Polymorphisms of XRCC1 gene, alcohol consumption and colorectal cancer

To evaluate contribution of polymorphisms of the XRCC1 gene to the risk of colorectal cancer, we conducted a case-control study of 209 colorectal cancer cases and 209 age- and gender-matched controls in the Korean population. We tested the hypothesis by constructing allele combinations with known SNP. Allelic variants of the XRCC1 gene at codons 194, 280 and 399 were analyzed in lymphocyte DNA by PCR-RFLP. We observed an increased risk of colorectal cancer associated with the 399Gln allele. The odds ratio (OR) was 1.61 (95% confidence interval [CI] 1.09-2.39) for the 399Gln allele. When combined allele-specific OR were calculated after estimating frequencies, 3 common allele combinations were found to be associated with an increased risk of colorectal cancer. The OR for the 194Trp-280Arg-399Arg was 1.48 (95% CI = 1.06-2.07) using 194Arg-280Arg-399Arg as the reference. The OR for the 194Arg-280His-399Arg and the 194Arg-280Arg-399Gln were 1.78 (95% CI = 1.09-2.89) and 1.78 (95% CI = 1.23-2.59), respectively. Analysis after controlling for smoking, exercise and dietary habits indicated that alcohol consumption (> or =80 g/week) is a significant risk factor of colorectal cancer (OR = 2.60, 95% CI = 1.46-4.62). An increased risk for colorectal cancer was identified in alcohol drinkers with the risky allele combinations. Our results suggest that polymorphisms in the XRCC1 genes may contribute to colorectal cancer susceptibility, and some evidence was obtained of a genetic modification for the relationship between alcohol intake and colorectal cancer.     

Association between X-ray repair cross complementing group 1 codon 399 and 194 polymorphisms and lung cancer risk: A meta-analysis

Genetic variations in DNA repair genes are thought to modify DNA repair capacity and suggested to be related to cancer risk. However, epidemiological results have been inconsistent. In this meta-analysis, we assessed reported studies of association between polymorphisms of X-ray repair cross complementing group 1 (XRCC1) codon 399 and 194, and lung cancer risk. We found decreased lung cancer risk among subjects carrying XRCC1 codon 194 Arg/Trp genotype [odds ratio (OR) = 0.88, 95% confidence interval (95% CI): 0.79–0.97], using 4848 cases and 6592 controls from 16 studies. There was no association between lung cancer risk and XRCC1 codon 399 polymorphism in total population, when stratified by source of control, we found a protective effect of the XRCC1 codon 399 Gln/Gln and Arg/Gln or Gln/Gln polymorphisms for lung cancer on the basis of population control (OR = 0.73, 95% CI: 0.58–0.92; OR = 0.86, 95% CI: 0.77–0.97, respectively). Data indicated that certain XRCC1 codon 399 and 194 variant may affect the susceptibility of lung cancer. Recommendations for further studies include pooling of individual data to facilitate evaluation of multigenic effects and detailed analysis of effect modification by environmental exposure.     

Polymorphisms in DNA repair gene XRCC1 and increased genetic susceptibility to glioma

Background: The XRCC1 gene encodes the XRCC1 protein, which complexes with three other DNA repair enzymes involved in the base-excision repair (BER) pathways. Different XRCC1 polymorphisms may increase the risk of cancers by impairing interaction with other enzymatic proteins and consequently altering DNA repair activity, and result in carcinogenesis. Our study aimed to investigate any association between three polymorphisms of the XRCC1 gene at codon 194, 280 and 399 and potential glioma risk. Methods: We collected 127 patients with primary glioma and 249 controls who requested general health examinations from Union Hospital of Tongji Medical College hospital from March 2007 to September 2010. A total of 5 ml venous blood was drawn from each subject. The polymorphisms of XRCC1 gene at codons 194, 280 and 399 were analyzed based on duplex polymerase-chain-reactions with the confronting-two-pair primer (PCR-CTPP) method. Results: The homozygous Trp/Trp and heterozygotes Arg/Trp variants of codon 194 had a 2.12 fold and 1.46 fold increased risk of glioma compared to the homozygous Arg/Arg wide genotypes. The same effect was found in codon 399, the codon 399 Gln/Gln and Arg/Gln genotypes being associated with a 2.24 fold and 1.67 fold increased risk in glioma. When comparing the codon 194 Arg/Arg and 399 Arg/Arg genotypes, the combination of codon 194 Trp allele and 399 Gln allele had a heavy increase in glioma risk (OR=2.87, 95%CI=1.56-6.73). Conclusion: The present study provided evidence of a potential role for XRCC1 codon 194 and 399 polymorphisms in genetic predisposition to glioma among the Chinese population. This analysis of correlation of DNA repair genes and glioma may provide a deeper insight into the genetic and environment factors for cancer risk.     

