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Maksoud S. The DNA Double-Strand Break Repair in Glioma: Molecular Players and Therapeutic Strategies. Mol Neurobiol 2022; 59:5326-5365. [PMID: 35696013 DOI: 10.1007/s12035-022-02915-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 06/05/2022] [Indexed: 12/12/2022]
Abstract
Gliomas are the most frequent type of tumor in the central nervous system, which exhibit properties that make their treatment difficult, such as cellular infiltration, heterogeneity, and the presence of stem-like cells responsible for tumor recurrence. The response of this type of tumor to chemoradiotherapy is poor, possibly due to a higher repair activity of the genetic material, among other causes. The DNA double-strand breaks are an important type of lesion to the genetic material, which have the potential to trigger processes of cell death or cause gene aberrations that could promote tumorigenesis. This review describes how the different cellular elements regulate the formation of DNA double-strand breaks and their repair in gliomas, discussing the therapeutic potential of the induction of this type of lesion and the suppression of its repair as a control mechanism of brain tumorigenesis.
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Affiliation(s)
- Semer Maksoud
- Experimental Therapeutics and Molecular Imaging Unit, Department of Neurology, Neuro-Oncology Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA.
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2
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Raina A, Sahu PK, Laskar RA, Rajora N, Sao R, Khan S, Ganai RA. Mechanisms of Genome Maintenance in Plants: Playing It Safe With Breaks and Bumps. Front Genet 2021; 12:675686. [PMID: 34239541 PMCID: PMC8258418 DOI: 10.3389/fgene.2021.675686] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/04/2021] [Indexed: 01/14/2023] Open
Abstract
Maintenance of genomic integrity is critical for the perpetuation of all forms of life including humans. Living organisms are constantly exposed to stress from internal metabolic processes and external environmental sources causing damage to the DNA, thereby promoting genomic instability. To counter the deleterious effects of genomic instability, organisms have evolved general and specific DNA damage repair (DDR) pathways that act either independently or mutually to repair the DNA damage. The mechanisms by which various DNA repair pathways are activated have been fairly investigated in model organisms including bacteria, fungi, and mammals; however, very little is known regarding how plants sense and repair DNA damage. Plants being sessile are innately exposed to a wide range of DNA-damaging agents both from biotic and abiotic sources such as ultraviolet rays or metabolic by-products. To escape their harmful effects, plants also harbor highly conserved DDR pathways that share several components with the DDR machinery of other organisms. Maintenance of genomic integrity is key for plant survival due to lack of reserve germline as the derivation of the new plant occurs from the meristem. Untowardly, the accumulation of mutations in the meristem will result in a wide range of genetic abnormalities in new plants affecting plant growth development and crop yield. In this review, we will discuss various DNA repair pathways in plants and describe how the deficiency of each repair pathway affects plant growth and development.
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Affiliation(s)
- Aamir Raina
- Mutation Breeding Laboratory, Department of Botany, Aligarh Muslim University, Aligarh, India
- Botany Section, Women’s College, Aligarh Muslim University, Aligarh, India
| | - Parmeshwar K. Sahu
- Department of Genetics and Plant Breeding, Indira Gandhi Agriculture University, Raipur, India
| | | | - Nitika Rajora
- National Agri-Food Biotechnology Institute, Mohali, India
| | - Richa Sao
- Department of Genetics and Plant Breeding, Indira Gandhi Agriculture University, Raipur, India
| | - Samiullah Khan
- Mutation Breeding Laboratory, Department of Botany, Aligarh Muslim University, Aligarh, India
| | - Rais A. Ganai
- Watson-Crick Centre for Molecular Medicine, Islamic University of Science and Technology, Awantipora, India
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Erdal S, McCarthy BJ, Gurule N, Berwick M, Gonzales E, Byrd J, Flores K, Shimek J, Il'yasova D, Ali-Osman F, Bigner DD, Davis FG, Leyba AN, White KAM. Application of mutagen sensitivity assay in a glioma case-control study. Toxicol Rep 2018; 5:183-188. [PMID: 29854587 PMCID: PMC5977159 DOI: 10.1016/j.toxrep.2017.12.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 12/03/2022] Open
Abstract
MSA is an appropriate molecular epidemiology tool in case control studies. Case-control status/exposure categories are not associated with the number of breaks. Cell lines of glioma patients did not show reduced DNA repair capacity in response to acrylamide in the MSA assay.
