhanced by multitargeting of FLT3-ITD signaling pathways. FLT3-ITD drives both STAT5-dependent transcription of oncogenic Pim-1 kinase and inactivation of the tumor-suppressor protein phosphatase 2A (PP2A), and FLT3-ITD, Pim-1, and PP2A all regulate the c-Myc oncogene. We studied mechanisms of action of cotreatment of FLT3-ITD-expressing cells with FLT3 inhibitors and PP2A-activating drugs (PADs), which are in development. PADs, including FTY720 and DT-061, enhanced FLT3 inhibitor growth suppression and apoptosis induction in FLT3-ITD-expressing cell lines and primary AML cells in vitro and MV4-11 growth suppression in vivo PAD and FLT3 inhibitor cotreatment independently downregulated c-Myc and Pim-1 protein through enhanced proteasomal degradation. c-Myc and Pim-1 downregulation was preceded by AKT inactivation, did not occur in cells expressing myristoylated (constitutively active) AKT1, and could be induced by AKT inhibition. AKT inactivation resulted in activation of GSK-3β, and GSK-3β inhibition blocked downregulation of both c-Myc and Pim-1 by PAD and FLT3 inhibitor cotreatment. GSK-3β activation increased c-Myc proteasomal degradation through c-Myc phosphorylation on T58; infection with c-Myc with T58A substitution, preventing phosphorylation, blocked downregulation of c-Myc by PAD and FLT3 inhibitor cotreatment. GSK-3β also phosphorylated Pim-1L/Pim-1S on S95/S4. Thus, PADs enhance efficacy of FLT3 inhibitors in FLT3-ITD-expressing cells through a novel mechanism involving AKT inhibition-dependent GSK-3β-mediated increased c-Myc and Pim-1 proteasomal degradation.
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Affiliation(s)
- Mario Scarpa
- The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center
- Department of Medicine
| | - Prerna Singh
- The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center
| | - Christopher M Bailey
- Department of Surgery and
- Division of Immunotherapy, Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jonelle K Lee
- The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center
| | - Shivani Kapoor
- The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center
| | - Rena G Lapidus
- The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center
- Department of Medicine
| | - Sandrine Niyongere
- The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center
- Department of Medicine
| | - Jaya Sangodkar
- Division of Genetic Medicine, Department of Medicine, University of Michigan, Ann Arbor, Michigan
| | - Yin Wang
- The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center
- Department of Surgery and
- Division of Immunotherapy, Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Danilo Perrotti
- The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center
- Department of Medicine
| | - Goutham Narla
- Division of Genetic Medicine, Department of Medicine, University of Michigan, Ann Arbor, Michigan
| | - Maria R Baer
- The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center,
- Department of Medicine
- Veterans Affairs Medical Center, Baltimore, Maryland
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22
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Pan C, Zhang L, Meng X, Qin H, Xiang Z, Gong W, Luo W, Li D, Han X. Chronic exposure to microcystin-LR increases the risk of prostate cancer and induces malignant transformation of human prostate epithelial cells. CHEMOSPHERE 2021; 263:128295. [PMID: 33297237 DOI: 10.1016/j.chemosphere.2020.128295] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 09/02/2020] [Accepted: 09/06/2020] [Indexed: 06/12/2023]
Abstract
Microcystins-LR (MC-LR) acts as a possible carcinogen for humans and causes a serious risk to public environmental health. The current study aimed to evaluate the interaction between MC-LR exposure and prostate cancer development and elucidate the underlying mechanism. In this study, mice were exposed to MC-LR at various doses for 180 days. MC-LR was able to induce the progression of prostatic intraepithelial neoplasia (PIN) and microinvasion. Furthermore, MC-LR notably increased angiogenesis and susceptibility to prostate cancer in vivo. In vitro, over 25 weeks of MC-LR exposure, normal human prostate epithelial (RWPE-1) cells increased secretion of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and colony formation, features typical for cancer cells. These MC-LR-transformed prostate epithelial cells displayed increased expression of forkhead box M1 (FOXM1) and cyclooxygenase-2 (COX-2); abrogation of FOXM1 or COX-2 activity by specific inhibitors could abolish the invasion and migration of MC-LR-treated cells. In conclusion, we have provided compelling evidence demonstrating the induction of a malignant phenotype in human prostate epithelial cells and the in vivo development of prostate cancer by exposure to MC-LR, which might be a potential tumor promoter in the progression of prostate cancer.
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Affiliation(s)
- Chun Pan
- Immunology and Reproduction Biology Laboratory, State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China
| | - Ling Zhang
- Immunology and Reproduction Biology Laboratory, State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China
| | - Xiannan Meng
- Immunology and Reproduction Biology Laboratory, State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China
| | - Haixiang Qin
- Department of Urology, Drum Tower Hospital, Medical School of Nanjing University, Institute of Urology, Nanjing University, 321 Zhongshan Road, Nanjing, 210008, Jiangsu, China
| | - Zou Xiang
- Department of Health Technology and Informatics, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Wenyue Gong
- Immunology and Reproduction Biology Laboratory, State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China
| | - Wenxin Luo
- Immunology and Reproduction Biology Laboratory, State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China
| | - Dongmei Li
- Immunology and Reproduction Biology Laboratory, State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China
| | - Xiaodong Han
- Immunology and Reproduction Biology Laboratory, State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
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23
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The Molecular 'Myc-anisms' Behind Myc-Driven Tumorigenesis and the Relevant Myc-Directed Therapeutics. Int J Mol Sci 2020; 21:ijms21249486. [PMID: 33322239 PMCID: PMC7764474 DOI: 10.3390/ijms21249486] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 02/07/2023] Open
Abstract
MYC, a well-studied proto-oncogene that is overexpressed in >20% of tumors across all cancers, is classically known as “undruggable” due to its crucial roles in cell processes and its lack of a drug binding pocket. Four decades of research and creativity led to the discovery of a myriad of indirect (and now some direct!) therapeutic strategies targeting Myc. This review explores the various mechanisms in which Myc promotes cancer and highlights five key therapeutic approaches to disrupt Myc, including transcription, Myc-Max dimerization, protein stability, cell cycle regulation, and metabolism, in order to develop more specific Myc-directed therapies.
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24
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He X, Li M, Yu H, Liu G, Wang N, Yin C, Tu Q, Narla G, Tao Y, Cheng S, Yin H. Loss of hepatic aldolase B activates Akt and promotes hepatocellular carcinogenesis by destabilizing the Aldob/Akt/PP2A protein complex. PLoS Biol 2020; 18:e3000803. [PMID: 33275593 PMCID: PMC7744066 DOI: 10.1371/journal.pbio.3000803] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 12/16/2020] [Accepted: 11/13/2020] [Indexed: 12/21/2022] Open
Abstract
Loss of hepatic fructose-1, 6-bisphosphate aldolase B (Aldob) leads to a paradoxical up-regulation of glucose metabolism to favor hepatocellular carcinogenesis (HCC), but the upstream signaling events remain poorly defined. Akt is highly activated in HCC, and targeting Akt is being explored as a potential therapy for HCC. Herein, we demonstrate that Aldob suppresses Akt activity and tumor growth through a protein complex containing Aldob, Akt, and protein phosphatase 2A (PP2A), leading to inhibition of cell viability, cell cycle progression, glucose uptake, and metabolism. Interestingly, Aldob directly interacts with phosphorylated Akt (p-Akt) and promotes the recruitment of PP2A to dephosphorylate p-Akt, and this scaffolding effect of Aldob is independent of its enzymatic activity. Loss of Aldob or disruption of Aldob/Akt interaction in Aldob R304A mutant restores Akt activity and tumor-promoting effects. Consistently, Aldob and p-Akt expression are inversely correlated in human HCC tissues, and Aldob down-regulation coupled with p-Akt up-regulation predicts a poor prognosis for HCC. We have further discovered that Akt inhibition or a specific small-molecule activator of PP2A (SMAP) efficiently attenuates HCC tumorigenesis in xenograft mouse models. Our work reveals a novel nonenzymatic role of Aldob in negative regulation of Akt activation, suggesting that directly inhibiting Akt activity or through reactivating PP2A may be a potential therapeutic approach for HCC treatment.
