1
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Lee CF, Pienta KJ, Amend SR. The involvement of cyclin-dependent kinase 7 (CDK7) and 9 (CDK9) in coordinating transcription and cell cycle checkpoint regulation. Cell Cycle 2025:1-13. [PMID: 40223539 DOI: 10.1080/15384101.2025.2485844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 09/24/2024] [Accepted: 10/08/2024] [Indexed: 04/15/2025] Open
Abstract
Cells regulate the expression of cell cycle-related genes, including cyclins essential for mitosis, through the transcriptional activity of the positive transcription elongation factor b (P-TEFb), a complex comprising CDK9, cyclin T, and transcription factors. P-TEFb cooperates with CDK7 to activate RNA polymerase. In response to DNA stress, the cell cycle shifts from mitosis to repair, triggering cell cycle arrest and the activation of DNA repair genes. This tight coordination between transcription, cell cycle progression, and DNA stress response is crucial for maintaining cellular integrity. Cyclin-dependent kinases CDK7 and CDK9 are central to both transcription and cell cycle regulation. CDK7 functions as the CDK-activating kinase (CAK), essential for activating other CDKs, while CDK9 acts as a critical integrator of signals from both the cell cycle and transcriptional machinery. This review elucidates the mechanisms by which CDK7 and CDK9 regulate the mitotic process and cell cycle checkpoints, emphasizing their roles in balancing cell growth, homeostasis, and DNA repair through transcriptional control.
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Affiliation(s)
- Cheng-Fan Lee
- Cancer Ecology Center, The Brady Urological Institute, Johns Hopkins School of Medicine, Baltimore, USA
| | - Kenneth J Pienta
- Cancer Ecology Center, The Brady Urological Institute, Johns Hopkins School of Medicine, Baltimore, USA
| | - Sarah R Amend
- Cancer Ecology Center, The Brady Urological Institute, Johns Hopkins School of Medicine, Baltimore, USA
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2
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Oikonomidi I, Kameswaran V, Pham VC, Zuazo-Gaztelu I, Gutgesell LM, Marsters S, Daniel B, Lill JR, Modrusan Z, Ashkenazi A. Interferon regulatory factor 4 mediates nonenzymatic IRE1 dependency in multiple myeloma cells. PLoS Biol 2025; 23:e3003096. [PMID: 40215234 PMCID: PMC12052183 DOI: 10.1371/journal.pbio.3003096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2024] [Revised: 05/05/2025] [Accepted: 03/04/2025] [Indexed: 05/07/2025] Open
Abstract
Multiple myeloma (MM) arises through oncogenic transformation of immunoglobulin-secreting plasma cells. MM often co-opts the central endoplasmic reticulum (ER)-stress mitigator, inositol-requiring enzyme 1 (IRE1), to sustain malignant growth. While certain MMs require enzymatic IRE1-dependent activation of the transcription factor XBP1s, others display a nonenzymatic IRE1 dependency that is not yet mechanistically understood. Here we identify interferon regulatory factor 4 (IRF4), which stimulates genes that promote immune-cell proliferation, as a key conduit for IRE1's nonenzymatic control of cell-cycle progression in MM. IRE1 silencing increased inhibitory S114/S270 phosphorylation on IRF4, disrupting IRF4's chromatin-binding and transcriptional activity. IRF4 knockdown recapitulated, whereas IRF4 repletion reversed, the anti-proliferative phenotype of IRE1 silencing. Furthermore, phospho-deficient, but not phospho-mimetic, IRF4 mutants rescued proliferation under IRE1 silencing. Functional studies revealed that IRF4 engages the E2F1 and CDC25A genes and promotes CDK2 activation to drive cell-cycle progression. Our results advance mechanistic understanding of IRE1 and IRF4 in MM.
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Affiliation(s)
- Ioanna Oikonomidi
- Department of Research Oncology, Genentech, Inc., South San Francisco, California, United States of America
| | - Vasumathi Kameswaran
- Department of Proteomic and Genomic Technologies, Genentech, Inc., South San Francisco, California, United States of America
| | - Victoria C. Pham
- Department of Proteomic and Genomic Technologies, Genentech, Inc., South San Francisco, California, United States of America
| | - Iratxe Zuazo-Gaztelu
- Department of Research Oncology, Genentech, Inc., South San Francisco, California, United States of America
| | - Lauren M. Gutgesell
- Department of Research Oncology, Genentech, Inc., South San Francisco, California, United States of America
| | - Scot Marsters
- Department of Research Oncology, Genentech, Inc., South San Francisco, California, United States of America
| | - Bence Daniel
- Department of Proteomic and Genomic Technologies, Genentech, Inc., South San Francisco, California, United States of America
| | - Jennie R. Lill
- Department of Proteomic and Genomic Technologies, Genentech, Inc., South San Francisco, California, United States of America
| | - Zora Modrusan
- Department of Proteomic and Genomic Technologies, Genentech, Inc., South San Francisco, California, United States of America
| | - Avi Ashkenazi
- Department of Research Oncology, Genentech, Inc., South San Francisco, California, United States of America
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3
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Kumarasamy V, Wang J, Roti M, Wan Y, Dommer AP, Rosenheck H, Putta S, Trub A, Bisi J, Strum J, Roberts P, Rubin SM, Frangou C, McLean K, Witkiewicz AK, Knudsen ES. Discrete vulnerability to pharmacological CDK2 inhibition is governed by heterogeneity of the cancer cell cycle. Nat Commun 2025; 16:1476. [PMID: 39924553 PMCID: PMC11808123 DOI: 10.1038/s41467-025-56674-4] [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: 05/08/2024] [Accepted: 01/27/2025] [Indexed: 02/11/2025] Open
Abstract
Cyclin dependent kinase 2 (CDK2) regulates cell cycle and is an emerging target for cancer therapy. There are relatively small numbers of tumor models that exhibit strong dependence on CDK2 and undergo G1 cell cycle arrest following CDK2 inhibition. The expression of P16INK4A and cyclin E1 determines this sensitivity to CDK2 inhibition. The co-expression of these genes occurs in breast cancer patients highlighting their clinical significance as predictive biomarkers for CDK2-targeted therapies. In cancer models that are genetically independent of CDK2, pharmacological inhibitors suppress cell proliferation by inducing 4N cell cycle arrest and increasing the expressions of phospho-CDK1 (Y15) and cyclin B1. CRISPR screens identify CDK2 loss as a mediator of resistance to a CDK2 inhibitor, INX-315. Furthermore, CDK2 deletion reverses the G2/M block induced by CDK2 inhibitors and restores cell proliferation. Complementary drug screens define multiple means to cooperate with CDK2 inhibition beyond G1/S. These include the depletion of mitotic regulators as well as CDK4/6 inhibitors cooperate with CDK2 inhibition in multiple phases of the cell cycle. Overall, this study underscores two fundamentally distinct features of response to CDK2 inhibitors that are conditioned by tumor context and could serve as the basis for differential therapeutic strategies in a wide range of cancers.
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Affiliation(s)
- Vishnu Kumarasamy
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Jianxin Wang
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Michelle Roti
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Yin Wan
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Adam P Dommer
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Hanna Rosenheck
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Sivasankar Putta
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | | | | | | | | | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Costakis Frangou
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Karen McLean
- Department of Pharmacology and Therapeutics, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Agnieszka K Witkiewicz
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA.
| | - Erik S Knudsen
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA.
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4
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Pellarin I, Dall'Acqua A, Favero A, Segatto I, Rossi V, Crestan N, Karimbayli J, Belletti B, Baldassarre G. Cyclin-dependent protein kinases and cell cycle regulation in biology and disease. Signal Transduct Target Ther 2025; 10:11. [PMID: 39800748 PMCID: PMC11734941 DOI: 10.1038/s41392-024-02080-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Revised: 10/16/2024] [Accepted: 11/13/2024] [Indexed: 01/18/2025] Open
Abstract
Cyclin Dependent Kinases (CDKs) are closely connected to the regulation of cell cycle progression, having been first identified as the kinases able to drive cell division. In reality, the human genome contains 20 different CDKs, which can be divided in at least three different sub-family with different functions, mechanisms of regulation, expression patterns and subcellular localization. Most of these kinases play fundamental roles the normal physiology of eucaryotic cells; therefore, their deregulation is associated with the onset and/or progression of multiple human disease including but not limited to neoplastic and neurodegenerative conditions. Here, we describe the functions of CDKs, categorized into the three main functional groups in which they are classified, highlighting the most relevant pathways that drive their expression and functions. We then discuss the potential roles and deregulation of CDKs in human pathologies, with a particular focus on cancer, the human disease in which CDKs have been most extensively studied and explored as therapeutic targets. Finally, we discuss how CDKs inhibitors have become standard therapies in selected human cancers and propose novel ways of investigation to export their targeting from cancer to other relevant chronic diseases. We hope that the effort we made in collecting all available information on both the prominent and lesser-known CDK family members will help in identify and develop novel areas of research to improve the lives of patients affected by debilitating chronic diseases.
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Affiliation(s)
- Ilenia Pellarin
- Division of Molecular Oncology, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, National Cancer Institute, Aviano, Italy
| | - Alessandra Dall'Acqua
- Division of Molecular Oncology, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, National Cancer Institute, Aviano, Italy
| | - Andrea Favero
- Division of Molecular Oncology, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, National Cancer Institute, Aviano, Italy
| | - Ilenia Segatto
- Division of Molecular Oncology, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, National Cancer Institute, Aviano, Italy
| | - Valentina Rossi
- Division of Molecular Oncology, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, National Cancer Institute, Aviano, Italy
| | - Nicole Crestan
- Division of Molecular Oncology, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, National Cancer Institute, Aviano, Italy
| | - Javad Karimbayli
- Division of Molecular Oncology, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, National Cancer Institute, Aviano, Italy
| | - Barbara Belletti
- Division of Molecular Oncology, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, National Cancer Institute, Aviano, Italy
| | - Gustavo Baldassarre
- Division of Molecular Oncology, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, National Cancer Institute, Aviano, Italy.
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5
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Wang Q, Bode AM, Zhang T. Targeting CDK1 in cancer: mechanisms and implications. NPJ Precis Oncol 2023; 7:58. [PMID: 37311884 DOI: 10.1038/s41698-023-00407-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 05/25/2023] [Indexed: 06/15/2023] Open
Abstract
Cyclin dependent kinases (CDKs) are serine/threonine kinases that are proposed as promising candidate targets for cancer treatment. These proteins complexed with cyclins play a critical role in cell cycle progression. Most CDKs demonstrate substantially higher expression in cancer tissues compared with normal tissues and, according to the TCGA database, correlate with survival rate in multiple cancer types. Deregulation of CDK1 has been shown to be closely associated with tumorigenesis. CDK1 activation plays a critical role in a wide range of cancer types; and CDK1 phosphorylation of its many substrates greatly influences their function in tumorigenesis. Enrichment of CDK1 interacting proteins with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was conducted to demonstrate that the associated proteins participate in multiple oncogenic pathways. This abundance of evidence clearly supports CDK1 as a promising target for cancer therapy. A number of small molecules targeting CDK1 or multiple CDKs have been developed and evaluated in preclinical studies. Notably, some of these small molecules have also been subjected to human clinical trials. This review evaluates the mechanisms and implications of targeting CDK1 in tumorigenesis and cancer therapy.
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Affiliation(s)
- Qiushi Wang
- The Hormel Institute, University of Minnesota, 801 16th Ave NE, Austin, MN, 55912, USA
| | - Ann M Bode
- The Hormel Institute, University of Minnesota, 801 16th Ave NE, Austin, MN, 55912, USA.
| | - Tianshun Zhang
- The Hormel Institute, University of Minnesota, 801 16th Ave NE, Austin, MN, 55912, USA.