Genetic polymorphism of XRCC1 and lung cancer risk among African-Americans and Caucasians.

Reduced DNA repair capacity may influence susceptibility to lung cancer. XRCC1 plays an important role in base excision repair and in rejoining DNA strand breaks. In the XRCC1 gene, two common polymorphisms induce amino acid changes in codon 194 and codon 399 and correlate with levels of genotoxic damage. We examined the relation between these two polymorphisms and susceptibility to lung cancer among 334 incident cases and 704 population controls of African-American and Caucasian ethnicity in Los Angeles County, California. African-American and Caucasian subjects smoking 20+ cigarettes/day and carrying at least one copy of the codon 194 variant allele were at somewhat decreased risk of lung cancer (African-Americans OR=0.2, 95% CI 0.1-0.9; Caucasians OR=0.5, 95% CI 0.2-1.1). Similarly, for the codon 399 polymorphism, there was some evidence of a decreased risk for the homozygous variant genotype among heavier smokers (African-Americans OR=0.3, 95% CI 0.0-2.9; Caucasians OR=0.4, 95% CI 0.2-1.0). These results suggest that genetic variation in XRCC1 might contribute to lung cancer and may interact with the amount smoked.     

DNA repair polymorphisms might contribute differentially on familial and sporadic breast cancer susceptibility: a study on a Portuguese population

The purpose of this study was to evaluate the role of polymorphisms in DNA repair genes as genetic indicators of susceptibility to familial and sporadic breast cancer. We analysed DNA samples from 285 breast cancer patients and 442 control subjects, for XRCC1 Arg399Gln, XPD Lys751Gln, RAD51 G135C and XRCC3 Thr241Met polymorphisms using PCR-RFLP. We observed that women carriers of XRCC1 399Gln genotypes and without family history of breast cancer have a protective effect concerning this disease (OR = 0.54 95% CI 0.35–0.84; p = 0.006). Furthermore, we found that carriers of XRCC3 241Met genotypes without FH have an increased susceptibility of breast cancer (OR = 2.21 95% CI 1.42–3.44; p < 0.001). Additionally, we verified an increased risk of breast cancer in women with FH and carrying RAD51 135C genotypes (OR = 2.17 95% CI 1.19–3.98; p = 0.012). Our results suggest XRCC1 Arg399Gln and XRCC3 Thr241Met DNA repair polymorphisms as important biomarkers to sporadic breast cancer susceptibility, as well as, RAD51 G135C polymorphism as a real risk modifier in familial breast cancer cases.     

Genetic polymorphisms of XRCC1 and risk of gastric cancer

Coding polymorphisms of the DNA repair gene XRCC1 have been shown to affect the DNA repair capacity and to be associated with genetic susceptibility to carcinogenesis. In our association study between three amino acid substitution polymorphisms of XRCC1 (Arg194Trp, Arg280His, and Arg399Gln) and the risk of gastric cancer in the Korean population, none of the polymorphisms were associated with increased risk of gastric cancer. We then extended our study by building haplotypes of the entire XRCC1 gene with six single neuclotide polymorphisms (SNPs), including two novel polymorphisms at the 5'-flanking sequence. When haplotype frequencies in cases and controls and haplotype-specific odds ratios (ORs) were estimated, haplotype A (194Trp, 280Arg, and 399Arg) was associated with significant reduction in gastric cancer risk (adjusted OR=0.65, 95% CI=0.43-0.99) whereas haplotype D (194Arg, 280Arg, and 399Arg alleles) was a risk type for gastric cancer (adjusted OR=1.57, 95% CI=0.93-2.65). The association with the haplotype D was more pronounced in the cancers of antrum (adjusted OR=2.06, 95% CI=1.03-2.00). Our results suggest that the haplotype estimation is advantageous for association studies of such a complex disease as gastric cancer.     

Differences in base excision repair capacity may modulate the effect of dietary antioxidant intake on prostate cancer risk: an example of polymorphisms in the XRCC1 gene.

