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Wang Y, Yu T, Han Y, He Y, Song Y, Guo L, An L, Yang C, Wang F. Phosphorylation of MAD2 at Ser195 Promotes Spindle Checkpoint Defects and Sensitizes Cancer Cells to Radiotherapy in ATM Deficient Cells. Front Cell Dev Biol 2022; 10:817831. [PMID: 35309941 PMCID: PMC8924061 DOI: 10.3389/fcell.2022.817831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/18/2022] [Indexed: 11/13/2022] Open
Abstract
The spindle assembly checkpoint (SAC) is a critical monitoring device in mitosis for the maintenance of genomic stability. Specifically, the SAC complex comprises several factors, including Mad1, Mad2, and Bub1. Ataxia-telangiectasia mutated (ATM) kinase, the crucial regulator in DNA damage response (DDR), also plays a critical role in mitosis by regulating Mad1 dimerization and SAC. Here, we further demonstrated that ATM negatively regulates the phosphorylation of Mad2, another critical component of the SAC, which is also involved in DDR. Mechanistically, we found that phosphorylation of Mad2 is aberrantly increased in ATM-deficient cells. Point-mutation analysis further revealed that Serine 195 mainly mediated Mad2 phosphorylation upon ATM ablation. Functionally, the phosphorylation of Mad2 causes decreased DNA damage repair capacity and is related to the resistance to cancer cell radiotherapy. Altogether, this study unveils the key regulatory role of Mad2 phosphorylation in checkpoint defects and DNA damage repair in ATM-deficient cells.
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Affiliation(s)
- Yang Wang
- Department of Gastroenterology, Shanghai 10th People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Tianyu Yu
- Department of General Surgery, Pudong New Area Gongli Hospital Affiliated to Naval Military Medical University, Naval Military Medical University, Shanghai, China
| | - Yi Han
- Department of Gastroenterology, Shanghai 10th People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yazhi He
- Department of Gastroenterology, Shanghai 10th People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yiran Song
- Department of Gastroenterology, Shanghai 10th People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Leiming Guo
- Department of R&D, Shanghai Creative Immune Therapeutics Co., Ltd, Shanghai, China
| | - Liwei An
- Department of Gastroenterology, Shanghai 10th People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Chunying Yang
- Central Laboratory, Shanghai Putuo District People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Feng Wang
- Department of Gastroenterology, Shanghai 10th People's Hospital, Tongji University School of Medicine, Shanghai, China.,Central Laboratory, Shanghai Putuo District People's Hospital, Tongji University School of Medicine, Shanghai, China
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2
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Luna-Maldonado F, Andonegui-Elguera MA, Díaz-Chávez J, Herrera LA. Mitotic and DNA Damage Response Proteins: Maintaining the Genome Stability and Working for the Common Good. Front Cell Dev Biol 2021; 9:700162. [PMID: 34966733 PMCID: PMC8710681 DOI: 10.3389/fcell.2021.700162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Accepted: 11/22/2021] [Indexed: 12/14/2022] Open
Abstract
Cellular function is highly dependent on genomic stability, which is mainly ensured by two cellular mechanisms: the DNA damage response (DDR) and the Spindle Assembly Checkpoint (SAC). The former provides the repair of damaged DNA, and the latter ensures correct chromosome segregation. This review focuses on recently emerging data indicating that the SAC and the DDR proteins function together throughout the cell cycle, suggesting crosstalk between both checkpoints to maintain genome stability.
