1
|
Wolf B, Muralidharan P, Lee MY, Hua W, Green E, Wang H, Strange C. Overexpression of Alpha-1 Antitrypsin Increases the Proliferation of Mesenchymal Stem Cells by Upregulation of Cyclin D1. Int J Mol Sci 2024; 25:2015. [PMID: 38396691 PMCID: PMC10889413 DOI: 10.3390/ijms25042015] [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: 11/10/2023] [Revised: 01/08/2024] [Accepted: 01/31/2024] [Indexed: 02/25/2024] Open
Abstract
Alpha-1 antitrypsin-overexpressing mesenchymal stromal/stem cells (AAT-MSCs) showed improved innate properties with a faster proliferation rate when studied for their protective effects in mouse models of diseases. Here, we investigated the potential mechanism(s) by which AAT gene insertion increases MSC proliferation. Human bone marrow-derived primary or immortalized MSCs (iMSCs) or AAT-MSCs (iAAT-MSCs) were used in the study. Cell proliferation was measured by cell counting and cell cycle analysis. Possible pathways involved in the pro-proliferation effect of AAT were investigated by measuring mRNA and protein expression of key cell cycle genes. Interval cell counting showed increased proliferation in AAT-MSCs or iAAT-MSCs compared to their corresponding MSC controls. Cell cycle analysis revealed more cells progressing into the S and G2/M phases in iAAT-MSCs, with a notable increase in the cell cycle protein, Cyclin D1. Moreover, treatment with Cyclin D1 inhibitors showed that the increase in proliferation is due to Cyclin D1 and that the AAT protein is upstream and a positive regulator of Cyclin D1. Furthermore, AAT's effect on Cyclin D1 is independent of the Wnt signaling pathway as there were no differences in the expression of regulatory proteins, including GSK3β and β-Catenin in iMSC and iAAT-MSCs. In summary, our results indicate that AAT gene insertion in an immortalized MSC cell line increases cell proliferation and growth by increasing Cyclin D1 expression and consequently causing cells to progress through the cell cycle at a significantly faster rate.
Collapse
Affiliation(s)
- Bryan Wolf
- Department of Surgery and Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (B.W.); (P.M.); (W.H.); (E.G.); (H.W.)
| | - Prasanth Muralidharan
- Department of Surgery and Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (B.W.); (P.M.); (W.H.); (E.G.); (H.W.)
| | - Michael Y. Lee
- Academic Magnet High School, North Charleston, SC 29405, USA;
| | - Wei Hua
- Department of Surgery and Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (B.W.); (P.M.); (W.H.); (E.G.); (H.W.)
| | - Erica Green
- Department of Surgery and Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (B.W.); (P.M.); (W.H.); (E.G.); (H.W.)
| | - Hongjun Wang
- Department of Surgery and Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (B.W.); (P.M.); (W.H.); (E.G.); (H.W.)
- Ralph H. Johnson Veterans Affairs Medical Center, Medical University of South Carolina, Charleston, SC 29401, USA
| | - Charlie Strange
- Department of Medicine, Medical University of South Carolina, CSB 816, 96 Jonathan Lucas St., Charleston, SC 29425, USA
| |
Collapse
|
2
|
Sizer RE, Butterfield SP, Hancocks LA, Gato De Sousa L, White RJ. Selective Occupation by E2F and RB of Loci Expressed by RNA Polymerase III. Cancers (Basel) 2024; 16:481. [PMID: 38339234 PMCID: PMC10854548 DOI: 10.3390/cancers16030481] [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: 12/19/2023] [Revised: 01/15/2024] [Accepted: 01/15/2024] [Indexed: 02/12/2024] Open
Abstract
In all cases tested, TFIIIB is responsible for recruiting pol III to its genetic templates. In mammalian cells, RB binds TFIIIB and prevents its interactions with both promoter DNA and pol III, thereby suppressing transcription. As TFIIIB is not recruited to its target genes when bound by RB, the mechanism predicts that pol III-dependent templates will not be occupied by RB; this contrasts with the situation at most genes controlled by RB, where it can be tethered by promoter-bound sequence-specific DNA-binding factors such as E2F. Contrary to this prediction, however, ChIP-seq data reveal the presence of RB in multiple cell types and the related protein p130 at many loci that rely on pol III for their expression, including RMRP, RN7SL, and a variety of tRNA genes. The sets of genes targeted varies according to cell type and growth state. In such cases, recruitment of RB and p130 can be explained by binding of E2F1, E2F4 and/or E2F5. Genes transcribed by pol III had not previously been identified as common targets of E2F family members. The data provide evidence that E2F may allow for the selective regulation of specific non-coding RNAs by RB, in addition to its influence on overall pol III output through its interaction with TFIIIB.
Collapse
Affiliation(s)
| | | | | | | | - Robert J. White
- Department of Biology, University of York, York YO10 5DD, UK; (R.E.S.)
| |
Collapse
|
3
|
Yue F, Ku AT, Stevens PD, Michalski MN, Jiang W, Tu J, Shi Z, Dou Y, Wang Y, Feng XH, Hostetter G, Wu X, Huang S, Shroyer NF, Zhang B, Williams BO, Liu Q, Lin X, Li Y. Loss of ZNRF3/RNF43 Unleashes EGFR in Cancer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.10.574969. [PMID: 38260423 PMCID: PMC10802575 DOI: 10.1101/2024.01.10.574969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
ZNRF3 and RNF43 are closely related transmembrane E3 ubiquitin ligases with significant roles in development and cancer. Conventionally, their biological functions have been associated with regulating WNT signaling receptor ubiquitination and degradation. However, our proteogenomic studies have revealed EGFR as the most negatively correlated protein with ZNRF3/RNF43 mRNA levels in multiple human cancers. Through biochemical investigations, we demonstrate that ZNRF3/RNF43 interact with EGFR via their extracellular domains, leading to EGFR ubiquitination and subsequent degradation facilitated by the E3 ligase RING domain. Overexpression of ZNRF3 reduces EGFR levels and suppresses cancer cell growth in vitro and in vivo, whereas knockout of ZNRF3/RNF43 stimulates cell growth and tumorigenesis through upregulated EGFR signaling. Together, these data highlight ZNRF3 and RNF43 as novel E3 ubiquitin ligases of EGFR and establish the inactivation of ZNRF3/RNF43 as a driver of increased EGFR signaling, ultimately promoting cancer progression. This discovery establishes a connection between two fundamental signaling pathways, EGFR and WNT, at the level of cytoplasmic membrane receptor, uncovering a novel mechanism underlying the frequent co-activation of EGFR and WNT signaling in development and cancer.
Collapse
Affiliation(s)
- Fei Yue
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Amy T. Ku
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Payton D. Stevens
- Van Andel Institute, Department of Cell Biology, Grand Rapids, Michigan, 49503, USA
| | - Megan N. Michalski
- Van Andel Institute, Department of Cell Biology, Grand Rapids, Michigan, 49503, USA
| | - Weiyu Jiang
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Jianghua Tu
- Texas Therapeutics Institute and Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Zhongcheng Shi
- Advanced Technology Cores, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Yongchao Dou
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Yi Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 102206, China
| | - Xin-Hua Feng
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Galen Hostetter
- Van Andel Institute, Core Technologies and Services, Grand Rapids, Michigan 49503, USA
| | - Xiangwei Wu
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Shixia Huang
- Advanced Technology Cores, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Education, Innovation & Technology, Baylor College of Medicine, Houston, Texas 77030, USA
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Noah F. Shroyer
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Bing Zhang
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas 77030, USA
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Bart O. Williams
- Van Andel Institute, Department of Cell Biology, Grand Rapids, Michigan, 49503, USA
- Van Andel Institute, Core Technologies and Services, Grand Rapids, Michigan 49503, USA
| | - Qingyun Liu
- Texas Therapeutics Institute and Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Xia Lin
- The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang 310003, China
| | - Yi Li
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA
| |
Collapse
|
4
|
Wolf B, Muralidharan P, Lee M, Hua W, Green E, Wang H, Strange C. Overexpression of Alpha-1 Antitrypsin Increases the Proliferation of Mesenchymal Stem Cells by Upregulation of Cyclin D1 and is Independent of the Wnt Signaling Pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.28.564526. [PMID: 37961658 PMCID: PMC10634889 DOI: 10.1101/2023.10.28.564526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Alaph-1 antitrypsin overexpressing mesenchymal stromal/stem cells (AAT-MSCs) showed improved innate properties with a faster proliferation rate when studied for their protective effects in mouse models of diseases. Here, we investigated the potential mechanism(s) by which AAT gene insertion increases MSC proliferation. Human bone marrow-derived primary or immortalized MSCs (iMSCs) or AAT-MSCs (iAAT-MSCs) were used in the study. Cell proliferation was measured by cell counting and cell cycle analysis. Possible pathways involved in the pro-proliferation effect of AAT were investigated by measuring mRNA and protein expression of key cell cycle genes. Interval cell counting showed increased proliferation in AAT-MSCs or iAAT-MSCs compared to their corresponding MSC controls. Cell cycle analysis revealed more cells progressing into the S and G2/M phases in iAAT-MSCs, with a notable increase in the cell cycle protein, Cyclin D1. Moreover, treatment with Cyclin D1 inhibitors showed that the increase in proliferation is due to Cyclin D1 and that the AAT protein is upstream and a positive regulator of Cyclin D1. Furthermore, AAT's effect on Cyclin D1 is independent of the Wnt signaling pathway as there were no differences in the expression of regulatory proteins, including GSK3β and β-Catenin in iMSC and iAAT-MSCs. In summary, our results indicate that AAT gene insertion in an immortalized MSC cell line increases cell proliferation and growth by increasing Cyclin D1 expression and consequently causing cells to progress through the cell cycle at a significantly faster rate.
Collapse
|
5
|
Militi S, Nibhani R, Jalali M, Pauklin S. RBL2-E2F-GCN5 guide cell fate decisions during tissue specification by regulating cell-cycle-dependent fluctuations of non-cell-autonomous signaling. Cell Rep 2023; 42:113146. [PMID: 37725511 DOI: 10.1016/j.celrep.2023.113146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 05/30/2023] [Accepted: 08/31/2023] [Indexed: 09/21/2023] Open
Abstract
The retinoblastoma family proteins (RBs) and E2F transcription factors are cell-autonomous regulators of cell-cycle progression, but they also impact fate choice in addition to tumor suppression. The range of mechanisms involved remains to be uncovered. Here, we show that RBs, particularly RBL2/p130, repress WNT ligands such as WNT4 and WNT8A, thereby directing ectoderm specification between neural crest to neuroepithelium. RBL2 achieves this function through cell-cycle-dependent cooperation with E2Fs and GCN5 on the regulatory regions of WNT loci, which direct neuroepithelial versus neural crest specification by temporal fluctuations of WNT/β-catenin and DLL/NOTCH signaling activity. Thus, the RB-E2F bona fide cell-autonomous axis controls cell fate decisions, and RBL2 regulates field effects via WNT ligands. This reveals a non-cell-autonomous function of RBL2-E2F in stem cell and tissue progenitor differentiation that has broader implications for cell-cycle-dependent cell fate specification in organogenesis, adult stem cells, tissue homeostasis, and tumorigenesis.
