No significant association between the XRCC3 Thr241Met polymorphism and lung cancer risk: a meta-analysis

Genetic polymorphisms and lung cancer risk: Evidence from meta-analyses and genome-wide association studies

A growing number of studies investigating the association between Single Nucleotide Polymorphisms (SNPs) and lung cancer risk have been published since over a decade ago. An updated integrative assessment on the credibility and strength of the associations is required. We searched PubMed, Medline, and Web of Science on or before August 29^th, 2016. A total of 198 articles were deemed eligible for inclusion, which addressed the associations between 108 variants and lung cancer. Among the 108 variants, 63 were reported to be significantly associated with lung cancer while the remaining 45 were reported non-significant. Further evaluation integrating the Venice Criteria and false-positive report probability (FPRP) was performed to determine the strength of cumulative epidemiological evidence for the 63 significant associations. As a result, 15 SNPs on or near 12 genes and one miRNA with strong evidence of association with lung cancer risk were identified, including TERT (rs2736098), CHRNA3 (rs1051730), AGPHD1 (rs8034191), CLPTM1L (rs401681 and rs402710), BAT3 (rs3117582), TRNAA (rs4324798), ERCC2 (Lys751Gln), miR-146a2 (rs2910164), CYP1B1 (Arg48Gly), GSTM1 (null/present), SOD2 (C47T), IL-10 (-592C/A and -819C/T), and TP53 (intron 6). 19 SNPs were given moderate rating and 17 SNPs were rated as having weak evidence. In addition, all of the 29 SNPs identified in 12 genome-wide association studies (GWAS) were proved to be noteworthy based on FPRP value. This review summarizes and evaluates the cumulative evidence of genetic polymorphisms and lung cancer risk, which can serve as a general and useful reference for further genetic studies.

XRCC3 Thr241Met Polymorphism is not Associated with Lung Cancer Risk in a Romanian Population

BACKGROUND AND AIMS

Deoxyribonucleic Acid (DNA) repair mechanisms play a critical role in protecting the cellular genome against carcinogens. X-ray cross-complementing gene 3 (XRCC3) is involved in DNA repair and therefore certain genetic polymorphisms that occur in DNA repair genes may affect the ability to repair DNA defects and may represent a risk factor in carcinogenesis. The purpose of our study was to investigate the association between XRCC3 gene substitution of Threonine with Methionine in codon 241 of XRCC3 gene (Thr241Met) polymorphism and the risk of lung cancer, in a Romanian population.

METHODS

We recruited 93 healthy controls and 85 patients with lung cancer, all smokers. Thr241Met, XRCC3 gene genotyping was determined by multiplex Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP).

RESULTS

Statistical analysis (OR, recessive model), did not revealed an increased risk for lung cancer, for the variant 241Met allele and Thr241Met genotypes (p=0.138, OR=0.634, CI=0.348-1.157; p=0.023, OR=0.257, CI=0.085-6.824). Also, there were no positive statistical associations between Thr241Met polymorphism of XRCC3 gene, gender, tobacco and various histopathological tumor type of lung cancer.

CONCLUSION

In conclusion, the results of the study suggest that the XRCC3 gene Thr241Met polymorphism is not associated with an increased risk for the development of lung cancer in this Romanian group.

DNA repair gene XRCC3 Thr241Met polymorphisms and lung cancer risk: a meta-analysis

BACKGROUND

The X-ray repair cross-complementing group 3 (XRCC3) is a highly suspected candidate gene for cancer susceptibility, and a large amount studies have examined the association of the rs861539 in XRCC3 (Thr241Met) with lung cancer risk in various populations. However, the results remain inconclusive.

METHODS

The electronic database of PubMed, Medline, Embase and CNKI (China National Knowledge Infrastructure) were searched for case-control studies published up to December 05, 2013. A systematic review and meta-analysis was performed to evaluate the relationship between XRCC3 Thr241Met polymorphism and lung cancer risk. Data were extracted and pooled odds ratio (OR) with its 95% confidence intervals (CI) were calculated.

RESULTS

Total 21 studies, including 6880 lung cancer cases and 8329 controls, were available for meta-analysis. Overall, our results showed that the XRCC3 Thr241Met polymorphism was not associated with risk of lung cancer in all genetic contrast models (P>0.05). Stratified analyses by ethnicity (Asians, Caucasians and mixed population) showed similar results. Additionally, no evidence of publication bias was observed by using the funnel plot.