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6
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Al-Rawi A, Kaye E, Korolchuk S, Endicott JA, Ly T. Cyclin A and Cks1 promote kinase consensus switching to non-proline-directed CDK1 phosphorylation. Cell Rep 2023; 42:112139. [PMID: 36840943 DOI: 10.1016/j.celrep.2023.112139] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 11/17/2022] [Accepted: 02/02/2023] [Indexed: 02/26/2023] Open
Abstract
Ordered protein phosphorylation by CDKs is a key mechanism for regulating the cell cycle. How temporal order is enforced in mammalian cells remains unclear. Using a fixed cell kinase assay and phosphoproteomics, we show how CDK1 activity and non-catalytic CDK1 subunits contribute to the choice of substrate and site of phosphorylation. Increases in CDK1 activity alter substrate choice, with intermediate- and low-sensitivity CDK1 substrates enriched in DNA replication and mitotic functions, respectively. This activity dependence is shared between Cyclin A- and Cyclin B-CDK1. Cks1 has a proteome-wide role as an enhancer of multisite CDK1 phosphorylation. Contrary to the model of CDK1 as an exclusively proline-directed kinase, we show that Cyclin A and Cks1 enhance non-proline-directed phosphorylation, preferably on sites with a +3 lysine residue. Indeed, 70% of cell-cycle-regulated phosphorylations, where the kinase carrying out this modification has not been identified, are non-proline-directed CDK1 sites.
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Affiliation(s)
- Aymen Al-Rawi
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK; Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Edward Kaye
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | | | - Jane A Endicott
- Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Tony Ly
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK; Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK.
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7
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Meng X, Zhu X, Ji J, Zhong H, Li X, Zhao H, Xie G, Wang K, Shu H, Wang X. Erdafitinib Inhibits Tumorigenesis of Human Lung Adenocarcinoma A549 by Inducing S-Phase Cell-Cycle Arrest as a CDK2 Inhibitor. Molecules 2022; 27:6733. [PMID: 36235266 PMCID: PMC9573074 DOI: 10.3390/molecules27196733] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/25/2022] [Accepted: 10/06/2022] [Indexed: 11/16/2022] Open
Abstract
Lung adenocarcinoma (LADC) is the most prevalent lung cancer sub-type, and targeted therapy developed in recent years has made progress in its treatment. Erdafitinib, a potent and selective pan-FGFR tyrosine kinase inhibitor, has been confirmed to be effective for the treatment of LADC; however, the molecular mechanism responsible for this effect is unclear. The in vitro study showed that erdafitinib exhibited an outstanding anti-cancer activity in human LADC cell line A549 by inducing S-phase cell-cycle arrest and cell apoptosis. The mechanistic study based on the transcriptomic data revealed that erdafitinib exerted its anti-cancer effect by affecting the cell cycle-related pathway, and CDK2 was the regulatory target of this drug. In addition, CDK2 overexpression significantly attenuated the anti-cancer effect of erdafitinib by affecting the transcriptional activity and expression of E2F1, as well as the expression of CDK1. The in vivo study showed that erdafitinib presented an obvious anti-cancer effect in the A549 xenograft mice model, which was accompanied by the reduced expression of CDK2. Thus, this study demonstrates the anti-cancer effect of erdafitinib against LADC for the first time based on in vitro and in vivo models, whose activity is achieved by targeting CDK2 and regulating downstream E2F1-CDK1 signaling. This study may be helpful for expanding the clinical application of erdafitinib in treating LADC.
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Affiliation(s)
- Xinmin Meng
- Department of Clinical Laboratory, Guangxi Medical University Cancer Hospital, Nanning 530021, China
| | - Xue Zhu
- National Health Commission (NHC) Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
- Department of Radiopharmaceuticals, School of Pharmacy, Nanjing Medical University, Nanjing 210000, China
| | - Jiali Ji
- Department of Respiratory and Critical Care Medicine, The Affiliated Wuxi No.2 People’s Hospital of Nanjing Medical University, Wuxi 214002, China
| | - Hongqin Zhong
- Department of Respiratory and Critical Care Medicine, Wuxi Clinical College Affiliated to Nantong University, Wuxi 214002, China
| | - Xiyue Li
- Department of Respiratory and Critical Care Medicine, The Affiliated Wuxi No.2 People’s Hospital of Nanjing Medical University, Wuxi 214002, China
| | - Hongqing Zhao
- Department of Respiratory and Critical Care Medicine, The Affiliated Wuxi No.2 People’s Hospital of Nanjing Medical University, Wuxi 214002, China
| | - Guijuan Xie
- Department of Respiratory and Critical Care Medicine, The Affiliated Wuxi No.2 People’s Hospital of Nanjing Medical University, Wuxi 214002, China
| | - Ke Wang
- National Health Commission (NHC) Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
- Department of Radiopharmaceuticals, School of Pharmacy, Nanjing Medical University, Nanjing 210000, China
| | - Hong Shu
- Department of Clinical Laboratory, Guangxi Medical University Cancer Hospital, Nanning 530021, China
| | - Xun Wang
- Department of Respiratory and Critical Care Medicine, The Affiliated Wuxi No.2 People’s Hospital of Nanjing Medical University, Wuxi 214002, China
- Department of Respiratory and Critical Care Medicine, Wuxi Clinical College Affiliated to Nantong University, Wuxi 214002, China
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8
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Teng C, Zhu Y, Li Y, Dai L, Pan Z, Wanggou S, Li X. Recurrence- and Malignant Progression-Associated Biomarkers in Low-Grade Gliomas and Their Roles in Immunotherapy. Front Immunol 2022; 13:899710. [PMID: 35677036 PMCID: PMC9168984 DOI: 10.3389/fimmu.2022.899710] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 04/12/2022] [Indexed: 12/15/2022] Open
Abstract
Despite a generally better prognosis than high-grade glioma (HGG), recurrence and malignant progression are the main causes for the poor prognosis and difficulties in the treatment of low-grade glioma (LGG). It is of great importance to learn about the risk factors and underlying mechanisms of LGG recurrence and progression. In this study, the transcriptome characteristics of four groups, namely, normal brain tissue and recurrent LGG (rLGG), normal brain tissue and secondary glioblastoma (sGBM), primary LGG (pLGG) and rLGG, and pLGG and sGBM, were compared using Chinese Glioma Genome Atlas (CGGA) and Genotype-Tissue Expression Project (GTEx) databases. In this study, 296 downregulated and 396 upregulated differentially expressed genes (DEGs) with high consensus were screened out. Univariate Cox regression analysis of data from The Cancer Genome Atlas (TCGA) yielded 86 prognostically relevant DEGs; a prognostic prediction model based on five key genes (HOXA1, KIF18A, FAM133A, HGF, and MN1) was established using the least absolute shrinkage and selection operator (LASSO) regression dimensionality reduction and multivariate Cox regression analysis. LGG was divided into high- and low-risk groups using this prediction model. Gene Set Enrichment Analysis (GSEA) revealed that signaling pathway differences in the high- and low-risk groups were mainly seen in tumor immune regulation and DNA damage-related cell cycle checkpoints. Furthermore, the infiltration of immune cells in the high- and low-risk groups was analyzed, which indicated a stronger infiltration of immune cells in the high-risk group than that in the low-risk group, suggesting that an immune microenvironment more conducive to tumor growth emerged due to the interaction between tumor and immune cells. The tumor mutational burden and tumor methylation burden in the high- and low-risk groups were also analyzed, which indicated higher gene mutation burden and lower DNA methylation level in the high-risk group, suggesting that with the accumulation of genomic mutations and epigenetic changes, tumor cells continued to evolve and led to the progression of LGG to HGG. Finally, the value of potential therapeutic targets for the five key genes was analyzed, and findings demonstrated that KIF18A was the gene most likely to be a potential therapeutic target. In conclusion, the prediction model based on these five key genes can better identify the high- and low-risk groups of LGG and lay a solid foundation for evaluating the risk of LGG recurrence and malignant progression.
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Affiliation(s)
- Chubei Teng
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China.,Department of Neurosurgery, The First Affiliated Hospital, University of South China, Hengyang, China
| | - Yongwei Zhu
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Yueshuo Li
- Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Luohuan Dai
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Zhouyang Pan
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Siyi Wanggou
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Xuejun Li
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
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9
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Clemm von Hohenberg K, Müller S, Schleich S, Meister M, Bohlen J, Hofmann TG, Teleman AA. Cyclin B/CDK1 and Cyclin A/CDK2 phosphorylate DENR to promote mitotic protein translation and faithful cell division. Nat Commun 2022; 13:668. [PMID: 35115540 PMCID: PMC8813921 DOI: 10.1038/s41467-022-28265-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 01/12/2022] [Indexed: 12/11/2022] Open
Abstract
DENR and MCTS1 have been identified as oncogenes in several different tumor entities. The heterodimeric DENR·MCTS1 protein complex promotes translation of mRNAs containing upstream Open Reading Frames (uORFs). We show here that DENR is phosphorylated on Serine 73 by Cyclin B/CDK1 and Cyclin A/CDK2 at the onset of mitosis, and then dephosphorylated as cells exit mitosis. Phosphorylation of Ser73 promotes mitotic stability of DENR protein and prevents its cleavage at Asp26. This leads to enhanced translation of mRNAs involved in mitosis. Indeed, we find that roughly 40% of all mRNAs with elevated translation in mitosis are DENR targets. In the absence of DENR or of Ser73 phosphorylation, cells display elevated levels of aberrant mitoses and cell death. This provides a mechanism how the cell cycle regulates translation of a subset of mitotically relevant mRNAs during mitosis.
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Affiliation(s)
- Katharina Clemm von Hohenberg
- German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- Heidelberg University, 69120, Heidelberg, Germany
- CellNetworks-Cluster of Excellence, Heidelberg University, Heidelberg, Germany
- Department of Medicine III, Universitätsmedizin Mannheim, 68167, Mannheim, Germany
| | - Sandra Müller
- German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- Heidelberg University, 69120, Heidelberg, Germany
| | - Sibylle Schleich
- German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- Heidelberg University, 69120, Heidelberg, Germany
| | - Matthias Meister
- Division of Viral Transformation Mechanisms, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Jonathan Bohlen
- German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
- Heidelberg University, 69120, Heidelberg, Germany
- CellNetworks-Cluster of Excellence, Heidelberg University, Heidelberg, Germany
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, INSERM U1163, Paris, France
- University of Paris, Imagine Institute, Paris, France
| | - Thomas G Hofmann
- Institute of Toxicology, University Medical Center Mainz at the Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Aurelio A Teleman
- German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany.
- Heidelberg University, 69120, Heidelberg, Germany.
- CellNetworks-Cluster of Excellence, Heidelberg University, Heidelberg, Germany.
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10
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Chen Q, Zhang J, Wang J, Xie Y, Cui Y, Du X, Li L, Fu J, Liu Y, Wang J, Wang G, Gu R. Small kernel 501 (smk501) encodes the RUBylation activating enzyme E1 subunit ECR1 (E1 C-TERMINAL RELATED 1) and is essential for multiple aspects of cellular events during kernel development in maize. THE NEW PHYTOLOGIST 2021; 230:2337-2354. [PMID: 33749863 DOI: 10.1111/nph.17354] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/13/2021] [Indexed: 05/27/2023]
Abstract
RUBylation plays essential roles in plant growth and development through regulating Cullin-RING ubiquitin E3 ligase (CRL) activities and the CRL-mediated protein degradations. However, the function of RUBylation in regulating kernel development remains unclear. Through genetic and molecular analyses of a small kernel 501 (smk501) mutant in maize (Zea mays), we cloned the smk501 gene, revealed its molecular function, and defined its roles in RUBylation pathway and seed development. Smk501 encodes a RUBylation activating enzyme E1 subunit ZmECR1 (E1 C-TERMINAL RELATED 1) protein. Destruction in RUBylation by smk501 mutation resulted in less embryo and endosperm cell number and smaller kernel size. The transcriptome and proteome profiling, hormone evaluation and cell proliferation observation revealed that disturbing ZmECR1 expression mainly affects pathways on hormone signal transduction, cell cycle progression and starch accumulation during kernel development. In addition, mutant in zmaxr1 (Auxin resistant 1), another RUB E1 subunit, also showed similar defects in kernel development. Double mutation of zmecr1 and zmaxr1 lead to empty pericarp kernel phenotype. RUBylation is a novel regulatory pathway affecting maize kernel development, majorly through its functions in modifying multiple cellular progresses.