Collapse
Affiliation(s)
- Stefania Militi
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Old Road, Headington, Oxford OX3 7LD, UK
| | - Reshma Nibhani
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Old Road, Headington, Oxford OX3 7LD, UK
| | - Morteza Jalali
- Anne McLaren Laboratory for Regenerative Medicine, Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Siim Pauklin
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Old Road, Headington, Oxford OX3 7LD, UK.
| |
Collapse
|
6
|
Role of RUNX3 in Restriction Point Regulation. Cells 2023; 12:cells12050708. [PMID: 36899846 PMCID: PMC10000377 DOI: 10.3390/cells12050708] [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: 01/26/2023] [Revised: 02/17/2023] [Accepted: 02/19/2023] [Indexed: 03/02/2023] Open
Abstract
A cell cycle is a series of events that takes place in a cell as it grows and divides. At the G1 phase of cell cycle, cells monitor their cumulative exposure to specific signals and make the critical decision to pass through the restriction (R)-point. The R-point decision-making machinery is fundamental to normal differentiation, apoptosis, and G1-S transition. Deregulation of this machinery is markedly associated with tumorigenesis. Therefore, identification of the molecular mechanisms that govern the R-point decision is one of the fundamental issues in tumor biology. RUNX3 is one of the genes frequently inactivated in tumors by epigenetic alterations. In particular, RUNX3 is downregulated in most K-RAS-activated human and mouse lung adenocarcinomas (ADCs). Targeted inactivation of Runx3 in the mouse lung induces adenomas (ADs), and markedly shortens the latency of ADC formation induced by oncogenic K-Ras. RUNX3 participates in the transient formation of R-point-associated activator (RPA-RX3-AC) complexes, which measure the duration of RAS signals and thereby protect cells against oncogenic RAS. This review focuses on the molecular mechanism by which the R-point participates in oncogenic surveillance.
Collapse
|
7
|
The Breast Cancer Protooncogenes HER2, BRCA1 and BRCA2 and Their Regulation by the iNOS/NOS2 Axis. Antioxidants (Basel) 2022; 11:antiox11061195. [PMID: 35740092 PMCID: PMC9227079 DOI: 10.3390/antiox11061195] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 06/01/2022] [Accepted: 06/06/2022] [Indexed: 02/04/2023] Open
Abstract
The expression of inducible nitric oxide synthase (iNOS; NOS2) and derived NO in various cancers was reported to exert pro- and anti-tumorigenic effects depending on the levels of expression and the tumor types. In humans, the breast cancer level of iNOS was reported to be overexpressed, to exhibit pro-tumorigenic activities, and to be of prognostic significance. Likewise, the expression of the oncogenes HER2, BRCA1, and BRCA2 has been associated with malignancy. The interrelationship between the expression of these protooncogenes and oncogenes and the expression of iNOS is not clear. We have hypothesized that there exist cross-talk signaling pathways between the breast cancer protooncogenes, the iNOS axis, and iNOS-mediated NO mutations of these protooncogenes into oncogenes. We review the molecular regulation of the expression of the protooncogenes in breast cancer and their interrelationships with iNOS expression and activities. In addition, we discuss the roles of iNOS, HER2, BRCA1/2, and NO metabolism in the pathophysiology of cancer stem cells. Bioinformatic analyses have been performed and have found suggested molecular alterations responsible for breast cancer aggressiveness. These include the association of BRCA1/2 mutations and HER2 amplifications with the dysregulation of the NOS pathway. We propose that future studies should be undertaken to investigate the regulatory mechanisms underlying the expression of iNOS and various breast cancer oncogenes, with the aim of identifying new therapeutic targets for the treatment of breast cancers that are refractory to current treatments.
Collapse
|
8
|
Kambara T, Amatya V, Kushitani K, Fujii Y, Endo I, Takeshima Y. Downregulation of FTL decreases proliferation of malignant mesothelioma cells by inducing G 1 cell cycle arrest. Oncol Lett 2022; 23:174. [PMID: 35497939 PMCID: PMC9019860 DOI: 10.3892/ol.2022.13294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 03/15/2022] [Indexed: 12/03/2022] Open
Abstract
Pleural malignant mesothelioma is a malignant tumor with a poor prognosis that is strongly associated with asbestos exposure during its development. Because there is no adequate treatment for malignant mesothelioma, investigation of its molecular mechanism is important. The ferritin light chain (FTL) is a subunit of ferritin, and its high expression in malignant tumors, including malignant mesothelioma, has recently been reported; however, its role in malignant mesothelioma is unclear. The purpose of the present study was to clarify the function of FTL in malignant mesothelioma. The expression levels of FTL in malignant mesothelioma were examined using the Cancer Cell Line Encyclopedia database and our previous data. The short interfering (si)RNA against FTL was transfected into two mesothelioma cell lines, ACC-MESO-1 and CRL-5915, and functional analysis was performed. Expression of p21, p27, cyclin-dependent kinase 2 (CDK2) and phosphorylated retinoblastoma protein (pRb) associated with the cell cycle were examined as candidate genes associated with FTL. The expression levels of the FTL mRNA were higher in malignant mesothelioma compared with other tumors in the Cancer Cell Line Encyclopedia database, and among other genes in our previous study. Reverse transcription-quantitative PCR and western blotting demonstrated suppression of FTL expression in two cell lines transfected with FTL siRNA compared with cells transfected with negative control (NC) siRNA. In the two cell lines transfected with FTL siRNA, proliferation was significantly suppressed, and cell cycle arrest was observed in the G1 phase. The levels of p21 and p27 were increased, while those of CDK2 and pRb were decreased compared with NC. However, no significant differences in invasion and migration ability were revealed between FTL siRNA-transfected cells and NC. In conclusion, FTL may increase the proliferative capacity of malignant mesothelioma cells by affecting p21, p27, CDK2 and pRb, and promoting the cell cycle at the G1 phase.
Collapse
Affiliation(s)
- Takahiro Kambara
- Department of Pathology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Hiroshima 734‑8551, Japan
| | - Vishwa Amatya
- Department of Pathology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Hiroshima 734‑8551, Japan
| | - Kei Kushitani
- Department of Pathology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Hiroshima 734‑8551, Japan
| | - Yutaro Fujii
- Department of Pathology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Hiroshima 734‑8551, Japan
| | - Ihiro Endo
- Department of Pathology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Hiroshima 734‑8551, Japan
| | - Yukio Takeshima
- Department of Pathology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Hiroshima 734‑8551, Japan
| |
Collapse
|
9
|
Ando K, Nakagawara A. Acceleration or Brakes: Which Is Rational for Cell Cycle-Targeting Neuroblastoma Therapy? Biomolecules 2021; 11:biom11050750. [PMID: 34069817 PMCID: PMC8157238 DOI: 10.3390/biom11050750] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/09/2021] [Accepted: 05/12/2021] [Indexed: 11/27/2022] Open
Abstract
Unrestrained proliferation is a common feature of malignant neoplasms. Targeting the cell cycle is a therapeutic strategy to prevent unlimited cell division. Recently developed rationales for these selective inhibitors can be subdivided into two categories with antithetical functionality. One applies a “brake” to the cell cycle to halt cell proliferation, such as with inhibitors of cell cycle kinases. The other “accelerates” the cell cycle to initiate replication/mitotic catastrophe, such as with inhibitors of cell cycle checkpoint kinases. The fate of cell cycle progression or arrest is tightly regulated by the presence of tolerable or excessive DNA damage, respectively. This suggests that there is compatibility between inhibitors of DNA repair kinases, such as PARP inhibitors, and inhibitors of cell cycle checkpoint kinases. In the present review, we explore alterations to the cell cycle that are concomitant with altered DNA damage repair machinery in unfavorable neuroblastomas, with respect to their unique genomic and molecular features. We highlight the vulnerabilities of these alterations that are attributable to the features of each. Based on the assessment, we offer possible therapeutic approaches for personalized medicine, which are seemingly antithetical, but both are promising strategies for targeting the altered cell cycle in unfavorable neuroblastomas.
Collapse
Affiliation(s)
- Kiyohiro Ando
- Research Institute for Clinical Oncology, Saitama Cancer Center, 818 Komuro, Ina, Saitama 362-0806, Japan
- Correspondence: (K.A.); (A.N.); Tel.: +81-48-722-1111 (K.A.); +81-942-50-8829 (A.N.)
| | - Akira Nakagawara
- Saga International Carbon Particle Beam Radiation Cancer Therapy Center, Saga HIMAT Foundation, 3049 Harakoga-Machi, Saga 841-0071, Japan
- Correspondence: (K.A.); (A.N.); Tel.: +81-48-722-1111 (K.A.); +81-942-50-8829 (A.N.)
| |
Collapse
|
10
|
Romero-Pozuelo J, Figlia G, Kaya O, Martin-Villalba A, Teleman AA. Cdk4 and Cdk6 Couple the Cell-Cycle Machinery to Cell Growth via mTORC1. Cell Rep 2021; 31:107504. [PMID: 32294430 DOI: 10.1016/j.celrep.2020.03.068] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 03/03/2020] [Accepted: 03/20/2020] [Indexed: 12/20/2022] Open
Abstract
Cell growth is coupled to cell-cycle progression in mitotically proliferating mammalian cells, but the underlying molecular mechanisms are not well understood. CyclinD-Cdk4/6 is known to phosphorylate RB to promote S-phase entry, but recent work suggests they have additional functions. We show here that CyclinD-Cdk4/6 activates mTORC1 by binding and phosphorylating TSC2 on Ser1217 and Ser1452. Pharmacological inhibition of Cdk4/6 leads to a rapid, TSC2-dependent reduction of mTORC1 activity in multiple human and mouse cell lines, including breast cancer cells. By simultaneously driving mTORC1 and E2F, CyclinD-Cdk4/6 couples cell growth to cell-cycle progression. Consistent with this, we see that mTORC1 activity is cell cycle dependent in proliferating neural stem cells of the adult rodent brain. We find that Cdk4/6 inhibition reduces cell proliferation partly via TSC2 and mTORC1. This is of clinical relevance, because Cdk4/6 inhibitors are used for breast cancer therapy.
Collapse
Affiliation(s)
- Jesús Romero-Pozuelo
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; Heidelberg University, 69120 Heidelberg, Germany
| | - Gianluca Figlia
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; Heidelberg University, 69120 Heidelberg, Germany
| | - Oguzhan Kaya
- Heidelberg University, 69120 Heidelberg, Germany; Molecular Neurobiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Ana Martin-Villalba
- Molecular Neurobiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Aurelio A Teleman
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; Heidelberg University, 69120 Heidelberg, Germany.
| |
Collapse
|
11
|
Zatulovskiy E, Zhang S, Berenson DF, Topacio BR, Skotheim JM. Cell growth dilutes the cell cycle inhibitor Rb to trigger cell division. Science 2020; 369:466-471. [PMID: 32703881 PMCID: PMC7489475 DOI: 10.1126/science.aaz6213] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 05/19/2020] [Indexed: 12/21/2022]
Abstract
Cell size is fundamental to cell physiology. For example, cell size determines the spatial scale of organelles and intracellular transport and thereby affects biosynthesis. Although some genes that affect mammalian cell size have been identified, the molecular mechanisms through which cell growth drives cell division have remained elusive. We show that cell growth during the G1 phase of the cell division cycle dilutes the cell cycle inhibitor Retinoblastoma protein (Rb) to trigger division in human cells. RB overexpression increased cell size and G1 duration, whereas RB deletion decreased cell size and removed the inverse correlation between cell size at birth and the duration of the G1 phase. Thus, Rb dilution through cell growth in G1 provides one of the long-sought molecular mechanisms that promotes cell size homeostasis.
