Base Excision Repair Gene Polymorphisms Research Articles

Association of Polymorphisms in Base Excision Repair Genes With the Risk of Breast Cancer: A Case-Control Study in North Indian Women

Inheritance of common genetic variants at one or more base excision repair (BER) genes may result in a reduced DNA repair capacity and in an increased risk of cancers like breast cancer. The present case-control study with 390 north Indian women (155 breast cancer cases and 235 controls) was aimed to investigate the association of seven nonsynonymous BER gene polymorphisms viz. rs1130409/T1865G (APEX1), rs1799782/T22142C (XRCC1), rs25487/G23990A (XRCC1), rs4989588/T3337A (FEN1), rs4989586/ G3259A (FEN1), rs4989587/C3315T (FEN1), and rs1050525/G6941T (PCNA) with breast cancer susceptibility. Statistically significant association with breast cancer risk was observed for rs1130409 homozygous mutant GG [odds ratio (OR) 3.35, 95% confidence interval (CI) 1.36-8.26), heterozygous GT (OR 2.42, 95% CI 1.56-3.76), and combined mutant (GT + GG) (OR 2.52, 95% CI 1.65-3.86] genotypes and rs25487 homozygous mutant AA (OR 2.91, 95% CI 1.66-5.10) and combined mutant (AA + AG) (OR 1.41, 95% CI 0.903-2.19) genotypes, whereas protective association was exhibited by rs1799782 homozygous mutant CC (OR 0.413, 95% CI 0.082-2.08), heterozygous TC (OR 0.351, 95% CI 0.189-0.650), and combined mutant (TC + CC) (OR 0.357, 95% CI 0.199-0.641) genotypes. Association study using reconstructed haplotypes of XRCC1 gene showed positive association for the TA haplotype (OR 2.014, 95% CI 1.462-2.775) and a protective association for the CG haplotype (OR 0.173, 95% CI 0.052-0.576) pertaining to breast cancer risk. The results indicate that the polymorphisms rs1130409 (APEX1) and rs25487 (XRCC1) might be involved in contributing towards breast cancer susceptibility, while rs1799782 (XRCC1) might have protective influence.

Selected base excision repair gene polymorphisms and susceptibility to biliary tract cancer and biliary stones: a population-based case-control study in China

Base excision repair (BER) corrects DNA damage caused by oxidative stress and chronic inflammation, putative risk factors for cancer. To understand the relationship between genetic variation in BER genes and risk of biliary tract cancer and biliary stones, we examined non-synonymous polymorphisms in three key BER genes-x-ray repair cross-complementing group 1 (XRCC1) (R194W, rs1799782; R280H, rs25489 and R399Q, rs25487), apurinic/apyrimidinic endonuclease (APEX1) (D148E, rs3136820) and 8-oxoguanine DNA glycosylase (OGG1) (S326C, rs1052133), in a population-based study of 411 biliary tract cancer cases (237 gallbladder, 127 bile duct and 47 ampulla of Vater), 891 biliary (gallbladder or bile duct) stone cases and 786 population controls conducted in Shanghai, China. Compared with subjects carrying the XRCC1 194RR genotype, those with the WW genotype had a 1.9-fold risk of bile duct cancer [odds ratio (OR) = 1.9, 95% confidence interval (CI) = 1.1-3.5, P(trend) = 0.03], and compared with subjects carrying the XRCC1 280RR genotype, those with the XRCC1 280H allele had a 50% reduced risk of bile duct cancer (OR = 0.5, 95% CI = 0.3-0.9, P(trend) = 0.05). The effect of the R280H polymorphism persisted (P(trend) = 0.03), when all three XRCC1 polymorphisms were jointly considered in the model, a finding supported by the haplotype results (covariate-adjusted global permutation P = 0.03). We also found an inverse association between the APEX1 148E allele and gallbladder stones (P(trend) = 0.03), but no association for the OGG1 polymorphism. This study suggests that genetic variants in XRCC1 and APEX1 may alter susceptibility to biliary tract cancer and stones. Further studies are required to confirm the reported associations.