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Affiliation(s)
- Quanquan Chen
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, Key Laboratory of Crop Heterosis Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Jie Zhang
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, Key Laboratory of Crop Heterosis Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China
| | - Jie Wang
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, Key Laboratory of Crop Heterosis Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China
| | - Yuxin Xie
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Yu Cui
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Xuemei Du
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, Key Laboratory of Crop Heterosis Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China
| | - Li Li
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, Key Laboratory of Crop Heterosis Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China
| | - Junjie Fu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Yunjun Liu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Jianhua Wang
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, Key Laboratory of Crop Heterosis Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China
| | - Guoying Wang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Riliang Gu
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, Key Laboratory of Crop Heterosis Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China
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11
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Torky ZA, Moussa AY, Abdelghffar EA, Abdel-Hameed UK, Eldahshan OA. Chemical profiling, antiviral and antiproliferative activities of the essential oil of Phlomis aurea Decne grown in Egypt. Food Funct 2021; 12:4630-4643. [PMID: 33912870 DOI: 10.1039/d0fo03417g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here, we investigated the chemical composition of the edible Phlomis aurea oil and its anticancer potential on three human cancer cell lines, as well as its antiviral activity against Herpes simplex-1 (HSV-1). Exploring Phlomis aurea Decne essential oil by gas chromatography coupled with mass spectrometry (GC/MS) revealed the presence of four major components: germacrene D (51.56%), trans-β-farnesene (11.36%), α-pinene (22.96%) & limonene (6.26%). An antiproliferative effect, as determined by the MTT assay, against human hepatic, breast and colon cancer cell lines, manifested IC50 values of 10.14, 328.02, & 628.43 μg mL-1, respectively. Cytotoxicity assay of the Phlomis oil against Vero cell lines revealed a safe profile within the range of 50 μg ml-1. Phlomis essential oil induced the apoptosis of HepG2 cells through increasing cell accumulation in sub G1 & G2/M phases, decreasing both S & G0/G1 phases of the cell cycle, triggering both caspases-3 &-9, and inhibiting cyclin dependent kinase-2 (CDK2). The antiviral activity of the oil against HSV-1 was investigated using the plaque reduction assay, which showed 80% of virus inhibition. Moreover, the molecular docking in silico study of the four major chemical constituents of the oil at the CDK2 binding site demonstrated marked interactions with the ATP-binding site residues through alkyl & Pi-alkyl interactions. Cell cycle distribution of HepG2 cells was studied using flow cytometry to highlight the apoptotic mechanistic approaches by measuring caspases-3 &-9 and CDK2 activities. Thus, the edible Phlomis oil can be regarded as a candidate for in vivo studies to prove that it is a promising natural antiviral/anticancer agent.
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Affiliation(s)
- Zenab Aly Torky
- Department of Microbiology, Faculty of Science, Ain Shams University, Egypt
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12
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Silva Cascales H, Burdova K, Middleton A, Kuzin V, Müllers E, Stoy H, Baranello L, Macurek L, Lindqvist A. Cyclin A2 localises in the cytoplasm at the S/G2 transition to activate PLK1. Life Sci Alliance 2021; 4:e202000980. [PMID: 33402344 PMCID: PMC7812317 DOI: 10.26508/lsa.202000980] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 01/23/2023] Open
Abstract
Cyclin A2 is a key regulator of the cell cycle, implicated both in DNA replication and mitotic entry. Cyclin A2 participates in feedback loops that activate mitotic kinases in G2 phase, but why active Cyclin A2-CDK2 during the S phase does not trigger mitotic kinase activation remains unclear. Here, we describe a change in localisation of Cyclin A2 from being only nuclear to both nuclear and cytoplasmic at the S/G2 border. We find that Cyclin A2-CDK2 can activate the mitotic kinase PLK1 through phosphorylation of Bora, and that only cytoplasmic Cyclin A2 interacts with Bora and PLK1. Expression of predominately cytoplasmic Cyclin A2 or phospho-mimicking PLK1 T210D can partially rescue a G2 arrest caused by Cyclin A2 depletion. Cytoplasmic presence of Cyclin A2 is restricted by p21, in particular after DNA damage. Cyclin A2 chromatin association during DNA replication and additional mechanisms contribute to Cyclin A2 localisation change in the G2 phase. We find no evidence that such mechanisms involve G2 feedback loops and suggest that cytoplasmic appearance of Cyclin A2 at the S/G2 transition functions as a trigger for mitotic kinase activation.
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Affiliation(s)
| | - Kamila Burdova
- Laboratory of Cancer Cell Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Anna Middleton
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Vladislav Kuzin
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Erik Müllers
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Henriette Stoy
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Laura Baranello
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Libor Macurek
- Laboratory of Cancer Cell Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Arne Lindqvist
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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13
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Mohallem R, Aryal UK. Regulators of TNFα mediated insulin resistance elucidated by quantitative proteomics. Sci Rep 2020; 10:20878. [PMID: 33257747 PMCID: PMC7705713 DOI: 10.1038/s41598-020-77914-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/03/2020] [Indexed: 12/21/2022] Open
Abstract
Obesity is a growing epidemic worldwide and is a major risk factor for several chronic diseases, including diabetes, kidney disease, heart disease, and cancer. Obesity often leads to type 2 diabetes mellitus, via the increased production of proinflammatory cytokines such as tumor necrosis factor-α (TNFα). Our study combines different proteomic techniques to investigate the changes in the global proteome, secretome and phosphoproteome of adipocytes under chronic inflammation condition, as well as fundamental cross-talks between different cellular pathways regulated by chronic TNFα exposure. Our results show that many key regulator proteins of the canonical and non-canonical NF-κB pathways, such as Nfkb2, and its downstream effectors, including Csf-1 and Lgals3bp, directly involved in leukocyte migration and invasion, were significantly upregulated at the intra and extracellular proteomes suggesting the progression of inflammation. Our data provides evidence of several key proteins that play a role in the development of insulin resistance.
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Affiliation(s)
- Rodrigo Mohallem
- Department of Comparative Pathobiology, Purdue University, West Lafayette, USA
- Purdue Proteomics Facility, Bindley Bioscience Center, Purdue University, West Lafayette, USA
| | - Uma K Aryal
- Department of Comparative Pathobiology, Purdue University, West Lafayette, USA.
- Purdue Proteomics Facility, Bindley Bioscience Center, Purdue University, West Lafayette, USA.
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14
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Markiewicz E, Idowu OC. DNA damage in human skin and the capacities of natural compounds to modulate the bystander signalling. Open Biol 2019; 9:190208. [PMID: 31847786 PMCID: PMC6936251 DOI: 10.1098/rsob.190208] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 11/19/2019] [Indexed: 12/20/2022] Open
Abstract
Human skin is a stratified organ frequently exposed to sun-generated ultraviolet radiation (UVR), which is considered one of the major factors responsible for DNA damage. Such damage can be direct, through interactions of DNA with UV photons, or indirect, mainly through enhanced production of reactive oxygen species that introduce oxidative changes to the DNA. Oxidative stress and DNA damage also associate with profound changes at the cellular and molecular level involving several cell cycle and signal transduction factors responsible for DNA repair or irreversible changes linked to ageing. Crucially, some of these factors constitute part of the signalling known for the induction of biological changes in non-irradiated, neighbouring cells and defined as the bystander effect. Network interactions with a number of natural compounds, based on their known activity towards these biomarkers in the skin, reveal the capacity to inhibit both the bystander signalling and cell cycle/DNA damage molecules while increasing expression of the anti-oxidant enzymes. Based on this information, we discuss the likely polypharmacology applications of the natural compounds and next-generation screening technologies in improving the anti-oxidant and DNA repair capacities of the skin.
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15
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Warren NJH, Donahue KL, Eastman A. Differential Sensitivity to CDK2 Inhibition Discriminates the Molecular Mechanisms of CHK1 Inhibitors as Monotherapy or in Combination with the Topoisomerase I Inhibitor SN38. ACS Pharmacol Transl Sci 2019; 2:168-182. [PMID: 32259055 DOI: 10.1021/acsptsci.9b00001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Indexed: 02/06/2023]
Abstract
DNA damage activates checkpoints to arrest cell cycle progression in S and G2 phases, thereby providing time for repair and recovery. The combination of DNA-damaging agents and inhibitors of CHK1 (CHK1i) is an emerging strategy for sensitizing cancer cells. CHK1i induce replication on damaged DNA and mitosis before repair is complete, and this occurs in a majority of cell lines. However, ∼15% of cancer cell lines are hypersensitive to single-agent CHK1i. As both abrogation of S phase arrest and single-agent activity depend on CDK2, this study resolved how activation of CDK2 can be essential for both replication and cytotoxicity. S phase arrest was induced with the topoisomerase I inhibitor SN38; the addition of CHK1i rapidly activated CDK2, inducing S phase progression that was inhibited by the CDK2 inhibitor CVT-313. In contrast, DNA damage and cytotoxicity induced by single-agent CHK1i in hypersensitive cell lines were also inhibited by CVT-313 but at 20-fold lower concentrations. The differential sensitivity to CVT-313 is explained by different activity thresholds required for phosphorylation of CDK2 substrates. While the critical CDK2 substrates are not yet defined, we conclude that hypersensitivity to single-agent CHK1i depends on phosphorylation of substrates that require high CDK2 activity levels. Surprisingly, CHK1i did not increase SN38-mediated cytotoxicity. In contrast, while inhibition of WEE1 also abrogated S phase arrest, it more directly activated CDK1, induced premature mitosis, and enhanced cytotoxicity. Hence, while high activity of CDK2 is critical for cytotoxicity of single-agent CHK1i, CDK1 is additionally required for sensitivity to the drug combination.
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Affiliation(s)
- Nicholas J H Warren
- Geisel School of Medicine at Dartmouth and Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, New Hampshire 03756, United States
| | - Katelyn L Donahue
- Geisel School of Medicine at Dartmouth and Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, New Hampshire 03756, United States
| | - Alan Eastman
- Geisel School of Medicine at Dartmouth and Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, New Hampshire 03756, United States
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16
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Kundrotas G, Gasperskaja E, Slapsyte G, Gudleviciene Z, Krasko J, Stumbryte A, Liudkeviciene R. Identity, proliferation capacity, genomic stability and novel senescence markers of mesenchymal stem cells isolated from low volume of human bone marrow. Oncotarget 2017; 7:10788-802. [PMID: 26910916 PMCID: PMC4905439 DOI: 10.18632/oncotarget.7456] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 02/05/2016] [Indexed: 12/16/2022] Open
Abstract
Human bone marrow mesenchymal stem cells (hBM-MSCs) hold promise for treating incurable diseases and repairing of damaged tissues. However, hBM-MSCs face the disadvantages of painful invasive isolation and limited cell numbers. In this study we assessed characteristics of MSCs isolated from residual human bone marrow transplantation material and expanded to clinically relevant numbers at passages 3-4 and 6-7. Results indicated that early passage hBM-MSCs are genomically stable and retain identity and high proliferation capacity. Despite the chromosomal stability, the cells became senescent at late passages, paralleling the slower proliferation, altered morphology and immunophenotype. By qRT-PCR array profiling, we revealed 13 genes and 33 miRNAs significantly differentially expressed in late passage cells, among which 8 genes and 30 miRNAs emerged as potential novel biomarkers of hBM-MSC aging. Functional analysis of genes with altered expression showed strong association with biological processes causing cellular senescence. Altogether, this study revives hBM as convenient source for cellular therapy. Potential novel markers provide new details for better understanding the hBM-MSC senescence mechanisms, contributing to basic science, facilitating the development of cellular therapy quality control, and providing new clues for human disease processes since senescence phenotype of the hematological patient hBM-MSCs only very recently has been revealed.