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Affiliation(s)
- Fernando Luna-Maldonado
- Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas–Universidad Nacional Autónoma de México, Instituto Nacional de Cancerología, México City, Mexico
| | - Marco A. Andonegui-Elguera
- Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas–Universidad Nacional Autónoma de México, Instituto Nacional de Cancerología, México City, Mexico
| | - José Díaz-Chávez
- Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas–Universidad Nacional Autónoma de México, Instituto Nacional de Cancerología, México City, Mexico
| | - Luis A. Herrera
- Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas–Universidad Nacional Autónoma de México, Instituto Nacional de Cancerología, México City, Mexico
- Instituto Nacional de Medicina Genómica, Mexico City, Mexico
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3
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Bates M, Furlong F, Gallagher MF, Spillane CD, McCann A, O'Toole S, O'Leary JJ. Too MAD or not MAD enough: The duplicitous role of the spindle assembly checkpoint protein MAD2 in cancer. Cancer Lett 2020; 469:11-21. [DOI: 10.1016/j.canlet.2019.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/26/2019] [Accepted: 10/01/2019] [Indexed: 12/11/2022]
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4
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Maciver SK. Ancestral Eukaryotes Reproduced Asexually, Facilitated by Polyploidy: A Hypothesis. Bioessays 2019; 41:e1900152. [DOI: 10.1002/bies.201900152] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 10/10/2019] [Indexed: 12/29/2022]
Affiliation(s)
- Sutherland K. Maciver
- Centre for Discovery Brain Sciences, Edinburgh Medical SchoolBiomedical SciencesUniversity of Edinburgh Hugh Robson Building, George Square Edinburgh EH8 9XD Scotland UK
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5
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Fang X, Yin H, Zhang H, Wu F, Liu Y, Fu Y, Yu D, Zong L. p53 mediates hydroxyurea resistance in aneuploid cells of colon cancer. Exp Cell Res 2019; 376:39-48. [PMID: 30684461 DOI: 10.1016/j.yexcr.2019.01.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/11/2019] [Accepted: 01/22/2019] [Indexed: 01/08/2023]
Abstract
Aneuploidy refers to aberrancies in cellular chromosome count, which is prevalent in most human cancers. Chemotherapy is an effective cancer treatment; however, the development of drug resistance is a major concern of conventional chemotherapy. The chemotherapy agent hydroxyurea (HU) targets proliferating cells and has long been applied to treat various human cancers. It remains elusive whether aneuploidy affects the drug sensitivity of hydroxyurea. By generating an inducible aneuploidy model, we found that aneuploid colon cancer cells were resistant to HU treatment compared to euploid controls. Surprisingly, further analyses showed that the HU resistance was dependent on the expression of wild type p53. Activation of the p53 pathway in aneuploidy cells reduced cell proliferation but generated resistance of tumor cells to HU treatment. HU resistance was abrogated in aneuploid cells if p53 was absent but re-gained when inducing proliferation repression in cells by serum deprivation. Our results demonstrate that the HU resistance developed in aneuploid colon cancer cells is mediated by wild type p53 and indicates the prognostic value of combining karyotypic and p53 status in clinical cancer treatment.
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Affiliation(s)
- Xiao Fang
- Peking University Health Science Center, Beijing 100191, China; Clinical Medical College, Yangzhou University, Yangzhou 225001, Jiangsu, China; Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou 225001, China; Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou 225001, China
| | - Hua Yin
- Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou 225001, China; Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou 225001, China
| | - Hanqing Zhang
- Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou 225001, China; Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou 225001, China
| | - Fan Wu
- Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou 225001, China; Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou 225001, China
| | - Yin Liu
- Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou 225001, China; Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou 225001, China
| | - Yi Fu
- School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, China
| | - Duonan Yu
- Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, Yangzhou University, Yangzhou 225001, China; Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou 225001, China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonosis, Yangzhou, China.
| | - Liang Zong
- Clinical Medical College, Yangzhou University, Yangzhou 225001, Jiangsu, China.
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Funk LC, Zasadil LM, Weaver BA. Living in CIN: Mitotic Infidelity and Its Consequences for Tumor Promotion and Suppression. Dev Cell 2017; 39:638-652. [PMID: 27997823 DOI: 10.1016/j.devcel.2016.10.023] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Errors in chromosome segregation during mitosis have been recognized as a hallmark of tumor cells since the late 1800s, resulting in the long-standing hypothesis that mitotic abnormalities drive tumorigenesis. Recent work has shown that mitotic defects can promote tumors, suppress them, or do neither, depending on the rate of chromosome missegregation. Here we discuss the causes of chromosome missegregation, their effects on tumor initiation and progression, and the evidence that increasing the rate of chromosome missegregation may be an effective chemotherapeutic strategy.