We propose a hypothesis that differences in base excision repair capacity modulate the effect of dietary antioxidant intake on prostate cancer risk. As a preliminary test of this hypothesis, we conducted a pilot case-control study to evaluate prostate cancer risk in men with polymorphisms in the XRCC1 gene, a key player in base excision repair, across different strata of antioxidant intake. Seventy-seven prostate cancer patients and 183 community controls, for whom we have detailed dietary information, were frequency matched on age and race. We found a somewhat lower prostate cancer risk for men with one or two copies of the variant alleles at the XRCC1 codons 194 and 399 than for those who were homozygous for the common allele [codon 194: odds ratio (OR) = 0.8; 95% confidence interval (CI), 0.4-1.8 and codon 399: OR = 0.8; 95% CI, 0.5-1.3]. The variant at codon 280 was associated with a slightly increased prostate cancer risk (OR = 1.5; 95% CI, 0.7-3.6). Only the codon 399 polymorphism occurred frequently enough to investigate its joint effect with antioxidant intake. Prostate cancer risk was highest among men who were homozygous for the common allele at codon 399 and had low dietary intake of vitamin E (OR = 2.4; 95% CI, 1.0-5.6) or lycopene (OR = 2.0; 95% CI, 0.8-4.9), whereas low intake of these antioxidants in men without this genotype hardly increased prostate cancer risk. The polymorphism did not modulate risk associated with low intake of vitamin C, A, or beta-carotene. The data give some support for our hypothesis but should be regarded as preliminary, because it is limited by small sample size. We discuss what kind of data and what kind of studies are needed for future evaluation of this hypothesis.     

Predictive Value of Xrcc1 Gene Polymorphisms for Side Effects in Patients undergoing Whole Breast Radiotherapy: a Metaanalysis

Radiation-induced side effects on normal tissue are determined largely by the capacity of cells to repairradiation-induced DNA damage. X-ray repair cross-complementing group 1 (XRCC1) plays an important role inthe repair of DNA single-strand breaks. Studies have shown conflicting results regarding the association betweenXRCC1 gene polymorphisms (Arg399Gln, Arg194Trp, -77T>C and Arg280His) and radiation-induced side effectsin patients undergoing whole breast radiotherapy. Therefore, we conducted a meta-analysis to determine thepredictive value of XRCC1 gene polymorphisms in this regard. Analysis of the 11 eligible studies comprising2,199 cases showed that carriers of the XRCC1 399 Gln allele had a higher risk of radiation-induced toxicity thanthose with the 399 ArgArg genotype in studies based on high-quality genotyping methods [Gln vs. ArgArg: OR,1.85; 95% CI, 1.20-2.86] or in studies with mixed treatment regimens of radiotherapy alone and in combinationwith chemotherapy [Gln vs. ArgArg: OR, 1.60; 95% CI, 1.09-2.23]. The XRCC1 Arg399Gln variant allele wasassociated with mixed acute and late adverse reactions when studies on late toxicity only were excluded [Gln allelevs. Arg allele: OR, 1.22; 95% CI, 1.00-1.49]. In contrast, the XRCC1 Arg280His variant allele was protectiveagainst radiation-induced toxicity in studies including patients treated by radiotherapy alone [His allele vs.Arg allele: OR, 0.58; 95% CI, 0.35-0.96]. Our results suggest that XRCC1 399Gln and XRCC1 280Arg may beindependent predictors of radiation-induced toxicity in post-surgical breast cancer patients, and the selectionof genotyping method is an important factor in determining risk factors. No evidence for any predictive valueof XRCC1 Arg194Trp and XRCC1 -77T>C was found. So, larger and well-designed studies might be requiredto further evaluate the predictive value of XRCC1 gene variation on radiation-induced side effects in patientsundergoing whole breast radiotherapy.     