Few risk factors for glioma have been identified other than ionizing radiation. The alkylating agent acrylamide is a compound found in both occupational and the general environment and identified as one of the forty known or suspected neurocarcinogens in animal models. The mutagen sensitivity assay (MSA) has been used to indirectly show reduced DNA repair capacity upon exposure to ionizing radiation in those with glioma compared to controls. In this study, MSA was used to assess its applicability to a glioma case-control study and to test the hypothesis that subjects with glioma may have lower DNA repair capacity after exposure to selected potential human neurocarcinogens (i.e. acrylamide), compared to controls. Approximately 50 case and 50 control subjects were identified from a clinic-based study that investigated environmental risk factors for glioma, who completed an exposure survey, and had frozen immortalized lymphocytes available. A total of 50 metaphase spreads were read and reported for each participant. The association of case-control status with MSA for acrylamide, i.e. breaks per spread, was examined by multivariable logistic regression models. The mean number of breaks per slide was similar between hospital-based controls and cases. In addition, case-control status or exposure categories were not associated with the number of breaks per spread. Although the MSA has been shown as a useful molecular epidemiology tool for identifying individuals at higher risk for cancer, our data do not support the hypothesis that glioma patients have reduced DNA repair capacity in response to exposure to acrylamide. Further research is needed before the MSA is utilized in large-scale epidemiological investigations of alkylating agents.
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Affiliation(s)
- Serap Erdal
- Divisions of Environmental, Occupational Health Science, University of Illinois at Chicago, Chicago, IL, United States
| | - Bridget J McCarthy
- Epidemiology and Biostatistics, University of Illinois at Chicago, Chicago, IL, United States.,University of Illinois at Chicago Cancer Center, University of Illinois at Chicago, Chicago, IL, United States
| | - Natalia Gurule
- Department of Cancer Biology, University of Colorado Anschutz Medical Campus, United States
| | - Marianne Berwick
- Molecular Epidemiology Lab, University of New Mexico, Albuquerque, NM, United States.,Division of Epidemiology, University of New Mexico, Albuquerque, NM, United States
| | - Emily Gonzales
- Molecular Epidemiology Lab, University of New Mexico, Albuquerque, NM, United States
| | - Johanna Byrd
- Molecular Epidemiology Lab, University of New Mexico, Albuquerque, NM, United States
| | - Kristina Flores
- UNM Cancer Center, University of New Mexico, Albuquerque, NM, United States
| | - JoAnna Shimek
- Department of Environmental Health, Indiana University Bloomington, IN, United States
| | - Dora Il'yasova
- Duke Comprehensive Cancer Center, Duke University Medical Center, Durham, NC, United States.,Preston Robert Tisch Brain Tumor Center at Duke, Duke University Medical Center, Durham, NC, United States
| | - Francis Ali-Osman
- Department of Surgery, Duke University Medical Center, Durham, NC, United States.,Duke Comprehensive Cancer Center, Duke University Medical Center, Durham, NC, United States.,Preston Robert Tisch Brain Tumor Center at Duke, Duke University Medical Center, Durham, NC, United States.,Pediatric Brain Tumor Foundation Institute at Duke, Duke University Medical Center, Durham, NC, United States
| | - Darell D Bigner
- Department of Pathology, Duke University Medical Center, Durham, NC, United States.,Duke Comprehensive Cancer Center, Duke University Medical Center, Durham, NC, United States.,Preston Robert Tisch Brain Tumor Center at Duke, Duke University Medical Center, Durham, NC, United States.,Pediatric Brain Tumor Foundation Institute at Duke, Duke University Medical Center, Durham, NC, United States
| | - Faith G Davis
- Epidemiology and Biostatistics, University of Illinois at Chicago, Chicago, IL, United States.,University of Illinois at Chicago Cancer Center, University of Illinois at Chicago, Chicago, IL, United States.,School of Public Health, University of Alberta, Edmonton, Alberta, Canada
| | - Alexis N Leyba
- UNM Cancer Center, University of New Mexico, Albuquerque, NM, United States
| | - Kirsten A M White
- Molecular Epidemiology Lab, University of New Mexico, Albuquerque, NM, United States
