Polymorphisms of the DNA repair gene XPD and risk of lung cancer in a Chinese population

Single-nucleotide polymorphisms of nucleotide excision repair genes and their association with overall survival in North Indian lung cancer patients treated with platinum-based doublet chemotherapy

BACKGROUND

The aim of the study is to understand the association of Nucleotide excision repair (NER) inter-genetic polymorphic combinations with overall survival (OS) in lung cancer as well as its histological subtypes in the North Indian population.

MATERIALS AND METHODS

Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism. For survival analysis, the univariate Kaplan-Meier and multivariate Cox regression model were applied. Recursive partitioning method, survival analysis tree was applied to study unfavorable genotypic combinations in NER single-nucleotide polymorphisms.

RESULTS

Combinatorial studies suggested no association between polymorphic combinations of NER genes and OS in lung cancer patients. When stratified as per lung cancer histological subtypes, adenocarcinomas patients with XPG 670 and XPC 499 polymorphism a significant increase in OS in combined heterozygous and mutant genotype with a lower hazardous ratio (Hazard Ratio1 (HR) = 0.20; P = 0.004). Small-cell lung carcinoma (SCLC) patients with XPF 11985A>G and XPD Arg156Arg polymorphism showed a 4-fold hazard ratio among heterozygous genotype (HR1 = 4.84; P = 0.007) where no significant results are obtained in patients suffering from squamous cell carcinoma histological subtypes. STREE showed XPG Asp1104His (W), XPD Lys751Gln (H + M), XPF Arg415Gln (H + M) genotype was associated with a lower hazard ratio (P = 0.0007) showing survival of 11.6 months when compared with the reference (median survival time = 3.52).

CONCLUSION

It can be concluded that SCLC patients with polymorphic combinations of the NER pathway were associated with a higher risk of mortality. STREE depicted the association of NER polymorphic combinations with a lower hazard ratio predicting them to be a good prognostic factor for lung cancer.

The multi-faceted high order polymorphic synergistic interactions among nucleotide excision repair genes increase the risk of lung cancer in North Indians

It is evident that gene-gene interactions are pervasive in the determination of the susceptibility of human diseases. Polymorphisms in nucleotide excision repair pathway (NER) genes can cause variations in the repair capacity and therefore, might lead to increase in susceptibility towards lung cancer through complex gene-gene and gene-smoking interactions. Logistic regression analysis, along with high order genetic interaction were analyzed using data mining tools such as multifactor dimensionality reduction (MDR) and classification and regression tree analysis (CART). Overall, a protective effect was reported when a combinatorial effect of SNPs were studied by applying logistic regression analysis. Multifactor dimensionality reduction (MDR) analysis, revealed that the four factor model i.e. XPC K939Q, XPA 5'UTR, XPG F670W and XPG D1104H had the best ability to predict lung cancer risk (CVC = 100, p < 0.0001). While a two factor model, including smoking and XPG F670W suggested smoking was associated with the risk of developing lung cancer (CVC = 100, p < 0.0001). Individually XPG F670W was identified as the primary risk factor. In classification and regression tree analysis (CART), we observed a 6-fold risk for SCLC patients carrying XPA 5'UTR (M), XPD K751Q (W) (OR: 6.20; 95%CI: 2.40-16.01, p = 0.0001).Polymorphic NER genes might jointly modulate lung cancer risk through gene-gene and gene-smoking interaction.

Genetic variants of DNA repair pathway genes on lung cancer risk

As is commonly perceived, polymorphisms in genes of deoxyribonucleic acid (DNA) repair pathway plays a fundamental role in defective DNA repair and mutagenesis prevention and serves to contribute to the individual susceptibility to the development of a variety of cancers. Recently, an increasing number of studies have been dedicated to the contentious and ambiguous links between polymorphisms in genes of DNA repair pathway and lung cancer (LC) risk. In response, a comprehensive updated meta-analysis has been proposed herein to assess the correlation between polymorphisms of DNA repair pathway genes and susceptibility to LC. This paper has identified and retrieved eligible articles from PubMed, Google Scholar, Web of Science, and CNKI databases till February 20, 2019. Finally, 295 case-control studies as to the fourteen polymorphisms of DNA repair pathway genes were enrolled. When the results have been pooled, we have brought to light the conclusion that ERCC2-rs13181 polymorphism has an elevated association with LC risk under allele, heterozygote, and dominant comparisons. In the subgroup analysis by ethnicity, we have found that the Caucasian individuals with "B" variant possess risk of LC which was more than twice as much as allele, homozygote, and recessive models. In comparison, Asian carriers of rs13181 polymorphism in ERCC2 gene are more susceptible to LC in heterozygote, dominant models. To sum up, ERCC2-rs13181 polymorphism could be a critical factor in stimulating LC evolvement. Future studies with a larger sample size and multivariate factors are needed to vindicate these findings.