Polymorphisms in XPC, XPD, XRCC1, and XRCC3 DNA repair genes and lung cancer risk in a population of Northern Spain

BackgroundPolymorphisms in DNA repair genes have been associated to repair DNA lesions, and might contribute to the individual susceptibility to develop different types of cancer. Nucleotide excision repair (NER), base excision repair (BER), and double-strand break repair (DSBR) are the main DNA repair pathways. We investigated the relationship between polymorphisms in two NER genes, XPC (poly (AT) insertion/deletion: PAT-/+) and XPD (Asp312Asn and Lys751Gln), the BER gene XRCC1 (Arg399Gln), and the DSBR gene XRCC3 (Thr241Met) and the risk of developing lung cancer.MethodsA hospital-based case-control study was designed with 516 lung cancer patients and 533 control subjects, matched on ethnicity, age, and gender. Genotypes were determined by PCR-RFLP and the results were analysed using multivariate unconditional logistic regression, adjusting for age, gender and pack-years.ResultsBorderline association was found for XPC and XPD NER genes polymorphisms, while no association was observed for polymorphisms in BER and DSBR genes. XPC PAT+/+ genotype was associated with no statistically significant increased risk among ever smokers (OR = 1.40; 95%CI = 0.94–2.08), squamous cell carcinoma (OR = 1.44; 95%CI = 0.85–2.44), and adenocarcinoma (OR = 1.72; 95%CI = 0.97–3.04). XPD variant genotypes (312Asn/Asn and 751Gln/Gln) presented a not statistically significant risk of developing lung cancer (OR = 1.52; 95%CI = 0.91–2.51; OR = 1.38; 95%CI = 0.85–2.25, respectively), especially among ever smokers (OR = 1.58; 95%CI = 0.96–2.60), heavy smokers (OR = 2.07; 95%CI = 0.74–5.75), and adenocarcinoma (OR = 1.88; 95%CI = 0.97–3.63). On the other hand, individuals homozygous for the XRCC1 399Gln allele presented no risk of developing lung cancer (OR = 0.87; 95%CI = 0.57–1.31) except for individuals carriers of 399Gln/Gln genotype and without family history of cancer (OR = 0.57; 95%CI = 0.33–0.98) and no association was found between XRCC3 Thr241Met polymorphism and lung cancer risk (OR = 0.92; 95%CI = 0.56–1.50), except for the 241Met/Met genotype and squamous cell carcinoma risk (OR = 0.47; 95%CI = 0.23–1.00).ConclusionIn conclusion, we analysed the association between XPC, XPD, XRCC1, and XRCC3 polymorphisms and the individual susceptibility to develop lung cancer in the Spanish population, specifically with a highly tobacco exposed population. We attempt to contribute to the discovery of which biomarkers of DNA repair capacity are useful for screening this high-risk population for primary preventing and early detection of lung cancer.

Effects of base excision repair gene polymorphisms on pancreatic cancer survival

To explore the association between single nucleotide polymorphisms of DNA repair genes and overall survival of patients with pancreatic cancer, we conducted a study in 378 cases of pancreatic adenocarcinoma who were treated at The University of Texas M. D. Anderson Cancer Center between February 1999 and October 2004 and were followed up to April 2006. Genotypes were determined using genomic DNA and the MassCode method. Overall survival was analyzed using the Kaplan-Meier plot, log-rank test and Cox regression. We observed a strong effect of the POLB A165G and T2133C genotypes on overall survival. The median survival time (MST) was 35.7 months for patients carrying at least 1 of the 2 homozygous variant POLB GG or CC genotypes, compared with 14.8 months for those carrying the AA/AG or TT/TC genotypes (p = 0.02, log rank test). The homozygous variants of hOGG1 G2657A, APEX1 D148E and XRCC1 R194W polymorphisms all showed a weak but significant effect on overall survival as demonstrated by either log rank test or multivariate COX regression after adjusting for other potential confounders. In combined genotype analysis, a predominant effect of the POLB homozygous variants on survival was observed. When POLB was not included in the model, a slightly better survival was observed among those carrying none of the adverse genotypes than those carrying at least one of the adverse genotypes. These observations suggest that polymorphisms of base excision repair genes significantly affect the clinical outcome of patients with pancreatic cancer. These observations need to be confirmed in a larger study of homogenous patient population.