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Qin CJ, Song XM, Chen ZH, Ren XQ, Xu KW, Jing H, He YL. XRCC2 as a predictive biomarker for radioresistance in locally advanced rectal cancer patients undergoing preoperative radiotherapy. Oncotarget 2016; 6:32193-204. [PMID: 26320178 PMCID: PMC4741669 DOI: 10.18632/oncotarget.4975] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 07/16/2015] [Indexed: 12/15/2022] Open
Abstract
XRCC2 has been shown to increase the radioresistance of some cancers. Here, XRCC2 expression was investigated as a predictor of preoperative radiotherapy (PRT) treatment response in locally advanced rectal cancer (LARC). XRCC2 was found to be overexpressed in rectal cancer tissues resected from patients who underwent surgery without PRT. In addition, overall survival for LARC patients was improved in XRCC2-negative patients compared with XRCC2-positive patients after treatment with PRT (P < 0.001). XRCC2 expression was also associated with an increase in LARC radioresistance. Conversely, XRCC2-deficient cancer cells were more sensitive to irradiation in vitro, and a higher proportion of these cells underwent cell death induced by G2/M phase arrest and apoptosis. When XRCC2 was knocked down, the repair of DNA double-strand breaks caused by irradiation was impaired. Therefore, XRCC2 may increases LARC radioresistance by repairing DNA double-strand breaks and preventing cancer cell apoptosis. Moreover, the present data suggest that XRCC2 is a useful predictive biomarker of PRT treatment response in LARC patients. Thus, inhibition of XRCC2 expression or activity represents a potential therapeutic strategy for improving PRT response in LARC patients.
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Affiliation(s)
- Chang-Jiang Qin
- Department of Gastrointestinal and Pancreatic Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Department of Gastrointestinal Surgery, Huaihe Hospital of Hennan University, Kaifeng, China
| | - Xin-Ming Song
- Department of Gastrointestinal and Pancreatic Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Zhi-Hui Chen
- Department of Gastrointestinal and Pancreatic Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xue-Qun Ren
- Department of Gastrointestinal Surgery, Huaihe Hospital of Hennan University, Kaifeng, China
| | - Kai-Wu Xu
- Department of Gastrointestinal and Pancreatic Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Hong Jing
- Department of Pathology, Huaihe Hospital of Hennan University, Kaifeng, China
| | - Yu-Long He
- Department of Gastrointestinal and Pancreatic Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
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Hang D, Zhou W, Jia M, Wang L, Zhou J, Yin Y, Ma H, Hu Z, Li N, Shen H. Genetic variants within microRNA-binding site of RAD51B are associated with risk of cervical cancer in Chinese women. Cancer Med 2016; 5:2596-601. [PMID: 27334422 PMCID: PMC5055154 DOI: 10.1002/cam4.797] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/30/2016] [Accepted: 05/19/2016] [Indexed: 12/19/2022] Open
Abstract
RAD51B plays a central role in homologous recombinational repair (HRR) of DNA double-strand breaks (DSBs), which is important to prevent genomic instability, a hallmark of cancer. Recent studies suggested that common genetic variants of RAD51B may contribute to cancer susceptibility. In this study, we aimed to investigate whether potentially functional variants within miRNA-binding sites of RAD51B are associated with risk of cervical cancer. A total of 1486 cervical cancer patients and 1536 cancer-free controls were enrolled, and two genetic variants, rs963917 (A > G) and rs963918 (T > C), were genotyped in all participants. Using multivariate logistic regression analyses, we found that G allele of rs963917 conferred lower risk of cervical cancer compared to A allele (adjusted OR = 0.89, 95% CI = 0.80-0.99, P = 0.039). Similarly, rs963918 allele C was associated with a decreased risk for cervical cancer compared with allele T (adjusted OR = 0.84, 95% CI = 0.74-0.94, P = 0.004). Haplotype analyses showed that haplotype GC was also correlated with lower risk (OR = 0.83, 95% CI = 0.73-0.95, P = 0.005) compared with the most common haplotype AT. In summary, our study suggested that miRNA-binding site genetic variants of RAD51B may modify the susceptibility to cervical cancer, which is important to identify individuals with differential risk for this malignancy and to improve the effectiveness of preventive intervention.