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Affiliation(s)
- Gabrielis Kundrotas
- Department of Botany and Genetics, Faculty of Natural Sciences, Vilnius University, Vilnius, Lithuania.,Biobank, National Cancer Institute, Vilnius, Lithuania
| | - Evelina Gasperskaja
- Department of Botany and Genetics, Faculty of Natural Sciences, Vilnius University, Vilnius, Lithuania
| | - Grazina Slapsyte
- Department of Botany and Genetics, Faculty of Natural Sciences, Vilnius University, Vilnius, Lithuania
| | | | - Jan Krasko
- Laboratory of Immunology, National Cancer Institute, Vilnius, Lithuania
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17
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Cdk2 strengthens the intra-S checkpoint and counteracts cell cycle exit induced by DNA damage. Sci Rep 2017; 7:13429. [PMID: 29044141 PMCID: PMC5647392 DOI: 10.1038/s41598-017-12868-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 07/17/2017] [Indexed: 02/03/2023] Open
Abstract
Although cyclin-dependent kinase 2 (Cdk2) controls the G1/S transition and promotes DNA replication, it is dispensable for cell cycle progression due to redundancy with Cdk1. Yet Cdk2 also has non-redundant functions that can be revealed in certain genetic backgrounds and it was reported to promote the G2/M DNA damage response checkpoint in TP53 (p53)-deficient cancer cells. However, in p53-proficient cells subjected to DNA damage, Cdk2 is inactivated by the CDK inhibitor p21. We therefore investigated whether Cdk2 differentially affects checkpoint responses in p53-proficient and deficient cell lines. We show that, independently of p53 status, Cdk2 stimulates the ATR/Chk1 pathway and is required for an efficient DNA replication checkpoint response. In contrast, Cdk2 is not required for a sustained DNA damage response and G2 arrest. Rather, eliminating Cdk2 delays S/G2 progression after DNA damage and accelerates appearance of early markers of cell cycle exit. Notably, Cdk2 knockdown leads to down-regulation of Cdk6, which we show is a non-redundant pRb kinase whose elimination compromises cell cycle progression. Our data reinforce the notion that Cdk2 is a key p21 target in the DNA damage response whose inactivation promotes exit from the cell cycle in G2.
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18
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Allen L, Buckner A, Buckner CA, Cano P, Lafrenie RM. Uncaria tomentosa (Willd. ex Schult.) DC (Rubiaceae) Sensitizes THP-1 Cells to Radiation-induced Cell Death. Pharmacognosy Res 2017; 9:221-229. [PMID: 28827961 PMCID: PMC5541476 DOI: 10.4103/pr.pr_83_16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Background: Uncaria tomentosa (Willd. ex Schult.) DC (Rubiaceae), known as Cat's Claw or Uña de gato, is a traditionally used medicinal plant native to Peru. Some studies have shown that U. tomentosa can act as an antiapoptotic agent and enhance DNA repair in chemotherapy-treated cells although others have shown that U. tomentosa enhanced apoptosis. Objective: To determine if treatment with U. tomentosa can significantly enhance cell death in THP-1 cells exposed to ionizing radiation. Materials and Methods: THP-1 monocyte-like cells were treated with ethanolic extracts of U. tomentosa in the presence or absence of bacterial lipopolysaccharide and then exposed to ionizing radiation. Cell proliferation was assessed by MTT and clonogenic assays and the effects on cell cycle measured by flow cytometry and immunoblotting. Changes in cell signaling were determined by immunoblotting and cytokine ELISA and activation of apoptosis measured by caspase activation and DNA fragmentation analysis. Results: Treatment of THP-1 cells with U. tomentosa had a small effect on cell proliferation. However, when the U. tomentosa-pretreated cells were also subjected to 5–9 Gy ionizing radiation, they showed a significant decrease in cell proliferation and increased cellular apoptosis as measured by DNA fragmentation and caspase activation. Treatment with U. tomentosa also decreased the expression of Cyclin E and Cyclin B, key regulators of normal cell cycle progression, and decreased the phosphorylation of various stress-activated, cell survival proteins including p38, ERK, and SAP/JNK kinase. Conclusions: These results suggest that U. tomentosa could be useful in enhancing cell death following anticancer therapies including ionizing radiation. SUMMARY Treatment of THP-1 cells with Uncaria tomentosa increases their susceptibility to X-rays. The combination of Uncaria tomentosa and X-ray exposure strongly inhibits cell signaling and promotes apoptosis.
Abbreviations Used: LPS: Lipopolysaccharide, TNF: Tumor necrosis factor: IL-1, Interleukin-1: SDS: Sodium dodecylsulphate, TBS: Tris-buffered saline.
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Affiliation(s)
- Lisa Allen
- Program in Biomolecular Science, Laurentian University, Sudbury, ON P3E 2C6, Canada.,Health Sciences North, Sudbury, ON P3E 5J1, Canada
| | - Alison Buckner
- Program in Biomolecular Science, Laurentian University, Sudbury, ON P3E 2C6, Canada.,Health Sciences North, Sudbury, ON P3E 5J1, Canada
| | - Carly A Buckner
- Program in Biomolecular Science, Laurentian University, Sudbury, ON P3E 2C6, Canada.,Health Sciences North, Sudbury, ON P3E 5J1, Canada
| | - Pablo Cano
- Health Sciences North, Sudbury, ON P3E 5J1, Canada
| | - Robert M Lafrenie
- Program in Biomolecular Science, Laurentian University, Sudbury, ON P3E 2C6, Canada.,Health Sciences North, Sudbury, ON P3E 5J1, Canada.,Division of Medical Science, Northern Ontario School of Medicine, Sudbury, ON P3E 2C6, Canada.,Health Sciences North Research Institute, Sudbury, ON, P3E 5J1, Canada
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19
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Mazzolini L, Broban A, Froment C, Burlet-Schiltz O, Besson A, Manenti S, Dozier C. Phosphorylation of CDC25A on SER283 in late S/G2 by CDK/cyclin complexes accelerates mitotic entry. Cell Cycle 2016; 15:2742-52. [PMID: 27580187 DOI: 10.1080/15384101.2016.1220455] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Cdc25A phosphatase is an essential activator of CDK-cyclin complexes at all steps of the eukaryotic cell cycle. The activity of Cdc25A is itself regulated in part by positive and negative feedback regulatory loops performed by its CDK-cyclin substrates that occur in G1 as well as during the G1/S and G2/M transitions. However, the regulation of Cdc25A during G2 phase progression before mitotic entry has not been intensively characterized. Here, we identify by mass spectrometry analysis a new phosphorylation event of Cdc25A on Serine283. Phospho-specific antibodies revealed that the phosphorylation of this residue appears in late S/G2 phase of an unperturbed cell cycle and is performed by CDK-cyclin complexes. Overexpression studies of wild-type and non-phosphorylatable mutant forms of Cdc25A indicated that Ser283 phosphorylation increases the G2/M-promoting activity of the phosphatase without impacting its stability or subcellular localization. Our results therefore identify a new positive regulatory loop between Cdc25A and its CDK-cyclin substrates which contributes to accelerate entry into mitosis through the regulation of Cdc25A activity in G2.
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Affiliation(s)
- Laurent Mazzolini
- a Centre de Recherche en Cancérologie de Toulouse, INSERM UMR1037, CNRS ERL5294 , Université Toulouse III Paul Sabatier , Toulouse , France.,b Equipe labellisée LIGUE contre le Cancer , CNRS ERL5294 , Toulouse , France
| | - Anaïs Broban
- a Centre de Recherche en Cancérologie de Toulouse, INSERM UMR1037, CNRS ERL5294 , Université Toulouse III Paul Sabatier , Toulouse , France
| | - Carine Froment
- c Institut de Pharmacologie et de Biologie Structurale , Université Toulouse III Paul Sabatier Toulouse , CNRS UMR5089 , Toulouse , France
| | - Odile Burlet-Schiltz
- c Institut de Pharmacologie et de Biologie Structurale , Université Toulouse III Paul Sabatier Toulouse , CNRS UMR5089 , Toulouse , France
| | - Arnaud Besson
- a Centre de Recherche en Cancérologie de Toulouse, INSERM UMR1037, CNRS ERL5294 , Université Toulouse III Paul Sabatier , Toulouse , France.,b Equipe labellisée LIGUE contre le Cancer , CNRS ERL5294 , Toulouse , France
| | - Stéphane Manenti
- a Centre de Recherche en Cancérologie de Toulouse, INSERM UMR1037, CNRS ERL5294 , Université Toulouse III Paul Sabatier , Toulouse , France.,b Equipe labellisée LIGUE contre le Cancer , CNRS ERL5294 , Toulouse , France
| | - Christine Dozier
- a Centre de Recherche en Cancérologie de Toulouse, INSERM UMR1037, CNRS ERL5294 , Université Toulouse III Paul Sabatier , Toulouse , France.,b Equipe labellisée LIGUE contre le Cancer , CNRS ERL5294 , Toulouse , France
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20
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Iskit S, Lieftink C, Halonen P, Shahrabi A, Possik PA, Beijersbergen RL, Peeper DS. Integrated in vivo genetic and pharmacologic screening identifies co-inhibition of EGRF and ROCK as a potential treatment regimen for triple-negative breast cancer. Oncotarget 2016; 7:42859-42872. [PMID: 27374095 PMCID: PMC5189992 DOI: 10.18632/oncotarget.10230] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 06/09/2016] [Indexed: 12/21/2022] Open
Abstract
Breast cancer is the second most common cause of cancer-related deaths worldwide among women. Despite several therapeutic options, 15% of breast cancer patients succumb to the disease owing to tumor relapse and acquired therapy resistance. Particularly in triple-negative breast cancer (TNBC), developing effective treatments remains challenging owing to the lack of a common vulnerability that can be exploited by targeted approaches. We have previously shown that tumor cells have different requirements for growth in vivo than in vitro. Therefore, to discover novel drug targets for TNBC, we performed parallel in vivo and in vitro genetic shRNA dropout screens. We identified several potential drug targets that were required for tumor growth in vivo to a greater extent than in vitro. By combining pharmacologic inhibitors acting on a subset of these candidates, we identified a synergistic interaction between EGFR and ROCK inhibitors. This combination effectively reduced TNBC cell growth by inducing cell cycle arrest. These results illustrate the power of in vivo genetic screens and warrant further validation of EGFR and ROCK as combined pharmacologic targets for breast cancer.