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Affiliation(s)
- Laura C Funk
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Lauren M Zasadil
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Beth A Weaver
- Department of Cell and Regenerative Biology, Carbone Cancer Center, University of Wisconsin-Madison, 1111 Highland Avenue, 6109 WIMR I, Madison, WI 53705-2275, USA.
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López-Saavedra A, Ramírez-Otero M, Díaz-Chávez J, Cáceres-Gutiérrez R, Justo-Garrido M, Andonegui MA, Mendoza J, Downie-Ruíz Á, Cortés-González C, Reynoso N, Castro-Hernández C, Domínguez-Gómez G, Santibáñez M, Fabián-Morales E, Pruefer F, Luna-Maldonado F, González-Barrios R, Herrera LA. MAD2γ, a novel MAD2 isoform, reduces mitotic arrest and is associated with resistance in testicular germ cell tumors. Cell Cycle 2016; 15:2066-76. [PMID: 27315568 PMCID: PMC4968973 DOI: 10.1080/15384101.2016.1198863] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Background: Prolonged mitotic arrest in response to anti-cancer chemotherapeutics, such as DNA-damaging agents, induces apoptosis, mitotic catastrophe, and senescence. Disruptions in mitotic checkpoints contribute resistance to DNA-damaging agents in cancer. MAD2 has been associated with checkpoint failure and chemotherapy response. In this study, a novel splice variant of MAD2, designated MAD2γ, was identified, and its association with the DNA damage response was investigated. Methods: Endogenous expression of MAD2γ and full-length MAD2 (MAD2α) was measured using RT-PCR in cancer cell lines, normal foreskin fibroblasts, and tumor samples collected from patients with testicular germ cell tumors (TGCTs). A plasmid expressing MAD2γ was transfected into HCT116 cells, and its intracellular localization and checkpoint function were evaluated according to immunofluorescence and mitotic index. Results: MAD2γ was expressed in several cancer cell lines and non-cancerous fibroblasts. Ectopically expressed MAD2γ localized to the nucleus and reduced the mitotic index, suggesting checkpoint impairment. In patients with TGCTs, the overexpression of endogenous MAD2γ, but not MAD2α, was associated with resistance to cisplatin-based chemotherapy. Likewise, cisplatin induced the overexpression of endogenous MAD2γ, but not MAD2α, in HCT116 cells. Conclusions: Overexpression of MAD2γ may play a role in checkpoint disruption and is associated with resistance to cisplatin-based chemotherapy in TGCTs.
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Affiliation(s)
- Alejandro López-Saavedra
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Miguel Ramírez-Otero
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - José Díaz-Chávez
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Rodrigo Cáceres-Gutiérrez
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Monserrat Justo-Garrido
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Marco A Andonegui
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Julia Mendoza
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Ángela Downie-Ruíz
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Carlo Cortés-González
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Nancy Reynoso
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Clementina Castro-Hernández
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Guadalupe Domínguez-Gómez
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Miguel Santibáñez
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Eunice Fabián-Morales
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Franz Pruefer
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Fernando Luna-Maldonado
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Rodrigo González-Barrios
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
| | - Luis A Herrera
- a Unidad de Investigación Biomédica en Cáncer , Instituto Nacional de Cancerología (INCan) - Instituto de Investigaciones Biomédicas - Universidad Nacional Autónoma de México (UNAM) , Del. Tlalpan , Mexico D.F
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8
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Chilà R, Celenza C, Lupi M, Damia G, Carrassa L. Chk1-Mad2 interaction: a crosslink between the DNA damage checkpoint and the mitotic spindle checkpoint. Cell Cycle 2013; 12:1083-90. [PMID: 23454898 DOI: 10.4161/cc.24090] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Chk1 is implicated in several checkpoints of the cell cycle acting as a key player in the signal transduction pathway activated in response to DNA damage and crucial for the maintenance of genomic stability. Chk1 also plays a role in the mitotic spindle checkpoint, which ensures the fidelity of mitotic segregation during mitosis, preventing chromosomal instability and aneuploidy. Mad2 is one of the main mitotic checkpoint components and also exerts a role in the cellular response to DNA damage. To investigate a possible crosslink existing between Chk1 and Mad2, we studied Mad2 protein levels after Chk1 inhibition either by specific siRNAs or by a specific and selective Chk1 inhibitor (PF-00477736), and we found that after Chk1 inhibition, Mad2 protein levels decrease only in tumor cells sensitive to Chk1 depletion. We then mapped six Chk1's phosphorylatable sites on Mad2 protein, and found that Chk1 is able to phosphorylate Mad2 in vitro on more than one site, while it is incapable of phoshorylating the Mad2 form mutated on all six phosphorylatable sites. Moreover our studies demonstrate that Chk1 co-localizes and physically associates with Mad2 in cells both under unstressed conditions and after DNA damage, thus providing new and interesting evidence on Chk1 and Mad2 crosstalk in the DNA damage checkpoint and in the mitotic spindle checkpoint.