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Affiliation(s)
- Dong Hang
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Wen Zhou
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Meiqun Jia
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Lihua Wang
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Jing Zhou
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Yin Yin
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Hongxia Ma
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China.,State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Zhibin Hu
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China.,State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Ni Li
- National Office for Cancer Prevention and Control, Cancer Institute and Hospital, Chinese Academy of Medical Sciences, Beijing, China.
| | - Hongbin Shen
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China. .,Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.
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6
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Kitahara CM, Linet MS, Rajaraman P, Ntowe E, Berrington de González A. A New Era of Low-Dose Radiation Epidemiology. Curr Environ Health Rep 2016; 2:236-49. [PMID: 26231501 DOI: 10.1007/s40572-015-0055-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The last decade has introduced a new era of epidemiologic studies of low-dose radiation facilitated by electronic record linkage and pooling of cohorts that allow for more direct and powerful assessments of cancer and other stochastic effects at doses below 100 mGy. Such studies have provided additional evidence regarding the risks of cancer, particularly leukemia, associated with lower-dose radiation exposures from medical, environmental, and occupational radiation sources, and have questioned the previous findings with regard to possible thresholds for cardiovascular disease and cataracts. Integrated analysis of next generation genomic and epigenetic sequencing of germline and somatic tissues could soon propel our understanding further regarding disease risk thresholds, radiosensitivity of population subgroups and individuals, and the mechanisms of radiation carcinogenesis. These advances in low-dose radiation epidemiology are critical to our understanding of chronic disease risks from the burgeoning use of newer and emerging medical imaging technologies, and the continued potential threat of nuclear power plant accidents or other radiological emergencies.
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Affiliation(s)
- Cari M Kitahara
- Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, 9609 Medical Center Drive, Rm 7E566, Rockville, MD, 20850, USA,
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shRNA-mediated XRCC2 gene knockdown efficiently sensitizes colon tumor cells to X-ray irradiation in vitro and in vivo. Int J Mol Sci 2014; 15:2157-71. [PMID: 24481064 PMCID: PMC3958843 DOI: 10.3390/ijms15022157] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 12/30/2013] [Accepted: 01/16/2014] [Indexed: 12/02/2022] Open
Abstract
Colon cancer is one of the most common tumors of the digestive tract. Resistance to ionizing radiation (IR) decreased therapeutic efficiency in these patients’ radiotherapy. XRCC2 is the key protein of DNA homologous recombination repair, and its high expression is associated with enhanced resistance to DNA damage induced by IR. Here, we investigated the effect of XRCC2 silencing on colon tumor cells’ growth and sensitivity to X-radiation in vitro and in vivo. Colon tumor cells (T84 cell line) were cultivated in vitro and tumors originated from the cell line were propagated as xenografts in nude mice. The suppression of XRCC2 expression was achieved by using vector-based short hairpin RNA (shRNA) in T84 cells. We found that the knockdown of XRCC2 expression effectively decreased T84 cellular proliferation and colony formation, and led to cell apoptosis and cell cycle arrested in G2/M phase induced by X-radiation in vitro. In addition, tumor xenograft studies suggested that XRCC2 silencing inhibited tumorigenicity after radiation treatment in vivo. Our data suggest that the suppression of XRCC2 expression rendered colon tumor cells more sensitive to radiation therapy in vitro and in vivo, implying XRCC2 as a promising therapeutic target for the treatment of radioresistant human colon cancer.