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Affiliation(s)
- Sedef Iskit
- Department of Molecular Oncology, The Netherlands Cancer Institute, Plesmanlaan, Amsterdam, The Netherlands
| | - Cor Lieftink
- Department of Molecular Carcinogenesis, The Netherlands Cancer Institute, Plesmanlaan, Amsterdam, The Netherlands
| | - Pasi Halonen
- Drug Discovery Research and Screening Services, BioFocus, Darwinweg, Leiden
| | - Aida Shahrabi
- Department of Molecular Oncology, The Netherlands Cancer Institute, Plesmanlaan, Amsterdam, The Netherlands
| | | | - Roderick L. Beijersbergen
- Department of Molecular Carcinogenesis, The Netherlands Cancer Institute, Plesmanlaan, Amsterdam, The Netherlands
| | - Daniel S. Peeper
- Department of Molecular Oncology, The Netherlands Cancer Institute, Plesmanlaan, Amsterdam, The Netherlands
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21
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Cdk2 catalytic activity is essential for meiotic cell division in vivo. Biochem J 2016; 473:2783-98. [PMID: 27371320 DOI: 10.1042/bcj20160607] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 06/29/2016] [Indexed: 01/18/2023]
Abstract
Cyclin-dependent kinases (Cdks) control the eukaryotic cell cycle by phosphorylating serine and threonine residues in key regulatory proteins, but some Cdk family members may exert kinase-independent functions that cannot easily be assessed using gene knockout approaches. While Cdk2-deficient mice display near-normal mitotic cell proliferation due to the compensatory activities of Cdk1 and Cdk4, they are unable to undergo meiotic generation of gametes and are consequently sterile. To investigate whether Cdk2 regulates meiosis via protein phosphorylation or by alternative kinase-independent mechanisms, we generated two different knockin mouse strains in which Cdk2 point mutations ablated enzyme activity without altering protein expression levels. Mice homozygous for the mutations Cdk2(D145N/D145N) or Cdk2(T160A/T160A) expressed only 'kinase-dead' variants of Cdk2 under the control of the endogenous promoter, and despite exhibiting normal expression of cell cycle regulatory proteins and complexes, both mutations rendered mice sterile. Mouse cells that expressed only 'kinase-dead' variants of Cdk2 displayed normal mitotic cell cycle progression and proliferation both in vitro and in vivo, indicating that loss of Cdk2 kinase activity exerted little effect on this mode of cell division. In contrast, the reproductive organs of Cdk2 mutant mice exhibited abnormal morphology and impaired function associated with defective meiotic cell division and inability to produce gametes. Cdk2 mutant animals were therefore comparable to gene knockout mice, which completely lack the Cdk2 protein. Together, our data indicate that the essential meiotic functions of Cdk2 depend on its kinase activity, without which the generation of haploid cells is disrupted, resulting in sterility of otherwise healthy animals.
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22
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Gold-Smith F, Fernandez A, Bishop K. Mangiferin and Cancer: Mechanisms of Action. Nutrients 2016; 8:E396. [PMID: 27367721 PMCID: PMC4963872 DOI: 10.3390/nu8070396] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 05/30/2016] [Accepted: 06/22/2016] [Indexed: 01/30/2023] Open
Abstract
Mangiferin, a bioactive compound derived primarily from Anacardiaceae and Gentianaceae families and found in mangoes and honeybush tea, has been extensively studied for its therapeutic properties. Mangiferin has shown promising chemotherapeutic and chemopreventative potential. This review focuses on the effect of mangiferin on: (1) inflammation, with respect to NFκB, PPARү and the immune system; (2) cell cycle, the MAPK pathway G₂/M checkpoint; (3) proliferation and metastasis, and implications on β-catenin, MMPs, EMT, angiogenesis and tumour volume; (4) apoptosis, with a focus on Bax/Bcl ratios, intrinsic/extrinsic apoptotic pathways and telomerase activity; (5) oxidative stress, through Nrf2/ARE signalling, ROS elimination and catalase activity; and (6) efficacy of chemotherapeutic agents, such as oxaliplatin, etoposide and doxorubicin. In addition, the need to enhance the bioavailability and delivery of mangiferin are briefly addressed, as well as the potential for toxicity.
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Affiliation(s)
- Fuchsia Gold-Smith
- Auckland Cancer Society Research Center, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
| | - Alyssa Fernandez
- Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
| | - Karen Bishop
- Auckland Cancer Society Research Center, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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Li QQ, Hao JJ, Zhang Z, Hsu I, Liu Y, Tao Z, Lewi K, Metwalli AR, Agarwal PK. Histone deacetylase inhibitor-induced cell death in bladder cancer is associated with chromatin modification and modifying protein expression: A proteomic approach. Int J Oncol 2016; 48:2591-607. [PMID: 27082124 PMCID: PMC4864178 DOI: 10.3892/ijo.2016.3478] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 03/17/2016] [Indexed: 12/19/2022] Open
Abstract
The Cancer Genome Atlas (TCGA) project recently identified the importance of mutations in chromatin remodeling genes in human carcinomas. These findings imply that epigenetic modulators might have a therapeutic role in urothelial cancers. To exploit histone deacetylases (HDACs) as targets for cancer therapy, we investigated the HDAC inhibitors (HDACIs) romidepsin, trichostatin A, and vorinostat as potential chemotherapeutic agents for bladder cancer. We demonstrate that the three HDACIs suppressed cell growth and induced cell death in the bladder cancer cell line 5637. To identify potential mechanisms associated with the anti-proliferative and cytotoxic effects of the HDACIs, we used quantitative proteomics to determine the proteins potentially involved in these processes. Our proteome studies identified a total of 6003 unique proteins. Of these, 2472 proteins were upregulated and 2049 proteins were downregulated in response to HDACI exposure compared to the untreated controls (P<0.05). Bioinformatic analysis further revealed that those differentially expressed proteins were involved in multiple biological functions and enzyme-regulated pathways, including cell cycle progression, apoptosis, autophagy, free radical generation and DNA damage repair. HDACIs also altered the acetylation status of histones and non-histone proteins, as well as the levels of chromatin modification proteins, suggesting that HDACIs exert multiple cytotoxic actions in bladder cancer cells by inhibiting HDAC activity or altering the structure of chromatin. We conclude that HDACIs are effective in the inhibition of cell proliferation and the induction of apoptosis in the 5637 bladder cancer cells through multiple cell death-associated pathways. These observations support the notion that HDACIs provide new therapeutic options for bladder cancer treatment and thus warrant further preclinical exploration.
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Affiliation(s)
- Qingdi Quentin Li
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | - Zheng Zhang
- Poochon Scientific, Frederick, MD 21704, USA
| | - Iawen Hsu
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yi Liu
- Poochon Scientific, Frederick, MD 21704, USA
| | - Zhen Tao
- Poochon Scientific, Frederick, MD 21704, USA
| | - Keidren Lewi
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Adam R Metwalli
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Piyush K Agarwal
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Oakes V, Wang W, Harrington B, Lee WJ, Beamish H, Chia KM, Pinder A, Goto H, Inagaki M, Pavey S, Gabrielli B. Cyclin A/Cdk2 regulates Cdh1 and claspin during late S/G2 phase of the cell cycle. Cell Cycle 2015; 13:3302-11. [PMID: 25485510 DOI: 10.4161/15384101.2014.949111] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Whereas many components regulating the progression from S phase through G2 phase into mitosis have been identified, the mechanism by which these components control this critical cell cycle progression is still not fully elucidated. Cyclin A/Cdk2 has been shown to regulate the timing of Cyclin B/Cdk1 activation and progression into mitosis although the mechanism by which this occurs is only poorly understood. Here we show that depletion of Cyclin A or inhibition of Cdk2 during late S/early G2 phase maintains the G2 phase arrest by reducing Cdh1 transcript and protein levels, thereby stabilizing Claspin and maintaining elevated levels of activated Chk1 which contributes to the G2 phase observed. Interestingly, the Cyclin A/Cdk2 regulated APC/C(Cdh1) activity is selective for only a subset of Cdh1 targets including Claspin. Thus, a normal role for Cyclin A/Cdk2 during early G2 phase is to increase the level of Cdh1 which destabilises Claspin which in turn down regulates Chk1 activation to allow progression into mitosis. This mechanism links S phase exit with G2 phase transit into mitosis, provides a novel insight into the roles of Cyclin A/Cdk2 in G2 phase progression, and identifies a novel role for APC/C(Cdh1) in late S/G2 phase cell cycle progression.
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Affiliation(s)
- Vanessa Oakes
- a The University of Queensland Diamantina Institute; Translational Research Institute ; Brisbane , Queensland , Australia
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25
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Lv TZ, Wang GS. Antiproliferation potential of withaferin A on human osteosarcoma cells via the inhibition of G2/M checkpoint proteins. Exp Ther Med 2015; 10:323-329. [PMID: 26170956 DOI: 10.3892/etm.2015.2480] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 02/24/2015] [Indexed: 12/12/2022] Open
Abstract
Withaferin A (WA) is a well-known steroidal lactone of the medicinally important plant, Withania somnifera. This secondary metabolite has been noted for its anticancer effects against a number of human cancer cell lines. However, there are a limited number of studies investigating the growth inhibitory potential of WA against human osteosarcoma cells and the underlying molecular mechanisms. Thus, in the present study, the antiproliferative activities of WA, along with the underlying mechanisms of action, were investigated using flow cytometry for cell cycle distribution and western blot analysis for the assessment of various checkpoint proteins. In addition, the antiproliferative activity was evaluated using a sulforhodamine B assay, where MG-63 and U2OS human osteosarcoma cell lines were treated with different concentrations of WA. Furthermore, the mRNA expression levels of the checkpoint proteins in the WA-treated MG-63 and U2OS cells were examined. The results obtained corresponded with the western blot analysis results. Furthermore, WA was shown to significantly inhibit the proliferation of the two types of treated cell lines (MG-63 and U2OS). Flow cytometric analysis revealed that WA induced cell cycle arrest at the G2/M phase, which was associated with the inhibition of cyclin B1, cyclin A, Cdk2 and p-Cdc2 (Tyr15) expression and an increase in the levels of p-Chk1 (Ser345) and p-Chk2 (Thr68). In conclusion, the present study found that the antiproliferative potential of WA was associated with the induction of cell cycle arrest at the G2/M phase, which was a result of the attenuation of the expression levels of G2/M checkpoint proteins.
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Affiliation(s)
- Ting-Zhuo Lv
- Department of Orthopedics, Baodi District People's Hospital of Tianjin City, Tianjin 301800, P.R. China
| | - Guang-Shun Wang
- Department of Orthopedics, Baodi District People's Hospital of Tianjin City, Tianjin 301800, P.R. China
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26
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Linzen U, Lilischkis R, Pandithage R, Schilling B, Ullius A, Lüscher-Firzlaff J, Kremmer E, Lüscher B, Vervoorts J. ING5 is phosphorylated by CDK2 and controls cell proliferation independently of p53. PLoS One 2015; 10:e0123736. [PMID: 25860957 PMCID: PMC4393124 DOI: 10.1371/journal.pone.0123736] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 02/27/2015] [Indexed: 11/19/2022] Open
Abstract
Inhibitor of growth (ING) proteins have multiple functions in the control of cell proliferation, mainly by regulating processes associated with chromatin regulation and gene expression. ING5 has been described to regulate aspects of gene transcription and replication. Moreover deregulation of ING5 is observed in different tumors, potentially functioning as a tumor suppressor. Gene transcription in late G1 and in S phase and replication is regulated by cyclin-dependent kinase 2 (CDK2) in complex with cyclin E or cyclin A. CDK2 complexes phosphorylate and regulate several substrate proteins relevant for overcoming the restriction point and promoting S phase. We have identified ING5 as a novel CDK2 substrate. ING5 is phosphorylated at a single site, threonine 152, by cyclin E/CDK2 and cyclin A/CDK2 in vitro. This site is also phosphorylated in cells in a cell cycle dependent manner, consistent with it being a CDK2 substrate. Furthermore overexpression of cyclin E/CDK2 stimulates while the CDK2 inhibitor p27KIP1 represses phosphorylation at threonine 152. This site is located in a bipartite nuclear localization sequence but its phosphorylation was not sufficient to deregulate the subcellular localization of ING5. Although ING5 interacts with the tumor suppressor p53, we could not establish p53-dependent regulation of cell proliferation by ING5 and by phospho-site mutants. Instead we observed that the knockdown of ING5 resulted in a strong reduction of proliferation in different tumor cell lines, irrespective of the p53 status. This inhibition of proliferation was at least in part due to the induction of apoptosis. In summary we identified a phosphorylation site at threonine 152 of ING5 that is cell cycle regulated and we observed that ING5 is necessary for tumor cell proliferation, without any apparent dependency on the tumor suppressor p53.