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Affiliation(s)
- Xuxiao He
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Min Li
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Hongming Yu
- The Eastern Hepatobiliary Surgery Hospital, Shanghai, China
| | - Guijun Liu
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Ningning Wang
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Chunzhao Yin
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Qiaochu Tu
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Goutham Narla
- Division of Genetic Medicine, Department of International Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Yongzhen Tao
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Shuqun Cheng
- The Eastern Hepatobiliary Surgery Hospital, Shanghai, China
| | - Huiyong Yin
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing, China
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25
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Hao J, Ci X, Wang Y, Choi SYC, Sullivan SE, Xue H, Wu R, Dong X, Haegert AM, Collins CC, Lin D, Wang Y. GRB10 sustains AR activity by interacting with PP2A in prostate cancer cells. Int J Cancer 2020; 148:469-480. [PMID: 33038264 DOI: 10.1002/ijc.33335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 09/06/2020] [Accepted: 09/30/2020] [Indexed: 01/22/2023]
Abstract
Prostate cancer (PCa) progression is driven by androgen receptor (AR) signaling. Unfortunately, androgen-deprivation therapy and the use of even more potent AR pathway inhibitors (ARPIs) cannot bring about a cure. ARPI resistance (ie, castration-resistant PCa, CRPC) will inevitably develop. Previously, we demonstrated that GRB10 is an AR transcriptionally repressed gene that functionally contributes to CRPC development and ARPI resistance. GRB10 expression is elevated prior to CRPC development in our patient-derived xenograft models and is significantly upregulated in clinical CRPC samples. Here, we analyzed transcriptomic data from GRB10 knockdown in PCa cells and found that AR signaling is downregulated. While the mRNA expression of AR target genes decreased upon GRB10 knockdown, AR expression was not affected at the mRNA or protein level. We further found that phosphorylation of AR serine 81 (S81), which is critical for AR transcriptional activity, is decreased by GRB10 knockdown and increased by its overexpression. Luciferase assay using GRB10-knockdown cells also indicate reduced AR activity. Immunoprecipitation coupled with mass spectrometry revealed an interaction between GRB10 and the PP2A complex, which is a known phosphatase of AR. Further validations and analyses showed that GRB10 binds to the PP2Ac catalytic subunit with its PH domain. Mechanistically, GRB10 knockdown increased PP2Ac protein stability, which in turn decreased AR S81 phosphorylation and reduced AR activity. Our findings indicate a reciprocal feedback between GRB10 and AR signaling, implying the importance of GRB10 in PCa progression.
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Affiliation(s)
- Jun Hao
- Vancouver Prostate Centre, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Experimental Therapeutics, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Xinpei Ci
- Vancouver Prostate Centre, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Experimental Therapeutics, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Yong Wang
- Vancouver Prostate Centre, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Urology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Stephen Yiu Chuen Choi
- Vancouver Prostate Centre, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Experimental Therapeutics, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Sarah E Sullivan
- Vancouver Prostate Centre, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Kinesiology and Physical Education, McGill University, Quebec, Canada
| | - Hui Xue
- Department of Experimental Therapeutics, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Rebecca Wu
- Department of Experimental Therapeutics, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Xin Dong
- Department of Experimental Therapeutics, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Anne M Haegert
- Vancouver Prostate Centre, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Colin C Collins
- Vancouver Prostate Centre, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Dong Lin
- Vancouver Prostate Centre, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Experimental Therapeutics, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Yuzhuo Wang
- Vancouver Prostate Centre, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Experimental Therapeutics, BC Cancer Agency, Vancouver, British Columbia, Canada
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26
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Brown R, Nath S, Lora A, Samaha G, Elgamal Z, Kaiser R, Taggart C, Weldon S, Geraghty P. Cathepsin S: investigating an old player in lung disease pathogenesis, comorbidities, and potential therapeutics. Respir Res 2020; 21:111. [PMID: 32398133 PMCID: PMC7216426 DOI: 10.1186/s12931-020-01381-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 05/01/2020] [Indexed: 12/13/2022] Open
Abstract
Dysregulated expression and activity of cathepsin S (CTSS), a lysosomal protease and a member of the cysteine cathepsin protease family, is linked to the pathogenesis of multiple diseases, including a number of conditions affecting the lungs. Extracellular CTSS has potent elastase activity and by processing cytokines and host defense proteins, it also plays a role in the regulation of inflammation. CTSS has also been linked to G-coupled protein receptor activation and possesses an important intracellular role in major histocompatibility complex class II antigen presentation. Modulated CTSS activity is also associated with pulmonary disease comorbidities, such as cancer, cardiovascular disease, and diabetes. CTSS is expressed in a wide variety of immune cells and is biologically active at neutral pH. Herein, we review the significance of CTSS signaling in pulmonary diseases and associated comorbidities. We also discuss CTSS as a plausible therapeutic target and describe recent and current clinical trials examining CTSS inhibition as a means for treatment.
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Affiliation(s)
- Ryan Brown
- Airway Innate Immunity Research (AiiR) Group, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Sridesh Nath
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, State University of New York Downstate Medical Centre, Brooklyn, NY, USA
| | - Alnardo Lora
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, State University of New York Downstate Medical Centre, Brooklyn, NY, USA
| | - Ghassan Samaha
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, State University of New York Downstate Medical Centre, Brooklyn, NY, USA
| | - Ziyad Elgamal
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, State University of New York Downstate Medical Centre, Brooklyn, NY, USA
| | - Ryan Kaiser
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, State University of New York Downstate Medical Centre, Brooklyn, NY, USA
| | - Clifford Taggart
- Airway Innate Immunity Research (AiiR) Group, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Sinéad Weldon
- Airway Innate Immunity Research (AiiR) Group, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Patrick Geraghty
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, State University of New York Downstate Medical Centre, Brooklyn, NY, USA.
- Department of Cell Biology, State University of New York Downstate Medical Centre, Brooklyn, NY, USA.
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27
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Morita K, He S, Nowak RP, Wang J, Zimmerman MW, Fu C, Durbin AD, Martel MW, Prutsch N, Gray NS, Fischer ES, Look AT. Retracted: Allosteric Activators of Protein Phosphatase 2A Display Broad Antitumor Activity Mediated by Dephosphorylation of MYBL2. Cell 2020; 181:702-715.e20. [PMID: 32315619 PMCID: PMC7397863 DOI: 10.1016/j.cell.2020.03.051] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 02/02/2020] [Accepted: 03/20/2020] [Indexed: 11/21/2022]
Abstract
Protein phosphatase 2A (PP2A) enzymes can suppress tumors, but they are often inactivated in human cancers overexpressing inhibitory proteins. Here, we identify a class of small-molecule iHAPs (improved heterocyclic activators of PP2A) that kill leukemia cells by allosterically assembling a specific heterotrimeric PP2A holoenzyme consisting of PPP2R1A (scaffold), PPP2R5E (B56ε, regulatory), and PPP2CA (catalytic) subunits. One compound, iHAP1, activates this complex but does not inhibit dopamine receptor D2, a mediator of neurologic toxicity induced by perphenazine and related neuroleptics. The PP2A complex activated by iHAP1 dephosphorylates the MYBL2 transcription factor on Ser241, causing irreversible arrest of leukemia and other cancer cells in prometaphase. In contrast, SMAPs, a separate class of compounds, activate PP2A holoenzymes containing a different regulatory subunit, do not dephosphorylate MYBL2, and arrest tumor cells in G1 phase. Our findings demonstrate that small molecules can serve as allosteric switches to activate distinct PP2A complexes with unique substrates.
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Affiliation(s)
- Ken Morita
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Shuning He
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Radosław P Nowak
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Jinhua Wang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Mark W Zimmerman
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Cong Fu
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Adam D Durbin
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Megan W Martel
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Nicole Prutsch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Nathanael S Gray
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Eric S Fischer
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - A Thomas Look
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA.