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Zhao P, Zou P, Zhao L, Yan W, Kang C, Jiang T, You Y. Genetic polymorphisms of DNA double-strand break repair pathway genes and glioma susceptibility. BMC Cancer 2013; 13:234. [PMID: 23663450 PMCID: PMC3655843 DOI: 10.1186/1471-2407-13-234] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Accepted: 05/03/2013] [Indexed: 11/10/2022] Open
Abstract
Background Genetic variations in DNA double-strand break repair genes can influence the ability of a cell to repair damaged DNA and alter an individual’s susceptibility to cancer. We studied whether polymorphisms in DNA double-strand break repair genes are associated with an increased risk of glioma development. Methods We genotyped 10 potentially functional single nucleotide polymorphisms (SNPs) in 7 DNA double-strand break repair pathway genes (XRCC3, BRCA2, RAG1, XRCC5, LIG4, XRCC4 and ATM) in a case–control study including 384 glioma patients and 384 cancer-free controls in a Chinese Han population. Genotypes were determined using the OpenArray platform. Results In the single-locus analysis there was a significant association between gliomas and the LIG4 rs1805388 (Ex2 +54C>T, Thr9Ile) TT genotype (adjusted OR, 3.27; 95% CI, 1.87-5.71), as well as the TC genotype (adjusted OR, 1.62; 95% CI, 1.20-2.18). We also found that the homozygous variant genotype (GG) of XRCC4 rs1805377 (IVS7-1A>G, splice-site) was associated with a significantly increased risk of gliomas (OR, 1.77; 95% CI, 1.12-2.80). Interestingly, we detected a significant additive and multiplicative interaction effect between the LIG4 rs1805388 and XRCC4 rs1805377 polymorphisms with an increasing risk of gliomas. When we stratified our analysis by smoking status, LIG4 rs1805388 was associated with an increased glioma risk among smokers. Conclusions These results indicate for the first time that LIG4 rs1805388 and XRCC4 rs1805377, alone or in combination, are associated with a risk of gliomas.
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Affiliation(s)
- Peng Zhao
- Department of Neurosurgery, the First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China.
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Wang X, Byars SG, Stearns SC. Genetic links between post-reproductive lifespan and family size in Framingham. Evol Med Public Health 2013; 2013:241-53. [PMID: 24481203 PMCID: PMC3868361 DOI: 10.1093/emph/eot013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 06/17/2013] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Is there a trade-off between children ever born (CEB) and post-reproductive lifespan in humans? Here, we report a comprehensive analysis of reproductive trade-offs in the Framingham Heart Study (FHS) dataset using phenotypic and genotypic correlations and a genome-wide association study (GWAS) to look for single-nucleotide polymorphisms (SNPs) that are related to the association between CEB and lifespan. METHODOLOGY We calculated the phenotypic and genetic correlations of lifespan with CEB for men and women in the Framingham dataset, and then performed a GWAS to search for SNPs that might affect the relationship between post-reproductive lifespan and CEB. RESULTS We found significant negative phenotypic correlations between CEB and lifespan in both women (rP = -0.133, P < 0.001) and men (rP = -0. 079, P = 0.036). The genetic correlation was large, highly significant and strongly negative in women (rG = -0.877, P = 0.009) in a model without covariates, but not in men (P = 0.777). The GWAS identified five SNPs associated with the relationship between CEB and post-reproductive lifespan in women; some are near genes that have been linked to cancer. None were identified in men. CONCLUSIONS AND IMPLICATIONS We identified several SNPs for which the relationship between CEB and post-reproductive lifespan differs by genotype in women in the FHS who were born between 1889 and 1958. That result was not robust to changes in the sample. Further studies on larger samples are needed to validate the antagonistic pleiotropy of these genes.