Three polymorphisms of DNA repair gene XRCC1 and the risk of glioma: a case–control study in northwest China

Three polymorphisms of X-ray repair cross-complementing groups 1 (XRCC1) Arg194Trp, Arg280His, and Arg399Gln may be associated with the individual susceptibility to glioma. The aim of this study was to investigate any association between three polymorphisms of the XRCC1 gene at codon 194, 280, and 399 and potential glioma risk. We conducted a hospital-based case–control study in northwest China. A total of 1,772 subjects, including 886 glioma patients and 886 healthy controls, were recruited in this study. The peripheral blood samples were extracted. Polymerase chain reaction–restriction fragment length polymorphism method was used to test genotypes. Glioma patients had a significantly higher frequency of XRCC1 194 TT (odds ratio [OR]?=?1.76, 95 % confidence interval [CI]?=?1.14, 2.72; P?=?0.01) and XRCC1 399 AA genotype (OR?=?1.62, 95 % CI?=?1.09, 2.40; P?=?0.02) than controls. When stratified by the grade of glioma, patients with WHO IV glioma had a significantly higher frequency of XRCC1 194 TT (OR?=?1.60, 95 % CI?=?1.02, 2.51; P?=?0.04) and XRCC1 399 AA genotype (OR?=?1.59, 95 % CI?=?1.04, 2.42; P?=?0.03). When stratified by the histology of glioma, there was no significant difference in the distribution of each genotype. This study suggested that XRCC1 Arg194Trp and Arg399Gln polymorphisms were associated with the risk of glioma.     

Menopausal age and XRCC1 gene polymorphisms: role in breast cancer risk

BACKGROUND: Recent evidence that some DNA-repair functions are haploinsufficient adds weight to the notion that variants in DNA-repair genes constitute part of the spectrum of defects contributing to cancer risk. X-ray repair cross-complementing group 1 gene (XRCC1) is involved in base excision repair (BER) pathway, acting on spontaneous and induced DNA damage. This gene encodes for a scaffolding protein that brings together different proteins involved in the repair process. Among the non-synonymous polymorphisms in XRCC1 gene, codons 194 and 399 lead to amino acid changes at evolutionary conserved regions, and seem to alter the efficiency of the protein. METHODS: A hospital based case-control study was carried out in a Caucasian Portuguese population (241 cancer patients and 457 controls matched for sex and age) in order to evaluate the potential modifying role of the XRCC1 polymorphisms on the individual susceptibility to breast cancer. RESULTS: Our data did not reveal a positive association between the polymorphisms individually and breast cancer, or with the combination of the different genotypic associations. However, after stratification to the menopausal status, it was observed that carriers of the Gln/Gln genotype of the R399Q polymorphism with a menopausal age above 55 years are at increased risk for breast cancer (OR=4.074; CI=1.562-10.626; P=0.004). Concerning the Arg194Trp polymorphism, after stratification by menopausal status, it was observed that heterozygous individuals (Arg/Trp) with a menopausal age between 45 and 54 are at increased risk for breast cancer (adjusted OR=1.964; CI=1.174-3.288; P=0.01) as well as carriers of the variant allele (Arg/Trp+Trp/Trp) (adjusted OR=1.932; CI=1.156-3.228; P=0.012). CONCLUSIONS: Our results suggest that menopausal age together with Arg194Trp and Arg399Gln XRCC1 gene polymorphisms might be involved in individual susceptibility to breast cancer.     

No association between XRCC1 and XRCC3 gene polymorphisms and breast cancer risk: Iowa Women's Health Study

BACKGROUND: Genetic variation in DNA repair may contribute to differences in the susceptibility of several cancers. We evaluated two polymorphisms in the base excision repair pathway (BER) (XRCC1; Arg194Trp and Arg399Gln) and one polymorphism in the double strand DNA repair pathway (XRCC3; Thr241Met) for their association with breast cancer risk. METHODS: The association was analyzed in a nested case control study of 460 breast cancer cases and 324 cancer-free controls within the Iowa Women's Health Cohort. DNA was obtained from blood samples or paraffin embedded tissues (PET) and all samples were genotyped by one of three genotyping platforms-PCR-RFLP, PCR-INVADER, or Sequenom. RESULTS: None of the three polymorphisms studied were significantly associated with breast cancer risk (XRCC1: Arg194Trp (OR=1.21, 95% CI: 0.78-1.88); Arg399Gln (OR=1.20, 95% CI: 0.80-1.79); XRCC3: Thr241Met (OR=1.04, 95% CI: 0.76-1.41). CONCLUSIONS: These results suggest that independently these polymorphisms of XRCC1 and XRCC3 genes do not contribute significantly to the genetic susceptibility of breast cancer.     