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28
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Leonard D, Huang W, Izadmehr S, O'Connor CM, Wiredja DD, Wang Z, Zaware N, Chen Y, Schlatzer DM, Kiselar J, Vasireddi N, Schüchner S, Perl AL, Galsky MD, Xu W, Brautigan DL, Ogris E, Taylor DJ, Narla G. Selective PP2A Enhancement through Biased Heterotrimer Stabilization. Cell 2020; 181:688-701.e16. [PMID: 32315618 DOI: 10.1016/j.cell.2020.03.038] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 12/04/2019] [Accepted: 03/17/2020] [Indexed: 12/15/2022]
Abstract
Impairment of protein phosphatases, including the family of serine/threonine phosphatases designated PP2A, is essential for the pathogenesis of many diseases, including cancer. The ability of PP2A to dephosphorylate hundreds of proteins is regulated by over 40 specificity-determining regulatory "B" subunits that compete for assembly and activation of heterogeneous PP2A heterotrimers. Here, we reveal how a small molecule, DT-061, specifically stabilizes the B56α-PP2A holoenzyme in a fully assembled, active state to dephosphorylate selective substrates, such as its well-known oncogenic target, c-Myc. Our 3.6 Å structure identifies molecular interactions between DT-061 and all three PP2A subunits that prevent dissociation of the active enzyme and highlight inherent mechanisms of PP2A complex assembly. Thus, our findings provide fundamental insights into PP2A complex assembly and regulation, identify a unique interfacial stabilizing mode of action for therapeutic targeting, and aid in the development of phosphatase-based therapeutics tailored against disease specific phospho-protein targets.
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Affiliation(s)
- Daniel Leonard
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Wei Huang
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Sudeh Izadmehr
- Division of Hematology and Medical Oncology, Department of Medicine, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Caitlin M O'Connor
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48105, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Danica D Wiredja
- Department of Nutrition, Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Zhizhi Wang
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Nilesh Zaware
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Yinghua Chen
- PEPCC Facility, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA
| | - Daniela M Schlatzer
- Department of Nutrition, Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Janna Kiselar
- Department of Nutrition, Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Nikhil Vasireddi
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Stefan Schüchner
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9/2, Vienna 1030, Austria
| | - Abbey L Perl
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Matthew D Galsky
- Division of Hematology and Medical Oncology, Department of Medicine, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Wenqing Xu
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - David L Brautigan
- Department of Microbiology, Immunology, and Cancer Biology, Center for Cell Signaling, University of Virginia, Charlottesville, VA 22903, USA
| | - Egon Ogris
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9/2, Vienna 1030, Austria
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48105, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA.
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29
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Riess JW, Jahchan NS, Das M, Zach Koontz M, Kunz PL, Wakelee HA, Schatzberg A, Sage J, Neal JW. A PHASE IIA STUDY REPOSITIONING DESIPRAMINE IN SMALL CELL LUNG CANCER AND OTHER HIGH-GRADE NEUROENDOCRINE TUMORS. Cancer Treat Res Commun 2020; 23:100174. [PMID: 32413603 PMCID: PMC7572629 DOI: 10.1016/j.ctarc.2020.100174] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 04/03/2020] [Indexed: 01/22/2023]
Abstract
BACKGROUND A bioinformatics approach identified antitumor effects of tricyclic antidepressants (TCAs) in small cell lung cancer (SCLC) and other high-grade neuroendocrine carcinomas (grade 3 neuroendocrine carcinomas) (G3NEC) that was subsequently validated in preclinical models with a putative mechanism of action via inhibition of neuroendocrine signaling pathways. This study was undertaken to reposition the candidate TCA desipramine in a clinical trial in SCLC and G3NEC. METHODS In this prospective, phase IIa intrapatient dose escalation clinical trial, patients were required to have failed at least one prior chemotherapy for metastatic SCLC or G3NEC. Treatment with desipramine began at 75 mg nightly with escalation in increments of 75 mg weekly to a maximum of 450 mg daily. RESULTS Six patients were enrolled, 3 with SCLC, and 3 with G3NEC (lung, rectal, and pancreas). Tolerability of desipramine was worse than predicted. Of the 6 patients enrolled: 1 patient achieved 300 mg daily, 2 patients reached 150 mg daily, 1 patient reached 75 mg daily, and 2 patients were unable to tolerate any stable dose. Reasons for discontinuation included drug-related grade 3 colon pseudo-obstruction, unrelated GI bleed, and grade 1-2 neurocognitive adverse events. Median clinical or radiographic progression free survival was 1.2 months (range 0.2-3.3) and median overall survival from study entry was 2.7 months (range 1.3-5.6). CONCLUSIONS No clinical or radiographic benefit was observed using desipramine to treat SCLC and G3NEC, so this trial was terminated. Intolerable low and medium grade neurocognitive side effects led to intermittent treatment and early discontinuation in most patients; given this limitation, doses achieved may be inadequate compared to the preclinical studies. MICROABSTRACT A bioinformatics approach previously identified a potential antitumor effect of tricyclic antidepressants (TCAs) in small cell lung cancer (SCLC) and other high-grade neuroendocrine carcinomas (grade 3 neuroendocrine carcinoma) (G3NEC), which was validated in preclinical models. In this prospective, phase IIa clinical trial, patients were required to have failed at least one prior chemotherapy for metastatic SCLC or G3NEC (Ki-67 ≥ 20% or ≥ 20 mitoses/10 HPF). Treatment with desipramine began at 75 mg nightly with escalation by 75 mg weekly to a maximum dose of 450 mg daily. Six patients were enrolled on this clinical trial, 3 with SCLC, and 3 with G3NEC (lung, rectal, and pancreatic). Tolerability of desipramine was worse than predicted. In the 6 patients enrolled: 1 patient achieved 300 mg daily, 2 patients reached 150 mg daily, 1 patient reached 75 mg daily, and 2 patients were unable to tolerate any stable dose. Reasons for discontinuation included drug-related grade 3 colon pseudo-obstruction, unrelated GI bleed, and grade 1-2 drug related dizziness, confusion, and somnolence. Though numbers are small, median clinical or radiographic progression free survival was 1.2 months (range 0.2-3.3) and median overall survival from study entry was 2.7 months (range 1.3-5.6). Although preclinical evidence was promising, no clinical or radiographic benefit was observed using desipramine to treat SCLC and G3NEC, so this trial was terminated.
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Affiliation(s)
- Jonathan W Riess
- UC Davis School of Medicine, Department of Medicine, Division of Hematology/Oncology, UC Davis Comprehensive Cancer Center.
| | - Nadine S Jahchan
- Stanford University School of Medicine, Department of Pediatrics and Genetics
| | - Millie Das
- Stanford University School of Medicine, Department of Internal Medicine, Division of Oncology, Stanford Cancer Institute, VA Palo Alto Health Care System, Department of Medicine
| | - M Zach Koontz
- Stanford University School of Medicine, Department of Internal Medicine, Division of Oncology, Stanford Cancer Institute
| | - Pamela L Kunz
- Stanford University School of Medicine, Department of Internal Medicine, Division of Oncology, Stanford Cancer Institute
| | - Heather A Wakelee
- Stanford University School of Medicine, Department of Internal Medicine, Division of Oncology, Stanford Cancer Institute
| | - Alan Schatzberg
- Stanford University School of Medicine Department of Psychiatry
| | - Julien Sage
- Stanford University School of Medicine, Department of Pediatrics and Genetics
| | - Joel W Neal
- Stanford University School of Medicine, Department of Internal Medicine, Division of Oncology, Stanford Cancer Institute
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30
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Nassal D, Gratz D, Hund TJ. Challenges and Opportunities for Therapeutic Targeting of Calmodulin Kinase II in Heart. Front Pharmacol 2020; 11:35. [PMID: 32116711 PMCID: PMC7012788 DOI: 10.3389/fphar.2020.00035] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 01/14/2020] [Indexed: 12/19/2022] Open
Abstract
Heart failure remains a major health burden around the world. Despite great progress in delineation of molecular mechanisms underlying development of disease, standard therapy has not advanced at the same pace. The multifunctional signaling molecule Ca2+/calmodulin-dependent protein kinase II (CaMKII) has received considerable attention over recent years for its central role in maladaptive remodeling and arrhythmias in the setting of chronic disease. However, these basic science discoveries have yet to translate into new therapies for human patients. This review addresses both the promise and barriers to developing translational therapies that target CaMKII signaling to abrogate pathologic remodeling in the setting of chronic disease. Efforts in small molecule design are discussed, as well as alternative targeting approaches that exploit novel avenues for compound delivery and/or genetic approaches to affect cardiac CaMKII signaling. These alternative strategies provide hope for overcoming some of the challenges that have limited the development of new therapies.