Collapse
Affiliation(s)
| | - Shuyuan Zhang
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | | | | | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
| |
Collapse
|
12
|
Pennycook BR, Barr AR. Restriction point regulation at the crossroads between quiescence and cell proliferation. FEBS Lett 2020; 594:2046-2060. [PMID: 32564372 DOI: 10.1002/1873-3468.13867] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/08/2020] [Accepted: 06/10/2020] [Indexed: 02/11/2024]
Abstract
The coordination of cell proliferation with reversible cell cycle exit into quiescence is crucial for the development of multicellular organisms and for tissue homeostasis in the adult. The decision between quiescence and proliferation occurs at the restriction point, which is widely thought to be located in the G1 phase of the cell cycle, when cells integrate accumulated extracellular and intracellular signals to drive this binary cellular decision. On the molecular level, decision-making is exerted through the activation of cyclin-dependent kinases (CDKs). CDKs phosphorylate the retinoblastoma (Rb) transcriptional repressor to regulate the expression of cell cycle genes. Recently, the classical view of restriction point regulation has been challenged. Here, we review the latest findings on the activation of CDKs, Rb phosphorylation and the nature and position of the restriction point within the cell cycle.
Collapse
Affiliation(s)
- Betheney R Pennycook
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, UK
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Alexis R Barr
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, UK
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| |
Collapse
|
13
|
Maugein A, Diedisheim M, Bailly K, Scharfmann R, Albagli O. The RB gene family controls the maturation state of the EndoC-βH2 human pancreatic β-cells. Differentiation 2020; 113:1-9. [PMID: 32120156 DOI: 10.1016/j.diff.2020.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/17/2020] [Accepted: 02/17/2020] [Indexed: 01/18/2023]
Abstract
The functional maturation of human pancreatic β-cells remains poorly understood. EndoC-βH2 is a human β-cell line with a reversible immortalized phenotype. Removal of the two oncogenes, SV40LT and hTERT introduced for its propagation, stops proliferation, triggers cell size increase and senescence, promotes mitochondrial activity and amplifies several β-cell traits and functions. Overall, these events recapitulate several aspects of functional β-cell maturation. We report here that selective depletion of SV40LT, but not of hTERT, is sufficient to revert EndoC-βH2 immortalization. SV40LT inhibits the activity of the RB family members and of P53. In EndoC-βH2 cells, the knock-down of RB itself, and, to a lesser extent, of its relative P130, precludes most events triggered by SV40LT depletion. In contrast, the knock-down of P53 does not prevent reversion of immortalization. Thus, an increase in RB and P130 activity, but not in P53 activity, is required for functional maturation of EndoC-βH2 cells upon SV40LT-depletion. In addition, RB and/or P130 depletion in SV40LT-expressing EndoC-βH2 cells decreases cell size, stimulates proliferation, and decreases the expression of key β-cell genes. Thus, despite SV40LT expression, EndoC-βH2 cells have a residual RB activity, which when suppressed reverts them to a more immature phenotype. These results show that the expression and activity levels of RB family members, especially RB itself, regulate the maturation state of EndoC-βH2 cells.
Collapse
Affiliation(s)
- Alicia Maugein
- Paris University, Institut Cochin, INSERM, U1016, CNRS, UMR8104, 75014, Paris, France
| | - Marc Diedisheim
- Assistance Publique - Hôpitaux de Paris, Diabetology Department, Paris University, Cochin Hospital, and INSERM, UMRS 1138, Centre de Recherche des Cordeliers, Paris University, 75006, Paris, France
| | - Karine Bailly
- Paris University, Institut Cochin, INSERM, U1016, CNRS, UMR8104, 75014, Paris, France
| | - Raphaël Scharfmann
- Paris University, Institut Cochin, INSERM, U1016, CNRS, UMR8104, 75014, Paris, France
| | - Olivier Albagli
- Paris University, Institut Cochin, INSERM, U1016, CNRS, UMR8104, 75014, Paris, France.
| |
Collapse
|
14
|
Uxa S, Bernhart SH, Mages CFS, Fischer M, Kohler R, Hoffmann S, Stadler PF, Engeland K, Müller GA. DREAM and RB cooperate to induce gene repression and cell-cycle arrest in response to p53 activation. Nucleic Acids Res 2019; 47:9087-9103. [PMID: 31400114 PMCID: PMC6753476 DOI: 10.1093/nar/gkz635] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 07/07/2019] [Accepted: 07/16/2019] [Indexed: 12/17/2022] Open
Abstract
Most human cancers acquire mutations causing defects in the p53 signaling pathway. The tumor suppressor p53 becomes activated in response to genotoxic stress and is essential for arresting the cell cycle to facilitate DNA repair or to initiate apoptosis. p53-induced cell cycle-arrest is mediated by expression of the CDK inhibitor p21WAF1/Cip1, which prevents phosphorylation and inactivation of the pocket proteins RB, p130, and p107. In a hypophosphorylated state, pocket proteins bind to E2F factors forming RB-E2F and DREAM transcriptional repressor complexes. Here, we analyze the influence of RB and DREAM on p53-induced gene repression and cell-cycle arrest. We show that abrogation of DREAM function by knockout of the DREAM component LIN37 results in a reduced repression of cell-cycle genes. We identify the genes repressed by the p53-DREAM pathway and describe a set of genes that is downregulated by p53 independent of LIN37/DREAM. Most strikingly, p53-dependent repression of cell-cycle genes is completely abrogated in LIN37-/-;RB-/- cells leading to a loss of the G1/S checkpoint. Taken together, we show that DREAM and RB are key factors in the p53 signaling pathway to downregulate a large number of cell-cycle genes and to arrest the cell cycle at the G1/S transition.
Collapse
Affiliation(s)
- Sigrid Uxa
- Molecular Oncology, Department of Gynaecology, Medical School, Leipzig University, 04103 Leipzig, Germany
| | - Stephan H Bernhart
- Transcriptome Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, Leipzig University, 04107 Leipzig, Germany
| | - Christina F S Mages
- Molecular Oncology, Department of Gynaecology, Medical School, Leipzig University, 04103 Leipzig, Germany
| | - Martin Fischer
- Computational Biology Group, Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), 07745 Jena, Germany
| | - Robin Kohler
- Molecular Oncology, Department of Gynaecology, Medical School, Leipzig University, 04103 Leipzig, Germany
| | - Steve Hoffmann
- Computational Biology Group, Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), 07745 Jena, Germany
| | - Peter F Stadler
- Transcriptome Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, Leipzig University, 04107 Leipzig, Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Leipzig Research Center for Civilization Diseases; and Competence Center for Scalable Data Services and Solutions Dresden/Leipzig, Leipzig University, 04107 Leipzig, Germany.,Max Planck Institute for Mathematics in the Sciences, 04103 Leipzig, Germany.,Institute for Theoretical Chemistry, University of Vienna, A-1090 Wien, Austria.,Facultad de Ciencias, Universidad National de Colombia, Sede Bogota, Colombia.,Santa Fe Institute, Santa Fe, NM 87501, USA
| | - Kurt Engeland
- Molecular Oncology, Department of Gynaecology, Medical School, Leipzig University, 04103 Leipzig, Germany
| | - Gerd A Müller
- Molecular Oncology, Department of Gynaecology, Medical School, Leipzig University, 04103 Leipzig, Germany.,Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| |
Collapse
|
15
|
Liao Y, Du W. An Rb family-independent E2F3 transcription factor variant impairs STAT5 signaling and mammary gland remodeling during pregnancy in mice. J Biol Chem 2018; 293:3156-3167. [PMID: 29330306 DOI: 10.1074/jbc.ra117.000583] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/08/2018] [Indexed: 01/02/2023] Open
Abstract
E2F transcription factors are regulated by binding to the retinoblastoma (Rb) tumor suppressor family of proteins. Previously, we reported an E2FLQ mutation that disrupts the binding with Rb proteins without affecting the transcriptional activity of E2F. We also showed that mouse embryonic fibroblasts with an E2F3LQ mutation exhibit increased E2F activity and more rapid cell proliferation. In this report, we analyzed E2F3LQ mice to further characterize the in vivo consequences of Rb family-independent E2F3 activity. We found that homozygous E2F3LQ mice were viable and had no obvious developmental defects or tumor growth. Our results also indicated that E2F3LQ cells largely retain normal control of cell proliferation in vivo However, female E2F3LQ mice had partial nursing defects. Examination of the E2F3LQ mammary glands revealed increased caveolin-1 (CAV1) expression, reduced prolactin receptor/Stat5 signaling, and impaired pregnancy-induced cell proliferation and differentiation. Of note, ChIP experiments disclosed that E2F3 binds the CAV1 promoter. Furthermore, E2F3 overexpression induced CAV1 expression, and CRISPR/CAS9-mediated E2F3 knockout reduced CAV1 levels and also increased prolactin receptor-induced Stat5 signaling in mammary epithelial cells. Our results suggest that the Rb family-independent E2F3 LQ variant inhibits pregnancy-induced mammary gland cell proliferation and differentiation by up-regulating CAV1 expression and inhibiting Stat5 signaling.
Collapse
Affiliation(s)
- Yang Liao
- From the Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois 60637
| | - Wei Du
- From the Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois 60637
| |
Collapse
|
16
|
Araki T, Liu NA. Cell Cycle Regulators and Lineage-Specific Therapeutic Targets for Cushing Disease. Front Endocrinol (Lausanne) 2018; 9:444. [PMID: 30147673 PMCID: PMC6096271 DOI: 10.3389/fendo.2018.00444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 07/18/2018] [Indexed: 11/22/2022] Open
Abstract
Cell cycle proteins are critical to pituitary development, but their contribution to lineage-specific tumorigenesis has not been well-elucidated. Emerging evidence from in vitro human tumor analysis and transgenic mouse models indicates that G1/S-related cell cycle proteins, particularly cyclin E, p27, Rb, and E2F1, drive molecular mechanisms that underlie corticotroph-specific differentiation and development of Cushing disease. The aim of this review is to summarize the literature and discuss the complex role of cell cycle regulation in Cushing disease, with a focus on identifying potential targets for therapeutic intervention in patients with these tumors.
Collapse
Affiliation(s)
- Takako Araki
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, MN, United States
- *Correspondence: Takako Araki
| | - Ning-Ai Liu
- Department of Medicine, Pituitary Center, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| |
Collapse
|
17
|
Vidya MK, Kumar VG, Sejian V, Bagath M, Krishnan G, Bhatta R. Toll-like receptors: Significance, ligands, signaling pathways, and functions in mammals. Int Rev Immunol 2017; 37:20-36. [PMID: 29028369 DOI: 10.1080/08830185.2017.1380200] [Citation(s) in RCA: 272] [Impact Index Per Article: 38.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This review attempts to cover the implication of the toll-like receptors (TLRs) in controlling immune functions with emphasis on their significance, function, regulation and expression patterns. The tripartite TLRs are type I integral transmembrane receptors that are involved in recognition and conveying of pathogens to the immune system. These paralogs are located on cell surfaces or within endosomes. The TLRs are found to be functionally involved in the recognition of self and non-self-antigens, maturation of DCs and initiation of antigen-specific adaptive immune responses as they bridge the innate and adaptive immunity. Interestingly, they also have a significant role in immunotherapy and vaccination. Signals generated by TLRs are transduced through NFκB signaling and MAP kinases pathway to recruit pro-inflammatory cytokines and co-stimulatory molecules, which promote inflammatory responses. The excess production of these cytokines leads to grave systemic disorders like tumor growth and autoimmune disorders. Hence, regulation of the TLR signaling pathway is necessary to keep the host system safe. Many molecules like LPS, SOCS1, IRAK1, NFκB, and TRAF3 are involved in modulating the TLR pathways to induce appropriate response. Though quantification of these TLRs helps in correlating the magnitude of immune response exhibited by the animal, there are several internal, external, genetic and animal factors that affect their expression patterns. So it can be concluded that any identification based on those expression profiles may lead to improper diagnosis during certain conditions.