XPC Polymorphism and Risk for Lung Cancer in North Indian Patients Treated with Platinum Based Chemotherapy and Its Association with Clinical Outcomes

Xeroderma pigmentosum complementation group C plays an important role in the human repair system. As reported in previous studies its polymorphism are associated with lung cancer susceptibility. The purpose of this study is to investigate the association of XPC gene with lung cancer susceptibility, overall response and clinical outcomes amongst North Indians. A hospital based study of 370 lung cancer cases and 370 healthy controls was conducted and genotypes were determined using PCR-RFLP assay. Results were assessed using logistic linear regression adjusted for age, sex and smoking status. Survival analysis was conducted using Kaplan-Meier survival analysis and Cox regression analysis. The treatment outcomes of 167 lung cancer patients treated with platinum based chemotherapy were evaluated.The mutant genotypic variant of XPC Lys939Gln has been associated with elevated risk of lung cancer(OR:2.30;95%CI:1.41-3.73;p=0.0007) whereas XPC Ala499Val showed a highly protective effect (OR:0.25;95%CI:0.10-0.63;p=0.003). The mutant genotype of XPC Lys939Gln presented a higher risk of developing lung cancer in heavy smokers (OR: 3.71; 95%CI:1.46-9.45; p=0.005). The survival analysis presented that heterozygous genotype showed least survival in comparison with mutant genotype in XPC Ala499Val genetic variant whereas no significant association was observed in XPC Lys939Gln. In conclusion, XPC Lys939Gln is associated with significant risk towards the lung cancer whereas on contrary XPC Ala499Val shows a protective effect.

Xeroderma pigmentosum complementation group D polymorphism toward lung cancer susceptibility survival and response in patients treated with platinum chemotherapy

AIM

The study investigated role of xeroderma pigmentosum complementation group D (XPD) single nucleotide polymorphisms in modulating lung cancer risk and its association with overall survival and clinical outcomes.

METHODS

 XPD polymorphisms were detected using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP).

RESULTS

 CC genotype of A751C polymorphism was associated with an increased lung cancer risk (p = 0.01). Classification and Regression Tree (CART) analysis depicted C156A as the major contributing factor. Patients having CC, treated with irinotecan-cisplatin/carboplatin regimen showed a better survival (median survival time = 25.2) whereas a poor survival was for XPD G312A. Similarly, patients treated with pemetrexed and carrying heterozygous genotype of G312A polymorphism had a poor survival (p = 0.01).

CONCLUSION

 A751C and G312A act as a predictive marker in lung cancer patients treated with platinum chemotherapy. These findings might facilitate therapeutic decisions for individualized therapy in lung cancer patient. [Formula: see text].

Single nucleotide polymorphisms in DNA repair genes and putative cancer risk

Single nucleotide polymorphisms (SNPs) are the most frequent type of genetic alterations between individuals. An SNP located within the coding sequence of a gene may lead to an amino acid substitution and in turn might alter protein function. Such a change in protein sequence could be functionally relevant and therefore might be associated with susceptibility to human diseases, such as cancer. DNA repair mechanisms are known to play an important role in cancer development, as shown in various human cancer syndromes, which arise due to mutations in DNA repair genes. This leads to the question whether subtle genetic changes such as SNPs in DNA repair genes may contribute to cancer susceptibility. In numerous epidemiological studies, efforts have been made to associate specific SNPs in DNA repair genes with altered DNA repair and cancer. The present review describes some of the common and most extensively studied SNPs in DNA repair genes and discusses whether they are functionally relevant and subsequently increase the likelihood that cancer will develop.

Polymorphisms in ERCC1 and ERCC2/XPD genes and carcinogen DNA adducts in human lung

OBJECTIVES

In this exploratory study, we aimed to investigate whether polymorphisms in excision repair cross-complementing group 1 (ERCC1) and excision repair cross-complementing group 2/xeroderma pigmentosum group D (ERCC2/XPD) in the nucleotide excision repair (NER) pathways associated with DNA adducts in human lung tissue. We also analyzed the association stratified by the major histologic subtypes of non-small cell lung cancer (NSCLC): adenocarcinoma (ADC) and squamous cell carcinoma (SQCC).

METHODS

The study population consisted of 107 early stage NSCLC patients from the Massachusetts General Hospital (MGH) in Boston who underwent curative surgical resection. Genotyping was completed for SNPs in ERCC1 [C8092A (rs3212986) and C118T (rs11615)] and ERCC2/XPD [Asp312Asn (rs1799793) and Lys751Gln (rs1052559)] using a PCR-RFLP method and the PCR with fluorescent allele-specific oligonucleotide probes (Taqman). DNA adduct levels were measured as relative adduct levels per 10(10) nucleotides by (32)P-postlabeling in non-tumor lung tissue.

RESULTS

After adjusting for potential confounders, lung DNA adduct levels increased by 103.2% [95% confidence interval (CI), -11.5 to 366.6] for ERCC2/XPD rs1799793AA genotype compared with their corresponding wild type homozygous genotypes in overall NSCLC, but the difference did not reach statistical significance. When we stratified by the subtypes of NSCLC, we found that DNA adducts levels in lung increased by 204.9% (95% CI, 0.8 to 822.2, P=0.059) for ERCC2/XPD rs1799793AA genotype in subjects with SQCC and the trend was statistically significant (P for trend=0.0489).