A prospective study of XRCC1 (X-ray cross-complementing group 1) polymorphisms and breast cancer risk

Introduction

The gene XRCC1 (X-ray repair cross-complementing group 1) encodes a protein involved in DNA base excision repair. Two non-synonymous polymorphisms in XRCC1 (Arg194Trp and Arg399Gln) have been shown to alter DNA repair capacity in some studies in vitro. However, results of previous association studies of these two XRCC1 variants and breast cancer have been inconsistent. We examined the association between polymorphisms in XRCC1 and breast cancer in the American Cancer Society Cancer Prevention Study II (CPS-II) Nutrition Cohort, a large prospective study of cancer incidence in the USA.

Methods

Among the 21,965 women who were cancer-free in 1992 and gave blood between 1998 and 2001, 502 postmenopausal breast cancer cases were diagnosed between 1992 and 2001; 502 controls were matched to cases on age, race/ethnicity, and date of blood collection. Genotyping on DNA extracted from buffy coat was performed with Taqman. Conditional logistic regression was used to examine the association between each polymorphism and breast cancer risk controlling for breast cancer risk factors. We also examined whether factors associated with DNA damage, such as smoking and antioxidant intake, modified the association between XRCC1 polymorphisms and breast cancer.

Results

We observed a significant inverse association between Trp194 carriers (Trp/Trp and Trp/Arg) compared with Trp194 non-carriers in relation to breast cancer (Arg/Arg) (odds ratio (OR) 0.62, 95% confidence interval (CI) 0.40 to 0.95). The inverse association between breast cancer and Trp194 carriers compared with non-carriers was slightly stronger among smokers (OR 0.47, 95% CI 0.24 to 0.94) than never smokers (OR 0.78, 95% CI 0.43 to 1.40). An increased risk associated with the Arg399Gln polymorphism (Gln/Gln versus Arg/Arg) was observed only among women who reported ever smoking cigarettes (OR 2.76, 95% CI 1.36 to 5.63), and not in women who were lifelong non-smokers (OR 0.64, 95% CI 0.33 to 1.26). No other factor examined modified the association between XRCC1 polymorphisms and breast cancer risk.

Conclusion

Our results support the hypothesis that genetic variation in XRCC1, particularly in Arg194Trp, may influence postmenopausal breast cancer risk. In our study, genetic variation in XRCC1 Arg399Gln was associated with breast cancer risk only among women with a history of smoking cigarettes.     

XRCC1 genotype and breast cancer: functional studies and epidemiologic data show interactions between XRCC1 codon 280 His and smoking

Tobacco smoke produces oxidative and alkylative DNA damage that necessitates repair by base excision repair coordinated by X-ray cross-complementing gene 1 (XRCC1). We investigated whether polymorphisms in XRCC1 alter DNA repair capacity and modify breast cancer risk associated with smoking. To show the functionality of the 280His variant, we evaluated single-strand break (SSB) repair capacity of isogenic Chinese hamster ovary cells expressing human forms of XRCC1 after exposure to hydrogen peroxide (H(2)O(2)), methyl methanesulfonate (MMS), or camptothecin by monitoring NAD(P)H. We used data from the Carolina Breast Cancer Study (CBCS), a population-based, case-control study that included 2,077 cases (786 African Americans and 1,281 Whites) and 1,818 controls (681 African Americans and 1,137 Whites), to examine associations among XRCC1 codon 194, 280, and 399 genotypes, breast cancer, and smoking. Odds ratios and 95% confidence intervals (95% CI) were calculated by unconditional logistic regression. Only cells expressing the 280His protein accumulated SSB, indicated by NAD(P)H depletion, from both H(2)O(2) and MMS exposures. In the CBCS, positive associations were observed between breast cancer and smoking dose for participants with XRCC1 codon 194 Arg/Arg (P(trend) = 0.046), 399 Arg/Arg (P(trend) = 0.012), and 280 His/His or His/Arg (P(trend) = 0.047) genotypes. The 280His allele was in strong linkage disequilibrium with 194Arg (Lewontin's D' = 1.0) and 399Arg (D' = 1.0). These data suggest that less common, functional polymorphisms may lie within common haplotypes and drive gene-environment interactions.     