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Affiliation(s)
- Drew Nassal
- The Frick Center for Heart Failure and Arrhythmia and Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Daniel Gratz
- The Frick Center for Heart Failure and Arrhythmia and Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, United States
| | - Thomas J Hund
- The Frick Center for Heart Failure and Arrhythmia and Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, United States.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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31
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Merisaari J, Denisova OV, Doroszko M, Le Joncour V, Johansson P, Leenders WPJ, Kastrinsky DB, Zaware N, Narla G, Laakkonen P, Nelander S, Ohlmeyer M, Westermarck J. Monotherapy efficacy of blood-brain barrier permeable small molecule reactivators of protein phosphatase 2A in glioblastoma. Brain Commun 2020; 2:fcaa002. [PMID: 32954276 PMCID: PMC7425423 DOI: 10.1093/braincomms/fcaa002] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/26/2019] [Accepted: 11/26/2019] [Indexed: 12/22/2022] Open
Abstract
Glioblastoma is a fatal disease in which most targeted therapies have clinically failed. However, pharmacological reactivation of tumour suppressors has not been thoroughly studied as yet as a glioblastoma therapeutic strategy. Tumour suppressor protein phosphatase 2A is inhibited by non-genetic mechanisms in glioblastoma, and thus, it would be potentially amendable for therapeutic reactivation. Here, we demonstrate that small molecule activators of protein phosphatase 2A, NZ-8-061 and DBK-1154, effectively cross the in vitro model of blood–brain barrier, and in vivo partition to mouse brain tissue after oral dosing. In vitro, small molecule activators of protein phosphatase 2A exhibit robust cell-killing activity against five established glioblastoma cell lines, and nine patient-derived primary glioma cell lines. Collectively, these cell lines have heterogeneous genetic background, kinase inhibitor resistance profile and stemness properties; and they represent different clinical glioblastoma subtypes. Moreover, small molecule activators of protein phosphatase 2A were found to be superior to a range of kinase inhibitors in their capacity to kill patient-derived primary glioma cells. Oral dosing of either of the small molecule activators of protein phosphatase 2A significantly reduced growth of infiltrative intracranial glioblastoma tumours. DBK-1154, with both higher degree of brain/blood distribution, and more potent in vitro activity against all tested glioblastoma cell lines, also significantly increased survival of mice bearing orthotopic glioblastoma xenografts. In summary, this report presents a proof-of-principle data for blood–brain barrier—permeable tumour suppressor reactivation therapy for glioblastoma cells of heterogenous molecular background. These results also provide the first indications that protein phosphatase 2A reactivation might be able to challenge the current paradigm in glioblastoma therapies which has been strongly focused on targeting specific genetically altered cancer drivers with highly specific inhibitors. Based on demonstrated role for protein phosphatase 2A inhibition in glioblastoma cell drug resistance, small molecule activators of protein phosphatase 2A may prove to be beneficial in future glioblastoma combination therapies.
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Affiliation(s)
- Joni Merisaari
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku 20520, Finland.,Institute of Biomedicine, University of Turku, Turku 20520, Finland
| | - Oxana V Denisova
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku 20520, Finland
| | - Milena Doroszko
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 85, Sweden
| | - Vadim Le Joncour
- Translational Cancer Medicine Research Program, Faculty of Medicine, University of Helsinki, Helsinki 00014, Finland
| | - Patrik Johansson
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 85, Sweden
| | - William P J Leenders
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Nijmegen 6525, The Netherlands
| | - David B Kastrinsky
- Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.,Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY 11549, USA
| | - Nilesh Zaware
- Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-5624, USA
| | - Pirjo Laakkonen
- Translational Cancer Medicine Research Program, Faculty of Medicine, University of Helsinki, Helsinki 00014, Finland.,Laboratory Animal Centre, Helsinki Institute of Life Science - HiLIFE, University of Helsinki, Helsinki 00014, Finland
| | - Sven Nelander
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 85, Sweden
| | - Michael Ohlmeyer
- Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.,Atux Iskay LLC, Plainsboro, NJ 08536, USA
| | - Jukka Westermarck
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku 20520, Finland.,Institute of Biomedicine, University of Turku, Turku 20520, Finland
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32
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O'Connor CM, Leonard D, Wiredja D, Avelar RA, Wang Z, Schlatzer D, Bryson B, Tokala E, Taylor SE, Upadhyay A, Sangodkar J, Gingras AC, Westermarck J, Xu W, DiFeo A, Brautigan DL, Haider S, Jackson M, Narla G. Inactivation of PP2A by a recurrent mutation drives resistance to MEK inhibitors. Oncogene 2020; 39:703-717. [PMID: 31541192 PMCID: PMC6980487 DOI: 10.1038/s41388-019-1012-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 06/26/2019] [Accepted: 08/09/2019] [Indexed: 12/27/2022]
Abstract
The serine/threonine Protein Phosphatase 2A (PP2A) functions as a tumor suppressor by negatively regulating multiple oncogenic signaling pathways. The canonical PP2A holoenzyme comprises a scaffolding subunit (PP2A Aα/β), which serves as the platform for binding of both the catalytic C subunit and one regulatory B subunit. Somatic heterozygous missense mutations in PPP2R1A, the gene encoding the PP2A Aα scaffolding subunit, have been identified across multiple cancer types, but the effects of the most commonly mutated residue, Arg-183, on PP2A function have yet to be fully elucidated. In this study, we used a series of cellular and in vivo models and discovered that the most frequent Aα R183W mutation formed alternative holoenzymes by binding of different PP2A regulatory subunits compared with wild-type Aα, suggesting a rededication of PP2A functions. Unlike wild-type Aα, which suppressed tumorigenesis, the R183W mutant failed to suppress tumor growth in vivo through activation of the MAPK pathway in RAS-mutant transformed cells. Furthermore, cells expressing R183W were less sensitive to MEK inhibitors. Taken together, our results demonstrate that the R183W mutation in PP2A Aα scaffold abrogates the tumor suppressive actions of PP2A, thereby potentiating oncogenic signaling and reducing drug sensitivity of RAS-mutant cells.
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Affiliation(s)
- Caitlin M O'Connor
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Daniel Leonard
- Department of Pathology, Case Western Reserve University, Cleveland, OH, USA
| | - Danica Wiredja
- Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, OH, USA
| | - Rita A Avelar
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Zhizhi Wang
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Daniela Schlatzer
- Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, OH, USA
| | - Benjamin Bryson
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
| | - Eesha Tokala
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
| | - Sarah E Taylor
- Department of Pathology, Case Western Reserve University, Cleveland, OH, USA
| | - Aditya Upadhyay
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
| | - Jaya Sangodkar
- Department of Internal Medicine: Genetic Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Jukka Westermarck
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland
| | - Wenqing Xu
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Analisa DiFeo
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, USA
- Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MI, USA
| | - David L Brautigan
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA
| | - Shozeb Haider
- Department of Pharmaceutical and Biological Chemistry, University College London, London, UK
| | - Mark Jackson
- Department of Pathology, Case Western Reserve University, Cleveland, OH, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
| | - Goutham Narla
- Department of Internal Medicine: Genetic Medicine, University of Michigan, Ann Arbor, MI, USA.
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, USA.