CONCLUSIONS

Polymorphisms in ERCC2/XPD Asp312Asn may be associated with increased DNA adduct levels in the lung, especially among subjects with SQCC. Further large scale studies are needed to confirm our findings.

Are SNP-Smoking Association Studies Needed in Controls? DNA Repair Gene Polymorphisms and Smoking Intensity

Variations in tobacco-related cancers, incidence and prevalence reflect differences in tobacco consumption in addition to genetic factors. Besides, genes related to lung cancer risk could be related to smoking behavior. Polymorphisms altering DNA repair capacity may lead to synergistic effects with tobacco carcinogen-induced lung cancer risk. Common problems in genetic association studies, such as presence of gene-by-environment (G x E) correlation in the population, may reduce the validity of these designs. The main purpose of this study was to evaluate the independence assumption for selected SNPs and smoking behaviour in a cohort of 320 healthy Spanish smokers. We found an association between the wild type alleles of XRCC3 Thr241Met or KLC3 Lys751Gln and greater smoking intensity (OR = 12.98, 95% CI = 2.86–58.82 and OR=16.90, 95% CI=2.09-142.8; respectively). Although preliminary, the results of our study provide evidence that genetic variations in DNA-repair genes may influence both smoking habits and the development of lung cancer. Population-specific G x E studies should be carried out when genetic and environmental factors interact to cause the disease.

XPD Lys751Gln polymorphisms and the risk of esophageal cancer: an updated meta-analysis

OBJECTIVE

Published data regarding the association between xeroderma pigmentosum group D XPD Lys751Gln polymorphisms and esophageal cancer (EC) cancer remain controversial. The present meta-analysis aimed to obtain a more precise estimation of the relationship between XPD Lys751Gln polymorphisms and the risk of EC.

METHODS

All eligible case-control studies of Lys751Gln polymorphisms and susceptibility to EC were selected from PubMed, Web of Science and CNKI up to October 2013. The data were extracted, and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

RESULTS

A total of 21 case-control studies from 19 reports were assessed in this meta-analysis, including 6,581 cases and 8,251 controls. There was a significant association between the XPD Lys751Gln polymorphism and the risk of esophageal cancer in the overall population (Dominant model: OR=1.30, 95%CI: 1.07-1.57, p<0.05; Lys/Gln vs. Gln/Gln: OR=1.20, 95%CI: 1.05-137, p<0.05; Gln/Gln vs. Lys/Lys: OR=1.76, 95%CI: 1.08-2.85, p=0.02; Recessive model: OR=1.48, 95%CI: 1.06-2.07, p=0.02). Similar results were found when stratified according to the cancer type, ethnicity and control source. However, no associations were found among smokers or drinkers.

CONCLUSION

The results of this meta-analysis suggest that XPD Lys751Gln polymorphisms contribute to susceptibility to EC.

Comprehensive assessment of the association between XPD rs13181 polymorphism and lung cancer risk

Xeroderma pigmentosum group D (XPD) rs13181 may reduce DNA repair capacity (DRC) through modifying XPD protein product. Reduced DRC is reportedly related to an increase in the risk of lung cancer. To precisely estimate the association between XPD rs13181 and lung cancer risk, we carried out the current meta-analysis. We searched multiple databases (up to 31 October 2013) for studies investigating the association of XPD rs13181 and lung cancer. Odds ratio (OR) was estimated with the fixed effect model to assess the association. Heterogeneity between studies was measured using Q test. Subgroup analyses were conducted by ethnicity, histological type, and sample size. Meta-analysis of 30 studies suggested that individuals carrying Gln/Gln genotype were more likely than the individuals with Lys/Lys or Lys/Gln + Lys/Lys genotypes (homozygous model, OR 1.18, 95 % confidence interval (CI) 1.07-1.31; recessive model, OR 1.17, 95 % CI 1.06-1.29) to develop lung cancer, without any substantial heterogeneity. This significantly increased risk was also revealed in the individuals harboring Gln/Gln + Lys/Gln genotypes (dominant model, OR 1.07, 95 % CI 1.01-1.12). Further stratification by histological type, ethnicity, and sample size yielded statistically significant estimates in subgroup of Caucasian subjects, non-small cell lung cancer, and relatively large studies, but borderline association in Asians. Our analyses demonstrate that XPD rs13181 may be associated with an increase in the risk of lung cancer among Caucasian populations.

Nucleotide excision repair gene polymorphisms and prognosis of non-small cell lung cancer patients receiving platinum-based chemotherapy: A meta-analysis based on 44 studies

Genetic variations are linked to DNA repair ability and varied drug metabolism that largely affects the prognosis of antineoplastic agents, including platinum. The purpose of the present meta-analysis was to determine the roles of the genetic variants of the nucleotide excision repair genes on the prognosis of platinum-based chemotherapy in patients with non-small cell lung cancer (NSCLC). A meta-analysis was performed, including 44 original studies with a total number of 5,944 patients with NSCLC according to the search strategy. The tumor responses [complete response, partial response, stable disease (SD) and progressive disease (PD)] were estimated and the Stata package was used for the comprehensive quantitative analyses. The results showed that the XPG C46T polymorphism was significantly associated with tumor chemotherapy when SD or PD was considered as a non-response [TT vs. CC: risk ratio (RR), 1.31; 95% confidence interval (CI), 1.14-1.5; and P=0.00; TT/CT vs. CC: RR, 1.23; 95% CI, 1.11-1.36; and P=0.00; and TT vs.