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Affiliation(s)
- Rosaria Chilà
- Laboratory of Molecular Pharmacology, Department of Oncology, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy
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9
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Furlong F, Fitzpatrick P, O'Toole S, Phelan S, McGrogan B, Maguire A, O'Grady A, Gallagher M, Prencipe M, McGoldrick A, McGettigan P, Brennan D, Sheils O, Martin C, W Kay E, O'Leary J, McCann A. Low MAD2 expression levels associate with reduced progression-free survival in patients with high-grade serous epithelial ovarian cancer. J Pathol 2012; 226:746-55. [PMID: 22069160 PMCID: PMC3593171 DOI: 10.1002/path.3035] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 10/07/2011] [Accepted: 10/21/2011] [Indexed: 01/20/2023]
Abstract
Epithelial ovarian cancer (EOC) has an innate susceptibility to become chemoresistant. Up to 30% of patients do not respond to conventional chemotherapy [paclitaxel (Taxol®) in combination with carboplatin] and, of those who have an initial response, many patients relapse. Therefore, an understanding of the molecular mechanisms that regulate cellular chemotherapeutic responses in EOC cells has the potential to impact significantly on patient outcome. The mitotic arrest deficiency protein 2 (MAD2), is a centrally important mediator of the cellular response to paclitaxel. MAD2 immunohistochemical analysis was performed on 82 high-grade serous EOC samples. A multivariate Cox regression analysis of nuclear MAD2 IHC intensity adjusting for stage, tumour grade and optimum surgical debulking revealed that low MAD2 IHC staining intensity was significantly associated with reduced progression-free survival (PFS) (p = 0.0003), with a hazard ratio of 4.689. The in vitro analyses of five ovarian cancer cell lines demonstrated that cells with low MAD2 expression were less sensitive to paclitaxel. Furthermore, paclitaxel-induced activation of the spindle assembly checkpoint (SAC) and apoptotic cell death was abrogated in cells transfected with MAD2 siRNA. In silico analysis identified a miR-433 binding domain in the MAD2 3′ UTR, which was verified in a series of experiments. Firstly, MAD2 protein expression levels were down-regulated in pre-miR-433 transfected A2780 cells. Secondly, pre-miR-433 suppressed the activity of a reporter construct containing the 3′-UTR of MAD2. Thirdly, blocking miR-433 binding to the MAD2 3′ UTR protected MAD2 from miR-433 induced protein down-regulation. Importantly, reduced MAD2 protein expression in pre-miR-433-transfected A2780 cells rendered these cells less sensitive to paclitaxel. In conclusion, loss of MAD2 protein expression results in increased resistance to paclitaxel in EOC cells. Measuring MAD2 IHC staining intensity may predict paclitaxel responses in women presenting with high-grade serous EOC. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Fiona Furlong
- UCD School of Medicine and Medical Science, UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
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10
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Yang C, Wang H, Xu Y, Brinkman KL, Ishiyama H, Wong STC, Xu B. The kinetochore protein Bub1 participates in the DNA damage response. DNA Repair (Amst) 2011; 11:185-91. [PMID: 22071147 DOI: 10.1016/j.dnarep.2011.10.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The DNA damage response (DDR) and the spindle assembly checkpoint (SAC) are two critical mechanisms by which mammalian cells maintain genome stability. There is a growing body of evidence that DDR elements and SAC components crosstalk. Here we report that Bub1 (budding uninhibited by benzimidazoles 1), one of the critical kinetochore proteins essential for SAC, is required for optimal DDRs. We found that knocking-down Bub1 resulted in prolonged H2AX foci and comet tail formation as well as hypersensitivity in response to ionizing radiation (IR). Further, we found that Bub1-mediated Histone H2A Threonine 121 phosphorylation was induced after IR in an ATM-dependent manner. We demonstrated that ATM phosphorylated Bub1 on serine 314 in response to DNA damage in vivo. Finally, we showed that ATM-mediated Bub1 serine 314 phosphorylation was required for IR-induced Bub1 activation and for the optimal DDR. Together, we elucidate the molecular mechanism of DNA damage-induced Bub1 activation and highlight a critical role of Bub1 in DDR.