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Affiliation(s)
- Ulrike Linzen
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, Pauwelsstrasse 30, 52057, Aachen, Germany
| | - Richard Lilischkis
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, Pauwelsstrasse 30, 52057, Aachen, Germany
| | - Ruwin Pandithage
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, Pauwelsstrasse 30, 52057, Aachen, Germany
| | - Britta Schilling
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, Pauwelsstrasse 30, 52057, Aachen, Germany
| | - Andrea Ullius
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, Pauwelsstrasse 30, 52057, Aachen, Germany
| | - Juliane Lüscher-Firzlaff
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, Pauwelsstrasse 30, 52057, Aachen, Germany
| | - Elisabeth Kremmer
- Helmholtz Zentrum München, Institute of Molecular Immunology, Marchioninistrasse 25, 81377, München, Germany
| | - Bernhard Lüscher
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, Pauwelsstrasse 30, 52057, Aachen, Germany
- * E-mail: (BL); (JV)
| | - Jörg Vervoorts
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, Pauwelsstrasse 30, 52057, Aachen, Germany
- * E-mail: (BL); (JV)
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PUL21a-Cyclin A2 interaction is required to protect human cytomegalovirus-infected cells from the deleterious consequences of mitotic entry. PLoS Pathog 2014; 10:e1004514. [PMID: 25393019 PMCID: PMC4231158 DOI: 10.1371/journal.ppat.1004514] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 10/11/2014] [Indexed: 12/02/2022] Open
Abstract
Entry into mitosis is accompanied by dramatic changes in cellular architecture, metabolism and gene expression. Many viruses have evolved cell cycle arrest strategies to prevent mitotic entry, presumably to ensure sustained, uninterrupted viral replication. Here we show for human cytomegalovirus (HCMV) what happens if the viral cell cycle arrest mechanism is disabled and cells engaged in viral replication enter into unscheduled mitosis. We made use of an HCMV mutant that, due to a defective Cyclin A2 binding motif in its UL21a gene product (pUL21a), has lost its ability to down-regulate Cyclin A2 and, therefore, to arrest cells at the G1/S transition. Cyclin A2 up-regulation in infected cells not only triggered the onset of cellular DNA synthesis, but also promoted the accumulation and nuclear translocation of Cyclin B1-CDK1, premature chromatin condensation and mitotic entry. The infected cells were able to enter metaphase as shown by nuclear lamina disassembly and, often irregular, metaphase spindle formation. However, anaphase onset was blocked by the still intact anaphase promoting complex/cyclosome (APC/C) inhibitory function of pUL21a. Remarkably, the essential viral IE2, but not the related chromosome-associated IE1 protein, disappeared upon mitotic entry, suggesting an inherent instability of IE2 under mitotic conditions. Viral DNA synthesis was impaired in mitosis, as demonstrated by the abnormal morphology and strongly reduced BrdU incorporation rates of viral replication compartments. The prolonged metaphase arrest in infected cells coincided with precocious sister chromatid separation and progressive fragmentation of the chromosomal material. We conclude that the Cyclin A2-binding function of pUL21a contributes to the maintenance of a cell cycle state conducive for the completion of the HCMV replication cycle. Unscheduled mitotic entry during the course of the HCMV replication has fatal consequences, leading to abortive infection and cell death. Cyclin A2 is a key regulator of the cell division cycle. Interactors of Cyclin A2 typically contain short sequence elements (RXL/Cy motifs) that bind with high affinity to a hydrophobic patch in the Cyclin A2 protein. Two types of RXL/Cy-containing factors are known: i) cyclin-dependent kinase (CDK) substrates, which are processed by the CDK subunit that complexes to Cyclin A2, and ii) CDK inhibitors, which stably associate to Cyclin A2-CDK due to the lack of CDK phosphorylation sites. Human cytomegalovirus (HCMV) has evolved a novel type of RXL/Cy-containing protein. Its UL21a gene product, a small and highly unstable protein, binds to Cyclin A2 via an RXL/Cy motif in its N-terminus, leading to efficient degradation of Cyclin A2 by the proteasome. Here, we show that this mechanism is not only essential for viral inhibition of cellular DNA synthesis, but also to prevent entry of infected cells into mitosis. Unscheduled mitotic entry is followed by aberrant spindle formation, metaphase arrest, precocious separation of sister chromatids, chromosomal fragmentation and cell death. Viral DNA replication and expression of the essential viral IE2 protein are abrogated in mitosis. Thus, pUL21a-Cyclin A2 interaction protects HCMV from a collapse of viral and cellular functions in mitosis.
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Hong JY, Park SH, Min HY, Park HJ, Lee SK. Anti-proliferative effects of evodiamine in human lung cancer cells. J Cancer Prev 2014; 19:7-13. [PMID: 25337567 PMCID: PMC4189475 DOI: 10.15430/jcp.2014.19.1.7] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 03/18/2014] [Accepted: 03/18/2014] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Evodiamine, a compound isolated from the Evodia rutaecarpa Bentham (Rutaceae), is known to have a potential anti-proliferative activity in human cancer cells. However, the growth inhibitory activity against lung cancer cells and the underlying molecular mechanisms have been poorly determined. The present study was designed to examine the anti-proliferative effect of evodiamine in A549 human lung cancer cells. METHODS A549 cells were treated with the compounds from Evodia rutaecarpa, and the anti-proliferative activity was evaluated by the sulforhodamine B assay. The mechanisms of action for the growth inhibitory activity of evodiamine on A549 human lung cancer cells were evaluated using flow cytometry for cell cycle distribution, and Western blot for assessment of accumulation and phosphorylation of potential target proteins. RESULTS Evodiamine exhibited a potent anti-proliferative activity against A549 human lung cancer cells. Flow cytometric analysis revealed that evodiamine induced cell cycle arrest at G2/M phase and apoptosis in the A549 cells. The cell cycle arrest was well correlated with the inhibition of cyclin B1, cyclin A, cdk2 and p-cdc2 (Tyr15) and increase of p-chk1 (Ser345) and p-chk2 (Thr68). Evodiamine also significantly increased the ratio of Bax/Bcl-2 and decreased procaspase-3, suggesting evodiamine-induced apoptosis via the intrinsic apoptotic pathway. In addition, evodiamine inhibited the expression of p-ERK and ERK. CONCLUSIONS These findings suggest that the anti-proliferative effect of evodiamine was associated in part with the induction of G2/M phase cell cycle arrest and apoptosis, and down-regulation of ERK in human lung cancer cells.
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Affiliation(s)
- Ji-Young Hong
- College of Pharmacy, Seoul National University, Seoul, Korea
| | - So Hyun Park
- College of Pharmacy, Seoul National University, Seoul, Korea
| | - Hye-Young Min
- College of Pharmacy, Seoul National University, Seoul, Korea
| | - Hyen Joo Park
- College of Pharmacy, Seoul National University, Seoul, Korea
| | - Sang Kook Lee
- College of Pharmacy, Seoul National University, Seoul, Korea
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29
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Abstract
Rapid progression through the cell cycle and a very short G1 phase are defining characteristics of embryonic stem cells. This distinct cell cycle is driven by a positive feedback loop involving Rb inactivation and reduced oscillations of cyclins and cyclin-dependent kinase (Cdk) activity. In this setting, we inquired how ES cells avoid the potentially deleterious consequences of premature mitotic entry. We found that the pluripotency transcription factor Oct4 (octamer-binding transcription factor 4) plays an unappreciated role in the ES cell cycle by forming a complex with cyclin-Cdk1 and inhibiting Cdk1 activation. Ectopic expression of Oct4 or a mutant lacking transcriptional activity recapitulated delayed mitotic entry in HeLa cells. Reduction of Oct4 levels in ES cells accelerated G2 progression, which led to increased chromosomal missegregation and apoptosis. Our data demonstrate an unexpected nontranscriptional function of Oct4 in the regulation of mitotic entry.
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30
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Lin T, Wan L, Qi X, Shi W, Lin J. A moderate static magnetic field enhances TRAIL-induced apoptosis by the inhibition of Cdc2 and subsequent downregulation of survivin in human breast carcinoma cells. Bioelectromagnetics 2014; 35:337-46. [PMID: 24619849 DOI: 10.1002/bem.21849] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Accepted: 01/28/2014] [Indexed: 01/04/2023]
Abstract
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) exhibits its potent antitumor activity via membrane receptors on cancer cells without deleterious side effects for normal tissue. However, as many other cancer types, breast cancer cells develop a resistance to TRAIL. In the present study, we reported that exposure to 3.0 mT static magnetic field (SMF) mediated the sensitization of breast cancer cells to TRAIL-induced apoptosis. This effect was significantly reduced by the forced expression of survivin, suggesting the sensitization was mediated at least in part through the inhibition of survivin expression. In addition, SMF alone or in combination with TRAIL induced a cell cycle arrest within the G2 /M phase, and the reduction in the survivin protein level was associated with the downregulated expression of Cdc2, a cyclin B-dependent kinase that is necessary for the entry into the M phase. Taken together, our results demonstrated that SMF promoted TRAIL-induced apoptosis by inhibiting the expression of Cdc2 and, subsequently, survivin. Of note, SMF did not sensitize untransformed human mammary epithelial cells to TRAIL-mediated apoptosis. Therefore, the combined treatment of SMF and TRAIL may offer an attractive strategy for safely treating resistant breast cancers.
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Affiliation(s)
- Tingting Lin
- College of Instrumentation and Electrical Engineering, Jilin University, Changchun, People's Republic of China
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31
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Cell cycle: mechanisms of control and dysregulation in cancer. Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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32
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Purification and biochemical analysis of catalytically active human cdc25C dual specificity phosphatase. Biochimie 2013; 95:1450-61. [DOI: 10.1016/j.biochi.2013.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 03/22/2013] [Indexed: 11/18/2022]
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33
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Augello MA, Ostrander WF, Knudsen KE. Beyond the Cell Cycle: Implications of D-type Cyclin Deregulation in Prostate Cancer. Prostate Cancer 2013. [DOI: 10.1007/978-1-4614-6828-8_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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34
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Shen T, Huang S. The Role of Cdc25A in the Regulation of Cell Proliferation and Apoptosis. Anticancer Agents Med Chem 2012; 12:631-9. [DOI: 10.2174/187152012800617678] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 12/22/2011] [Accepted: 12/31/2011] [Indexed: 12/11/2022]
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35
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Kabadi SV, Stoica BA, Hanscom M, Loane DJ, Kharebava G, Murray II MG, Cabatbat RM, Faden AI. CR8, a selective and potent CDK inhibitor, provides neuroprotection in experimental traumatic brain injury. Neurotherapeutics 2012; 9:405-21. [PMID: 22167461 PMCID: PMC3324621 DOI: 10.1007/s13311-011-0095-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Traumatic brain injury (TBI) induces secondary injury mechanisms, including cell cycle activation (CCA), that leads to neuronal death and neurological dysfunction. We recently reported that delayed administration of roscovitine, a relatively selective cyclin-dependent kinase (CDK) inhibitor, inhibits CCA and attenuates neurodegeneration and functional deficits following controlled cortical impact (CCI) injury in mice. Here we evaluated the neuroprotective potential of CR8, a more potent second-generation roscovitine analog, using the mouse CCI model. Key CCA markers (cyclin A and B1) were significantly up-regulated in the injured cortex following TBI, and phosphorylation of CDK substrates was increased. Central administration of CR8 after TBI, at a dose 20 times less than previously required for roscovitine, attenuated CCA pathways and reduced post-traumatic apoptotic cell death at 24 h post-TBI. Central administration of CR8, at 3 h after TBI, significantly attenuated sensorimotor and cognitive deficits, decreased lesion volume, and improved neuronal survival in the cortex and dentate gyrus. Moreover, unlike roscovitine treatment in the same model, CR8 also attenuated post-traumatic neurodegeneration in the CA3 region of the hippocampus and thalamus at 21 days. Furthermore, delayed systemic administration of CR8, at a dose 10 times less than previously required for roscovitine, significantly improved cognitive performance after CCI. These findings further demonstrate the neuroprotective potential of cell cycle inhibitors following experimental TBI. Given the increased potency and efficacy of CR8 as compared to earlier purine analog types of CDK inhibitors, this drug should be considered as a candidate for future clinical trials of TBI.