CC/CT

RR, 1.22; 95% CI, 1.11-1.36; and P=0.00]. No significant association between the ERCC1 C118T/C8092A XPDLys751Gln and XPA A23G polymorphisms and tumor response was found. There was also no evidence found to support the use of the ERCC1 C118T/C8092A XPDLys751Gln and XPA A23G polymorphisms as prognostic predictors of platinum-based chemotherapies in NSCLC in the meta-analysis. For the XPG C46T polymorphisms, a significant association with an objective response was detected. Multiple and large-scale studies are required to further investigate the association between biomarkers and tumor prognosis.

Association between ERCC2 Lys751Gln polymorphism and lung cancer risk: a meta-analysis involving 23,370 subjects

Recent studies report a correlation between excision repair cross-complementing group 2 (ERCC2) Lys751Gln polymorphism and an increased risk of lung cancer, but results are controversial and inconclusive. Thus, we conducted a comprehensive meta-analysis in order to assess the correlation between them. Our study uses an odds ratio (OR) with a 95% confidence interval (95% CI) to evaluate the strength of the association; we also performed Begg's funnel plot and the Egger's test to assess the publication bias of previous articles. Finally, our meta-analysis is comprised of 28 full studies, including 23,370 subjects (10,242 cases and 13,128 controls). Our overall research shows that ERCC2 Lys751Gln polymorphism carries an increased risk of developing lung cancer (C vs. A: OR = 1.160, 95% CI = 1.081-1.245, p = .000; CC vs. AA: OR = 1.252, 95% CI = 1.130-1.388, p = .000; CA vs. AA: OR = 1.152, 95% CI = 1.060-1.252, p = .001; CC+CA vs. AA: OR = 1.186, 95% CI = 1.089-1.292, p = .000; CC vs. CA+AA: OR = 1.196, 95% CI = 1.087-1.316, p = .000). In ethnic subgroup analyses, we find a significant risk among Caucasians (C vs. A: OR = 1.106, 95% CI = 1.048-1.166, p = .000; CC vs. AA: OR = 1.233, 95% CI = 1.103-1.378, p = .000; CC+CA vs. AA: OR = 1.113, 95% CI = 1.033-1.199, p = .005; CC vs. CA+AA: OR = 1.185, 95% CI = 1.069-1.313, p = .001) and among Asians under two genetic models (CA vs. AA: OR = 1.265, 95% CI = 1.034-1.549, p = .023; CC+CA vs. AA: OR = 1.252, 95% CI = 1.015-1.544, p = .036). These results were confirmed by similar findings, demonstrated by stratified analyses in study design and histological typing. This meta-analysis indicates that ERCC2 Lys751Gln polymorphism may lead to an increased susceptibility to lung cancer risk among Caucasians and Asians.

Polymorphism of ERCC2 Asp312Asn with lung cancer risk: evidence from 20,101 subjects

The association between excision repair cross complementing group 2 (ERCC2) Asp312Asn polymorphism and lung cancer has been reported by many articles recently, but the results were controversial and inconclusive. Therefore, a meta-analysis was conducted to assess the relationship between them. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. A total of 22 full studies with 20,101 subjects (8719 cases and 11,382 controls) were included in our research. The meta-analysis result showed that no significant association was found between ERCC2 Asp312Asn polymorphism and lung cancer in overall analysis (AA vs. GG, OR=1.023, 95% CI=0.824-1.270, p=0.838; AG vs. GG, OR=1.003, 95% CI=0.936-1.074, p=0.942; AA+AG vs. GG, OR=1.013, 95% CI=0.949-1.082, p=0.697; AA vs. AG+GG, OR=1.033, 95% CI=0.841-1.270, p=0.755). In subset analyses of stratified ethnicity, significantly increased risk was found among Asians (AA vs. GG, OR=3.212, 95% CI=1.518-6.795, p=0.002; AA vs. AG+GG, OR=3.174, 95% CI=1.500-6.712, p=0.003), whereas the association was not found among Caucasians under any genetic models. When analyses were conducted based on the study design, it indicated that the risk of lung cancer might be significantly increased in a hospital-based study (AA vs. GG, OR=1.323, 95% CI=1.096-1.596, p=0.004; AA+AG vs. GG, OR=1.109, 95% CI=1.000-1.229, p=0.050; AA vs. AG+GG, OR=1.285, 95% CI=1.076-1.535, p=0.006). In addition, a significantly increased risk for nonsmokers was detected under the dominant model (AA+AG vs. GG, OR=1.460, 95% CI=1.095-1.948, p=0.010). In conclusion, this meta-analysis suggested ERCC2 Asp312Asn polymorphism may increase the risk of lung cancer among Asians, whereas not among Caucasians.

