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Miser-Salihoglu E, Demokan S, Karanlik H, Karahalil B, Önder S, Cömert S, Yardim-Akaydin S. Investigation of mRNA Expression Levels of Tip60 and Related DNA Repair Genes in Molecular Subtypes of Breast Cancer. Clin Breast Cancer 2023; 23:125-134. [PMID: 36463002 DOI: 10.1016/j.clbc.2022.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 09/29/2022] [Accepted: 10/24/2022] [Indexed: 11/14/2022]
Abstract
INTRODUCTION Studies in breast cancer (BC) have been shown that many tumor cells carry mutations that disrupt the DNA damage response mechanism. In eukaryotic cells, the overexpression or deprivation of DSBs repair genes is linked closely to a higher risk of cancer. PATIENTS AND METHODS In this study, mRNA expression levels of some genes, such as Tip60, ATM, p53, CHK2, BRCA1, H2AX, which are associated with DNA damage repair, were measured using RT-PCR method in tumor and matched-normal tissues of 58 patients with BC. RESULTS According to the study results, 55% in Tip60, 59% in ATM, 57% in BRCA1, 48% in H2AX, 66% in CHK2, and 43% in p53 decreased in tumor tissue of patients compared to the matched normal tissue. When evaluated according to molecular subtypes, expression of all genes in the pathway was found significantly higher in normal tissues than in tumor tissues especially in Luminal B and Luminal B+HER2 groups. One of the most important results of the study is that CHK2 mRNA expressions in normal tissues were higher than tumor tissue in 90% of patients in Luminal B and Luminal B-HER2 + groups. This is the first study showing DNA repair genes' expressions in molecular subtypes of breast cancer. In general, the decrease in the expression of DNA damage repair genes in tumor tissue indicates that these genes may have a role in the development of BC. Our study results also suggest that CHK2 may be a candidate marker in the molecular classification of breast cancer.
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Affiliation(s)
- Ece Miser-Salihoglu
- Faculty of Pharmacy, Department of Biochemistry, Gazi University, Ankara, Turkey.
| | - Semra Demokan
- Department of Basic Oncology, Istanbul University, Oncology Institute, Istanbul, Turkey
| | - Hasan Karanlik
- Department of Surgery, Istanbul University, Institute of Oncology, Istanbul, Turkey
| | - Bensu Karahalil
- Faculty of Pharmacy, Department of Toxicology, Gazi University, Ankara, Turkey
| | - Semen Önder
- Istanbul University, Istanbul Medical Faculty, Department of Pathology, Istanbul, Turkey
| | - Sevde Cömert
- Department of Basic Oncology, Istanbul University, Oncology Institute, Istanbul, Turkey
| | - Sevgi Yardim-Akaydin
- Faculty of Pharmacy, Department of Biochemistry, Gazi University, Ankara, Turkey
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Heterologous expression of the human polybromo-1 protein in the methylotrophic yeast Pichia pastoris. Protein Expr Purif 2018; 152:23-30. [PMID: 30009957 DOI: 10.1016/j.pep.2018.07.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 05/26/2018] [Accepted: 07/03/2018] [Indexed: 11/23/2022]
Abstract
The human polybromo-1 protein (BAF180) is a known driver mutation in clear cell renal cell carcinoma, where it is mutated in approximately 40% of cases. BAF180 is the chromatin-targeting subunit of the PBAF complex. BAF180 has six bromodomains, two BAH domains, and one HMG box. Bromodomains are known to recognize acetylated-lysines on histones and play a role in nucleosome recognition. BAH domains are required for ubiquitination of PCNA, a key regulator of DNA damage. The putative HMG box, if functional, may be involved in DNA-binding. While the binding specificities of individual bromodomains have been studied by our lab and others, the results have failed to reach a consensus. The acetyl-histone binding features of the full-length protein is unknown and is the motivation for this work. The hypothetical HMG and BAH domains have not been studied and the actual function of these regions is currently unknown. Thus, the precise interactions of this large and complex protein are not well-studied. Advances in understanding this large protein have been hindered by the inability to express and purify recombinant full-length BAF180 protein. Currently, only phenomenological studies using BAF180 expressed in mammalian cells have been conducted. Here, we report the successful expression, purification of full-length biologically active BAF180 protein using the GAP promoter in the heterologous host Pichia pastoris. The ability to express full-length and mutated BAF180 will allow for biophysical binding studies. Knowledge of the binding interactions is critical for us to understand the role of BAF180 in cancer development and its progression.
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Abstract
In 2011, Varela et al. reported that the PBRM1 gene is mutated in approximately 40% of clear cell renal cell carcinoma cases. Since then, the number of studies relating PBRM1 mutations to cancers has substantially increased. BAF180 has now been linked to more than 30 types of cancers, including ccRCC, cholangiocarcinomas, esophageal squamous cell carcinoma, bladder cancer, and breast cancer. The mutations associated with BAF180 are most often truncations, which result in a loss of protein expression. This loss has been shown to adversely affect the expression of genes, likely because BAF180 is the chromatin recognition subunit of PBAF. In addition, BAF180 functions in numerous DNA repair mechanisms. Its roles in mediating DNA repair are likely the mechanism by which BAF180 acts a tumor suppressor protein. As research on this protein gains more interest, scientists will begin to piece together the complicated puzzle of the BAF180 protein and why its loss often results in cancer.