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Affiliation(s)
- Xiaofei Wang
- Department of Statistics, Yale University, New Haven, CT 06520-8102, USA, Department of Biology, Copenhagen University, Universitetsparken 15, 2100 Copenhagen, Denmark and Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520-8102, USA
| | - Sean G. Byars
- Department of Statistics, Yale University, New Haven, CT 06520-8102, USA, Department of Biology, Copenhagen University, Universitetsparken 15, 2100 Copenhagen, Denmark and Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520-8102, USA
| | - Stephen C. Stearns
- Department of Statistics, Yale University, New Haven, CT 06520-8102, USA, Department of Biology, Copenhagen University, Universitetsparken 15, 2100 Copenhagen, Denmark and Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520-8102, USA
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Opposite modifying effects of HR and NHEJ deficiency on cancer risk in Ptc1 heterozygous mouse cerebellum. Oncogene 2011; 30:4740-9. [PMID: 21602895 DOI: 10.1038/onc.2011.178] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Heterozygous Patched1 (Ptc1(+/-)) mice are prone to medulloblastoma (MB), and exposure of newborn mice to ionizing radiation dramatically increases the frequency and shortens the latency of MB. In Ptc1(+/-) mice, MB is characterized by loss of the normal remaining Ptc1 allele, suggesting that genome rearrangements may be key events in MB development. Recent evidence indicates that brain tumors may be linked to defects in DNA-damage repair processes, as various combinations of targeted deletions in genes controlling cell-cycle checkpoints, apoptosis and DNA repair result in MB in mice. Non-homologous end joining (NHEJ) and homologous recombination (HR) contribute to genome stability, and deficiencies in either pathway predispose to genome rearrangements. To test the role of defective HR or NHEJ in tumorigenesis, control and irradiated Ptc1(+/-) mice with two, one or no functional Rad54 or DNA-protein kinase catalytic subunit (DNA-PKcs) alleles were monitored for MB development. We also examined the effect of Rad54 or DNA-PKcs deletion on the processing of endogenous and radiation-induced double-strand breaks (DSBs) in neural precursors of the developing cerebellum, the cells of origin of MB. We found that, although HR and NHEJ collaborate in protecting cells from DNA damage and apoptosis, they have opposite roles in MB tumorigenesis. In fact, although Rad54 deficiency increased both spontaneous and radiation-induced MB development, DNA-PKcs disruption suppressed MB tumorigenesis. Together, our data provide the first evidence that Rad54-mediated HR in vivo is important for suppressing tumorigenesis by maintaining genomic stability.
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Abdel-Rahman SZ, El-Zein RA. Evaluating the effects of genetic variants of DNA repair genes using cytogenetic mutagen sensitivity approaches. Biomarkers 2011; 16:393-404. [PMID: 21595606 DOI: 10.3109/1354750x.2011.577237] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mutagen sensitivity, measured in short-term cultures of peripheral blood lymphocytes by cytogenetic endpoints, is an indirect measure for DNA repair capacity and has been used for many years as a biomarker for intrinsic susceptibility for cancer. In this article, we briefly give an overview of the different cytogenetic mutagen sensitivity approaches that have been used successfully to evaluate the biological effects of polymorphisms in DNA repair genes based on a current review of the literature and based on the need for biomarkers that would allow the characterization of the biological and functional significance of such polymorphisms. We also address some of the future challenges facing this emerging area of research.
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Affiliation(s)
- Sherif Z Abdel-Rahman
- Department of Obstetrics and Gynecology, The University of Texas Medical Branch, Galveston, 77555-1062, USA.
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