Collapse
Affiliation(s)
- Mallenahally Kusha Vidya
- a Department of Veterinary Biochemistry , Veterinary College, Karnataka Veterinary Animal and Fisheries Sciences University , Hebbal, Bangalore , Karnataka , India.,b Animal Physiology Division , ICAR-National Institute of Animal Nutrition and Physiology , Adugodi, Bangalore , Karnataka , India
| | - V Girish Kumar
- a Department of Veterinary Biochemistry , Veterinary College, Karnataka Veterinary Animal and Fisheries Sciences University , Hebbal, Bangalore , Karnataka , India
| | - Veerasamy Sejian
- b Animal Physiology Division , ICAR-National Institute of Animal Nutrition and Physiology , Adugodi, Bangalore , Karnataka , India
| | - Madiajagan Bagath
- b Animal Physiology Division , ICAR-National Institute of Animal Nutrition and Physiology , Adugodi, Bangalore , Karnataka , India
| | - Govindan Krishnan
- b Animal Physiology Division , ICAR-National Institute of Animal Nutrition and Physiology , Adugodi, Bangalore , Karnataka , India
| | - Raghavendra Bhatta
- b Animal Physiology Division , ICAR-National Institute of Animal Nutrition and Physiology , Adugodi, Bangalore , Karnataka , India
| |
Collapse
|
18
|
Mages CF, Wintsche A, Bernhart SH, Müller GA. The DREAM complex through its subunit Lin37 cooperates with Rb to initiate quiescence. eLife 2017; 6. [PMID: 28920576 PMCID: PMC5602299 DOI: 10.7554/elife.26876] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 08/14/2017] [Indexed: 12/21/2022] Open
Abstract
The retinoblastoma Rb protein is an important factor controlling the cell cycle. Yet, mammalian cells carrying Rb deletions are still able to arrest under growth-limiting conditions. The Rb-related proteins p107 and p130, which are components of the DREAM complex, had been suggested to be responsible for a continued ability to arrest by inhibiting E2f activity and by recruiting chromatin-modifying enzymes. Here, we show that p130 and p107 are not sufficient for DREAM-dependent repression. We identify the MuvB protein Lin37 as an essential factor for DREAM function. Cells not expressing Lin37 proliferate normally, but DREAM completely loses its ability to repress genes in G0/G1 while all remaining subunits, including p130/p107, still bind to target gene promoters. Furthermore, cells lacking both Rb and Lin37 are incapable of exiting the cell cycle. Thus, Lin37 is an essential component of DREAM that cooperates with Rb to induce quiescence.
Collapse
Affiliation(s)
- Christina Fs Mages
- Molecular Oncology, Medical School, University of Leipzig, Leipzig, Germany
| | - Axel Wintsche
- Molecular Oncology, Medical School, University of Leipzig, Leipzig, Germany.,Computational EvoDevo Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany
| | - Stephan H Bernhart
- Transcriptome Bioinformatics Group, Department of Computer Science, University of Leipzig, Leipzig, Germany.,Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany
| | - Gerd A Müller
- Molecular Oncology, Medical School, University of Leipzig, Leipzig, Germany
| |
Collapse
|
19
|
Liao Y, Du W. Rb-independent E2F3 promotes cell proliferation and alters expression of genes involved in metabolism and inflammation. FEBS Open Bio 2017; 7:1611-1621. [PMID: 28979847 PMCID: PMC5623693 DOI: 10.1002/2211-5463.12306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/10/2017] [Accepted: 08/22/2017] [Indexed: 11/10/2022] Open
Abstract
E2F transcription factors are key targets of the retinoblastoma (Rb) tumor suppressor. Despite extensive studies, the in vivo consequences of disrupting the interaction between Rb and an individual E2F are not clear. Here, we report an E2F mutation that interfered with binding to Rb family proteins without significantly affecting protein level or transactivation function. Characterization of mouse embryonic fibroblasts with this Rb-independent E2F3LQ mutation revealed that disrupting the Rb and E2F3 interaction increased cell proliferation, allowed cells to accumulate to higher density, and significantly altered expression of genes involved in metabolism, inflammation, immunity, and response to stress. These results suggest that the Rb-independent E2FLQ mutations might provide useful tools to investigate the in vivo consequences of disrupting the interactions between Rb and E2F.
Collapse
Affiliation(s)
- Yang Liao
- Ben May Department for Cancer Research The University of Chicago IL USA
| | - Wei Du
- Ben May Department for Cancer Research The University of Chicago IL USA
| |
Collapse
|
20
|
Alessio N, Capasso S, Ferone A, Di Bernardo G, Cipollaro M, Casale F, Peluso G, Giordano A, Galderisi U. Misidentified Human Gene Functions with Mouse Models: The Case of the Retinoblastoma Gene Family in Senescence. Neoplasia 2017; 19:781-790. [PMID: 28865301 PMCID: PMC5577395 DOI: 10.1016/j.neo.2017.06.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 06/23/2017] [Accepted: 06/27/2017] [Indexed: 12/31/2022] Open
Abstract
Although mice models rank among the most widely used tools for understanding human genetics, biology, and diseases, differences between orthologous genes among species as close as mammals are possible, particularly in orthologous gene pairs in which one or more paralogous (i.e., duplicated) genes appear in the genomes of the species. Duplicated genes can possess overlapping functions and compensate for each other. The retinoblastoma gene family demonstrates typical composite functionality in its three member genes (i.e., RB1, RB2/P130, and P107), all of which participate in controlling the cell cycle and associated phenomena, including proliferation, quiescence, apoptosis, senescence, and cell differentiation. We analyzed the role of the retinoblastoma gene family in regulating senescence in mice and humans. Silencing experiments with each member of the gene family in mesenchymal stromal cells (MSCs) and fibroblasts from mouse and human tissues demonstrated that RB1 may be indispensable for senescence in mouse cells, but not in human ones, as an example of species specificity. Furthermore, although RB2/P130 seems to be implicated in maintaining human cell senescence, the function of RB1 within any given species might differ by cell type, as an example of cell specificity. For instance, silencing RB1 in mouse fibroblasts induced a reduced senescence not observed in mouse MSCs. Our findings could be useful as a general paradigm of cautions to take when inferring the role of human genes analyzed in animal studies and when examining the role of the retinoblastoma gene family in detail.
Collapse
Affiliation(s)
- Nicola Alessio
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Stefania Capasso
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Angela Ferone
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Giovanni Di Bernardo
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Marilena Cipollaro
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Fiorina Casale
- Dipartimento della Donna, del Bambino e di Chirurgia Generale e Specialistica, University of Campania "Luigi Vanvitelli", Naples, Italy
| | | | - Antonio Giordano
- Sbarro Institute for Cancer Research and Molecular Medicine and Department of Biology, College of Science and Technology, Temple University, Philadelphia PA; Department of Medicine, Surgery & Neuroscience, University of Siena, Siena, Italy
| | - Umberto Galderisi
- Sbarro Institute for Cancer Research and Molecular Medicine and Department of Biology, College of Science and Technology, Temple University, Philadelphia PA; Department of Experimental Medicine, Biotechnology and Molecular Biology Section, University of Campania "Luigi Vanvitelli", Naples, Italy; Institute of Bioscience and Bioresources, CNR, Naples, Italy.
| |
Collapse
|
21
|
Runx3 plays a critical role in restriction-point and defense against cellular transformation. Oncogene 2017; 36:6884-6894. [PMID: 28846108 PMCID: PMC5735299 DOI: 10.1038/onc.2017.290] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/21/2017] [Accepted: 07/13/2017] [Indexed: 12/14/2022]
Abstract
The restriction (R)-point decision is fundamental to normal differentiation and the G1-S transition, and the decision-making machinery is perturbed in nearly all cancer cells. The mechanisms underlying the cellular context-dependent R-point decision remain poorly understood. We found that the R-point was dysregulated in Runx3-/-mouse embryonic fibroblasts (MEFs), which formed tumors in nude mice. Ectopic expression of Runx3 restored the R-point and abolished the tumorigenicity of Runx3-/-MEFs and K-Ras-activated Runx3-/-MEFs (Runx3-/-;K-RasG12D/+). During the R-point, Runx3 transiently formed a complex with pRb and Brd2 and induced Cdkn1a (p21Waf1/Cip1/Sdi1; p21), a key regulator of the R-point transition. Cyclin D-CDK4/6 promoted dissociation of the pRb-Runx3-Brd2 complex, thus turning off p21 expression. However, cells harboring oncogenic K-Ras maintained the pRb-Runx3-Brd2 complex and p21 expression even after introduction of Cyclin D1. Thus, Runx3 plays a critical role in R-point regulation and defense against cellular transformation.
Collapse
|
22
|
Thwaites MJ, Cecchini MJ, Talluri S, Passos DT, Carnevale J, Dick FA. Multiple molecular interactions redundantly contribute to RB-mediated cell cycle control. Cell Div 2017; 12:3. [PMID: 28293272 PMCID: PMC5348811 DOI: 10.1186/s13008-017-0029-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 02/28/2017] [Indexed: 02/07/2023] Open
Abstract
Background The G1-S phase transition is critical to maintaining proliferative control and preventing carcinogenesis. The retinoblastoma tumor suppressor is a key regulator of this step in the cell cycle. Results Here we use a structure–function approach to evaluate the contributions of multiple protein interaction surfaces on pRB towards cell cycle regulation. SAOS2 cell cycle arrest assays showed that disruption of three separate binding surfaces were necessary to inhibit pRB-mediated cell cycle control. Surprisingly, mutation of some interaction surfaces had no effect on their own. Rather, they only contributed to cell cycle arrest in the absence of other pRB dependent arrest functions. Specifically, our data shows that pRB–E2F interactions are competitive with pRB–CDH1 interactions, implying that interchangeable growth arrest functions underlie pRB’s ability to block proliferation. Additionally, disruption of similar cell cycle control mechanisms in genetically modified mutant mice results in ectopic DNA synthesis in the liver. Conclusions Our work demonstrates that pRB utilizes a network of mechanisms to prevent cell cycle entry. This has important implications for the use of new CDK4/6 inhibitors that aim to activate this proliferative control network.
Collapse
Affiliation(s)
- Michael J Thwaites
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Matthew J Cecchini
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Srikanth Talluri
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Daniel T Passos
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Jasmyne Carnevale
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Frederick A Dick
- London Regional Cancer Program, London, Canada.,Children's Health Research Institute, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| |
Collapse
|
23
|
Zhang J, Xu K, Liu P, Geng Y, Wang B, Gan W, Guo J, Wu F, Chin YR, Berrios C, Lien EC, Toker A, DeCaprio JA, Sicinski P, Wei W. Inhibition of Rb Phosphorylation Leads to mTORC2-Mediated Activation of Akt. Mol Cell 2016; 62:929-942. [PMID: 27237051 DOI: 10.1016/j.molcel.2016.04.023] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 12/07/2015] [Accepted: 04/21/2016] [Indexed: 12/23/2022]
Abstract
The retinoblastoma (Rb) protein exerts its tumor suppressor function primarily by inhibiting the E2F family of transcription factors that govern cell-cycle progression. However, it remains largely elusive whether the hyper-phosphorylated, non-E2F1-interacting form of Rb has any physiological role. Here we report that hyper-phosphorylated Rb directly binds to and suppresses the function of mTORC2 but not mTORC1. Mechanistically, Rb, but not p107 or p130, interacts with Sin1 and blocks the access of Akt to mTORC2, leading to attenuated Akt activation and increased sensitivity to chemotherapeutic drugs. As such, inhibition of Rb phosphorylation by depleting cyclin D or using CDK4/6 inhibitors releases Rb-mediated mTORC2 suppression. This, in turn, leads to elevated Akt activation to confer resistance to chemotherapeutic drugs in Rb-proficient cells, which can be attenuated with Akt inhibitors. Therefore, our work provides a molecular basis for the synergistic usage of CDK4/6 and Akt inhibitors in treating Rb-proficient cancer.