CONCLUSIONS

There is no clear evidence showing a significant correlation between XRCC3 Thr241Met polymorphism and lung cancer risk in total population and stratified analysis by ethnicity. However, studies assessing the gene-gene interactions should be considered to further estimate this gene variant in lung cancer risk.

Frequency distribution of DNA repair genes ERCC1 and ERCC2 polymorphisms in South Indian healthy population

DNA repair genes are crucial in maintaining the integrity of the whole genome. Single nucleotide polymorphisms (SNPs) in DNA repair genes have been attributed to the development of various cancers. SNPs of DNA repair genes (ERCC1 and ERCC2) have been implicated in the causation of various cancers as well as inter-individual variability in the therapeutic outcomes of platinum based therapy. Thus establishing the frequency of these functional SNPs in the healthy population is of significance. The present study was aimed to establish the allele and genotype frequencies of ERCC1 (19007C>T, rs11615; 8092C>A, rs3212986) and ERCC2 (Asp312Asn, rs1799793) genes in South Indian healthy population and to compare the data from HapMap populations. The study population consisted of 128 healthy South Indian unrelated individuals of either sex aged between 18 and 60 years. Standard phenol-chloroform method was used to extract DNA from peripheral leukocytes. The genotype of DNA repair gene polymorphisms was determined by quantitative real-time polymerase chain reaction using TaqMan genotyping assay. The observed frequency of the studied polymorphisms followed Hardy-Weinberg equilibrium (p>0.05). The frequencies of the minor alleles of the SNPs rs11615 (T), rs3212986 (A) and rs1799793 (A) were 43.8%, 29.3% and 35.6%, respectively. Gender-based analysis showed no significant difference in the frequency pattern. The observed allele and genotype frequencies showed significant ethnic difference between South Indians and other HapMap populations. This is the first study to provide the normative frequency data of allele and genotype distribution of three SNPs of ERCC1 and ERCC2 in South Indian healthy population. It might be useful in future genotype-phenotype association studies, especially for predicting the efficacy and adverse events of platinum based drugs.

XRCC3 Thr241Met polymorphism and gastric cancer susceptibility: a meta-analysis

BACKGROUND AND OBJECTIVE

X-ray repair cross-complementing group 3 (XRCC3) is responsible for maintaining the integrity of the genome, playing a critical role in protecting it against mutations which lead to cancer. Polymorphisms at exons 7 of the XRCC3 gene may alter the XRCC3 repair efficiency. The aim of this study is to derive a precise estimation of the relationship between XRCC3 Thr241Met polymorphism and gastric cancer (GC) risk.

METHODS

Two investigators independently searched the databases of Pubmed, EMBASE and China National Knowledge Infrastructure (CNKI) up to May 15, 2013. Odds ratio (OR) and 95% confidence intervals (CI) for XRCC3 Thr241Met polymorphism and GC were calculated in a fixed- or random- effects model depending on statistical heterogeneity.

RESULTS

This meta-analysis included 9 case-control studies, which included 2209 cases and 3269 controls. Overall, the combined results based on all studies indicated that there was no association between XRCC3 Thr241Met polymorphism and GC susceptibility for all genetic models. When stratifying for race, we found the 241Met/Met genotype carriers might be at high risk of GC among Asians, but not among Caucasians. When stratifying by the location of gastric cancer, the combined results showed that Met/Met genotype carriers might have an increased risk of GC in non-cardiac gastric cancer, but not in cardiac cancer.

CONCLUSION

This meta-analysis confirmed that the XRCC3 Thr241Met gene polymorphism might be a risk factor for GC among Asians, and that differences in genotype distribution may be related to the location of gastric cancer. More well-designed studies based on larger population are needed to confirm our results.