The XRCC1 -77T->C variant: haplotypes, breast cancer risk, response to radiotherapy and the cellular response to DNA damage

X-ray repair cross-complementing 1 (XRCC1) is required for single-strand break repair in human cells and several polymorphisms in this gene have been implicated in cancer risk and clinical prognostic factors. We examined the frequency of the 5'-untranslated region (5'-UTR) variant -77T-->C (rs 3213235) in 247 French breast cancer (BC) patients, 66 of whom were adverse radiotherapy responders, and 380 controls and determined the haplotypes based on this and the previously genotyped variants Arg194Trp, Arg280His and Arg399Gln. The -77T-->C variant alone showed no significant association with BC risk or therapeutic radiation sensitivity. The H5 haplotype (variant allele codon 280, wild-type allele other positions) was associated with increased BC risk [odds ratio (OR), 1.90; 95% confidence interval (CI), 1.12-3.23] and the H3 haplotype (wild-type allele all four positions) was inversely associated with therapeutic radiation sensitivity compared with the reference group (H1 haplotype, -77C, wild-type allele codons 194, 280, 399) (OR, 0.39; 95% CI, 0.16-0.92). However given that the global tests for association were not significant these results should be interpreted carefully. Lymphoblastoid cell lines heterozygous for the H1/H3 haplotypes had a significantly higher cell survival (P=0.04) after exposure to ionising radiation (IR) than those with the H1/H1 haplotypes, in agreement with the association study. However no haplotype-specific differences in XRCC1 expression or cell cycle progression were noted in the 24 h following IR exposure. These results suggest that the -77T-->C genotype or another variant in linkage disequilibrium influences the cellular response to DNA damage, although the underlying molecular mechanisms remain to be established.     

Polymorphisms in XRCC1 modify the association between polycyclic aromatic hydrocarbon-DNA adducts, cigarette smoking, dietary antioxidants, and breast cancer risk.

The variability in DNA repair capacity of the general population may depend in part upon common variants in DNA repair genes. X-ray repair cross complementing group 1 (XRCC1) is an important DNA base excision repair gene and exhibits polymorphic variation. Using the Long Island Breast Cancer Study Project, a population-based case-control study, we evaluated the hypothesis that two common single nucleotide polymorphisms of XRCC1 (codon 194 Arg-->Trp and 399 Arg-->Gln) influence breast cancer susceptibility and interact with polycyclic aromatic hydrocarbon (PAH)-DNA adducts, cigarette smoking, and intake of fruits and vegetables and antioxidants. The available sample for genotyping included 1,067 cases and 1,110 controls. Genotyping was done by a high-throughput single-nucleotide extension assay with fluorescence polarization detection of the incorporated nucleotide. We observed no significant increases in risk among all subjects who were carriers of XRCC1 194Trp or 399Gln alleles. Among never smokers, we observed an increased risk of breast cancer in 399Gln carriers [odds ratio (OR), 1.3; 95% confidence interval (CI), 1.0-1.7). Further analysis indicated a suggestive weak additive interaction between the 399Gln allele and detectable PAH-DNA adducts (OR for exposure with mutant genotype, 1.9; 95% CI, 1.2-3.1). The estimated age-adjusted interaction contrast ratio (ICR) and 95% CI (ICR, 0.38; 95% CI, -0.32 to 1.10) indicated that the departure from additivity was not statistically significant, but that there was some suggestion of a relative excess risk due to the interaction. In subjects with at least one copy of XRCC1 194Trp allele, there was a moderate interaction with high intake of fruits and vegetables (>/=35 half-cup servings per week of any fruits, fruit juices, and vegetables, OR, 0.58; 95% CI, 0.38-0.89; ICR, -0.49; 95% CI, -0.03 to -0.95), and dietary plus supplement antioxidant intake with 33% to 42% decreases in breast cancer risk compared with those with the Arg194Arg genotype and low-intake individuals. These results do not show that the two genetic polymorphisms of XRCC1 independently influence breast cancer risk. However, there is evidence for interactions between the two XRCC1 single nucleotide polymorphisms and PAH-DNA adducts or fruit and vegetable and antioxidant intake on breast cancer risk. Further understanding of the biological function of XRCC1 variants and their interactions with PAH-DNA adducts, antioxidants, and other genes in the pathway are needed.     