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33
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Farrington CC, Yuan E, Mazhar S, Izadmehr S, Hurst L, Allen-Petersen BL, Janghorban M, Chung E, Wolczanski G, Galsky M, Sears R, Sangodkar J, Narla G. Protein phosphatase 2A activation as a therapeutic strategy for managing MYC-driven cancers. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49933-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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34
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Kleinberger T. Biology of the adenovirus E4orf4 protein: from virus infection to cancer cell death. FEBS Lett 2019; 594:1891-1917. [DOI: 10.1002/1873-3468.13704] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 11/24/2019] [Accepted: 11/25/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Tamar Kleinberger
- Department of Molecular Microbiology the Rappaport Faculty of Medicine Technion –Israel Institute of Technology Haifa Israel
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35
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Farrington CC, Yuan E, Mazhar S, Izadmehr S, Hurst L, Allen-Petersen BL, Janghorban M, Chung E, Wolczanski G, Galsky M, Sears R, Sangodkar J, Narla G. Protein phosphatase 2A activation as a therapeutic strategy for managing MYC-driven cancers. J Biol Chem 2019; 295:757-770. [PMID: 31822503 DOI: 10.1074/jbc.ra119.011443] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 12/04/2019] [Indexed: 12/14/2022] Open
Abstract
The tumor suppressor protein phosphatase 2A (PP2A) is a serine/threonine phosphatase whose activity is inhibited in most human cancers. One of the best-characterized PP2A substrates is MYC proto-oncogene basic helix-loop-helix transcription factor (MYC), whose overexpression is commonly associated with aggressive forms of this disease. PP2A directly dephosphorylates MYC, resulting in its degradation. To explore the therapeutic potential of direct PP2A activation in a diverse set of MYC-driven cancers, here we used biochemical assays, recombinant cell lines, gene expression analyses, and immunohistochemistry to evaluate a series of first-in-class small-molecule activators of PP2A (SMAPs) in Burkitt lymphoma, KRAS-driven non-small cell lung cancer, and triple-negative breast cancer. In all tested models of MYC-driven cancer, the SMAP treatment rapidly and persistently inhibited MYC expression through proteasome-mediated degradation, inhibition of MYC transcriptional activity, decreased cancer cell proliferation, and tumor growth inhibition. Importantly, we generated a series of cell lines expressing PP2A-dependent phosphodegron variants of MYC and demonstrated that the antitumorigenic activity of SMAPs depends on MYC degradation. Collectively, the findings presented here indicate a pharmacologically tractable approach to drive MYC degradation by using SMAPs for the management of a broad range of MYC-driven cancers.
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Affiliation(s)
| | - Eric Yuan
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Sahar Mazhar
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Sudeh Izadmehr
- Department of Medicine, Division of Hematology and Medical Oncology, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Lauren Hurst
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48105
| | - Brittany L Allen-Petersen
- Department of Molecular and Medical Genetics, Oregon Health and Sciences University, Portland, Oregon 97239
| | - Mahnaz Janghorban
- Department of Molecular and Medical Genetics, Oregon Health and Sciences University, Portland, Oregon 97239
| | - Eric Chung
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Grace Wolczanski
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48105
| | - Matthew Galsky
- Department of Medicine, Division of Hematology and Medical Oncology, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Rosalie Sears
- Department of Molecular and Medical Genetics, Oregon Health and Sciences University, Portland, Oregon 97239
| | - Jaya Sangodkar
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48105
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48105
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36
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Perl AL, O'Connor CM, Fa P, Mayca Pozo F, Zhang J, Zhang Y, Narla G. Protein phosphatase 2A controls ongoing DNA replication by binding to and regulating cell division cycle 45 (CDC45). J Biol Chem 2019; 294:17043-17059. [PMID: 31562245 DOI: 10.1074/jbc.ra119.010432] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 09/20/2019] [Indexed: 11/06/2022] Open
Abstract
Genomic replication is a highly regulated process and represents both a potential benefit and liability to rapidly dividing cells; however, the precise post-translational mechanisms regulating genomic replication are incompletely understood. Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase that regulates a diverse array of cellular processes. Here, utilizing both a gain-of-function chemical biology approach and loss-of-function genetic approaches to modulate PP2A activity, we found that PP2A regulates DNA replication. We demonstrate that increased PP2A activity can interrupt ongoing DNA replication, resulting in a prolonged S phase. The impaired replication resulted in a collapse of replication forks, inducing dsDNA breaks, homologous recombination, and a PP2A-dependent replication stress response. Additionally, we show that during replication, PP2A exists in complex with cell division cycle 45 (CDC45) and that increased PP2A activity caused dissociation of CDC45 and polymerase α from the replisome. Furthermore, we found that individuals harboring mutations in the PP2A Aα gene have a higher fraction of genomic alterations, suggesting that PP2A regulates ongoing replication as a mechanism for maintaining genomic integrity. These results reveal a new function for PP2A in regulating ongoing DNA replication and a potential role for PP2A in the intra-S-phase checkpoint.
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Affiliation(s)
- Abbey L Perl
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Caitlin M O'Connor
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Pengyan Fa
- Department of Radiation Oncology, Ohio State University James Comprehensive Cancer Center and College of Medicine, Columbus, Ohio 43210
| | - Franklin Mayca Pozo
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Junran Zhang
- Department of Radiation Oncology, Ohio State University James Comprehensive Cancer Center and College of Medicine, Columbus, Ohio 43210
| | - Youwei Zhang
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Goutham Narla
- Department of Internal Medicine, Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 .,Department of Internal Medicine, Division of Genetic Medicine, University of Michigan, Ann Arbor, Michigan 48105
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Abstract
Castration-resistant prostate cancer (CRPC) remains incurable despite the approval of several new treatments. Identification of new biomarkers and therapeutic targets to enable personalization of CRPC therapy, with the aim of maximizing therapeutic responses and minimizing toxicity in patients, is urgently needed. Prostate cancer progression and therapeutic resistance are frequently driven by aberrantly activated kinase signalling pathways that are amenable to pharmacological inhibition. Personalized phosphoproteomics, which enables the analysis of signalling networks in individual tumours, is a promising approach to advance personalized therapy by discovering biomarkers of pathway activity and clinically actionable targets. Several technologies for global and targeted phosphoproteomic analysis exist, each with its own strengths and shortcomings. Global discovery phosphoproteomics is predominantly conducted using liquid chromatography-tandem mass spectrometry coupled with data-dependent or data-independent acquisition technologies. Multiplexed targeted phosphoproteomics can be divided into platforms based on mass spectrometry or antibodies, including selected or parallel reaction monitoring and triggered by offset, multiplexed, accurate mass, high-resolution, absolute quantification (known as TOMAHAQ) or forward-phase or reverse-phase protein arrays, respectively. Several obstacles still need to be overcome before the full potential of phosphoproteomics can be realized in routine clinical practice, but a future phosphoproteomics-centric trans-omic profiling approach should enable optimized personalized CRPC management through improved biomarkers and targeted treatments.
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38
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Agbo L, Lambert JP. Proteomics contribution to the elucidation of the steroid hormone receptors functions. J Steroid Biochem Mol Biol 2019; 192:105387. [PMID: 31173874 DOI: 10.1016/j.jsbmb.2019.105387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 05/28/2019] [Accepted: 05/28/2019] [Indexed: 10/26/2022]
Abstract
Steroid hormones have far-ranging biological impacts and more are continuously being uncovered. Over the last decades, proteomics approaches have become key to better understand biological processes. Due to multiple technical breakthroughs allowing for the concurrent identification and/or quantification of thousands of analytes using mass spectrometers, researchers employing proteomics tools today can now obtain truly holistic views of multiple facets of the human proteome. Here, we review how the field of proteomics has contributed to discoveries about steroid hormones, their receptors and their impact on human pathologies. In particular, the involvement of steroid receptors in cancer initiation, development, metastasis and treatment will be highlighted. Techniques at the forefront of the proteomics field will also be discussed to present how they can contribute to a better understanding of steroid hormone receptors.