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Affiliation(s)
- Sarah Hopson
- Department of Chemistry, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, United States
| | - Martin J. Thompson
- Department of Chemistry, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, United States
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Manivannan B, Kuppusamy T, Venkatesan S, Perumal V. A comparison of estimates of doses to radiotherapy patients obtained with the dicentric chromosome analysis and the γ-H2AX assay: Relevance to radiation triage. Appl Radiat Isot 2017; 131:1-7. [PMID: 29080427 DOI: 10.1016/j.apradiso.2017.10.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 10/14/2017] [Accepted: 10/14/2017] [Indexed: 11/18/2022]
Abstract
The γ-H2AX assay was investigated as an alternative to the time-consuming dicentric chromosome assay (DCA). Radiation doses to 25 radiotherapy patients were estimated in parallel by DCA and the γ-H2AX assay. The γ-H2AX assay yielded doses in line with the calculated equivalent whole body doses in 92% of the patients, whereas the success rate of DCA was only 76%. The result shows that the γ-H2AX assay can be effectively used as a rapid and more precise alternative to DCA.
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Affiliation(s)
- Bhavani Manivannan
- Department of Human Genetics, College of Biomedical Sciences, Technology and Research, Sri Ramachandra University, Porur, Chennai 600116, Tamil Nadu, India.
| | - Thayalan Kuppusamy
- Dr. Kamakshi Memorial Hospital Pvt. Ltd., Pallikaranai, Chennai 600100, Tamil Nadu, India.
| | - Srinivasan Venkatesan
- Dr. Kamakshi Memorial Hospital Pvt. Ltd., Pallikaranai, Chennai 600100, Tamil Nadu, India.
| | - Venkatachalam Perumal
- Department of Human Genetics, College of Biomedical Sciences, Technology and Research, Sri Ramachandra University, Porur, Chennai 600116, Tamil Nadu, India.
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Paglia S, Sollazzo M, Di Giacomo S, de Biase D, Pession A, Grifoni D. Failure of the PTEN/aPKC/Lgl Axis Primes Formation of Adult Brain Tumours in Drosophila. BIOMED RESEARCH INTERNATIONAL 2017; 2017:2690187. [PMID: 29445734 PMCID: PMC5763105 DOI: 10.1155/2017/2690187] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/02/2017] [Accepted: 11/08/2017] [Indexed: 02/05/2023]
Abstract
Different regions in the mammalian adult brain contain immature precursors, reinforcing the concept that brain cancers, such as glioblastoma multiforme (GBM), may originate from cells endowed with stem-like properties. Alterations of the tumour suppressor gene PTEN are very common in primary GBMs. Very recently, PTEN loss was shown to undermine a specific molecular axis, whose failure is associated with the maintenance of the GBM stem cells in mammals. This axis is composed of PTEN, aPKC, and the polarity determinant Lethal giant larvae (Lgl): PTEN loss promotes aPKC activation through the PI3K pathway, which in turn leads to Lgl inhibition, ultimately preventing stem cell differentiation. To find the neural precursors responding to perturbations of this molecular axis, we targeted different neurogenic regions of the Drosophila brain. Here we show that PTEN mutation impacts aPKC and Lgl protein levels also in Drosophila. Moreover, we demonstrate that PI3K activation is not sufficient to trigger tumourigenesis, while aPKC promotes hyperplastic growth of the neuroepithelium and a noticeable expansion of the type II neuroblasts. Finally, we show that these neuroblasts form invasive tumours that persist and keep growing in the adult, leading the affected animals to untimely death, thus displaying frankly malignant behaviours.
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Affiliation(s)
- Simona Paglia
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Manuela Sollazzo
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Simone Di Giacomo
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Dario de Biase
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Annalisa Pession
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Daniela Grifoni
- Department of “Pharmacy and Biotechnology”, University of Bologna, Via Selmi 3, 40126 Bologna, Italy
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Ngo H, Tortorella SM, Ververis K, Karagiannis TC. The Warburg effect: molecular aspects and therapeutic possibilities. Mol Biol Rep 2015; 42:825-34. [PMID: 25253100 DOI: 10.1007/s11033-014-3764-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
It has been about nine decades since the proposal of Otto Warburg on the metabolism of cancer cells. Unlike normal cells which undergo glycolysis and oxidative phosphorylation in the presence of oxygen, proliferating and cancer cells exhibit an increased uptake of glucose and increased rate of glycolysis and predominantly undergo lactic acid fermentation. Whether this phenomenon is the consequence of genetic dysregulation in cancer or is the cause of cancer still remains unknown. However, there is certainly a strong link between the genetic factors, epigenetic modulation, cancer immunosurveillance and the Warburg effect, which will be discussed in this review. Dichloroacetate and 3-bromopyruvate are among the substances that have been studied as potential cancer therapies. With our expanding knowledge of cellular metabolism, therapies targeting the Warburg effect appear very promising. This review discusses different aspects of these emerging therapies.