A Ser326Cys polymorphism in the DNA repair gene hOGG1 is not associated with sporadic Alzheimer's disease

Oxidative damage accumulates in the DNA of the human brain over time, and is supposed to play a critical role in the pathogenesis of Alzheimer's disease (AD). It has been suggested that the brain in AD might be subjected to the double insult of increased oxidative stress, as well as deficiencies in repair mechanisms responsible for the removal of oxidized bases. The type of damage that is most likely to occur in neuronal cells is oxidative DNA damage which is primarily removed by the base excision repair (BER) pathway, and a decrease in BER activity was observed in post-mortem brain regions of AD individuals, especially in the activity of 8-oxoguanine DNA glycosylase. There is evidence that the Ser326Cys polymorphism of the human 8-oxoguanine DNA glycosylase 1 ( hOGG1) gene is associated with a reduced DNA repair activity. However, although a deficient BER was proposed in the etiology of AD by several authors, polymorphisms of BER genes have not been studied in AD yet. We performed a case-control study including 178 patients with sporadic AD (sAD) and 146 matched controls to evaluate the role of the Ser326Cys polymorphism as a risk factor for sAD. In the present study we failed to find any association between allele ( χ 2 = 0.03, p = 0.86) or genotype ( χ 2 = 0.25, p = 0.882) frequencies of hOGG1 Ser326Cys and the risk of sAD. Present results suggest that the Ser326Cys polymorphism of the hOGG1 gene is not an independent risk factor for sAD.

Gene–Environment Interactions: How Many False Positives?

Gene–Environment Interactions: How Many False Positives?

Large-Scale Investigation of Base Excision Repair Genetic Polymorphisms and Lung Cancer Risk in a Multicenter Study

Base excision repair (BER) is a highly conserved essential mechanism for maintaining genome integrity. We examined associations among four well-characterized polymorphisms of BER genes (OGG1 Ser326Cys, XRCC1 Arg194Trp, XRCC1 Arg280His, and XRCC1 Arg399Gln) and lung cancer risk. A total of 2188 patients with lung cancer and 2198 control subjects without lung cancer recruited at 15 centers in six Eastern European countries from February 1998 to October 2002 provided DNA samples for genotype analysis. Genetic polymorphisms were analyzed by the fluorescence 5' exonuclease and Amplifluor assays. Unconditional multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). We estimated the false-positive reporting probability (FPRP) for our results by incorporating a range of prior probabilities that specific polymorphisms are associated with lung cancer risk. All statistical tests were two-sided. The overall odds ratio for lung cancer among those with the OGG1 Cys/Cys genotype compared with those with the OGG1 Ser/Ser genotype was 1.34 (95% CI = 0.95 to 1.88); the association was most prominent for adenocarcinoma risk (OR = 1.66, 95% CI = 1.04 to 2.66). Overall, the XRCC1 polymorphisms were not associated with the risk of lung cancer. However, the XRCC1 Arg194Trp and Arg280His variants were each associated with a reduced risk of lung cancer among subjects in the highest quartile of pack-years of smoking compared with common allele homozygotes (ORs of 0.65 [95% CI = 0.46 to 0.93] and 0.56 [95% CI = 0.36 to 0.86], respectively). The associations between the OGG1 Cys/Cys genotype and adenocarcinoma risk and between XRCC1 Arg194Trp polymorphism and lung cancer risk among heavy smokers remained robust given prior probabilities of 25% (FPRP = 0.238) and 10% (FPRP = 0.276), respectively. Our results do not support a major independent role of BER gene polymorphisms in lung cancer risk. However, we cannot exclude the possibility that the OGG1 Ser326Cys and XRCC1 Arg194Trp polymorphisms play minor roles in lung carcinogenesis.