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Affiliation(s)
- Shruti V. Kabadi
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Bogdan A. Stoica
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Marie Hanscom
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - David J. Loane
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Giorgi Kharebava
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Michael G. Murray II
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Rainier M. Cabatbat
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Alan I. Faden
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201 USA
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Abstract
Mitosis is associated with profound changes in cell physiology and a spectacular surge in protein phosphorylation. To accomplish these, a remarkably large portion of the kinome is involved in the process. In the present review, we will focus on classic mitotic kinases, such as cyclin-dependent kinases, Polo-like kinases and Aurora kinases, as well as more recently characterized players such as NIMA (never in mitosis in Aspergillus nidulans)-related kinases, Greatwall and Haspin. Together, these kinases co-ordinate the proper timing and fidelity of processes including centrosomal functions, spindle assembly and microtubule-kinetochore attachment, as well as sister chromatid separation and cytokinesis. A recurrent theme of the mitotic kinase network is the prevalence of elaborated feedback loops that ensure bistable conditions. Sequential phosphorylation and priming phosphorylation on substrates are also frequently employed. Another important concept is the role of scaffolds, such as centrosomes for protein kinases during mitosis. Elucidating the entire repertoire of mitotic kinases, their functions, regulation and interactions is critical for our understanding of normal cell growth and in diseases such as cancers.
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Geminin escapes degradation in G1 of mouse pluripotent cells and mediates the expression of Oct4, Sox2, and Nanog. Curr Biol 2011; 21:692-9. [PMID: 21497086 PMCID: PMC3083515 DOI: 10.1016/j.cub.2011.03.026] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 02/25/2011] [Accepted: 03/09/2011] [Indexed: 11/21/2022]
Abstract
Geminin is an essential cell-cycle protein that is only present from S phase to early mitosis in metazoan somatic cells [1, 2]. Genetic ablation of geminin in the mouse results in preimplantation embryonic lethality because pluripotent cells fail to form and all cells differentiate to trophoblast [3, 4]. Here we show that geminin is present in G1 phase of mouse pluripotent cells in contrast to somatic cells, where anaphase-promoting complex/cyclosome (APC/C)-mediated proteasomal destruction removes geminin in G1 [1, 2, 5]. Silencing geminin directly or by depleting the APC/C inhibitor Emi1 causes loss of stem cell identity and trophoblast differentiation of mouse embryonal carcinoma and embryonic stem cells. Depletion of cyclins A2 or B1 does not induce this effect, even though both of these APC/C substrates are also present during G1 of pluripotent cells. Crucially, geminin antagonizes the chromatin-remodeling protein Brg1 to maintain expression of Oct4, Sox2, and Nanog. Our results define a pluripotency pathway by which suppressed APC/C activity protects geminin from degradation in G1, allowing sustained expression of core pluripotency factors. Collectively, these findings link the cell cycle to the pluripotent state but also raise an unexplained paradox: How is cell-cycle progression possible in pluripotent cells when oscillations of key regulatory proteins are lost?
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Corrionero A, Miñana B, Valcárcel J. Reduced fidelity of branch point recognition and alternative splicing induced by the anti-tumor drug spliceostatin A. Genes Dev 2011; 25:445-59. [PMID: 21363963 DOI: 10.1101/gad.2014311] [Citation(s) in RCA: 217] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Spliceostatin A (SSA) is a stabilized derivative of a Pseudomonas bacterial fermentation product that displays potent anti-proliferative and anti-tumor activities in cancer cells and animal models. The drug inhibits pre-mRNA splicing in vitro and in vivo and binds SF3b, a protein subcomplex of U2 small nuclear ribonucleoprotein (snRNP), which is essential for recognition of the pre-mRNA branch point. We report that SSA prevents interaction of an SF3b 155-kDa subunit with the pre-mRNA, concomitant with nonproductive recruitment of U2 snRNP to sequences 5' of the branch point. Differences in base-pairing potential with U2 snRNA in this region lead to different sensitivity of 3' splice sites to SSA, and to SSA-induced changes in alternative splicing. Indeed, rather than general splicing inhibition, splicing-sensitive microarray analyses reveal specific alternative splicing changes induced by the drug that significantly overlap with those induced by knockdown of SF3b 155. These changes lead to down-regulation of genes important for cell division, including cyclin A2 and Aurora A kinase, thus providing an explanation for the anti-proliferative effects of SSA. Our results reveal a mechanism that prevents nonproductive base-pairing interactions in the spliceosome, and highlight the regulatory and cancer therapeutic potential of perturbing the fidelity of splice site recognition.
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Enders GH. Gauchos and ochos: a Wee1-Cdk tango regulating mitotic entry. Cell Div 2010; 5:12. [PMID: 20465818 PMCID: PMC2886006 DOI: 10.1186/1747-1028-5-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 05/13/2010] [Indexed: 01/12/2023] Open
Abstract
The kinase Wee1 has been recognized for a quarter century as a key inhibitor of Cyclin dependent kinase 1 (Cdk1) and mitotic entry in eukaryotes. Nonetheless, Wee1 regulation is not well understood and its large amino-terminal regulatory domain (NRD) has remained largely uncharted. Evidence has accumulated that cyclin B/Cdk1 complexes reciprocally inhibit Wee1 activity through NRD phosphorylation. Recent studies have identified the first functional NRD elements and suggested that vertebrate cyclin A/Cdk2 complexes also phosphorylate the NRD. A short NRD peptide, termed the Wee box, augments the activity of the Wee1 kinase domain. Cdk1/2-mediated phosphorylation of the Wee box (on T239) antagonizes kinase activity. A nearby region harbors a conserved RxL motif (RxL1) that promotes cyclin A/Cdk2 binding and T239 phosphorylation. Mutation of either T239 or RxL1 bolsters the ability of Wee1 to block mitotic entry, consistent with negative regulation of Wee1 through these sites. The region in human somatic Wee1 that encompasses RxL1 also binds Crm1, directing Wee1 export from the nucleus. These studies have illuminated important aspects of Wee1 regulation and defined a specific molecular pathway through which cyclin A/Cdk2 complexes foster mitotic entry. The complexity, speed, and importance of regulation of mitotic entry suggest that there is more to be learned.
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Affiliation(s)
- Greg H Enders
- Department of Medicine, Fox Chase Cancer Center, 333 Cottman, Philadelphia, PA 19111, USA.
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Timofeev O, Cizmecioglu O, Settele F, Kempf T, Hoffmann I. Cdc25 phosphatases are required for timely assembly of CDK1-cyclin B at the G2/M transition. J Biol Chem 2010; 285:16978-90. [PMID: 20360007 DOI: 10.1074/jbc.m109.096552] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Progression through mitosis requires the coordinated regulation of Cdk1 kinase activity. Activation of Cdk1 is a multistep process comprising binding of Cdk1 to cyclin B, relocation of cyclin-kinase complexes to the nucleus, activating phosphorylation of Cdk1 on Thr(161) by the Cdk-activating kinase (CAK; Cdk7 in metazoans), and removal of inhibitory Thr(14) and Tyr(15) phosphorylations. This dephosphorylation is catalyzed by the dual specific Cdc25 phosphatases, which occur in three isoforms in mammalian cells, Cdc25A, -B, and -C. We find that expression of Cdc25A leads to an accelerated G(2)/M phase transition. In Cdc25A-overexpressing cells, Cdk1 exhibits high kinase activity despite being phosphorylated on Tyr(15). In addition, Tyr(15)-phosphorylated Cdk1 binds more cyclin B in Cdc25A-overexpressing cells compared with control cells. Consistent with this observation, we demonstrate that in human transformed cells, Cdc25A and Cdc25B, but not Cdc25C phosphatases have an effect on timing and efficiency of cyclin-kinase complex formation. Overexpression of Cdc25A or Cdc25B promotes earlier assembly and activation of Cdk1-cyclin B complexes, whereas repression of these phosphatases by short hairpin RNA has a reverse effect, leading to a substantial decrease in amounts of cyclin B-bound Cdk1 in G(2) and mitosis. Importantly, we find that Cdc25A overexpression leads to an activation of Cdk7 and increase in Thr(161) phosphorylation of Cdk1. In conclusion, our data suggest that complex assembly and dephosphorylation of Cdk1 at G(2)/M is tightly coupled and regulated by Cdc25 phosphatases.
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Affiliation(s)
- Oleg Timofeev
- Cell Cycle Control and Carcinogenesis, German Cancer Research Center, F045, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
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Chung JH, Bunz F. Cdk2 is required for p53-independent G2/M checkpoint control. PLoS Genet 2010; 6:e1000863. [PMID: 20195506 PMCID: PMC2829054 DOI: 10.1371/journal.pgen.1000863] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 01/28/2010] [Indexed: 01/03/2023] Open
Abstract
The activation of phase-specific cyclin-dependent kinases (Cdks) is associated with ordered cell cycle transitions. Among the mammalian Cdks, only Cdk1 is essential for somatic cell proliferation. Cdk1 can apparently substitute for Cdk2, Cdk4, and Cdk6, which are individually dispensable in mice. It is unclear if all functions of non-essential Cdks are fully redundant with Cdk1. Using a genetic approach, we show that Cdk2, the S-phase Cdk, uniquely controls the G2/M checkpoint that prevents cells with damaged DNA from initiating mitosis. CDK2-nullizygous human cells exposed to ionizing radiation failed to exclude Cdk1 from the nucleus and exhibited a marked defect in G2/M arrest that was unmasked by the disruption of P53. The DNA replication licensing protein Cdc6, which is normally stabilized by Cdk2, was physically associated with the checkpoint regulator ATR and was required for efficient ATR-Chk1-Cdc25A signaling. These findings demonstrate that Cdk2 maintains a balance of S-phase regulatory proteins and thereby coordinates subsequent p53-independent G2/M checkpoint activation. Metazoan cells contain multiple Cdks that regulate cell cycle progression. Recent studies have shown that mouse cells can grow normally with just Cdk1. The roles of the non-essential Cdks remain a fundamental question. In this study, we describe the generation and detailed characterization of CDK2-knockout human somatic cells. Our study demonstrates that Cdk2 is required for robust DNA damage checkpoint signaling. Loss of Cdk2 caused a marked deficiency in the G2/M arrest—a basic response to DNA damage—in cells that were also nullizygous for P53. We propose that the multiple Cdks present in metazoan cells provide a mechanism by which the cell cycle can be efficiently halted after DNA damage. Significantly, this study reveals a heretofore unrecognized dependence for Cdk2 in p53-deficient cancer cells.