Collapse
Affiliation(s)
- Jinfang Zhang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Kai Xu
- Department of Otolaryngology-Head and Neck Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, P.R. China.,Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Pengda Liu
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Yan Geng
- Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Bin Wang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.,Department of Gastroenterology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, 400042, P. R. China
| | - Wenjian Gan
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Jianping Guo
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Fei Wu
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.,Department of Urology, Huashan Hospital, Fudan University, Shanghai, 200040, P.R. China
| | - Y Rebecca Chin
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Christian Berrios
- Department of Medical Oncology, Dana-Farber Cancer Institute and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Evan C Lien
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Alex Toker
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - James A DeCaprio
- Department of Medical Oncology, Dana-Farber Cancer Institute and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Piotr Sicinski
- Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| |
Collapse
|
24
|
Hypoxia inhibits mesenchymal stem cell proliferation through HIF1α-dependent regulation of P27. Mol Cell Biochem 2016; 415:29-38. [PMID: 26920732 DOI: 10.1007/s11010-016-2674-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 02/17/2016] [Indexed: 02/01/2023]
Abstract
Stem cells have inherent properties of self-renewal and differentiation. High percentage of transplanted stem cells (95 %) die into ischemic heart due to unfavorable environment where in hypoxia considered among major contributing factors. Hypoxia inducible factor-1 α is a well-known transcription factor which robustly induced during hypoxia and an essential factor for adaptation under lower oxygen tension. The effects of hypoxia onto stem cells and its cell cycle are poorly understood. Mesenchymal stem cells were isolated from adult male Fischer-344 rats bone marrow and kept under hypoxia (1 % O2). Cell survival and proliferation were studied using MTT and CFSE assay which showed reduced proliferation rate with an arrest in G0/G1 phase of cell cycle using flow cytometry. Western blot analysis revealed an increase in expressions of HIF-1α along with P53, a tumor suppressor gene. Cyclin-dependent kinase inhibitor (CDKI), p27 was significantly increased, in concordance with the findings, cyclin D1 was also reduced under hypoxia and forestalling S phase entry. In addition, loss of function study with HIF-1α knockdown revealed progression of cell cycle even under hypoxia. Knocking down p27 abrogated the hypoxia-induced G1 checkpoint, suggesting a key regulator of G1/S transition in hypoxic cells. Hypoxia could cause HIF-1α-dependent increase in the expression of p27 leading to cell cycle arrest in G0/G1 phase. The demonstration of the molecular mechanism of hypoxia-induced G1/S regulation provides insight into a fundamental response of stem cells to low oxygen tension.
Collapse
|
25
|
Peek GW, Tollefsbol TO. Combinatorial PX-866 and Raloxifene Decrease Rb Phosphorylation, Cyclin E2 Transcription, and Proliferation of MCF-7 Breast Cancer Cells. J Cell Biochem 2015; 117:1688-96. [PMID: 26660119 DOI: 10.1002/jcb.25462] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 12/10/2015] [Indexed: 01/03/2023]
Abstract
As a potential means to reduce proliferation of breast cancer cells, a multiple-pathway approach with no effect on control cells was explored. The human interactome being constructed by the Center for Cancer Systems Biology will prove indispensable to understanding composite effects of multiple pathways, but its discovered protein-protein interactions require characterization. Accordingly, we explored the effects of regulators of one protein on downstream targets of the other protein. MCF-7 estrogen receptor-positive (ER+) breast cancer cells were treated with raloxifene to upregulate the TGF-β pathway and PX-866 to down-regulate the PI3K/Akt pathway. This resulted in highly significant downstream reduction of cell cycle proliferation in breast cancer cells with no significant proliferation reduction following similar treatment of noncancerous MCF10A breast epithelial cells. Reduced phosphorylation of p107 and substantial reduction of Rb phosphorylation were observed in response. The effects of reduced Rb and p107 phosphorylation were reflected in significant decline in E2F-1 transcriptional activity, which is dependent on pocket protein phosphorylation status. The reduced proliferation was related to decreased expression of cyclins, including E2F-1-regulated Cyclin E2, which was also in response to raloxifene and PX-866. All combinations of raloxifene and PX-866 produced significant or highly significant results for reduced MCF-7 cell proliferation, reduced Cyclin E2 transcription, and reduced Rb phosphorylation. These studies demonstrated that uncontrolled proliferation of ER+ breast cancer cells can be significantly reduced by combinational targeting of two relevant pathways. J. Cell. Biochem. 117: 1688-1696, 2016. © 2015 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Gregory W Peek
- Department of Biology, University of Alabama, Birmingham, Alabama
| | - Trygve O Tollefsbol
- Department of Biology, University of Alabama, Birmingham, Alabama.,Comprehensive Cancer Center, University of Alabama, Birmingham, Alabama.,Comprehensive Center for Healthy Aging, University of Alabama, Birmingham, Alabama.,Comprehensive Diabetes Center, University of Alabama, Birmingham, Alabama.,Nutrition Obesity Research Center, University of Alabama, Birmingham, Alabama
| |
Collapse
|
26
|
Asghar U, Witkiewicz AK, Turner NC, Knudsen ES. The history and future of targeting cyclin-dependent kinases in cancer therapy. Nat Rev Drug Discov 2015; 14:130-46. [PMID: 25633797 PMCID: PMC4480421 DOI: 10.1038/nrd4504] [Citation(s) in RCA: 1180] [Impact Index Per Article: 131.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cancer represents a pathological manifestation of uncontrolled cell division; therefore, it has long been anticipated that our understanding of the basic principles of cell cycle control would result in effective cancer therapies. In particular, cyclin-dependent kinases (CDKs) that promote transition through the cell cycle were expected to be key therapeutic targets because many tumorigenic events ultimately drive proliferation by impinging on CDK4 or CDK6 complexes in the G1 phase of the cell cycle. Moreover, perturbations in chromosomal stability and aspects of S phase and G2/M control mediated by CDK2 and CDK1 are pivotal tumorigenic events. Translating this knowledge into successful clinical development of CDK inhibitors has historically been challenging, and numerous CDK inhibitors have demonstrated disappointing results in clinical trials. Here, we review the biology of CDKs, the rationale for therapeutically targeting discrete kinase complexes and historical clinical results of CDK inhibitors. We also discuss how CDK inhibitors with high selectivity (particularly for both CDK4 and CDK6), in combination with patient stratification, have resulted in more substantial clinical activity.
Collapse
Affiliation(s)
- Uzma Asghar
- Breakthrough Breast Cancer Research Centre, Chester Beatty Laboratories, Institute of Cancer Research, London, SW3 6JB, UK
| | - Agnieszka K Witkiewicz
- Simmons Cancer Center and Department of Pathology, University of Texas Southwestern, Dallas, USA
| | - Nicholas C Turner
- Institute of Cancer Research and Royal Marsden NHS Foundation Trust Breast Cancer Unit, London, SW3 6JJ, UK
| | - Erik S Knudsen
- Simmons Cancer Center and Department of Pathology, University of Texas Southwestern, Dallas, USA
| |
Collapse
|
27
|
Jayapal SR, Wang CQ, Bisteau X, Caldez MJ, Lim S, Tergaonkar V, Osato M, Kaldis P. Hematopoiesis specific loss of Cdk2 and Cdk4 results in increased erythrocyte size and delayed platelet recovery following stress. Haematologica 2015; 100:431-8. [PMID: 25616574 DOI: 10.3324/haematol.2014.106468] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Mouse knockouts of Cdk2 and Cdk4 are individually viable whereas the double knockouts are embryonic lethal due to heart defects, and this precludes the investigation of their overlapping roles in definitive hematopoiesis. Here we use a conditional knockout mouse model to investigate the effect of combined loss of Cdk2 and Cdk4 in hematopoietic cells. Cdk2(fl/fl)Cdk4(-/-)vavCre mice are viable but displayed a significant increase in erythrocyte size. Cdk2(fl/fl)Cdk4(-/-)vavCre mouse bone marrow exhibited reduced phosphorylation of the retinoblastoma protein and reduced expression of E2F target genes such as cyclin A2 and Cdk1. Erythroblasts lacking Cdk2 and Cdk4 displayed a lengthened G1 phase due to impaired phosphorylation of the retinoblastoma protein. Deletion of the retinoblastoma protein rescued the increased size displayed by erythrocytes lacking Cdk2 and Cdk4, indicating that the retinoblastoma/Cdk2/Cdk4 pathway regulates erythrocyte size. The recovery of platelet counts following a 5-fluorouracil challenge was delayed in Cdk2(fl/fl)Cdk4(-/-)vavCre mice revealing a critical role for Cdk2 and Cdk4 in stress hematopoiesis. Our data indicate that Cdk2 and Cdk4 play important overlapping roles in homeostatic and stress hematopoiesis, which need to be considered when using broad-spectrum cyclin-dependent kinase inhibitors for cancer therapy.
Collapse
Affiliation(s)
- Senthil Raja Jayapal
- Institute of Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Republic of Singapore
| | - Chelsia Qiuxia Wang
- Institute of Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Republic of Singapore Cancer Science Institute of Singapore, National University of Singapore, Republic of Singapore
| | - Xavier Bisteau
- Institute of Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Republic of Singapore
| | - Matias J Caldez
- Institute of Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Republic of Singapore National University of Singapore, Department of Biochemistry, Republic of Singapore
| | - Shuhui Lim
- Institute of Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Republic of Singapore
| | - Vinay Tergaonkar
- Institute of Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Republic of Singapore
| | - Motomi Osato
- Cancer Science Institute of Singapore, National University of Singapore, Republic of Singapore
| | - Philipp Kaldis
- Institute of Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Republic of Singapore National University of Singapore, Department of Biochemistry, Republic of Singapore
| |
Collapse
|
28
|
Shackney SE, Chowdhury SA, Schwartz R. A Novel Subset of Human Tumors That Simultaneously Overexpress Multiple E2F-responsive Genes Found in Breast, Ovarian, and Prostate Cancers. Cancer Inform 2014; 13:89-100. [PMID: 25392696 PMCID: PMC4221091 DOI: 10.4137/cin.s14062] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 09/08/2014] [Accepted: 09/15/2014] [Indexed: 01/14/2023] Open
Abstract
Reasoning that overexpression of multiple E2F-responsive genes might be a useful marker for RB1 dysfunction, we compiled a list of E2F-responsive genes from the literature and evaluated their expression in publicly available gene expression microarray data of patients with breast cancer, serous ovarian cancer, and prostate cancer. In breast cancer, a group of tumors was identified, each of which simultaneously overexpressed multiple E2F-responsive genes. Seventy percent of these genes were concerned with cell cycle progression, DNA repair, or mitosis. These E2F-responsive gene overexpressing (ERGO) tumors frequently exhibited additional evidence of Rb/E2F axis dysfunction, were mostly triple negative, and preferentially overexpressed multiple basal cytokeratins, suggesting that they overlapped substantially with the basal-like tumor subset. ERGO tumors were also identified in serous ovarian cancer and prostate cancer. In these cancer types, there was no evidence for a tumor subset comparable to the breast cancer basal-like subset. A core group of about 30 E2F-responsive genes were overexpressed in all three cancer types. Thus, it appears that disorders of the Rb/E2F axis can arise at multiple organ sites and produce tumors that simultaneously overexpress multiple E2F-responsive genes.