XRCC1 gene polymorphisms and esophageal squamous cell carcinoma risk in Chinese population: A meta‐analysis of case–control studies

Two non‐synonymous polymorphisms Arg194Trp and Arg399Gln in the DNA‐base excision repair gene X‐ray repair cross‐complementing group 1 (XRCC1) have been implicated in risk for esophageal cancer. However, the results from different studies remain controversial. The present meta‐analysis of literatures was performed to clarify these associations in Chinese population. A comprehensive literature search was conducted to identify all case–control studies of XRCC1 polymorphisms Arg194Trp and Arg399Gln and risk for esophageal squamous cell carcinoma (ESCC). A total of 9 eligible studies, including 1,538 ESCC cases and 2,472 controls, were identified to the meta‐analysis. The odds ratio (OR) for the variant homozygous genotype Trp/Trp of the Arg194Trp polymorphism, compared with the wild‐type homozygote Arg/Arg, was 1.59 (p = 0.0007), with 95% confidence interval (95% CI) 1.22–2.09, for ESCC risk without between‐study heterogeneity. However, there was no statistically significant associations of ESCC risk in the dominant model Arg/Trp+Trp/Trp (OR 0.97; 95% CI 0.84–1.12; p = 0.69) and heterozygous genotype Arg/Trp (OR 0.90; 95% CI 0.77–1.04; p = 0.16) when comparing with wild‐type genotype Arg/Arg. For Arg399Gln, there was no effect in dominant modeling (Arg/Gln+Gln/Gln vs. Arg/Arg: OR 0.92; 95% CI 0.80–1.06; p = 0.25), and the variant Gln/Gln homozygote was not associated with ESCC risk (OR 1.29; 95% CI 0.79–2.10; p = 0.31), either. In conclusion, Arg194Trp genetic polymorphism may be associated with an increased risk for developing ESCC and a study with the larger sample size is needed to further evaluate gene–environment interaction on XRCC1 polymorphisms and ESCC risk. © 2009 UICC     

XRCC1 and XRCC3 variants and risk of glioma and meningioma

Several single nucleotide polymorphisms (SNPs) affecting DNA repair capacity and modifying cancer susceptibility have been described. We evaluated the association of SNPs Arg194Trp, Arg280His, and Arg399Gln in the X-ray cross-complementing group 1 (XRCC1) and Thr241Met in the X-ray cross-complementing group 3 (XRCC3) DNA repair genes with the risk of brain tumors. The Caucasian study population consisted of 701 glioma (including 320 glioblastoma) cases, 524 meningioma cases, and 1,560 controls in a prospective population-based case–control study conducted in Denmark, Finland, Sweden, and the UK. The studied SNPs were not significantly associated with the risk of brain tumors. The highest odds ratios (ORs) for the associations were observed between the homozygous variant genotype XRCC1 Gln399Gln and the risk of glioma (OR = 1.32; 95% confidence interval, CI, 0.97–1.81), glioblastoma (OR = 1.48; 95% CI, 0.98–2.24), and meningioma (OR = 1.34; 95% CI, 0.96–1.86). However, in pair-wise comparisons a few SNP combinations were associated with the risk of brain tumors: Among others, carriers of both homozygous variant genotypes, i.e., XRCC1 Gln399Gln and XRCC3 Met241Met, were associated with a three-fold increased risk of glioma (OR = 3.18; 95% CI, 1.26–8.04) and meningioma (OR = 2.99; 95% CI, 1.16–7.72). In conclusion, no significant association with brain tumors was found for any of the polymorphisms, when examined one by one. Our results indicated possible associations between combinations of XRCC1 and XRCC3 SNPs and the risk of brain tumors.     

Association of DNA Repair Genes XRCC1 and APE-1 with the Risk of Cervical Cancer in North Indian population

Backgrounds: Cervical cancer (CC) is one of the leading cause of death in women worldwide, HPV infection is the major risk factor in the disease development, 0and however other risk factor such as chemical carcinogens, genetic susceptibility and altered immune system are also a cause of the disease progression. In the light of the above statement we studied the base excision repair pathway (BER). Methods: We identified and studied the association of Single Nucleotide polymorphisms in the DNA repair genes of XRCC1 (Arg194Trp, Arg399G,) and APE-1Asp/148Glu to the susceptibility of cervical cancer (CC) in North Indian population. In our study of cases (n=102). Controls (n=109) were recruited from among women without cervical abnormalities. Genotypes were determined by PCR-CTPP method, Taking DNA from peripheral blood in a case control study. Results: A positive association was observed between the polymorphisms of XRCC1 genes, that is, in codons 194 (P=0.03, odds ratio (OR) =2.39, 95% confidence interval (CI)=5.2–1.1), 280 (P=0.01, OR=4.1, 95% CI=11.5–1.3) and 399 (P=0.01, OR=3.4, 95% CI=8.6–1.3) while APE-1 genotype GG (p=0.03,odds ratio(OR)=0.2,95% confidence interval (CI)=0.97-0.004) we observed a statistically significant protective role in developing cervical cancer. Conclusion: Our results suggested that, XRCC1 gene is an important candidate gene for susceptibility to cervical cancer. Although the sample size was small, the present study indicate a statistical association between cervical cancer and XRCC1 SNPs. Future studies are needed that may provide a better understanding of the association between gene polymorphism and cervical carcinoma risk.     