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Affiliation(s)
- Hanh Ngo
- Epigenomic Medicine, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, 75 Commercial Road, Melbourne, VIC, Australia
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Menegakis A, De Colle C, Yaromina A, Hennenlotter J, Stenzl A, Scharpf M, Fend F, Noell S, Tatagiba M, Brucker S, Wallwiener D, Boeke S, Ricardi U, Baumann M, Zips D. Residual γH2AX foci after ex vivo irradiation of patient samples with known tumour-type specific differences in radio-responsiveness. Radiother Oncol 2015; 116:480-5. [PMID: 26297183 DOI: 10.1016/j.radonc.2015.08.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 08/04/2015] [Accepted: 08/06/2015] [Indexed: 02/01/2023]
Abstract
PURPOSE To apply our previously published residual ex vivo γH2AX foci method to patient-derived tumour specimens covering a spectrum of tumour-types with known differences in radiation response. In addition, the data were used to simulate different experimental scenarios to simplify the method. MATERIALS AND METHODS Evaluation of residual γH2AX foci in well-oxygenated tumour areas of ex vivo irradiated patient-derived tumour specimens with graded single doses was performed. Immediately after surgical resection, the samples were cultivated for 24h in culture medium prior to irradiation and fixed 24h post-irradiation for γH2AX foci evaluation. Specimens from a total of 25 patients (including 7 previously published) with 10 different tumour types were included. RESULTS Linear dose response of residual γH2AX foci was observed in all specimens with highly variable slopes among different tumour types ranging from 0.69 (95% CI: 1.14-0.24) to 3.26 (95% CI: 4.13-2.62) for chondrosarcomas (radioresistant) and classical seminomas (radiosensitive) respectively. Simulations suggest that omitting dose levels might simplify the assay without compromising robustness. CONCLUSION Here we confirm clinical feasibility of the assay. The slopes of the residual foci number are well in line with the expected differences in radio-responsiveness of different tumour types implying that intrinsic radiation sensitivity contributes to tumour radiation response. Thus, this assay has a promising potential for individualized radiation therapy and prospective validation is warranted.
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Affiliation(s)
- Apostolos Menegakis
- Department of Radiation Oncology, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany; German Cancer Research Center (DKFZ), Heidelberg and German Consortium for Translational Cancer Research (DKTK) Partner Sites Tübingen, Germany.
| | - Chiara De Colle
- Department of Oncology, Radiation Oncology, University of Turin, Italy
| | - Ala Yaromina
- Department of Radiation Oncology (Maastro), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, The Netherlands
| | - Joerg Hennenlotter
- Department of Urology, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany
| | - Arnulf Stenzl
- Department of Urology, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany
| | - Marcus Scharpf
- Department of Pathology, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany
| | - Falko Fend
- Department of Pathology, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany
| | - Susan Noell
- Department of Neurosurgery, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany
| | - Marcos Tatagiba
- Department of Neurosurgery, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany
| | - Sara Brucker
- Department of and Research Institute for Women's Health, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany
| | - Diethelm Wallwiener
- Department of and Research Institute for Women's Health, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany
| | - Simon Boeke
- Department of Radiation Oncology, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany; German Cancer Research Center (DKFZ), Heidelberg and German Consortium for Translational Cancer Research (DKTK) Partner Sites Tübingen, Germany
| | - Umberto Ricardi
- Department of Oncology, Radiation Oncology, University of Turin, Italy
| | - Michael Baumann
- German Cancer Research Center (DKFZ), Heidelberg and German Consortium for Translational Cancer Research (DKTK) Partner Sites Dresden, Germany; Department of Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität, Germany; OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden - Rossendorf, Germany
| | - Daniel Zips
- Department of Radiation Oncology, Medical Faculty and University Hospital, Eberhard Karls University Tübingen, Germany; German Cancer Research Center (DKFZ), Heidelberg and German Consortium for Translational Cancer Research (DKTK) Partner Sites Tübingen, Germany
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Kang R, Chen R, Zhang Q, Hou W, Wu S, Cao L, Huang J, Yu Y, Fan XG, Yan Z, Sun X, Wang H, Wang Q, Tsung A, Billiar TR, Zeh HJ, Lotze MT, Tang D. HMGB1 in health and disease. Mol Aspects Med 2014; 40:1-116. [PMID: 25010388 PMCID: PMC4254084 DOI: 10.1016/j.mam.2014.05.001] [Citation(s) in RCA: 693] [Impact Index Per Article: 69.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 05/05/2014] [Indexed: 12/22/2022]
Abstract
Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.