Collapse
Affiliation(s)
- Stanley E Shackney
- President and CEO, Intelligent Oncotherapeutics Incorporated, Pittsburgh, PA, USA
| | - Salim Akhter Chowdhury
- Graduate student of Computational Biology, Lane Center for Computational Biology and Joint Carnegie Mellon/University of Pittsburgh Ph.D. Program in Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Russell Schwartz
- Professor of Biological Sciences and Computational Biology, Department of Biological Sciences and Lane Center for Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| |
Collapse
|
29
|
Rajabi HN, Takahashi C, Ewen ME. Retinoblastoma protein and MyoD function together to effect the repression of Fra-1 and in turn cyclin D1 during terminal cell cycle arrest associated with myogenesis. J Biol Chem 2014; 289:23417-27. [PMID: 25006242 DOI: 10.1074/jbc.m113.532572] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The acquisition of skeletal muscle-specific function and terminal cell cycle arrest represent two important features of the myogenic differentiation program. These cellular processes are distinct and can be separated genetically. The lineage-specific transcription factor MyoD and the retinoblastoma protein pRb participate in both of these cellular events. Whether and how MyoD and pRb work together to effect terminal cell cycle arrest is uncertain. To address this question, we focused on cyclin D1, whose stable repression is required for terminal cell cycle arrest and execution of myogenesis. MyoD and pRb are both required for the repression of cyclin D1; their actions, however, were found not to be direct. Rather, they operate to regulate the immediate early gene Fra-1, a critical player in mitogen-dependent induction of cyclin D1. Two conserved MyoD-binding sites were identified in an intronic enhancer of Fra-1 and shown to be required for the stable repression of Fra-1 and, in turn, cyclin D1. Localization of MyoD alone to the intronic enhancer of Fra-1 in the absence of pRb was not sufficient to elicit a block to Fra-1 induction; pRb was also recruited to the intronic enhancer in a MyoD-dependent manner. These observations suggest that MyoD and pRb work together cooperatively at the level of the intronic enhancer of Fra-1 during terminal cell cycle arrest. This work reveals a previously unappreciated link between a lineage-specific transcription factor, a tumor suppressor, and a proto-oncogene in the control of an important facet of myogenic differentiation.
Collapse
Affiliation(s)
- Hasan N Rajabi
- From the Dana-Farber Cancer Institute, Boston, Massachusetts 02215
| | - Chiaki Takahashi
- From the Dana-Farber Cancer Institute, Boston, Massachusetts 02215, the Cancer Research Institute of Kanazawa University, 13-1 Takara-machi, Kanazawa 920-0934, Japan, and
| | - Mark E Ewen
- From the Dana-Farber Cancer Institute, Boston, Massachusetts 02215, the Molecular Oncology Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| |
Collapse
|
30
|
A retinoblastoma allele that is mutated at its common E2F interaction site inhibits cell proliferation in gene-targeted mice. Mol Cell Biol 2014; 34:2029-45. [PMID: 24662053 DOI: 10.1128/mcb.01589-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The retinoblastoma protein (pRB) is best known for regulating cell proliferation through E2F transcription factors. In this report, we investigate the properties of a targeted mutation that disrupts pRB interactions with the transactivation domain of E2Fs. Mice that carry this mutation endogenously (Rb1(ΔG)) are defective for pRB-dependent repression of E2F target genes. Except for an accelerated entry into S phase in response to serum stimulation, cell cycle regulation in Rb1(ΔG/ΔG) mouse embryonic fibroblasts (MEFs) strongly resembles that of the wild type. In a serum deprivation-induced cell cycle exit, Rb1(ΔG/ΔG) MEFs display a magnitude of E2F target gene derepression similar to that of Rb1(-/-) cells, even though Rb1(ΔG/ΔG) cells exit the cell cycle normally. Interestingly, cell cycle arrest in Rb1(ΔG/ΔG) MEFs is responsive to p16 expression and gamma irradiation, indicating that alternate mechanisms can be activated in G1 to arrest proliferation. Some Rb1(ΔG/ΔG) mice die neonatally with a muscle degeneration phenotype, while the others live a normal life span with no evidence of spontaneous tumor formation. Most tissues appear histologically normal while being accompanied by derepression of pRB-regulated E2F targets. This suggests that non-E2F-, pRB-dependent pathways may have a more relevant role in proliferative control than previously identified.
Collapse
|
31
|
Capasso S, Alessio N, Di Bernardo G, Cipollaro M, Melone MA, Peluso G, Giordano A, Galderisi U. Silencing of RB1 and RB2/P130 during adipogenesis of bone marrow stromal cells results in dysregulated differentiation. Cell Cycle 2013; 13:482-90. [PMID: 24281253 DOI: 10.4161/cc.27275] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Bone marrow adipose tissue (BMAT) is different from fat found elsewhere in the body, and only recently have some of its functions been investigated. BMAT may regulate bone marrow stem cell niche and plays a role in energy storage and thermogenesis. BMAT may be involved also in obesity and osteoporosis onset. Given the paramount functions of BMAT, we decided to better clarify the human bone marrow adipogenesis by analyzing the role of the retinoblastoma gene family, which are key players in cell cycle regulation. Our data provide evidence that the inactivation of RB1 or RB2/P130 in uncommitted bone marrow stromal cells (BMSC) facilitates the first steps of adipogenesis. In cultures with silenced RB1 or RB2/P130, we observed an increase of clones with adipogenic potential and a higher percentage of cells accumulating lipid droplets. Nevertheless, the absence of RB1 or RB2/P130 impaired the terminal adipocyte differentiation and gave rise to dysregulated adipose cells, with alteration in lipid uptake and release. For the first time, we evidenced that RB2/P130 plays a role in bone marrow adipogenesis. Our data suggest that while the inactivation of retinoblastoma proteins may delay the onset of last cell division and allow more BMSC to be committed to adipocyte, it did not allow a permanent cell cycle exit, which is a prerequisite for adipocyte terminal maturation.
Collapse
Affiliation(s)
- Stefania Capasso
- Department of Experimental Medicine; Biotechnology and Molecular Biology Section; Second University of Naples; Naples, Italy
| | - Nicola Alessio
- Department of Experimental Medicine; Biotechnology and Molecular Biology Section; Second University of Naples; Naples, Italy; Institute of Protein Biochemistry; CNR; Naples, Italy
| | - Giovanni Di Bernardo
- Department of Experimental Medicine; Biotechnology and Molecular Biology Section; Second University of Naples; Naples, Italy
| | - Marilena Cipollaro
- Department of Experimental Medicine; Biotechnology and Molecular Biology Section; Second University of Naples; Naples, Italy
| | - Mariarosa Ab Melone
- Department of Clinical and Experimental Medicine; Second University of Naples; Naples, Italy
| | - Gianfranco Peluso
- Institute of Protein Biochemistry; CNR; Naples, Italy; Institute of Biomedicine and Bioresources; CNR; Naples, Italy
| | - Antonio Giordano
- Sbarro Institute for Cancer Research and Molecular Medicine; Center For Biotechnology; Temple University; Philadelphia, PA USA; Department of Medicine, Surgery and Neurociences; University of Siena; Siena, Italy
| | - Umberto Galderisi
- Department of Experimental Medicine; Biotechnology and Molecular Biology Section; Second University of Naples; Naples, Italy; Institute of Protein Biochemistry; CNR; Naples, Italy; Sbarro Institute for Cancer Research and Molecular Medicine; Center For Biotechnology; Temple University; Philadelphia, PA USA; GENKÖK; Genome and Stem Cell Center; Erciyes University; Kayseri, Turkey
| |
Collapse
|
32
|
Whole chromosome instability resulting from the synergistic effects of pRB and p53 inactivation. Oncogene 2013; 33:2487-94. [PMID: 23792446 DOI: 10.1038/onc.2013.201] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 04/10/2013] [Accepted: 04/12/2013] [Indexed: 01/24/2023]
Abstract
Whole chromosome instability (CIN) is a common feature of cancer cells and has been linked to increased tumor evolution and metastasis. Several studies have shown that the loss of the pRB tumor suppressor causes mitotic defects and chromosome mis-segregation. pRB is inactivated in many types of cancer and this raises the possibility that the loss of pRB may be a general cause of CIN in tumors. Paradoxically, retinoblastoma tumor cells have a relatively stable karyotype and currently the circumstances in which pRB inactivation causes CIN in human cancers are unclear. Here we utilize a fluorescence in situ hybridization-based approach to score numerical heterogeneity in chromosome copy number as a readout of CIN. Using this technique, we show that high levels of CIN correlate with the combined inactivation of pRB and p53 and that this association is evident in two independent panels of cancer cell lines. Retinoblastoma cell lines characteristically retain a wild-type TP53 gene, providing an opportunity to test the relevance of this functional relationship. We show that retinoblastoma cell lines display mitotic defects similar to those seen when pRB is depleted from non-transformed cells, but that the presence of wild-type p53 suppresses the accumulation of aneuploid cells. A similar synergy between pRB and p53 inactivation was observed in HCT116 cells. These results suggest that the loss of pRB promotes segregation errors, whereas loss of p53 allows tolerance and continued proliferation of the resulting, genomically unstable cancer cells. Hence, it is the cooperative effect of inactivation of both pRB and p53 tumor suppressor pathways that promotes CIN.
Collapse
|
33
|
Alessio N, Bohn W, Rauchberger V, Rizzolio F, Cipollaro M, Rosemann M, Irmler M, Beckers J, Giordano A, Galderisi U. Silencing of RB1 but not of RB2/P130 induces cellular senescence and impairs the differentiation potential of human mesenchymal stem cells. Cell Mol Life Sci 2013; 70:1637-51. [PMID: 23370776 PMCID: PMC11113310 DOI: 10.1007/s00018-012-1224-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 11/24/2012] [Accepted: 11/26/2012] [Indexed: 12/22/2022]
Abstract
Stem cell senescence is considered deleterious because it may impair tissue renewal and function. On the other hand, senescence may arrest the uncontrolled growth of transformed stem cells and protect organisms from cancer. This double function of senescence is strictly linked to the activity of genes that the control cell cycle such as the retinoblastoma proteins RB1, RB2/P130, and P107. We took advantage of the RNA interference technique to analyze the role of these proteins in the biology of mesenchymal stem cells (MSC). Cells lacking RB1 were prone to DNA damage. They showed elevated levels of p53 and p21(cip1) and increased regulation of RB2/P130 and P107 expression. These cells gradually adopted a senescent phenotype with impairment of self-renewal properties. No significant modification of cell growth was observed as it occurs in other cell types or systems. In cells with silenced RB2/P130, we detected a reduction of DNA damage along with a higher proliferation rate, an increase in clonogenic ability, and the diminution of apoptosis and senescence. Cells with silenced RB2/P130 were cultivated for extended periods of time without adopting a transformed phenotype. Of note, acute lowering of P107 did not induce relevant changes in the in vitro behavior of MSC. We also analyzed cell commitment and the osteo-chondro-adipogenic differentiation process of clones derived by MSC cultures. In all clones obtained from cells with silenced retinoblastoma genes, we observed a reduction in the ability to differentiate compared with the control clones. In summary, our data show evidence that the silencing of the expression of RB1 or RB2/P130 is not compensated by other gene family members, and this profoundly affects MSC functions.