DNA repair pathway genes and lung cancer susceptibility: a meta-analysis

OBJECTIVE

DNA repair pathway genes have been implicated to play an important role in the development of lung cancer. However, contradictory results are often reported by various studies, making it difficult to interpret them. So in this meta-analysis, we have assessed the association between lung cancer risk and two DNA repair pathway genes. XRCC1 and ERCC2, by analyzing 67 published case-control studies.

RESEARCH DESIGN AND METHODS

We searched PubMed, Embase and Web of Science using terms "XRCC1" or "XPD" or "ERCC2" and "lung cancer" on August 1, 2012. Three criteria were applied to select included studies for resulting studies. Information was carefully extracted by two investigators independently. We used pooled odds ratio (OR) to assess the effect of a polymorphism, and a dominant model was applied where genotypes that contain the non-reference allele were combined together. All the calculations were performed using STATA version 11.0.

MAIN OUTCOME MEASURES AND RESULTS

Three common nonsynonymous polymorphisms in XRCC1, codon 194, codon 280 and codon 399, and two common nonsynonymous polymorphisms in ERCC2, codon 312 and codon 751, were analyzed. The result showed in total population, Lys751Gln in ERCC2 is associated with an increase of lung cancer risk, with a summary OR as 1.15. No association was found for any other polymorphisms. When studies were stratified by ethnicity, the risk effect of Lys751Gln in ERCC2 was found only in Caucasians, not in Asians.

CONCLUSIONS

In conclusion, Lys751Gln in ERCC2 is associated with lung cancer, and the risk effect probably exists in Caucasians. By contrast, polymorphisms in XRCC1 are less likely to be susceptible to lung cancer risks.

Vascular endothelial growth factor -634G/C and vascular endothelial growth factor -2578C/A polymorphisms and lung cancer risk: a case-control study and meta-analysis

Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis in the process of tumor growth and metastasis. In present study, we conducted a case-control study and meta-analysis to evaluate the genetic effects of VEGF -634G/C and VEGF -2578C/A polymorphisms and risk of lung cancer. A total of 175 subjects were recruited for case-control study and seven studies were included in the meta-analysis. Our case-control study showed that VEGF -634G/C polymorphism had no association with lung cancer risk (CC vs. GG: OR = 0.88, 95% CI = 0.37-2.11), whereas there was an association between VEGF -2578CC genotype and decrease in lung cancer risk (CC vs.

CA/AA

OR = 0.52, 95% CI = 0.28-0.96). A meta-analysis was further performed and statistically similar results were obtained (CC vs. GG: OR = 0.91, 95% CI = 0.60-1.39 for VEGF -634; CC vs. AA: OR = 0.53, 95% CI = 0.32-0.89 for VEGF -2578). Our study showed that the variant genotypes of the VEGF -2578C/A polymorphism, but not the VEGF -634G/C polymorphism, was associated with lung cancer risk. More studies are needed to detect VEGF -634G/C and VEGF -2578 polymorphisms and their association with lung cancer in different ethnic populations incorporated with environmental exposures.

Genetic polymorphisms of ERCC1‑118, XRCC1‑399 and GSTP1‑105 are associated with the clinical outcome of gastric cancer patients receiving oxaliplatin‑based adjuvant chemotherapy

The aim of the present study was to determine whether specific molecular parameters may serve as predictors of treatment outcomes and toxicity of oxaliplatin (OXA)‑based chemotherapy, which is used as an adjuvant treatment in resected gastric cancer. All gastric cancer patients examined in the study received an OXA/5‑fluorouracil chemotherapeutic regimen. Genetic polymorphisms of certain platinum‑related genes were determined by the TaqMan 5' nuclease assay and direct sequencing. Relapse‑free survival (RFS), overall survival (OS) and toxicity were evaluated according to each genotype. Following adjustment for the most relevant clinical variables, excision repair cross‑complimentary group 1 (ERCC1)‑118 and X-ray repair cross-complementing protein 1 (XRCC1‑399) demonstrated significant predictive value for RFS and OS. We also demonstrated that carrying at least one variant XRCC1 Arg399Gln or glutathione S-transferase π 1 (GSTP1) Ile105Val allele significantly increased the risk of any grade 3 or 4 hematological toxicity. In particular, carrying at least one variant GSTP1 Ile105Val allele was also significantly correlated with an increased risk of grade 3 or 4 gastrointestinal toxicity and neurotoxicity. Our data suggested that gastric cancer patients harboring ERCC1‑118 C/C and XRCC1‑399 A/G or A/A genotypes may benefit from receiving OXA‑based adjuvant chemotherapy, and carrying at least one variant XRCC1 Arg399Gln or GSTP1 Ile105Val allele may contribute to the occurrence of adverse drug effects associated with OXA‑based chemotherapy.

DNA Repair Gene Polymorphisms in the Nucleotide Excision Repair Pathway and Lung Cancer Risk: A Meta-analysis

OBJECTIVE

A number of studies have reported the association of "XPA", "XPC", "XPD/ERCC2" gene polymorphisms with lung cancer risk. However, the results were conflict. To clarify the impact of polymorphisms of "XPA", "XPC", "XPD/ERCC2", on lung cancer risk, a meta-analysis was performed in this study.