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Affiliation(s)
- Rui Kang
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
| | - Ruochan Chen
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Qiuhong Zhang
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Wen Hou
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Sha Wu
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Lizhi Cao
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Jin Huang
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Yan Yu
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Xue-Gong Fan
- Department of Infectious Diseases, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Zhengwen Yan
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA; Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510120, China
| | - Xiaofang Sun
- Key Laboratory for Major Obstetric Diseases of Guangdong Province, Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, Experimental Department of Institute of Gynecology and Obstetrics, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510510, China
| | - Haichao Wang
- Laboratory of Emergency Medicine, The Feinstein Institute for Medical Research, Manhasset, NY 11030, USA
| | - Qingde Wang
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Allan Tsung
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Timothy R Billiar
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Herbert J Zeh
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Michael T Lotze
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Daolin Tang
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
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Valdiglesias V, Giunta S, Fenech M, Neri M, Bonassi S. γH2AX as a marker of DNA double strand breaks and genomic instability in human population studies. Mutat Res 2013; 753:24-40. [PMID: 23416207 DOI: 10.1016/j.mrrev.2013.02.001] [Citation(s) in RCA: 182] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 01/30/2013] [Accepted: 02/04/2013] [Indexed: 10/27/2022]
Abstract
DNA double strand breaks (DSB) are the gravest form of DNA damage in eukaryotic cells. Failure to detect DSB and activate appropriate DNA damage responses can cause genomic instability, leading to tumorigenesis and possibly accelerated aging. Phosphorylated histone H2AX (γH2AX) is used as a biomarker of cellular response to DSB and its potential for monitoring DNA damage and repair in human populations has been explored in this review. A systematic search was conducted in PubMed for articles, in English, on human studies reporting γH2AX as a biomarker of either DNA repair or DNA damage. A total of 68 publications were identified. Thirty-four studies (50.0%) evaluated the effect of medical procedures or treatments on γH2AX levels; 20 (29.4%) monitored γH2AX in specific pathological conditions with a case/control or case/case design; 5 studies (7.4%) evaluated the effect of environmental genotoxic exposures, and 9 (13.2%) were descriptive studies on cancer and aging. Peripheral blood lymphocytes (44.6%) or biopsies/tissue specimens (24.3%) were the most commonly used samples. γH2AX was scored by optical microscopy as immunostained foci (78%), or by flow cytometry (16%). Critical features affecting the reliability of the assay, including protocols heterogeneity, specimen, cell cycle, kinetics, study design, and statistical analysis, are hereby discussed. Because of its sensitivity, efficiency and mechanistic relevance, the γH2AX assay has great potential as a DNA damage biomarker; however, the technical and epidemiological heterogeneity highlighted in this review infer a necessity for experimental standardization of the assay.
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Affiliation(s)
- Vanessa Valdiglesias
- Unit of Clinical and Molecular Epidemiology, IRCCS San Raffaele Pisana, Roma, Italy
| | - Simona Giunta
- CSIRO Preventative Health Flagship, Adelaide 5000, Australia
| | - Michael Fenech
- CSIRO Preventative Health Flagship, Adelaide 5000, Australia
| | - Monica Neri
- Unit of Clinical and Molecular Epidemiology, IRCCS San Raffaele Pisana, Roma, Italy
| | - Stefano Bonassi
- Unit of Clinical and Molecular Epidemiology, IRCCS San Raffaele Pisana, Roma, Italy.
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Hiyoshi H, Abdelhady S, Segerström L, Sveinbjörnsson B, Nuriya M, Lundgren TK, Desfrere L, Miyakawa A, Yasui M, Kogner P, Johnsen JI, Andäng M, Uhlén P. Quiescence and γH2AX in neuroblastoma are regulated by ouabain/Na,K-ATPase. Br J Cancer 2012; 106:1807-15. [PMID: 22531632 PMCID: PMC3364115 DOI: 10.1038/bjc.2012.159] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Background: Cellular quiescence is a state of reversible proliferation arrest that is induced by anti-mitogenic signals. The endogenous cardiac glycoside ouabain is a specific ligand of the ubiquitous sodium pump, Na,K-ATPase, also known to regulate cell growth through unknown signalling pathways. Methods: To investigate the role of ouabain/Na,K-ATPase in uncontrolled neuroblastoma growth we used xenografts, flow cytometry, immunostaining, comet assay, real-time PCR, and electrophysiology after various treatment strategies. Results: The ouabain/Na,K-ATPase complex induced quiescence in malignant neuroblastoma. Tumour growth was reduced by >50% when neuroblastoma cells were xenografted into immune-deficient mice that were fed with ouabain. Ouabain-induced S-G2 phase arrest, activated the DNA-damage response (DDR) pathway marker γH2AX, increased the cell cycle regulator p21Waf1/Cip1 and upregulated the quiescence-specific transcription factor hairy and enhancer of split1 (HES1), causing neuroblastoma cells to ultimately enter G0. Cells re-entered the cell cycle and resumed proliferation, without showing DNA damage, when ouabain was removed. Conclusion: These findings demonstrate a novel action of ouabain/Na,K-ATPase as a regulator of quiescence in neuroblastoma, suggesting that ouabain can be used in chemotherapies to suppress tumour growth and/or arrest cells to increase the therapeutic index in combination therapies.
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Affiliation(s)
- H Hiyoshi
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-17177, Sweden
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Abstract
Until recently, myeloid neoplasms have been attributed to genomic and genetic instability leading to clonal outgrowth. However, it is now increasingly evident that epigenetic abnormalities also play a fundamental role in development of these malignancies. A growing body of evidence has underlined the involvement of epigenetic machinery in the malignant transformation of hematopoietic cells. Epigenetic dysfunction can lead to genetic alterations, including microsatellite instability, nucleotide changes, and chromosomal alterations. Conversely, putative epigenetic instability may be related to mutations of genes involved in epigenetic regulation. Therefore, this review focuses on epigenetic processes, including DNA methylation, post-translational histone modifications, and RNA interference via small noncoding RNAs, which play a critical role in controlling gene expression and are targets of dysregulation in many hematologic malignancies. Further, recent literature identified somatic mutations in several epigenetic regulators with a high frequency in myeloid malignancies.