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Affiliation(s)
- Jon H. Chung
- Department of Radiation Oncology and Molecular Radiation Sciences and The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Fred Bunz
- Department of Radiation Oncology and Molecular Radiation Sciences and The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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Abstract
Maintenance of genomic stability is needed for cells to survive many rounds of division throughout their lifetime. Key to the proper inheritance of intact genome is the tight temporal and spatial coordination of cell cycle events. Moreover, checkpoints are present that function to monitor the proper execution of cell cycle processes. For instance, the DNA damage and spindle assembly checkpoints ensure genomic integrity by delaying cell cycle progression in the presence of DNA or spindle damage, respectively. A checkpoint that has recently been gaining attention is the antephase checkpoint that acts to prevent cells from entering mitosis in response to a range of stress agents. We review here what is known about the pathway that monitors the status of the cells at the brink of entry into mitosis when cells are exposed to insults that threaten the proper inheritance of chromosomes. We highlight issues which are unresolved in terms of our understanding of the antephase checkpoint and provide some perspectives on what lies ahead in the understanding of how the checkpoint functions.
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Li C, Andrake M, Dunbrack R, Enders GH. A bifunctional regulatory element in human somatic Wee1 mediates cyclin A/Cdk2 binding and Crm1-dependent nuclear export. Mol Cell Biol 2010; 30:116-30. [PMID: 19858290 PMCID: PMC2798281 DOI: 10.1128/mcb.01876-08] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 01/11/2009] [Accepted: 10/10/2009] [Indexed: 01/12/2023] Open
Abstract
Sophisticated models for the regulation of mitotic entry are lacking for human cells. Inactivating human cyclin A/Cdk2 complexes through diverse approaches delays mitotic entry and promotes inhibitory phosphorylation of Cdk1 on tyrosine 15, a modification performed by Wee1. We show here that cyclin A/Cdk2 complexes physically associate with Wee1 in U2OS cells. Mutation of four conserved RXL cyclin A/Cdk binding motifs (RXL1 to RXL4) in Wee1 diminished stable binding. RXL1 resides within a large regulatory region of Wee1 that is predicted to be intrinsically disordered (residues 1 to 292). Near RXL1 is T239, a site of inhibitory Cdk phosphorylation in Xenopus Wee1 proteins. We found that T239 is phosphorylated in human Wee1 and that this phosphorylation was reduced in an RXL1 mutant. RXL1 and T239 mutants each mediated greater Cdk phosphorylation and G(2)/M inhibition than the wild type, suggesting that cyclin A/Cdk complexes inhibit human Wee1 through these sites. The RXL1 mutant uniquely also displayed increased nuclear localization. RXL1 is embedded within sequences homologous to Crm1-dependent nuclear export signals (NESs). Coimmunoprecipitation showed that Crm1 associated with Wee1. Moreover, treatment with the Crm1 inhibitor leptomycin B or independent mutation of the potential NES (NESm) abolished Wee1 nuclear export. Export was also reduced by Cdk inhibition or cyclin A RNA interference, suggesting that cyclin A/Cdk complexes contribute to Wee1 export. Somewhat surprisingly, NESm did not display increased G(2)/M inhibition. Thus, nuclear export of Wee1 is not essential for mitotic entry though an important functional role remains likely. These studies identify a novel bifunctional regulatory element in Wee1 that mediates cyclin A/Cdk2 association and nuclear export.
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Affiliation(s)
- Changqing Li
- Department of Medicine, Epigenetics and Progenitor Cell Keystone Program, Fox Chase Cancer Center, Philadelphia, Pennyslvania, Program in Molecular and Translational Medicine, Fox Chase Cancer Center, Philadelphia, Pennyslvania
| | - Mark Andrake
- Department of Medicine, Epigenetics and Progenitor Cell Keystone Program, Fox Chase Cancer Center, Philadelphia, Pennyslvania, Program in Molecular and Translational Medicine, Fox Chase Cancer Center, Philadelphia, Pennyslvania
| | - Roland Dunbrack
- Department of Medicine, Epigenetics and Progenitor Cell Keystone Program, Fox Chase Cancer Center, Philadelphia, Pennyslvania, Program in Molecular and Translational Medicine, Fox Chase Cancer Center, Philadelphia, Pennyslvania
| | - Greg H. Enders
- Department of Medicine, Epigenetics and Progenitor Cell Keystone Program, Fox Chase Cancer Center, Philadelphia, Pennyslvania, Program in Molecular and Translational Medicine, Fox Chase Cancer Center, Philadelphia, Pennyslvania
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Yamada T, Mehta RR, Lekmine F, Christov K, King ML, Majumdar D, Shilkaitis A, Green A, Bratescu L, Beattie CW, Das Gupta TK. A peptide fragment of azurin induces a p53-mediated cell cycle arrest in human breast cancer cells. Mol Cancer Ther 2009; 8:2947-58. [PMID: 19808975 DOI: 10.1158/1535-7163.mct-09-0444] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We report that amino acids 50 to 77 of azurin (p28) preferentially enter the human breast cancer cell lines MCF-7, ZR-75-1, and T47D through a caveolin-mediated pathway. Although p28 enters p53 wild-type MCF-7 and the isogenic p53 dominant-negative MDD2 breast cancer cell lines, p28 only induces a G(2)-M-phase cell cycle arrest and apoptosis in MCF-7 cells. p28 exerts its antiproliferative activity by reducing proteasomal degradation of p53 through formation of a p28:p53 complex within a hydrophobic DNA-binding domain (amino acids 80-276), increasing p53 levels and DNA-binding activity. Subsequent elevation of the cyclin-dependent kinase inhibitors p21 and p27 reduces cyclin-dependent kinase 2 and cyclin A levels in a time-dependent manner in MCF-7 cells but not in MDD2 cells. These results suggest that p28 and similar peptides that significantly reduce proteasomal degradation of p53 by a MDM2-independent pathway(s) may provide a unique series of cytostatic and cytotoxic (apoptotic) chemotherapeutic agents.
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Affiliation(s)
- Tohru Yamada
- Department of Surgical Oncology, University of Illinois College of Medicine, Chicago, Illinois, USA
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Beamish H, de Boer L, Giles N, Stevens F, Oakes V, Gabrielli B. Cyclin A/cdk2 regulates adenomatous polyposis coli-dependent mitotic spindle anchoring. J Biol Chem 2009; 284:29015-23. [PMID: 19703905 DOI: 10.1074/jbc.m109.042820] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mutations in adenomatous polyposis coli (APC) protein is a major contributor to tumor initiation and progression in several tumor types. These mutations affect APC function in the Wnt-beta-catenin signaling and influence mitotic spindle anchoring to the cell cortex and orientation. Here we report that the mitotic anchoring and orientation function of APC is regulated by cyclin A/cdk2. Knockdown of cyclin A and inhibition of cdk2 resulted in cells arrested in mitosis with activation of the spindle assembly checkpoint. The mitotic spindle was unable to form stable attachments to the cell cortex, and this resulted in the spindles failing to locate to the central position in the cells and undergo dramatic rotation. We have demonstrated that cyclin A/cdk2 specifically associates with APC in late G2 phase and phosphorylates it at Ser-1360, located in the mutation cluster region of APC. Mutation of APC Ser-1360 to Ala results in identical off-centered mitotic spindles. Thus, this cyclin A/cdk2-dependent phosphorylation of APC affects astral microtubule attachment to the cortical surface in mitosis.
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Affiliation(s)
- Heather Beamish
- University of Queensland Diamantina Institute for Cancer Immunology and Metabolic Medicine, Princess Alexandra Hospital, Brisbane, Queensland 4102, Australia
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Lindqvist A, Rodríguez-Bravo V, Medema RH. The decision to enter mitosis: feedback and redundancy in the mitotic entry network. ACTA ACUST UNITED AC 2009; 185:193-202. [PMID: 19364923 PMCID: PMC2700378 DOI: 10.1083/jcb.200812045] [Citation(s) in RCA: 421] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The decision to enter mitosis is mediated by a network of proteins that regulate activation of the cyclin B–Cdk1 complex. Within this network, several positive feedback loops can amplify cyclin B–Cdk1 activation to ensure complete commitment to a mitotic state once the decision to enter mitosis has been made. However, evidence is accumulating that several components of the feedback loops are redundant for cyclin B–Cdk1 activation during normal cell division. Nonetheless, defined feedback loops become essential to promote mitotic entry when normal cell cycle progression is perturbed. Recent data has demonstrated that at least three Plk1-dependent feedback loops exist that enhance cyclin B–Cdk1 activation at different levels. In this review, we discuss the role of various feedback loops that regulate cyclin B–Cdk1 activation under different conditions, the timing of their activation, and the possible identity of the elusive trigger that controls mitotic entry in human cells.
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Affiliation(s)
- Arne Lindqvist
- Department of Medical Oncology, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands
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47
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Asparanin A induces G2/M cell cycle arrest and apoptosis in human hepatocellular carcinoma HepG2 cells. Biochem Biophys Res Commun 2009; 381:700-5. [DOI: 10.1016/j.bbrc.2009.02.124] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 02/21/2009] [Indexed: 01/16/2023]
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48
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Nelson TJ, Alkon DL. Neuroprotective versus tumorigenic protein kinase C activators. Trends Biochem Sci 2009; 34:136-45. [PMID: 19233655 DOI: 10.1016/j.tibs.2008.11.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 11/20/2008] [Accepted: 11/21/2008] [Indexed: 10/21/2022]
Abstract
Protein kinase C (PKC) activators possess potent neurotrophic and neuroprotective activity, thus indicating potential applications in treating neurodegenerative diseases, stroke and traumatic brain injury. Although some activators, such as bryostatin and gnidimacrin, have been tested as antitumor agents, others, such as phorbol esters, are potent tumor promoters. All PKC activators downregulate PKC at high concentrations and long application times. However, tumorigenic activators downregulate certain PKC isozymes, especially PKCdelta, more strongly. Tumorigenic activators possess unique structural features that could account for this difference. At concentrations that minimize PKC downregulation, PKC activators can improve long-term memory, reduce beta-amyloid levels, induce synaptogenesis, promote neuronal repair and inhibit cell proliferation. Intermittent, low concentrations of structurally specific, non-tumorigenic PKC activators, therefore, could offer therapeutic benefit for a variety of neurologic disorders.
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Affiliation(s)
- T J Nelson
- Blanchette Rockefeller Neurosciences Institute, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
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49
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Functional Evolution of Cyclin-Dependent Kinases. Mol Biotechnol 2009; 42:14-29. [DOI: 10.1007/s12033-008-9126-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Accepted: 11/01/2008] [Indexed: 10/21/2022]
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50
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Rodriguez-Collazo P, Snyder SK, Chiffer RC, Bressler EA, Voss TC, Anderson EP, Genieser HG, Smith CL. cAMP signaling regulates histone H3 phosphorylation and mitotic entry through a disruption of G2 progression. Exp Cell Res 2008; 314:2855-69. [PMID: 18644368 DOI: 10.1016/j.yexcr.2008.06.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2008] [Revised: 06/28/2008] [Accepted: 06/30/2008] [Indexed: 01/06/2023]
Abstract
cAMP signaling is known to have significant effects on cell growth, either inhibitory or stimulatory depending on the cell type. Study of cAMP-induced growth inhibition in mammalian somatic cells has focused mainly on the combined role of protein kinase A (PKA) and mitogen-activated protein (MAP) kinases in regulation of progression through the G1 phase of the cell cycle. Here we show that cAMP signaling regulates histone H3 phosphorylation in a cell cycle-dependent fashion, increasing it in quiescent cells but dramatically reducing it in cycling cells. The latter is due to a rapid and dramatic loss of mitotic histone H3 phosphorylation caused by a disruption in G2 progression, as evidenced by the inhibition of mitotic entry and decreased activity of the CyclinB/Cdk1 kinase. The inhibition of G2 progression induced through cAMP signaling is dependent on expression of the catalytic subunit of PKA and is highly sensitive to intracellular cAMP concentration. The mechanism by which G2 progression is inhibited is independent of both DNA damage and MAP kinase signaling. Our results suggest that cAMP signaling activates a G2 checkpoint by a unique mechanism and provide new insight into normal cellular regulation of G2 progression.
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Affiliation(s)
- Pedro Rodriguez-Collazo
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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