METHODS

The electronic databases PubMed and Embase were retrieved for studies included in this meta-analysis by "XPA", "XPC", "XPD/ERCC2", "lung", "cancer/neoplasm/tumor/carcinoma", "polymorphism" (An upper date limit of October, 31, 2009). A meta-analysis was performed to evaluate the relationship among XPA, XPC and XPD polymorphism and lung cancer risks.

RESULTS

A total of 31 publications retrieved from Pubmed and Embase included in this study. XPC A939C CC genotype increased lung cancer risk in total population (recessive genetic model: OR=1.23, 95% CI:1.05-1.44; homozygote comparison: OR=1.21,95%CI:1.02-1.43and CC vs. CA contrast: OR=1.25,95%CI:1.06-1.48), except in Asians. XPD A751C, 751C allele and CC genotype also increased lung cancer risk in total population and in Caucasians (recessive genetic model: Total population: OR=1.20, 95%CI:1.07-1.35). No significant correlation was found between XPD A751C and lung cancer risk in Asians and African Americans. XPD G312A AA genotype increased lung cancer risk in total population, in Asians and Caucasians(recessive genetic model: Total population: OR=1.20, 95%CI: 1.06-1.36). No significant association was found between XPA G23A, XPC C499T, XPD C156A and lung cancer risk.

CONCLUSION

Our results suggest that the polymorphisms in XPC and XPD involve in lung cancer risks. XPA polymorphisms is less related to lung cancer risk.

Genetic susceptibility to lung cancer--light at the end of the tunnel?

Lung cancer is one of the most common and deadliest cancers in the world. The major socio-environmental risk factor involved in the development of lung cancer is cigarette smoking. Additionally, there are multiple genetic factors, which may also play a role in lung cancer risk. Early work focused on the presence of relatively prevalent but low-penetrance alterations in candidate genes leading to increased risk of lung cancer. Development of new technologies such as genomic profiling and genome-wide association studies has been helpful in the detection of new genetic variants likely involved in lung cancer risk. In this review, we discuss the role of multiple genetic variants and review their putative role in the risk of lung cancer. Identifying genetic biomarkers and patterns of genetic risk may be useful in the earlier detection and treatment of lung cancer patients.

Identification of sequence polymorphisms in the D-loop region of mitochondrial DNA as a risk factor for lung cancer

Accumulation of single nucleotide polymorphisms (SNPs) in the displacement loop (D-loop) of mitochondrial DNA (mtDNA) may be associated with an increased cancer risk. We investigated the lung cancer risk profile of D-loop SNPs in a case-controlled study. The minor alleles of nucleotides 235A/G and 324A/G were associated with an increased risk for lung cancer patients. The minor alleles of the nucleotides 151C/T, 200A/G, 524C/CA, and 16274G/A were specifically associated with the cancer risk of squamous cell carcinoma, whereas the minor allele of nucleotide 16298T/C was specifically associated with the risk of small cell lung cancer. In conclusion, SNPs in mtDNA are potential modifiers of lung cancer risk. The analysis of genetic polymorphisms in the mitochondrial D-loop can help identify subgroups of patients who are at a high risk of developing lung cancer.

Association of ERCC2/XPD polymorphisms and interaction with tobacco smoking in lung cancer susceptibility: a systemic review and meta-analysis

The association of the two ERCC polymorphisms, Asp312Asn and Lys751Gln, with lung cancer risk remains controversial and inconclusive. To better evaluate the potential role of the two polymorphisms and interaction with tobacco smoking in lung cancer susceptibility presented in diverse populations, we have conducted a meta-analysis based on 26 studies from 24 publications which included analyses of Asp312Asn (7121 cases, 8962 controls) and Lys751Gln (8396 cases, 10510 controls) polymorphisms. Overall, significantly elevated lung cancer risk was associated with ERCC2 312Asn allele(homozygous model: OR=1.20[1.05-1.36], P=0.006; recessive model: OR=1.20[1.06-1.35], P=0.004) and 751Gln allele(homozygous model: OR=1.31[1.17-1.46], P<0.00001; heterozygous model: OR=1.11[1.04-1.19], P=0.003; recessive model: OR=1.23[1.11-1.37], P<0.0001; dominant model: OR=1.15[1.08-1.23], P<0.0001). In ethnic subgroup analyses, significantly increased risk was associated with ERCC2 312Asn allele for both Caucasians and Asians, and 751Gln allele for both Caucasians and Latino-Americans. When stratified by smoking status, significantly elevated risk of both polymorphisms for never-smokers was detected (dominant model, OR=1.46[1.09-1.95] and 1.57[1.19-2.08], P=0.01 and 0.002, respectively). In conclusion, this meta-analysis suggests that the two ERCC2 polymorphisms may contribute to lung cancer susceptibility serving as low-penetrance risk factors. Extremely large-scale evidence would be necessary to confirm the effects on ethnically specific populations and gene-environment interactions.

XPD Lys751Gln polymorphism and esophageal cancer risk: A meta-analysis involving 2288 cases and 4096 controls

AIM: To evaluate the association between xeroderma pigmentosum group D (XPD), genetic polymorphism Lys751Gln and esophageal cancer risk.