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Affiliation(s)
- Anna M Jankowska
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, USA.
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Abstract
MicroRNAs (miRNAs) are aiding our understanding of cancer biology, and are now coming close to therapeutic use as well. Here, we focus specifically on the interaction between miRNAs and genomic instability. MiRNA regulation is essential to many cellular processes, and escape from this regulatory network seems to be a common characteristic of malignant transformation. Genomic instability may preferentially target miRNAs either because of selective pressure or because of inherent vulnerability related to their location near fragile sites. Furthermore, disruption of miRNA processing elements affords a more global release from miRNA regulation. Finally, we review how miRNAs function as both effectors and modulators of the DNA damage response, intricately weaved with traditional elements such as ATM, P53, and MMR. Thus, miRNAs are important substrates for genomic instability and play a crucial role in cellular DNA sensing and repair mechanisms.
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Affiliation(s)
- Dan-Avi Landau
- Department of Hematology, Yale University School of Medicine and the Yale Cancer Center, New Haven, CT, USA
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The host genetic background of DNA repair mechanisms is an independent predictor of survival in diffuse large B-cell lymphoma. Blood 2011; 117:2405-13. [DOI: 10.1182/blood-2010-07-296244] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Abstract
Several drugs used for diffuse large B-cell lymphoma (DLBCL) treatment rely on DNA damage for tumor cell killing. We verified the prognostic impact of the host DNA repair genotype in 2 independent cohorts of DLBCL treated with R-CHOP21 (training cohort, 163 cases; validation cohort, 145 cases). Among 35 single nucleotide polymorphisms analyzed in the training series, MLH1 rs1799977 was the sole predicting overall survival. DLBCL carrying the MLH1 AG/GG genotype displayed an increased death risk (hazard ratio [HR] = 3.23; P < .001; q =0 .009) compared with patients carrying the AA genotype. Multivariate analysis adjusted for International Prognostic Index identified MLH1 AG/GG as an independent OS predictor (P < .001). The poor prognosis of MLH1 AG/GG was the result of an increased risk of failing both R-CHOP21 (HR = 2.02; P = .007) and platinum-based second-line (HR = 2.26; P = .044) treatment. Survival analysis in the validation series confirmed all outcomes predicted by MLH1 rs1799977. The effect on OS of MLH1, a component of the DNA mismatch repair system, is consistent with its role in regulating the genotoxic effects of doxorubicin and platinum compounds, which are a mainstay of DLBCL first- and second-line treatment.
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Yan C, Lu J, Zhang G, Gan T, Zeng Q, Shao Z, Duerksen-Hughes PJ, Yang J. Benzo[a]pyrene induces complex H2AX phosphorylation patterns by multiple kinases including ATM, ATR, and DNA-PK. Toxicol In Vitro 2011; 25:91-9. [DOI: 10.1016/j.tiv.2010.09.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2009] [Revised: 09/03/2010] [Accepted: 09/24/2010] [Indexed: 10/19/2022]
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Ogiwara H, Ui A, Otsuka A, Satoh H, Yokomi I, Nakajima S, Yasui A, Yokota J, Kohno T. Histone acetylation by CBP and p300 at double-strand break sites facilitates SWI/SNF chromatin remodeling and the recruitment of non-homologous end joining factors. Oncogene 2011; 30:2135-46. [PMID: 21217779 DOI: 10.1038/onc.2010.592] [Citation(s) in RCA: 223] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Non-homologous end joining (NHEJ) is a major repair pathway for DNA double-strand breaks (DSBs) generated by ionizing radiation (IR) and anti-cancer drugs. Therefore, inhibiting the activity of proteins involved in this pathway is a promising way of sensitizing cancer cells to both radiotherapy and chemotherapy. In this study, we developed an assay for evaluating NHEJ activity against DSBs in chromosomal DNA in human cells to identify the chromatin modification/remodeling proteins involved in NHEJ. We showed that ablating the activity of the homologous histone acetyltransferases, CBP and p300, using inhibitors or small interfering RNAs-suppressed NHEJ. Ablation of CBP or p300 impaired IR-induced DSB repair and sensitized lung cancer cells to IR and the anti-cancer drug, etoposide, which induces DSBs that are repaired by NHEJ. The CBP/p300 proteins were recruited to sites of DSBs and their ablation suppressed acetylation of lysine 18 within histone H3, and lysines 5, 8, 12, and 16 within histone H4, at the DSB sites. This then suppressed the recruitment of KU70 and KU80, both key proteins for NHEJ, to the DSB sites. Ablation of CBP/p300 also impaired the recruitment of BRM, a catalytic subunit of the SWI/SNF complex involved in chromatin remodeling at DSB sites. These results indicate that CBP and p300 function as histone H3 and H4 acetyltransferases at DSB sites in NHEJ and facilitate chromatin relaxation. Therefore, inhibition CBP and p300 activity may sensitize cancer cells to radiotherapy and chemotherapy.