XRCC3 Thr241Met polymorphism and ovarian cancer risk: a meta-analysis

Genetic polymorphism of X-ray repair crosscomplementing group 3 (XRCC3) Thr241Met has been implicated to alter the risk of ovarian cancer, but the results are controversial. In order to get a more precise result, a meta-analysis was performed. All eligible studies were identified through an extensive search in PubMed, Excerpta Medica Database (Embase), Chinese National Knowledge Infrastructure database, and Chinese Biomedical Literature Database before August 2013. The association between the XRCC3 Thr241Met polymorphism and ovarian cancer risk was conducted by odds ratios (ORs) and 95 % confidence intervals (95 % CIs). Finally, a total of four publications including seven studies with 3,635 cases and 5,473 controls were included in our meta-analysis. Overall, there was no association between XRCC3 Thr241Met polymorphism and risk of ovarian cancer under all five genetic models in overall population (T vs. C: OR = 0.99, 95 % CI = 0.960–1.03, P = 0.752; TT vs. CC: OR = 1.00, 95 % CI = 0.91–1.10, P = 0.943; TC vs. TT: OR = 0.97, 95 % CI = 0.92–1.04, P = 0.396, Fig. 1; TT vs. TC/CC: OR = 1.00, 95 % CI = 0.91–1.12, P = 0.874; TT/TC vs. CC: OR = 0.98, 95 % CI = 0.94–1.03, P = 0.486). In the subgroup analysis according to ethnicity, the results suggested that XRCC3 Thr241Met polymorphism was not associated with the risk of ovarian cancer in Caucasians population. No significant association was found between the XRCC3 Thr241 Met polymorphism and the risk of ovarian cancer. Given the limited sample size and ethnicities included in the meta-analysis, further large scaled and well-designed studies are needed to confirm our results.

Quantitative assessment of the associations between DNA repair gene XRCC3 Thr241Met polymorphism and gastric cancer

Gastric cancer is one of the most prevalent types of cancer in the world today. Recently, there is a large sample volume of published case-control studies on XRCC3 Thr241Met polymorphism with gastric cancer. This will have an important impact on published article by meta-analysis regarding XRCC3 Thr241Met polymorphism with gastric cancer. Therefore, it is necessary to update by meta-analysis to comprehensively investigate the relationship between DNA repair gene XRCC3 Thr241Met polymorphism and gastric cancer. To preciously examine the association between the XRCC3 Thr241Met polymorphism and gastric cancer, we undertook a meta-analysis of 12 case-control studies. The association between the XRCC3 Thr241Met polymorphism and gastric cancer risk was assessed by odds ratios together with their 95 % confidence intervals using a fixed-effects model or random-effects model. We found that the XRCC3 Thr241Met polymorphism was not associated with an increased gastric cancer risk. However, the XRCC3 Thr241Met polymorphism was associated with decreased gastric cancer risk in Asians. In addition, there is no evidence of association on XRCC3 Thr241Met polymorphism with response to chemotherapy and prognosis in gastric cancer. The XRCC3 Thr241Met polymorphism might influence gastric cancer risk in Asians.

Association between XRCC1 and XRCC3 polymorphisms with lung cancer risk: a meta-analysis from case-control studies

Many studies have reported the association of X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln, Arg194Trp, Arg280His, −77T>C, and X-ray repair cross-complementing group 3 (XRCC3) T241M polymorphisms with lung cancer risk, but the results remained controversial. Hence, we performed a meta-analysis to investigate the association between lung cancer risk and XRCC1 Arg399Gln (14,156 cases and 16,667 controls from 41 studies), Arg194Trp (7,426 cases and 9,603 controls from 23 studies), Arg280His (6,211 cases and 6,763 controls from 16 studies), −77T>C (2,487 cases and 2,576 controls from 5 studies), and XRCC3 T241M (8,560 cases and 11,557 controls from 19 studies) in different inheritance models. We found that −77T>C polymorphism was associated with increased lung cancer risk (dominant model: odds ration [OR] = 1.45, 95% confidence interval [CI] = 1.27–1.66, recessive model: OR = 1.73, 95% CI = 1.14–2.62, additive model: OR = 1.91, 95% CI = 1.24–1.94) when all the eligible studies were pooled into the meta-analysis. In the stratified and sensitive analyses, significantly decreased lung cancer risk was observed in overall analysis (dominant model: OR = 0.83, 95% CI = 0.78–0.89; recessive model: OR = 0.90, 95% CI = 0.81–1.00; additive model: OR = 0.82, 95% CI = 0.74–0.92), Caucasians (dominant model: OR = 0.82, 95% CI = 0.76–0.87; recessive model: OR = 0.89, 95% CI = 0.80–0.99; additive model: OR = 0.81, 95% CI = 0.73–0.91), and hospital-based controls (dominant model: OR = 0.81, 95% CI = 0.76–0.88; recessive model: OR = 0.89, 95% CI = 0.79–1.00; additive model: OR = 0.80, 95% CI = 0.71–0.90) for XRCC3 T241M. In conclusion, this meta-analysis indicates that XRCC1 −77T>C shows an increased lung cancer risk and XRCC3 T241M polymorphism is associated with decreased lung cancer risk, especially in Caucasians.