Collapse
Affiliation(s)
- Nicola Alessio
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Naples, Italy
| | - Wolfgang Bohn
- Department of Tumorvirology, Heinrich-Pette-Institute, Leibniz-Institute for Experimental Virology, Hamburg, Germany
| | - Verena Rauchberger
- Department of Tumorvirology, Heinrich-Pette-Institute, Leibniz-Institute for Experimental Virology, Hamburg, Germany
| | - Flavio Rizzolio
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, 1900 North 12th Street, Philadelphia, PA 19107-6799 USA
| | - Marilena Cipollaro
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Naples, Italy
| | - Michael Rosemann
- Helmholtz Zentrum, National Research Center for Environment and Health, GmbH, Institute of Radiation Biology, Munich, Germany
| | - Martin Irmler
- Helmholtz Zentrum, National Research Center for Environment and Health, GmbH, Institute of Experimental Genetics, Munich, Germany
| | - Johannes Beckers
- Helmholtz Zentrum, National Research Center for Environment and Health, GmbH, Institute of Experimental Genetics, Munich, Germany
- WZW, Center of Life and Food Science Weihenstephan, Chair of Experimental Genetics, Technische Universität München, Freising-Weihenstephan, Germany
| | - Antonio Giordano
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, 1900 North 12th Street, Philadelphia, PA 19107-6799 USA
- Human Health Foundation, Spoleto, Italy
- Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy
| | - Umberto Galderisi
- Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Naples, Italy
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, 1900 North 12th Street, Philadelphia, PA 19107-6799 USA
- Human Health Foundation, Spoleto, Italy
| |
Collapse
|
34
|
Abstract
Cells decide to proliferate or remain quiescent using signaling pathways that link information about the cellular environment to the G1 phase of the cell cycle. Progression through G1 phase is controlled by pRB proteins, which function to repress the activity of E2F transcription factors in cells exiting mitosis and in quiescent cells. Phosphorylation of pRB proteins by the G1 cyclin-dependent kinases (CDKs) releases E2F factors, promoting the transition to S phase. CDK activity is primarily regulated by the binding of CDK catalytic subunits to cyclin partners and CDK inhibitors. Consequently, both mitogenic and antiproliferative signals exert their effects on cell proliferation through the transcriptional regulation and ubiquitin-dependent degradation of cyclins and CDK inhibitors.
Collapse
Affiliation(s)
- Robert J Duronio
- Department of Biology and Genetics, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
| | | |
Collapse
|
35
|
Dungrawala H, Hua H, Wright J, Abraham L, Kasemsri T, McDowell A, Stilwell J, Schneider BL. Identification of new cell size control genes in S. cerevisiae. Cell Div 2012; 7:24. [PMID: 23234503 PMCID: PMC3541103 DOI: 10.1186/1747-1028-7-24] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 12/04/2012] [Indexed: 12/13/2022] Open
Abstract
Cell size homeostasis is a conserved attribute in many eukaryotic species involving a tight regulation between the processes of growth and proliferation. In budding yeast S. cerevisiae, growth to a “critical cell size” must be achieved before a cell can progress past START and commit to cell division. Numerous studies have shown that progression past START is actively regulated by cell size control genes, many of which have implications in cell cycle control and cancer. Two initial screens identified genes that strongly modulate cell size in yeast. Since a second generation yeast gene knockout collection has been generated, we screened an additional 779 yeast knockouts containing 435 new ORFs (~7% of the yeast genome) to supplement previous cell size screens. Upon completion, 10 new strong size mutants were identified: nine in log-phase cells and one in saturation-phase cells, and 97% of the yeast genome has now been screened for cell size mutations. The majority of the logarithmic phase size mutants have functions associated with translation further implicating the central role of growth control in the cell division process. Genetic analyses suggest ECM9 is directly associated with the START transition. Further, the small (whi) mutants mrpl49Δ and cbs1Δ are dependent on CLN3 for cell size effects. In depth analyses of new size mutants may facilitate a better understanding of the processes that govern cell size homeostasis.
Collapse
Affiliation(s)
- Huzefa Dungrawala
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, 3601 4th St Rm, 5C119, Lubbock, TX, 79430, USA.
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Talluri S, Dick FA. Regulation of transcription and chromatin structure by pRB: here, there and everywhere. Cell Cycle 2012; 11:3189-98. [PMID: 22895179 PMCID: PMC3466518 DOI: 10.4161/cc.21263] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Commitment to divide is one of the most crucial steps in the mammalian cell division cycle. It is critical for tissue and organismal homeostasis, and consequently is highly regulated. The vast majority of cancers evade proliferative control, further emphasizing the importance of the commitment step in cell cycle regulation. The Retinoblastoma (RB) tumor suppressor pathway regulates this decision-making step. Since being the subject of Knudson's 'two hit hypothesis', there has been considerable interest in understanding pRB's role in cancer. It is best known for repressing E2F dependent transcription of cell cycle genes. However, pRB's role in controlling chromatin structure is expanding and bringing it into new regulatory paradigms. In this review we discuss pRB function through protein-protein interactions, at the level of transcriptional regulation of individual promoters and in organizing higher order chromatin domains.
Collapse
Affiliation(s)
- Srikanth Talluri
- London Regional Cancer Program; Western University; London, ON Canada
- Department of Biochemistry; Western University; London, ON Canada
| | - Frederick A. Dick
- London Regional Cancer Program; Western University; London, ON Canada
- Department of Biochemistry; Western University; London, ON Canada
- Children’s Health Research Institute; Western University; London, ON Canada
| |
Collapse
|
37
|
Collins MJ, Napoli I, Ribeiro S, Roberts S, Lloyd AC. Loss of Rb cooperates with Ras to drive oncogenic growth in mammalian cells. Curr Biol 2012; 22:1765-73. [PMID: 22885065 DOI: 10.1016/j.cub.2012.07.040] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 06/02/2012] [Accepted: 07/18/2012] [Indexed: 01/19/2023]
Abstract
BACKGROUND The p53, Rb, and Ras/PI3K pathways are implicated in the development of the majority of human cancers. A number of studies have established that these pathways cooperate at the level of the cell cycle leading to loss of normal proliferative controls. Here we have investigated how these signals influence a second critical component of tumor formation-cell growth. RESULTS We find that oncogenic Ras is sufficient to drive growth via the canonical growth pathway, PI3K-AKT-TOR; however, it does so relatively weakly and p53 loss does not drive cell growth at all. Importantly, we identify a novel role for the Rb family of tumor suppressors in directing cell growth via a signaling pathway distinct from PI3K-AKT-TOR and via an E2F-independent mechanism. However, we find that strong, sustained growth requires Rb loss together with Ras signaling, identifying an additional mechanism by which these oncogenic pathways cooperate and a critical role for Ras in preserving the uptake of extracellular nutrients required for biogenesis. CONCLUSIONS We have identified a new role for the Rb family in cell biogenesis and show that, as for other processes associated with tumor development, oncogenic cell growth is dependent on cooperating oncogenes.
Collapse
Affiliation(s)
- Melissa J Collins
- MRC Laboratory for Molecular Cell Biology and the UCL Cancer Institute, University College London, Gower Street, London WC1E 6BT, UK
| | | | | | | | | |
Collapse
|
38
|
Foster DA, Yellen P, Xu L, Saqcena M. Regulation of G1 Cell Cycle Progression: Distinguishing the Restriction Point from a Nutrient-Sensing Cell Growth Checkpoint(s). Genes Cancer 2011; 1:1124-31. [PMID: 21779436 DOI: 10.1177/1947601910392989] [Citation(s) in RCA: 172] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Most genetic changes that promote tumorigenesis involve dysregulation of G1 cell cycle progression. A key regulatory site in G1 is a growth factor-dependent restriction point (R) where cells commit to mitosis. In addition to the growth factor-dependent "R," which maps to a site about 3.5 hours after mitosis, there is another checkpoint later in G1 that is dependent on nutritional sufficiency that has also been referred to as R. However, this second site in late G1 can be distinguished both temporally and genetically from R. We are proposing that the late G1 regulatory site be more appropriately referred to as a "cell growth" checkpoint to distinguish it from R. This checkpoint, which likely has an evolutionary relationship to the yeast cell cycle checkpoint START, is regulated by signals governed by mTOR, the mammalian target of rapamycin. This review summarizes evidence that distinguishes R from the proposed cell growth checkpoint. Since both checkpoints are dysregulated in most, if not all, human cancers, distinguishing between these 2 distinct G1 regulatory checkpoints has significance for rational therapeutic strategies targeting oncogenic signals.
Collapse
Affiliation(s)
- David A Foster
- Department of Biological Sciences, Hunter College of The City University of New York, New York, NY, USA
| | | | | | | |
Collapse
|
39
|
Bourgo RJ, Thangavel C, Ertel A, Bergseid J, McClendon AK, Wilkens L, Witkiewicz AK, Wang JYJ, Knudsen ES. RB restricts DNA damage-initiated tumorigenesis through an LXCXE-dependent mechanism of transcriptional control. Mol Cell 2011; 43:663-72. [PMID: 21855804 DOI: 10.1016/j.molcel.2011.06.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 03/28/2011] [Accepted: 06/26/2011] [Indexed: 01/18/2023]
Abstract
The LXCXE peptide motif facilitates interaction between the RB tumor suppressor and a large number of cellular proteins that are expected to impinge on diverse biological processes. In vitro and in vivo analyses demonstrated that LXCXE binding function is dispensable for RB promoter association and control of basal gene expression. Dependence on this function of RB is unmasked after DNA damage, wherein LXCXE binding is essential for exerting control over E2F3 and suppressing cell-cycle progression in the presence of genotoxic stress. Gene expression profiling revealed that the transcriptional program coordinated by this specific aspect of RB is associated with progression of human hepatocellular carcinoma and poor disease outcome. Consistent with these findings, biological challenge revealed a requirement for LXCXE binding in suppression of genotoxin-initiated hepatocellular carcinoma in vivo. Together, these studies establish an essential role of the LXCXE binding motif for RB-mediated transcriptional control, response to genotoxic insult, and tumor suppression.
Collapse
Affiliation(s)
- Ryan J Bourgo
- Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Wong JV, Dong P, Nevins JR, Mathey-Prevot B, You L. Network calisthenics: control of E2F dynamics in cell cycle entry. Cell Cycle 2011; 10:3086-94. [PMID: 21900750 DOI: 10.4161/cc.10.18.17350] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Stimulation of quiescent mammalian cells with mitogens induces an abrupt increase in E2F1-3 expression just prior to the onset of DNA synthesis, followed by a rapid decline as replication ceases. This temporal adaptation in E2F facilitates a transient pattern of gene expression that reflects the ordered nature of DNA replication. The challenge to understand how E2F dynamics coordinate molecular events required for high-fidelity DNA replication has great biological implications. Indeed, precocious, prolonged, elevated or reduced accumulation of E2F can generate replication stress that culminates in either arrest or death. Accordingly, temporal characteristics of E2F are regulated by several network modules that include feedforward and autoregulatory loops. In this review, we discuss how these network modules contribute to "shaping" E2F dynamics in the context of mammalian cell cycle entry.
Collapse
Affiliation(s)
- Jeffrey V Wong
- Department of Biomedical Engineering, Institute for Genome Sciences and Policy, Duke University, Durham, NC, USA.
| | | | | | | | | |
Collapse
|
41
|
Manning AL, Dyson NJ. pRB, a tumor suppressor with a stabilizing presence. Trends Cell Biol 2011; 21:433-41. [PMID: 21664133 PMCID: PMC3149724 DOI: 10.1016/j.tcb.2011.05.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 05/04/2011] [Accepted: 05/05/2011] [Indexed: 01/19/2023]
Abstract
The product of the retinoblastoma tumor-susceptibility gene (RB1) is a key regulator of cell proliferation and this function is thought to be central to its tumor suppressive activity. Several studies have demonstrated that inactivation of pRB not only allows inappropriate proliferation but also undermines mitotic fidelity, leading to genome instability and ploidy changes. Such properties promote tumor evolution and correlate with increased resistance to therapeutics and tumor relapse. These observations suggest that inactivation of pRB could contribute to both tumor initiation and progression. Further characterization of the role of pRB in chromosome segregation will provide insight into processes that are misregulated in human tumors and could reveal new therapeutic targets to kill or stall these chromosomally unstable lesions. We review the evidence that pRB promotes genome stability and discuss the mechanisms that probably contribute to this effect.