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Affiliation(s)
- H Ogiwara
- Division of Genome Biology, National Cancer Center Research Institute, Chuo-ku, Tokyo, Japan
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17
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Houghtaling S, Tsukuda T, Osley MA. Molecular assays to investigate chromatin changes during DNA double-strand break repair in yeast. Methods Mol Biol 2011; 745:79-97. [PMID: 21660690 DOI: 10.1007/978-1-61779-129-1_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Multiple types of DNA damage, including bulky adducts, DNA single-strand breaks, and DNA double-strand breaks (DSBs), have deleterious effects on the genomes of eukaryotes. DSBs form normally during a variety of biological processes, such as V-D-J recombination and yeast mating type switching, but unprogrammed DSBs are among the most dangerous types of lesion because if left unrepaired they can lead to loss of genetic material or chromosomal rearrangements. The presence of DSBs leads to a DNA damage response involving activation of cell cycle checkpoints, recruitment of repair proteins, and chromatin remodeling. Because many of the proteins that mediate these processes are evolutionarily conserved, the budding yeast, Saccharomyces cerevisiae, has been used as a model organism to investigate the factors involved in the response to DSBs. Recent research on DSB repair has focused on the barrier that chromatin represents to the repair process. In this article, we describe molecular techniques available to analyze chromatin architecture near a defined DSB in budding yeast. These techniques may be of value to experimentalists who are investigating the role of a novel protein in DSB repair specifically in the context of chromatin.
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Affiliation(s)
- Scott Houghtaling
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
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18
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Podhorecka M, Skladanowski A, Bozko P. H2AX Phosphorylation: Its Role in DNA Damage Response and Cancer Therapy. J Nucleic Acids 2010; 2010. [PMID: 20811597 PMCID: PMC2929501 DOI: 10.4061/2010/920161] [Citation(s) in RCA: 359] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 06/28/2010] [Accepted: 07/05/2010] [Indexed: 11/20/2022] Open
Abstract
Double-strand breaks (DSBs) are the most deleterious DNA lesions, which, if left unrepaired, may have severe consequences for cell survival, as they lead to chromosome aberrations, genomic instability, or cell death. Various physical, chemical, and biological factors are involved in DSB induction. Cells respond to DNA damage by activating the so-called DNA damage response (DDR), a complex molecular mechanism developed to detect and repair DNA damage. The formation of DSBs triggers activation of many factors, including phosphorylation of the histone variant H2AX, producing gammaH2AX. Phosphorylation of H2AX plays a key role in DDR and is required for the assembly of DNA repair proteins at the sites containing damaged chromatin as well as for activation of checkpoints proteins which arrest the cell cycle progression. In general, analysis of gammaH2AX expression can be used to detect the genotoxic effect of different toxic substances. When applied to clinical samples from cancer patients, evaluation of gammaH2AX levels may allow not only to monitor the efficiency of anticancer treatment but also to predict of tumor cell sensitivity to DNA damaging anticancer agents and toxicity of anticancer treatment toward normal cells.
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Affiliation(s)
- Monika Podhorecka
- Department of Haematooncology and Bone Marrow Transplantation, Medical University of Lublin, 20081 Lublin, Poland
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19
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Yang X, Zou P, Yao J, Yun D, Bao H, Du R, Long J, Chen X. Proteomic dissection of cell type-specific H2AX-interacting protein complex associated with hepatocellular carcinoma. J Proteome Res 2010; 9:1402-15. [PMID: 20000738 DOI: 10.1021/pr900932y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The replacement histone variant H2AX senses DNA double-strand breaks (DSBs) and recruits characteristic sets of proteins at its phosphorylated (gamma-H2AX) foci for concurrent DNA repair. We reasoned that the H2AX interaction network, or interactome, formed in the tumor-associated DNA DSB environment such as in hepatocellular carcinoma (HCC) cells, where preneoplastic lesions frequently occur, is indicative of HCC pathogenic status. By using an in vivo dual-tagging quantitative proteomic method, we identified 102 H2AX-specific interacting partners in HCC cells that stably expressed FLAG-tagged H2AX at close to the endogenous level. Using bioinformatics tools for data-dependent network analysis, we further found binary relationships among these interactors in defined pathway modules, implicating H2AX in a multifunctional role of coordinating a variety of biological pathways involved in DNA damage recognition and DNA repair, apoptosis, nucleic acid metabolism, Ca(2+)-binding signaling, cell cycle, etc. Furthermore, our observations suggest that these pathways interconnect through key pathway components or H2AX interactors. The physiological accuracy of our quantitative proteomic approach in determining H2AX-specific interactors was evaluated by both coimmunoprecipitation/ immunoblotting and confocal colocalization experiments performed on HCC cells. Due to their involvement in diverse functions, the H2AX interactors involved in different pathway modules, such as Poly(ADP-ribose) polymerase 1, 14-3-3 zeta, coflin 1, and peflin 1, were examined for their relative H2AX binding affinities in paired hepatocytes and HCC cells. Treatment with the DSB-inducing agent bleomycin enhanced binding of these proteins to H2AX, suggesting an active role of H2AX in coordinating the functional pathways of each protein in DNA damage recognition and repair.