METHODS: We searched PubMed up to September 1, 2010 to identify eligible studies. A total of 10 case-control studies including 2288 cases and 4096 controls were included in the meta-analysis. Statistical analysis was performed with Review Manage version 4.2. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association.

RESULTS: The results suggested that there is no significant association between XPD Lys751Gln polymorphism and esophageal cancer susceptibility in the overall population. However, in subgroup analysis by histology type, a significant association was found between XPD Lys751Gln polymorphism and esophageal adenocarcinoma (for CC vs AA: OR = 1.25, 95% CI = 1.01-1.55, P = 0.05 for heterogeneity).

CONCLUSION: Our meta-analysis suggested that XPD Lys751Gln polymorphism may be associated with increased risk of esophageal adenocarcinoma.

Association of genetic polymorphisms in DNA repair pathway genes with non-small cell lung cancer risk

DNA repair function is believed to play an important role in cancer development and to be affected by genetic polymorphisms. Numerous epidemiological studies have examined the associations between single nucleotide polymorphisms (SNPs) in the DNA repair genes and lung cancer risk, but the results are inconsistent. The aim of this study was to investigate the associations of several SNPs in the DNA repair pathways and risk of non-small cell lung cancer (NSCLC) in a Chinese population. The study included 581 NSCLC cases and 603 healthy controls. The polymorphisms studied include XRCC1 (rs25487), hOGG1 (rs1052133), MUTYH (rs3219489) in the base excision repair (BER) pathway, XPA (rs1800975), ERCC2 (rs1799793 and rs13181) in the nucleotide excision repair (NER) pathway and XRCC3 (rs861539) in the double strand break repair (DSB) pathway. The associations between lung cancer risk and genetic polymorphisms were evaluated using the logistic regression models and subgroup analyses. Meta-analyses were conducted for the SNPs shown to be significantly associated with lung cancer risk in our study. Our findings showed that XPA -4G>A (rs1800975) had a significant association with lung cancer (OR=1.64; 95% CI: 1.03-2.60), and the association was more evident in squamous cell carcinoma (OR=1.69; 95% CI: 1.00-2.84). Three BER polymorphisms showed no independent effects on the risk of lung cancer. The stratified analysis showed higher lung cancer risk among the smokers carrying the variant XPA allele (OR=1.75; 95% CI: 1.15-2.65) and among the non-smokers carrying the variant ERCC2 allele of 312Asn (OR=2.10; 95% CI: 1.22-3.64). Meta-analysis showed that individuals with the variant AA genotype of XPA (-4G>A) had higher risk of lung cancer compared to those with the 'G' wild allele (OR=1.28; 95% CI: 1.12-1.47); and those with variant alleles of ERCC2 312Asn had higher risk compared to those with wild 312Asp alleles among nonsmokers (OR=1.58; 95% CI: 1.20-2.08). Although smoking is the dominant risk factor of lung cancer, XPA -4G>A (rs1800975) is also associated with the risk of NSCLC, especially for squamous cell carcinoma, among Asian young smokers. ERCC2 Asp/Asn (rs1799793) polymorphism may also affect lung cancer risk among nonsmokers. The NER pathway seems to have more strong influences on lung cancer than the BER pathway.

Smoking and selected DNA repair gene polymorphisms in controls: systematic review and meta-analysis

BACKGROUND

When the case-only study design is used to estimate statistical interaction between genetic (G) and environmental (E) exposures, G and E must be independent in the underlying population, or the case-only estimate of interaction (COR) will be biased. Few studies have examined the occurrence of G-E association in published control group data.

METHODS

To examine the assumption of G-E independence in empirical data, we conducted a systematic review and meta-analysis of G-E associations in controls for frequently investigated DNA repair genes (XRCC1 Arg399Gln, Arg194Trp, or Arg280His, XPD Lys751Gln, and Asp312Asn, and XRCC3 Thr241Met), and smoking (ever/never smoking, current/not current smoker, smoking duration, smoking intensity, and pack-years).

RESULTS

Across the 55 included studies, single nucleotide polymorphisms SNP-smoking associations in controls (OR(z)) were not reliably at the null value of 1.0 for any SNP-smoking combinations. Two G-E combinations were too heterogeneous for summary estimates: XRCC1 399 and ever-never smoking (N = 21), and XPD 751 and pack-years (N = 12). OR(z) ranges for these combinations were: [OR(z) (95% confidence interval (CI)] 0.7 (0.4, 1.2)-1.9 (1.2, 2.8) and 0.8 (0.5, 1.3)-2.3 (0.8, 6.1), respectively). Estimates for studies considered homogeneous (Cochran's Q P-value <0.10) varied 2- to 5-fold. No study characteristics were identified that could explain heterogeneity.

CONCLUSIONS

We recommend the independence assumption be evaluated in the population underlying any potential case-only study, rather than in a proxy control group(s) or pooled controls.

IMPACT

These results suggest that G-E association in controls may be population-specific. Increased access to control data would improve evaluation of the independence assumption.