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Affiliation(s)
- Lynda Agbo
- Department of Molecular Medicine and Cancer Research Centre, Université Laval, Québec, QC, Canada; Research Center CHU de Québec-Université Laval, Québec, QC G1V 4G2, Canada
| | - Jean-Philippe Lambert
- Department of Molecular Medicine and Cancer Research Centre, Université Laval, Québec, QC, Canada; Research Center CHU de Québec-Université Laval, Québec, QC G1V 4G2, Canada.
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Nath S, Ohlmeyer M, Salathe MA, Poon J, Baumlin N, Foronjy RF, Geraghty P. Chronic Cigarette Smoke Exposure Subdues PP2A Activity by Enhancing Expression of the Oncogene CIP2A. Am J Respir Cell Mol Biol 2019; 59:695-705. [PMID: 30011381 DOI: 10.1165/rcmb.2018-0173oc] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Phosphatase activity of the major serine threonine phosphatase, protein phosphatase 2A (PP2A), is blunted in the airways of individuals with chronic obstructive pulmonary disease (COPD), which results in heightened inflammation and proteolytic responses. The objective of this study was to investigate how PP2A activity is modulated in COPD airways. PP2A activity and endogenous inhibitors of PP2A were investigated in animal and cell models of COPD. In primary human bronchial epithelial (HBE) cells isolated from smokers and donors with COPD, we observed enhanced expression of cancerous inhibitor of PP2A (CIP2A), an oncoprotein encoded by the KIAA1524 gene, compared with cells from nonsmokers. CIP2A expression was induced by chronic cigarette smoke exposure in mice that coincided with a reduction in PP2A activity, airspace enlargements, and loss of lung function, as determined by PP2A phosphatase activity, mean linear intercept analysis, and forced expiratory volume in 0.05 second/forced vital capacity. Modulating CIP2A expression in HBE cells by silencing RNA or chemically with erlotinib enhanced PP2A activity, reduced extracellular-signal-regulated kinase phosphorylation, and reduced the responses of matrix metalloproteinases 1 and 9 in HBE cells isolated from subjects with COPD. Enhanced epithelial growth factor receptor responses in cells from subjects with COPD were observed to modulate CIP2A expression levels. Our study indicates that chronic cigarette smoke induction of epithelial growth factor receptor signaling and CIP2A expression can impair PP2A responses that are associated with loss of lung function and enhancement of proteolytic responses. Augmenting PP2A activity by manipulating CIP2A expression may represent a feasible therapeutic approach to counter smoke-induced lung disease.
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Affiliation(s)
- Sridesh Nath
- 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
| | | | - Matthias A Salathe
- 3 Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, Florida; and.,4 Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
| | - Justin Poon
- 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
| | - Nathalie Baumlin
- 3 Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, Florida; and.,4 Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
| | - Robert F Foronjy
- 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine, and.,5 Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York
| | - Patrick Geraghty
- 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine, and.,5 Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York
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40
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Doherty DF, Nath S, Poon J, Foronjy RF, Ohlmeyer M, Dabo AJ, Salathe M, Birrell M, Belvisi M, Baumlin N, Kim MD, Weldon S, Taggart C, Geraghty P. Protein Phosphatase 2A Reduces Cigarette Smoke-induced Cathepsin S and Loss of Lung Function. Am J Respir Crit Care Med 2019; 200:51-62. [PMID: 30641028 PMCID: PMC6603057 DOI: 10.1164/rccm.201808-1518oc] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 01/14/2019] [Indexed: 12/18/2022] Open
Abstract
Rationale: CTSS (cathepsin S) is a cysteine protease that is observed at higher concentrations in BAL fluid and plasma of subjects with chronic obstructive pulmonary disease (COPD). Objectives: To investigate whether CTSS is involved in the pathogenesis of cigarette smoke-induced COPD and determine whether targeting upstream signaling could prevent the disease. Methods: CTSS expression was investigated in animal and human tissue and cell models of COPD. Ctss-/- mice were exposed to long-term cigarette smoke and forced oscillation and expiratory measurements were recorded. Animals were administered chemical modulators of PP2A (protein phosphatase 2A) activity. Measurements and Main Results: Here we observed enhanced CTSS expression and activity in mouse lungs after exposure to cigarette smoke. Ctss-/- mice were resistant to cigarette smoke-induced inflammation, airway hyperresponsiveness, airspace enlargements, and loss of lung function. CTSS expression was negatively regulated by PP2A in human bronchial epithelial cells isolated from healthy nonsmokers and COPD donors and in monocyte-derived macrophages. Modulating PP2A expression or activity, with silencer siRNA or a chemical inhibitor or activator, during acute smoke exposure in mice altered inflammatory responses and CTSS expression and activity in the lung. Enhancement of PP2A activity prevented chronic smoke-induced COPD in mice. Conclusions: Our study indicates that the decrease in PP2A activity that occurs in COPD contributes to elevated CTSS expression in the lungs and results in impaired lung function. Enhancing PP2A activity represents a feasible therapeutic approach to reduce CTSS activity and counter smoke-induced lung disease.
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Affiliation(s)
- Declan F. Doherty
- Airway Innate Immunity Research Group, Centre for Experimental Medicine, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University Belfast, Belfast, United Kingdom
| | - Sridesh Nath
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
| | - Justin Poon
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
| | - Robert F. Foronjy
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
- Department of Cell Biology, State University of New York Downstate Medical Centre, Brooklyn, New York
| | - Michael Ohlmeyer
- Icahn School of Medicine at Mount Sinai, New York, New York
- Atux Iskay LLC, Plainsboro, New Jersey
| | - Abdoulaye J. Dabo
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
- Department of Cell Biology, State University of New York Downstate Medical Centre, Brooklyn, New York
| | - Matthias Salathe
- Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, Florida
| | - Mark Birrell
- Respiratory Pharmacology Group, Airway Disease Section, National Heart and Lung Institute, Imperial College, London, United Kingdom; and
- Respiratory, Inflammation and Autoimmunity, Innovative Medicines and Early Development Biotech Unit, AstraZeneca, London, United Kingdom
| | - Maria Belvisi
- Respiratory Pharmacology Group, Airway Disease Section, National Heart and Lung Institute, Imperial College, London, United Kingdom; and
- Respiratory, Inflammation and Autoimmunity, Innovative Medicines and Early Development Biotech Unit, AstraZeneca, London, United Kingdom
| | - Nathalie Baumlin
- Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, Florida
| | - Michael D. Kim
- Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, Florida
| | - Sinéad Weldon
- Airway Innate Immunity Research Group, Centre for Experimental Medicine, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University Belfast, Belfast, United Kingdom
| | - Clifford Taggart
- Airway Innate Immunity Research Group, Centre for Experimental Medicine, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University Belfast, Belfast, United Kingdom
| | - Patrick Geraghty
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
- Department of Cell Biology, State University of New York Downstate Medical Centre, Brooklyn, New York
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41
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Remmerie M, Janssens V. PP2A: A Promising Biomarker and Therapeutic Target in Endometrial Cancer. Front Oncol 2019; 9:462. [PMID: 31214504 PMCID: PMC6558005 DOI: 10.3389/fonc.2019.00462] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 05/14/2019] [Indexed: 12/14/2022] Open
Abstract
Over the last decade, the use of targeted therapies has immensely increased in the treatment of cancer. However, treatment for endometrial carcinomas (ECs) has lagged behind, although potential molecular markers have been identified. This is particularly problematic for the type II ECs, since these aggressive tumors are usually not responsive toward the current standard therapies. Therefore, type II ECs are responsible for most EC-related deaths, indicating the need for new treatment options. Interestingly, molecular analyses of type II ECs have uncovered frequent genetic alterations (up to 40%) in PPP2R1A, encoding the Aα subunit of the tumor suppressive heterotrimeric protein phosphatase type 2A (PP2A). PPP2R1A mutations were also reported in type I ECs and other common gynecologic cancers, albeit at much lower frequencies (0-7%). Nevertheless, PP2A inactivation in the latter cancer types is common via other mechanisms, in particular by increased expression of Cancerous Inhibitor of PP2A (CIP2A) and PP2A Methylesterase-1 (PME-1) proteins. In this review, we discuss the therapeutic potential of direct and indirect PP2A targeting compounds, possibly in combination with other anti-cancer drugs, in EC. Furthermore, we investigate the potential of the PP2A status as a predictive and/or prognostic marker for type I and II ECs.