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Affiliation(s)
- Chunying Yang
- Department of Radiation Oncology, The Methodist Hospital Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA
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11
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Kato T, Daigo Y, Aragaki M, Ishikawa K, Sato M, Kondo S, Kaji M. Overexpression of MAD2 predicts clinical outcome in primary lung cancer patients. Lung Cancer 2011; 74:124-31. [DOI: 10.1016/j.lungcan.2011.01.025] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 12/18/2010] [Accepted: 01/31/2011] [Indexed: 11/25/2022]
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Depression of MAD2 inhibits apoptosis and increases proliferation and multidrug resistance in gastric cancer cells by regulating the activation of phosphorylated survivin. Tumour Biol 2010; 31:225-32. [PMID: 20440596 DOI: 10.1007/s13277-010-0036-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 03/26/2010] [Indexed: 01/28/2023] Open
Abstract
Mitotic arrest-deficient 2 (MAD2) is one of the essential mitotic spindle checkpoint regulators, and it can protect cells from aberrant chromosome segregation. The Mad2 gene is very rarely mutated in many kinds of human cancer, but aberrantly reduced expression of MAD2 has been correlated with defective mitotic checkpoints in several human cancers. We have previously found that the MAD2 expression level is also shown to be associated with the multidrug resistance of tumour cells. In this study, we constructed a small interfering RNA (siRNA) eukaryotic expression vector of MAD2 and downregulated MAD2 expression in the gastric cancer cell line SGC7901 by transfection of MAD2-siRNA. SGC7901 cells stably transfected with the MAD2-siRNA exhibited significantly increased expression of phosphorylated survivin protein and enhanced drug resistance. Furthermore, MAD2-siRNA suppressed the proliferation of SGC7901 cells and inhibited tumour formation in athymic nude mice. This study clearly reveals that downregulation of MAD2 could regulate the cell cycle, increase proliferation, and improve the drug resistance of gastric cancer cells by regulating the activation of phosphorylated survivin. It also suggests both that MAD2 might play an important role in the development of human gastric cancer and that silencing the MAD2 gene may help to deal with the multidrug resistance of gastric cancer cells.
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Abstract
Impaired mitotic checkpoint signaling can both promote and suppress tumors. The mitotic checkpoint targets Cdc20, the specificity factor of the ubiquitin ligase that promotes anaphase by targeting cyclin B and securin for destruction. In this issue, Li et al. (2009. J. Cell Biol. doi:10.1083/jcb.200904020) use gene replacement to produce mice expressing a Cdc20 mutant that cannot be inhibited by the mitotic checkpoint. In addition to the expected aneuploidy, these animals have a high tumor incidence that is likely caused by persistent aneuploidy coupled with nonmitotic functions of mutant Cdc20.
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Affiliation(s)
- Beth A A Weaver
- Department of Pharmacology, University of Wisconsin-Madison, Madison, WI 53562, USA.
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