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Affiliation(s)
- Xiaoli Yang
- Department of Chemistry and Institute of Biomedical Sciences, Fudan University, Shanghai, China
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20
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Verheij M, Vens C, van Triest B. Novel therapeutics in combination with radiotherapy to improve cancer treatment: Rationale, mechanisms of action and clinical perspective. Drug Resist Updat 2010; 13:29-43. [DOI: 10.1016/j.drup.2010.01.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 01/21/2010] [Accepted: 01/22/2010] [Indexed: 12/27/2022]
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21
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Menegakis A, Yaromina A, Eicheler W, Dörfler A, Beuthien-Baumann B, Thames HD, Baumann M, Krause M. Prediction of clonogenic cell survival curves based on the number of residual DNA double strand breaks measured by gammaH2AX staining. Int J Radiat Biol 2009; 85:1032-41. [PMID: 19895280 DOI: 10.3109/09553000903242149] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
PURPOSE To assess the potential of using the residual phosphorylation of histone H2AX (gammaH2AX) after irradiation as a marker of radiosensitivity in vitro. MATERIAL AND METHODS Confluent cell cultures of FaDu and SKX human squamous cell carcinoma lines were irradiated with graded single doses. Twenty-four hours after irradiation cells were seeded for standard colony forming assay (CFA). In parallel, staining for gammaH2AX was performed to visualise the residual foci. RESULTS In the CFA, FaDu showed a higher radioresistance than SKX. After analysis of the residual foci data, we constructed 'predicted' survival curves using two different methods. First, the proportion of nuclei with <3 foci was found to correlate closely with the observed surviving fraction (SF) in FaDu, with a slight overestimation of the true SF in SKX. Second, there was a strong linear correlation of the mean number of residual foci and observed -lnSF. Based on regression analysis, we calculated the SF for both cell lines based on the mean number of residual gammaH2AX foci. This second approach again led to a good correlation of predicted and observed SF values in FaDu and a (slight) overestimation in SKX. CONCLUSION In the two cell lines investigated the mean number of residual foci of gammaH2AX can be used to predict differences in the radiation dose response relationship in vitro.
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Affiliation(s)
- Apostolos Menegakis
- Department of Radiation Oncology, OncoRay-Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, Germany
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22
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Dickey JS, Baird BJ, Redon CE, Sokolov MV, Sedelnikova OA, Bonner WM. Intercellular communication of cellular stress monitored by gamma-H2AX induction. Carcinogenesis 2009; 30:1686-95. [PMID: 19651821 DOI: 10.1093/carcin/bgp192] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
When cells are exposed to ionizing radiation (IR), unexposed cells that share media with damaged cells exhibit similar effects to irradiated cells including increased levels of DNA double-strand breaks (DSBs). Hypothesizing that this effect, known as the radiation-induced bystander effect, may be a specific instance of communication between damaged and undamaged cells regardless of damage source, we demonstrated that exposure of target cells to non-IR induces bystander damage in non-targeted cells as measured by gamma-H2AX and 53BP1 focal formation. Initially, bystander damage was found primarily in S-phase cells, but at later times, non-S-phase cells were also affected. In addition, media from undamaged malignant and senescent cells also was found to induce DSBs in primary cultures. Media conditioned on cells targeted with either ionizing or non-IR as well as on undamaged malignant and senescent cells contained elevated levels of several cytokines. One of these, transforming growth factor beta (TGF-beta), and nitric oxide (NO) were found to elevate numbers of gamma-H2AX/53BP1 foci in normal cell cultures similar to levels found in bystander cells, and this elevation was abrogated by NO synthase inhibitors, TGF-beta blocking antibody and antioxidants. These findings support the hypothesis that damage in bystander cells results from their exposure to cytokines or reactive compounds released from stressed cells, regardless of damage source. These results have implications for oncogenesis in that they indicate that damaged normal cells or undamaged tumor cells may induce genomic instability, leading to an increased risk of oncogenic transformation in other cells with which they share media or contact directly.
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Affiliation(s)
- Jennifer S Dickey
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20952, USA.
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23
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Hitchler MJ, Domann FE. Metabolic defects provide a spark for the epigenetic switch in cancer. Free Radic Biol Med 2009; 47:115-27. [PMID: 19362589 PMCID: PMC2728018 DOI: 10.1016/j.freeradbiomed.2009.04.010] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Revised: 04/07/2009] [Accepted: 04/08/2009] [Indexed: 12/18/2022]
Abstract
Cancer is a pathology that is associated with aberrant gene expression and an altered metabolism. Whereas changes in gene expression have historically been attributed to mutations, it has become apparent that epigenetic processes also play a critical role in controlling gene expression during carcinogenesis. Global changes in epigenetic processes, including DNA methylation and histone modifications, have been observed in cancer. These epigenetic alterations can aberrantly silence or activate gene expression during the formation of cancer; however, the process leading to this epigenetic switch in cancer remains unknown. Carcinogenesis is also associated with metabolic defects that increase mitochondrially derived reactive oxygen species, create an atypical redox state, and change the fundamental means by which cells produce energy. Here, we summarize the influence of these metabolic defects on epigenetic processes. Metabolic defects affect epigenetic enzymes by limiting the availability of cofactors like S-adenosylmethionine. Increased production of reactive oxygen species alters DNA methylation and histone modifications in tumor cells by oxidizing DNMTs and HMTs or through direct oxidation of nucleotide bases. Last, the Warburg effect and increased glutamine consumption in cancer influence histone acetylation and methylation by affecting the activity of sirtuins and histone demethylases.