DNA repair gene XRCC1 polymorphisms, smoking, and esophageal cancer risk

To investigate the effect of X-ray repair cross complementing 1 (XRCC1) genetic polymorphisms on esophageal cancer risk, we determined XRCC1 polymorphisms at codon 194 (Arg --> Trp) and codon 399 (Arg --> Gln) in 135 patients with esophageal squamous cell carcinoma (ESCC) and 152 normal controls from hospitals. Although polymorphism at codon 194 was not associated with risk for ESCC, we found that the frequency of XRCC1 399 Gln/Gln genotype in ESCC patients (14.1%) was significantly higher than that in normal controls (3.3%), and that XRCC1 399 Gln/Gln genotype was associated with an increased risk of ESCC (odds ratio (OR) = 5.15, 95% confidence interval (CI): 2.42-0.93). In addition, we found that the risk for smoker increased 4.2-fold than non-smokers in the 399 Gln/Gln genotype (OR = 4.20, 95% CI: 2.37-7.44). These results suggest that XRCC1 399 Gln/Gln genotype may contribute to the risk of ESCC and modify risk associated with smoking.     

Inheritance of the 194Trp and the 399Gln variant alleles of the DNA repair gene XRCC1 are associated with increased risk of early-onset colorectal carcinoma in Egypt

Patients under age 40 constitute 35.6% of all colorectal cancer cases in Egypt, an unusual disease pattern to which both environmental exposures and inefficient DNA repair may contribute. While a number of polymorphisms in DNA repair genes have been recently identified, their role as cancer risk modifiers is yet to be determined. In a pilot case-control study, we tested the hypothesis that polymorphisms in the gene for the DNA repair enzyme XRCC1 are associated with increased risk of colorectal cancer among Egyptians. Using a multiplex polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodology, allelic variants of the XRCC1 gene at codons 194 (Arg-->Trp) (194Trp) and 399 (Arg-->Gln) (399Gln), were analyzed in DNA from lymphocytes of 48 newly-diagnosed colorectal cancer cases and 48 age- and sex-matched controls. Overall, the inheritance of 194Trp allele (Arg/Trp genotype) and 399Gln allele (combined Arg/Gln and Gln/Gln genotypes) was associated with increased colorectal cancer risk (odds ratio (OR)=2.56, 95% confidence limits (CL) 0.73-9.40, and P=0. 08 for 194Trp allele and OR=3.98, 95% CL 1.50-10.6, and P<0.001 for 399Gln allele). Interestingly, the frequencies of 194Trp and 399Gln genotypes were higher in colorectal cancer cases under age 40 than in corresponding controls, and an association between both polymorphisms and early age of disease onset was observed (OR=3.33, 95% CL 0.48-35.90, and P=0.16 for 194Trp and OR=11.90, 95% CL 2.30-51.50, and P=0.0003 for 399Gln). Analysis of the data after adjustment for place of residence indicated that the frequencies of the genotypes with the 194Trp and the 399Gln alleles were higher among urban residents (OR=3.33, 95% CL 0.48-35.90, and P=0.16 for 194Trp and OR=9.97, 95% CL 1.98-43.76, and P<0.001 for 399Gln) than among rural residents (OR=2.00, 95% CL 0.36-26.00, and P=0.30 for 194Trp and OR=1.90, 95% CL 0.50-7.53, and P=0.20 for 399Gln). These findings support our hypothesis and suggest that polymorphisms in the XRCC1 gene, in conjunction with place of residence, may modify disease risk. This first demonstration that polymorphisms in DNA repair genes may contribute to colorectal cancer susceptibility and may increase the risk of early onset of the disease opens the door for future studies in that direction.