Collapse
Affiliation(s)
- Amity L Manning
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, USA.
| | | |
Collapse
|
42
|
Novel mechanism of reduced proliferation in ovarian clear cell carcinoma cells: cytoplasmic sequestration of CDK2 by p27. Gynecol Oncol 2011; 122:641-7. [PMID: 21652059 DOI: 10.1016/j.ygyno.2011.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 05/01/2011] [Accepted: 05/03/2011] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Ovarian clear cell carcinoma (CCC) carries a poor prognosis because of its insensitivity to chemotherapy. We previously found an association between reduced proliferation of CCC and chemoresistance; here we investigated the mechanism of the reduced proliferation. METHODS We assessed cell cycle function by measuring the activity of cyclin-dependent kinases (CDKs) and the protein expression of cyclins, the CDK inhibitors, and p53 in 22 ovarian cancer cell lines and 60 human ovarian cancer specimens. We examined the cellular location of p27, p27 phosphorylated at threonine 157 (p27(Thr157)), and CDK2 protein by confocal microscopy and western blotting. We tested the effect of the inhibitor of phosphatidylinositol-3-kinase (PI3K) and small interfering RNA against p27 (si-p27) in two CCC cell lines (RMG-I, SMOV-2). RESULTS CCC cells had lower CDK2 activity and higher p27 expression than serous adenocarcinoma (SA) cells. Low CDK2 activity correlated with high p27 protein expression. p27(Thr157) sequestered CDK2 in the cytoplasm, but PI3K inhibitor or si-p27 maintained CDK2 in the nucleus and restored its activity. In human specimens, CDK2 was mostly in the cytoplasm and was spatially associated with p27; CDK2 activity was lower in the CCC than in the SA specimens. si-p27 enhanced the cytotoxic effect of cisplatin, doxorubicin, and gemcitabine in both RMG-I cells and SMOV-2 cells. CONCLUSIONS Reduced CDK2 activity via the cytoplasmic sequestration of CDK2 by p27(Thr157) may contribute to suppression of CCC proliferation. A prospective study is needed to determine whether the cytoplasmic sequestration of CDK2 results in the chemoresistance of CCC.
Collapse
|
43
|
Lockwood WW, Stack D, Morris T, Grehan D, O'Keane C, Stewart GL, Cumiskey J, Lam WL, Squire JA, Thomas DM, O'Sullivan MJ. Cyclin E1 is amplified and overexpressed in osteosarcoma. J Mol Diagn 2011; 13:289-96. [PMID: 21458381 DOI: 10.1016/j.jmoldx.2010.11.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 10/11/2010] [Accepted: 11/18/2010] [Indexed: 11/25/2022] Open
Abstract
Osteosarcoma is a genetically complex malignancy, predominantly afflicting the adolescent population and associated still with relatively poor long-term outcomes. Although there has been some improvement in the understanding of osteosarcoma biology, this has not yet translated particularly well into therapeutic advances. By using a whole-genome tiling path array for comparative genomic hybridization analysis, we sought to evaluate DNA copy number changes in 22 osteosarcoma tumor samples. Regions of most frequent gains or losses generated by Genomic Identification of Significant Targets in Cancer analysis were evaluated for genes of interest. Correlation of the copy number data with preexisting expression data for these genes yielded not only targets known to be important in osteosarcoma but also novel targets, notably cyclin E1. Fluorescence in situ hybridization and immunohistochemical analysis confirmed the findings. Overexpression of cyclin E1 has potential prognostic and therapeutic implications that are discussed herein.
Collapse
Affiliation(s)
- William W Lockwood
- British Columbia Cancer Research Center, Vancouver, British Columbia, Canada
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Leloup C, Hopkins KM, Wang X, Zhu A, Wolgemuth DJ, Lieberman HB. Mouse Rad9b is essential for embryonic development and promotes resistance to DNA damage. Dev Dyn 2011; 239:2837-50. [PMID: 20842695 DOI: 10.1002/dvdy.22415] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
RAD9 participates in promoting resistance to DNA damage, cell cycle checkpoint control, DNA repair, apoptosis, embryogenesis, and regulation of transcription. A paralogue of RAD9 (named RAD9B) has been identified. To define the function of mouse Rad9b (Mrad9b), embryonic stem (ES) cells with a targeted gene deletion were constructed and used to generate Mrad9b mutant mice. Mrad9b(-/-) embryos are resorbed after E7.5 while some of the heterozygotes die between E12.5 and a few days after birth. Mrad9b is expressed in embryonic brain and Mrad9b(+/-) embryos exhibit abnormal neural tube closure. Mrad9b(-/-) mouse embryonic fibroblasts are not viable. Mrad9b(-/-) ES cells are more sensitive to gamma rays and mitomycin C than Mrad9b(+/+) controls, but show normal gamma-ray-induced G2/M checkpoint control. There is no evidence of spontaneous genomic instability in Mrad9b(-/-) cells. Our findings thus indicate that Mrad9b is essential for embryonic development and mediates resistance to certain DNA damaging agents.
Collapse
Affiliation(s)
- Corinne Leloup
- Center for Radiological Research, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
| | | | | | | | | | | |
Collapse
|
45
|
Bourgo RJ, Ehmer U, Sage J, Knudsen ES. RB deletion disrupts coordination between DNA replication licensing and mitotic entry in vivo. Mol Biol Cell 2011; 22:931-9. [PMID: 21289097 PMCID: PMC3069018 DOI: 10.1091/mbc.e10-11-0895] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The retinoblastoma tumor suppressor (RB) is functionally inactivated at high frequency in nearly all tumor types. Herein the acute deletion of RB in the liver reveals an immediate and profound dysregulation of spatiotemporal coordination in cell-cycle phases, resulting in robust DNA damage and aneuploidy that is not found in other tissues. The integrity of the retinoblastoma tumor suppressor (RB) pathway is critical for restraining inappropriate proliferation and suppressing tumor development in a plethora of tissues. Here adenovirus-mediated RB deletion in the liver of adult mice led to DNA replication in the absence of productive mitotic condensation. The replication induced by RB loss was E2F-mediated and associated with the induction of DNA damage and a nontranscriptional G2/M checkpoint that targeted the accumulation of Cyclin B1. In the context of RB deletion or E2F activation, there was an increase in hepatocyte ploidy that was accompanied by hyperphysiological assembly of prereplication complexes. In keeping with this dysregulation, initiation of DNA replication was readily observed in hepatocytes that were phenotypically in G2/M. Under such conditions, uncoupling of replication initiation from mitotic progression led to altered genome ploidy in the liver. Interestingly, these findings in hepatocytes were not recapitulated in the basally proliferative tissues of the gastrointestinal tract, where RB deletion, while increasing DNA replication, did not lead to a profound uncoupling from mitosis. Combined, these findings demonstrate the critical role of RB in controlling cell-cycle transitions and underscore the importance of intrinsic tissue environments in resultant phenotypes.
Collapse
Affiliation(s)
- Ryan J Bourgo
- Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | | | | | | |
Collapse
|
46
|
Odd-skipped related 2 regulates genes related to proliferation and development. Biochem Biophys Res Commun 2010; 398:184-90. [DOI: 10.1016/j.bbrc.2010.06.054] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 06/11/2010] [Indexed: 11/24/2022]
|
47
|
Coschi CH, Martens AL, Ritchie K, Francis SM, Chakrabarti S, Berube NG, Dick FA. Mitotic chromosome condensation mediated by the retinoblastoma protein is tumor-suppressive. Genes Dev 2010; 24:1351-63. [PMID: 20551166 DOI: 10.1101/gad.1917610] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Condensation and segregation of mitotic chromosomes is a critical process for cellular propagation, and, in mammals, mitotic errors can contribute to the pathogenesis of cancer. In this report, we demonstrate that the retinoblastoma protein (pRB), a well-known regulator of progression through the G1 phase of the cell cycle, plays a critical role in mitotic chromosome condensation that is independent of G1-to-S-phase regulation. Using gene targeted mutant mice, we studied this aspect of pRB function in isolation, and demonstrate that it is an essential part of pRB-mediated tumor suppression. Cancer-prone Trp53(-/-) mice succumb to more aggressive forms of cancer when pRB's ability to condense chromosomes is compromised. Furthermore, we demonstrate that defective mitotic chromosome structure caused by mutant pRB accelerates loss of heterozygosity, leading to earlier tumor formation in Trp53(+/-) mice. These data reveal a new mechanism of tumor suppression, facilitated by pRB, in which genome stability is maintained by proper condensation of mitotic chromosomes.
Collapse
Affiliation(s)
- Courtney H Coschi
- London Regional Cancer Program, University of Western Ontario, London, Ontario, Canada
| | | | | | | | | | | | | |
Collapse
|
48
|
Odd-skipped related 2 is epigenetically regulated in cellular quiescence. Biochem Biophys Res Commun 2010; 396:831-6. [PMID: 20450884 DOI: 10.1016/j.bbrc.2010.04.159] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 04/28/2010] [Indexed: 11/20/2022]
Abstract
Cellular behavior and development are extensively altered during the transition from cell cycle into quiescence, though the mechanism involved in establishing and maintaining quiescence is largely unknown. We found that Odd-skipped related 2 (Osr2) was up-regulated during cellular quiescence by serum starvation as well as culturing to confluence. To investigate the regulatory mechanism of Osr2 under these conditions, we characterized the mouse Osr2 promoter. CpG islands in the flanking region of the transcription start site were predominantly methylated in exponentially growing cells, resulting in silencing of Osr2 expression. In addition, CpG demethylation in quiescence caused activation of Osr2 expression, while acetylation of the H3 and H4 histones during quiescence also led to an increase in Osr2 expression. These results suggest that epigenetically regulated Osr2 plays an important role in cellular quiescence and proliferation.
Collapse
|
49
|
Berman HK, Gauthier ML, Tlsty TD. Premalignant breast neoplasia: a paradigm of interlesional and intralesional molecular heterogeneity and its biological and clinical ramifications. Cancer Prev Res (Phila) 2010; 3:579-87. [PMID: 20424132 DOI: 10.1158/1940-6207.capr-10-0073] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
As is well established in invasive breast disease, it is becoming increasingly clear that molecular heterogeneity, both between and within lesions, is a prevalent, distinct phenotype of premalignant lesions of the breast. Key pathways of tumorigenesis modulate critical features of premalignant lesions such as proliferation, differentiation, stress response, and even the generation of diversity. Current studies show that evaluation of these lesions may provide clinically useful information on future tumor formation as well as biological insights into the origin and functional significance of this distinct phenotype.
Collapse
Affiliation(s)
- Hal K Berman
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | | | | |
Collapse
|
50
|
Abstract
RB, p107, and p130 are highly related proteins, each capable of regulating cellular proliferation. However, only RB is frequently mutated in cancer. In this issue of Cancer Cell, Chicas et al. shed new light on this conundrum, defining a "special," nonredundant role for RB in promoting cellular senescence.
Collapse
Affiliation(s)
- Christin E. Burd
- Department of Genetics, The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7295, USA
- Curriculum in Toxicology, The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7295, USA
| | - Norman E. Sharpless
- Department of Genetics, The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7295, USA
- Curriculum in Toxicology, The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7295, USA
- Department of Medicine, The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7295, USA
- Correspondence:
| |
Collapse
|