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Affiliation(s)
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
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42
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Clark AR, Ohlmeyer M. Protein phosphatase 2A as a therapeutic target in inflammation and neurodegeneration. Pharmacol Ther 2019; 201:181-201. [PMID: 31158394 PMCID: PMC6700395 DOI: 10.1016/j.pharmthera.2019.05.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 05/29/2019] [Indexed: 12/11/2022]
Abstract
Protein phosphatase 2A (PP2A) is a highly complex heterotrimeric enzyme that catalyzes the selective removal of phosphate groups from protein serine and threonine residues. Emerging evidence suggests that it functions as a tumor suppressor by constraining phosphorylation-dependent signalling pathways that regulate cellular transformation and metastasis. Therefore, PP2A-activating drugs (PADs) are being actively sought and investigated as potential novel anti-cancer treatments. Here we explore the concept that PP2A also constrains inflammatory responses through its inhibitory effects on various signalling pathways, suggesting that PADs may be effective in the treatment of inflammation-mediated pathologies.
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Affiliation(s)
- Andrew R Clark
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
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43
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Umesalma S, Kaemmer CA, Kohlmeyer JL, Letney B, Schab AM, Reilly JA, Sheehy RM, Hagen J, Tiwari N, Zhan F, Leidinger MR, O'Dorisio TM, Dillon J, Merrill RA, Meyerholz DK, Perl AL, Brown BJ, Braun TA, Scott AT, Ginader T, Taghiyev AF, Zamba GK, Howe JR, Strack S, Bellizzi AM, Narla G, Darbro BW, Quelle FW, Quelle DE. RABL6A inhibits tumor-suppressive PP2A/AKT signaling to drive pancreatic neuroendocrine tumor growth. J Clin Invest 2019; 129:1641-1653. [PMID: 30721156 DOI: 10.1172/jci123049] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 01/24/2019] [Indexed: 12/15/2022] Open
Abstract
Hyperactivated AKT/mTOR signaling is a hallmark of pancreatic neuroendocrine tumors (PNETs). Drugs targeting this pathway are used clinically, but tumor resistance invariably develops. A better understanding of factors regulating AKT/mTOR signaling and PNET pathogenesis is needed to improve current therapies. We discovered that RABL6A, a new oncogenic driver of PNET proliferation, is required for AKT activity. Silencing RABL6A caused PNET cell-cycle arrest that coincided with selective loss of AKT-S473 (not T308) phosphorylation and AKT/mTOR inactivation. Restoration of AKT phosphorylation rescued the G1 phase block triggered by RABL6A silencing. Mechanistically, loss of AKT-S473 phosphorylation in RABL6A-depleted cells was the result of increased protein phosphatase 2A (PP2A) activity. Inhibition of PP2A restored phosphorylation of AKT-S473 in RABL6A-depleted cells, whereas PP2A reactivation using a specific small-molecule activator of PP2A (SMAP) abolished that phosphorylation. Moreover, SMAP treatment effectively killed PNET cells in a RABL6A-dependent manner and suppressed PNET growth in vivo. The present work identifies RABL6A as a new inhibitor of the PP2A tumor suppressor and an essential activator of AKT in PNET cells. Our findings offer what we believe is a novel strategy of PP2A reactivation for treatment of PNETs as well as other human cancers driven by RABL6A overexpression and PP2A inactivation.
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Affiliation(s)
| | | | | | | | | | | | - Ryan M Sheehy
- Department of Pharmacology.,Free Radical & Radiation Biology Training Program
| | | | | | | | - Mariah R Leidinger
- Department of Pathology, in the College of Medicine, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA
| | | | | | | | - David K Meyerholz
- Department of Pathology, in the College of Medicine, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA
| | - Abbey L Perl
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | | | | | | | | | - Agshin F Taghiyev
- Pediatrics, Colleges of Medicine, Engineering, or Public Health, University of Iowa, Iowa City, Iowa, USA
| | | | | | | | - Andrew M Bellizzi
- Department of Pathology, in the College of Medicine, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA
| | - Goutham Narla
- Department of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Benjamin W Darbro
- Pediatrics, Colleges of Medicine, Engineering, or Public Health, University of Iowa, Iowa City, Iowa, USA
| | | | - Dawn E Quelle
- Department of Pharmacology.,Molecular Medicine Graduate Program.,Free Radical & Radiation Biology Training Program.,Department of Pathology, in the College of Medicine, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa, USA
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44
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Elgenaidi IS, Spiers JP. Regulation of the phosphoprotein phosphatase 2A system and its modulation during oxidative stress: A potential therapeutic target? Pharmacol Ther 2019; 198:68-89. [PMID: 30797822 DOI: 10.1016/j.pharmthera.2019.02.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 02/15/2019] [Indexed: 02/06/2023]
Abstract
Phosphoprotein phosphatases are of growing interest in the pathophysiology of many diseases and are often the neglected partner of protein kinases. One family member, PP2A, accounts for dephosphorylation of ~55-70% of all serine/threonine phosphosites. Interestingly, dysregulation of kinase signalling is a hallmark of many diseases in which an increase in oxidative stress is also noted. With this in mind, we assess the evidence to support oxidative stress-mediated regulation of the PP2A system In this article, we first present an overview of the PP2A system before providing an analysis of the regulation of PP2A by endogenous inhibitors, post translational modification, and miRNA. Next, a detailed critique of data implicating reactive oxygen species, ischaemia, ischaemia-reperfusion, and hypoxia in regulating the PP2A holoenzyme and associated regulators is presented. Finally, the pharmacological targeting of PP2A, its endogenous inhibitors, and enzymes responsible for its post-translational modification are covered. There is extensive evidence that oxidative stress modulates multiple components of the PP2A system, however, most of the data pertains to the catalytic subunit of PP2A. Irrespective of the underlying aetiology, free radical-mediated attenuation of PP2A activity is an emerging theme. However, in many instances, a dichotomy exists, which requires clarification and mechanistic insight. Nevertheless, this raises the possibility that pharmacological activation of PP2A, either through small molecule activators of PP2A or CIP2A/SET antagonists may be beneficial in modulating the cellular response to oxidative stress. A better understanding of which, will have wide ranging implications for cancer, heart disease and inflammatory conditions.
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Affiliation(s)
- I S Elgenaidi
- Department of Pharmacology and Therapeutics, Trinity College Dublin, Ireland
| | - J P Spiers
- Department of Pharmacology and Therapeutics, Trinity College Dublin, Ireland.
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45
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Xi M, Wan S, Hua W, Zhou Y, Jiang W, Hu J. Correlation of SOX9 and NM23 genes with the incidence and prognosis of prostate cancer. Oncol Lett 2019; 17:2296-2302. [PMID: 30675295 PMCID: PMC6341668 DOI: 10.3892/ol.2018.9828] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 11/08/2018] [Indexed: 01/11/2023] Open
Abstract
Correlation of sex determining region Y-box (SOX)9 and NM23 genes with the incidence and prognosis of prostate cancer (PC) was investigated. SOX9-small interfering ribonucleic acid (siRNA) and NM23-siRNA were constructed and transfected into PC-3 cells. The expression levels of SOX9 and NM23 messenger RNAs (mRNAs) and proteins in PC-3 cells were detected via reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. MTT assay was adopted to examine the proliferation ability of the transfected cells, and Transwell assay was applied to detect the migration ability of the transfected cells. Sixty-three patients with PC and 56 patients with benign prostatic hyperplasia who were treated in Huadu District People's Hospital were enrolled. Correlation analyses were conducted for the relative expression levels of SOX9 and NM23 and the Gleason grade; and the survival curves of the patient SOX9/NM23 (S/N) Cq values were plotted. The proliferation and migration abilities of PC-3 cells were remarkably reduced after low expression of SOX9 (P<0.01), while those of PC-3 cells were significantly improved after low expression of NM23 (P<0.01). Compared with that in tissues of PC patients, the relative expression of SOX9 mRNA in patients with benign prostatic hyperplasia was obviously decreased (P<0.01), while that of NM23 mRNA was significantly elevated (P<0.01). The larger the S/N was, the shorter the patient's survival time would be (P<0.05). The low expression of SOX9 gene can significantly reduce the proliferation and migration abilities of PC cells, which is negatively associated with the incidence and prognosis of patients. The low expression of NM23 gene can markedly enhance the proliferation and migration abilities of PC cells, and it is positively related to the incidence and prognosis of patients.