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Affiliation(s)
- Michael J Hitchler
- Department of Radiation Oncology, Free Radical and Radiation Biology Program, University of Iowa, Iowa City, IA 52242, USA
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24
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Mladenov E, Kalev P, Anachkova B. The complexity of double-strand break ends is a factor in the repair pathway choice. Radiat Res 2009; 171:397-404. [PMID: 19397440 DOI: 10.1667/rr1487.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The repair of double-strand breaks in mammalian cells is carried out by two pathways: homologous recombination and nonhomologous end joining. The factors that regulate the mechanism through which a specific repair pathway is activated are still not clearly defined. To study whether the complexity of the double-strand break ends is a factor that determines the choice of the repair pathway, we examined the involvement of homologous recombination by the formation of Rad51 foci in human HeLa cells treated with bleomycin and ionizing radiation. The quantity of double-strand breaks was determined by gel electrophoresis and the formation of gamma-H2AX foci. Two hours after treatment with low doses of the agents that induced similar quantities of double-strand breaks that could be repaired effectively by the cells, Rad51 foci were observed only in the irradiated cells. Rad51 foci appeared in bleomycin-treated cells after prolonged exposure to the drug when the cells were arrested in the G2 phase of the cell cycle. Since bleomycin produces double-strand breaks that are less complex than the breaks induced by ionizing radiation, these results indicate that the complexity of the break ends is a factor in the choice of repair pathway and that homologous recombination is recruited in the repair of breaks with more complex multiply damaged ends during the late S and G2 phases of the cell cycle.
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Affiliation(s)
- Emil Mladenov
- Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
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25
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Thiriet C, Hayes JJ. Linker histone phosphorylation regulates global timing of replication origin firing. J Biol Chem 2008; 284:2823-2829. [PMID: 19015270 DOI: 10.1074/jbc.m805617200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Despite the presence of linker histone in all eukaryotes, the primary function(s) of this histone have been difficult to clarify. Knock-out experiments indicate that H1s play a role in regulation of only a small subset of genes but are an essential component in mouse development. Here, we show that linker histone (H1) is involved in the global regulation of DNA replication in Physarum polycephalum. We find that genomic DNA of H1 knock-down cells is more rapidly replicated, an effect due at least in part to disruption of the native timing of replication fork firing. Immunoprecipitation experiments demonstrate that H1 is transiently lost from replicating chromatin via a process facilitated by phosphorylation. Our results suggest that linker histones generate a chromatin environment refractory to replication and that their transient removal via protein phosphorylation during S phase is a critical step in the epigenetic regulation of replication timing.
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Affiliation(s)
- Christophe Thiriet
- 1UMR-CNRS 6204 U3B, Université de Nantes, Dynamique de la Chromatine et Épigénétique, 44322 Nantes, France.
| | - Jeffrey J Hayes
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642.
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26
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Srivastava N, Gochhait S, de Boer P, Bamezai RNK. Role of H2AX in DNA damage response and human cancers. Mutat Res 2008; 681:180-188. [PMID: 18804552 DOI: 10.1016/j.mrrev.2008.08.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 07/12/2008] [Accepted: 08/22/2008] [Indexed: 12/25/2022]
Abstract
H2AX, the evolutionarily conserved variant of histone H2A, has been identified as one of the key histones to undergo various post-translational modifications in response to DNA double-strand breaks (DSBs). By virtue of these modifications, that include acetylation, phosphorylation and ubiquitination, H2AX marks the damaged DNA double helix, facilitating local recruitment and retention of DNA repair and chromatin remodeling factors to restore genomic integrity. These modifications are essential for effective DSB repair, so is their removal for cell, to recover from checkpoint arrest. Because of these vital roles during DSB signaling and also its activation during early cancer stages, H2AX is emerging as an intriguing gene in tumor biology, supported further by frequent deletion of the region harboring this gene. This review focuses on the insights gained from recent studies on dynamic regulation of H2AX in DSB repair. Also, posing future challenges in the area of chromatin reorganization and retention of epigenetic signature post-DSB-repair with implication of its haploinsufficiency in human cancers.
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Affiliation(s)
- Niloo Srivastava
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University (JNU), Aruna Asafali Marg, New Delhi 110067, India
| | - Sailesh Gochhait
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University (JNU), Aruna Asafali Marg, New Delhi 110067, India
| | - Peter de Boer
- Department of Obstetrics and Gynaecology, Radboud University Nijmegen Medical Centre, The Netherlands
| | - Rameshwar N K Bamezai
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University (JNU), Aruna Asafali Marg, New Delhi 110067, India.
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