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Affiliation(s)
- Ming Xi
- Department of Urology, Huadu District People's Hospital, Southern Medical University, Guangzhou, Guangdong 510530, P.R. China
| | - Song Wan
- Department of Urology, Huadu District People's Hospital, Southern Medical University, Guangzhou, Guangdong 510530, P.R. China
| | - Wei Hua
- Department of Urology, Huadu District People's Hospital, Southern Medical University, Guangzhou, Guangdong 510530, P.R. China
| | - Yulin Zhou
- Department of Urology, Huadu District People's Hospital, Southern Medical University, Guangzhou, Guangdong 510530, P.R. China
| | - Wencong Jiang
- Department of Urology, Huadu District People's Hospital, Southern Medical University, Guangzhou, Guangdong 510530, P.R. China
| | - Jianxin Hu
- Department of Urology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
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46
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Raman D, Pervaiz S. Redox inhibition of protein phosphatase PP2A: Potential implications in oncogenesis and its progression. Redox Biol 2019; 27:101105. [PMID: 30686777 PMCID: PMC6859563 DOI: 10.1016/j.redox.2019.101105] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 01/04/2019] [Accepted: 01/09/2019] [Indexed: 01/17/2023] Open
Abstract
Cellular processes are dictated by the active signaling of proteins relaying messages to regulate cell proliferation, apoptosis, signal transduction and cell communications. An intricate web of protein kinases and phosphatases are critical to the proper transmission of signals across such cascades. By governing 30–50% of all protein dephosphorylation in the cell, with prominent substrate proteins being key regulators of signaling cascades, the phosphatase PP2A has emerged as a celebrated player in various developmental and tumorigenic pathways, thereby posing as an attractive target for therapeutic intervention in various pathologies wherein its activity is deregulated. This review is mainly focused on refreshing our understanding of the structural and functional complexity that cocoons the PP2A phosphatase, and its expression in cancers. Additionally, we focus on its physiological regulation as well as into recent advents and strategies that have shown promise in countering the deregulation of the phosphatase through its targeted reactivation. Finally, we dwell upon one of the key regulators of PP2A in cancer cells-cellular redox status-its multifarious nature, and its integration into the reactome of PP2A, highlighting some of the significant impacts that ROS can inflict on the structural modifications and functional aspect of PP2A.
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Affiliation(s)
- Deepika Raman
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Shazib Pervaiz
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Medical Science Cluster Cancer Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; National University Cancer Institute, National University Health System, Singapore, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.
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47
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Fowle H, Zhao Z, Graña X. PP2A holoenzymes, substrate specificity driving cellular functions and deregulation in cancer. Adv Cancer Res 2019; 144:55-93. [PMID: 31349904 PMCID: PMC9994639 DOI: 10.1016/bs.acr.2019.03.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PP2A is a highly conserved eukaryotic serine/threonine protein phosphatase of the PPP family of phosphatases with fundamental cellular functions. In cells, PP2A targets specific subcellular locations and substrates by forming heterotrimeric holoenzymes, where a core dimer consisting of scaffold (A) and catalytic (C) subunits complexes with one of many B regulatory subunits. PP2A plays a key role in positively and negatively regulating a myriad of cellular processes, as it targets a very sizable fraction of the cellular substrates phosphorylated on Ser/Thr residues. This review focuses on insights made toward the understanding on how the subunit composition and structure of PP2A holoenzymes mediates substrate specificity, the role of substrate modulation in the signaling of cellular division, growth, and differentiation, and its deregulation in cancer.
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Affiliation(s)
- Holly Fowle
- Fels Institute for Cancer Research and Molecular Biology and Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Ziran Zhao
- Fels Institute for Cancer Research and Molecular Biology and Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Xavier Graña
- Fels Institute for Cancer Research and Molecular Biology and Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States.
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48
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Nilsson J. Protein phosphatases in the regulation of mitosis. J Cell Biol 2018; 218:395-409. [PMID: 30446607 PMCID: PMC6363451 DOI: 10.1083/jcb.201809138] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 10/29/2018] [Accepted: 10/29/2018] [Indexed: 12/15/2022] Open
Abstract
The accurate segregation of genetic material to daughter cells during mitosis depends on the precise coordination and regulation of hundreds of proteins by dynamic phosphorylation. Mitotic kinases are major regulators of protein function, but equally important are protein phosphatases that balance their actions, their coordinated activity being essential for accurate chromosome segregation. Phosphoprotein phosphatases (PPPs) that dephosphorylate phosphoserine and phosphothreonine residues are increasingly understood as essential regulators of mitosis. In contrast to kinases, the lack of a pronounced peptide-binding cleft on the catalytic subunit of PPPs suggests that these enzymes are unlikely to be specific. However, recent exciting insights into how mitotic PPPs recognize specific substrates have revealed that they are as specific as kinases. Furthermore, the activities of PPPs are tightly controlled at many levels to ensure that they are active only at the proper time and place. Here, I will discuss substrate selection and regulation of mitotic PPPs focusing mainly on animal cells and explore how these actions control mitosis, as well as important unanswered questions.
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Affiliation(s)
- Jakob Nilsson
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
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Westermarck J. Targeted therapies don't work for a reason; the neglected tumor suppressor phosphatasePP2A strikes back. FEBS J 2018; 285:4139-4145. [DOI: 10.1111/febs.14617] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 07/26/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Jukka Westermarck
- Turku Centre for Biotechnology University of Turku and Åbo Akademi University Turku Finland
- Institute of Biomedicine University of Turku Finland
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50
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Remmerie M, Janssens V. Targeted Therapies in Type II Endometrial Cancers: Too Little, but Not Too Late. Int J Mol Sci 2018; 19:E2380. [PMID: 30104481 PMCID: PMC6121653 DOI: 10.3390/ijms19082380] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 08/02/2018] [Accepted: 08/08/2018] [Indexed: 01/14/2023] Open
Abstract
Type II endometrial carcinomas (ECs) are responsible for most endometrial cancer-related deaths due to their aggressive nature, late stage detection and high tolerance for standard therapies. However, there are no targeted therapies for type II ECs, and they are still treated the same way as the clinically indolent and easily treatable type I ECs. Therefore, type II ECs are in need of new treatment options. More recently, molecular analysis of endometrial cancer revealed phosphorylation-dependent oncogenic signalling in the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways to be most frequently altered in type II ECs. Consequently, clinical trials tested pharmacologic kinase inhibitors targeting these pathways, although mostly with rather disappointing results. In this review, we highlight the most common genetic alterations in type II ECs. Additionally, we reason why most clinical trials for ECs using targeted kinase inhibitors had unsatisfying results and what should be changed in future clinical trial setups. Furthermore, we argue that, besides kinases, phosphatases should no longer be ignored in clinical trials, particularly in type II ECs, where the tumour suppressive phosphatase protein phosphatase type 2A (PP2A) is frequently mutated. Lastly, we discuss the therapeutic potential of targeting PP2A for (re)activation, possibly in combination with pharmacologic kinase inhibitors.
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Affiliation(s)
- Michiel Remmerie
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), B-3000 Leuven, Belgium.
- Leuven Cancer Institute (LKI), B-3000 Leuven, Belgium.
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), B-3000 Leuven, Belgium.
- Leuven Cancer Institute (LKI), B-3000 Leuven, Belgium.
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