XPD Lys751Gln increases the risk of breast cancer

Breast cancer incidence has been on the increase in south Indian women. Polymorphisms in DNA repair genes modify an individual's risk to cancer. XPD (Xeroderma pigmentosum D), a DNA helicase gene involved in nucleotide excision repair and transcription coupled repair, may affect an individual's DNA repair capacity, particularly that of bulky adducts. This case-control study (250 breast cancer cases and 500 healthy controls) aimed to investigate the role of the XPD Lys751Gln polymorphism as a risk factor in the development of breast cancer. Genotyping was performed using the Taq Man allelic discrimination assay. Immunohisto-chemistry was used to quantitate the level of polycyclic aromatic hydrocarbon (PAH) adducts in biopsy samples obtained from the breast cancer patients. Results showed that the XPD Gln/Gln genotype was significantly associated with an increased risk of breast cancer (OR, 1.75; 95% CI 1.02-2.80), particularly in premenopausal female patients (OR, 2.6; 95% CI 1.33-4.79). PAH adduct levels were significantly higher in the cases with breast cancer as compared to the normal breast tissue. This study reveals that XPD may play a role in increasing breast cancer risk particularly in premenopausal females.

Polymorphisms in DNA repair genes XRCC1, XRCC3 and XPD, and colorectal cancer risk: a case-control study in an Indian population

PURPOSE

Genetic polymorphisms in DNA repair genes may influence variations in individual DNA repair capacity, which could be associated with the development of cancer. We detected the distributions of three single-nucleotide polymorphisms (XRCC1 Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln) in DNA repair genes, and assessed the associations of these genetic polymorphisms with colon and rectal cancer susceptibility as well as evaluated the interactions of gene-gene and gene-environment in a case-control study of an Indian population.

METHODS

This case-control study was conducted with 302 cases (including 59 colon and 243 rectal cancer patients) and 291 cancer-free healthy controls. Genotypes were determined by PCR-RLFP assays. The effects [odds ratios (ORs) and 95% confidence intervals (95% CIs)] of genetic polymorphisms on colorectal cancer were estimated using unconditional logistic regression.

RESULTS

The XRCC1 399Gln allele was found to be associated with a significantly increased rectal cancer risk among men (OR = 1.65, 95% CI 1.04-2.64). Whereas the XRCC3 241Met allele showed a protective tendency against rectal cancer (OR = 0.68, 95% CI 0.46-1.02) for both men and women. Furthermore, a combination of the XRCC1 399Gln allele with XRCC3 Thr/Thr genotype and the XPD 751Gln allele demonstrated the highest rectal cancer risk (OR = 3.52, 95% CI 1.43-9.44).

CONCLUSIONS

The combined effects of putative risk alleles/genotypes for different DNA repair pathways may strengthen the susceptibility to rectal cancer.

Effects of selected genetic polymorphisms in xeroderma pigmentosum complementary group D on gastric cancer

DNA repair capacity (DRC) can be altered based on sequence variations in DNA repair genes, which may result in cancer susceptibility. The current study was to evaluate the association between genetic polymorphisms, including associated haplotypes of xeroderma pigmentosum complementary group D (XPD), and individual susceptibility to gastric cancer. Two-hundred-eight patients with gastric cancer and 339 healthy controls were enrolled in this study. Their genomic DNA was extracted from peripheral blood leukocytes. The genotypes at exon 6, 10 and 23 were identified by polymerase chain reaction (PCR). Unconditional logistic regression model was used to analyze the effects of the polymorphisms, including the corresponding haplotypes, on the susceptibility to develop gastric cancer. The proportion of genotypes GA or AA at exon 10 in cases was showed to be significantly higher than that in controls (P < 0.01, P < 0.01, respectively). The risk of genotype GA or AA carriers to develop gastric cancer was simultaneously much higher (OR = 3.38, 95% CI 2.30-4.95; OR = 6.13, 95% CI 2.45-15.31, respectively). The allele A at exon 10 was also observed to manifest a substantially higher frequency in cases compared to controls (P < 0.01), which might indicate an increased tendency to gastric cancer (OR = 2.40, 95% CI 1.81-3.17). No significant differences were found in the distribution of genotypes at exon 6 or 23 between the two groups (P = 0.23, P = 0.52; P = 0.44, P = 0.56, respectively). By haplotype analysis, haplotype AAA could individually increase incidence of gastric cancer (P < 0.01, OR = 3.39, 95% CI 2.21-5.21). In contrast, haplotypes CGA and AGA were showed a decline in gastric cancer susceptibility (OR = 0.67, 95% CI 0.46-0.97; OR = 0.58, 95% CI 0.41-0.83, respectively). The rest of haplotypes made no statistically significant difference between cases and controls. Taken together, this study demonstrates that the genetic variation at exon 10 and haplotype AAA may be contributing factors in developing gastric cancer.

ERCC2 Lys751Gln polymorphism is associated with lung cancer among Caucasians

To derive a more precise estimation of the relationship between the excision repair cross-complementing rodent repair deficiency, group 2 (ERCC2) Lys751Gln polymorphism and lung cancer risk, a meta-analysis was performed. A total of 23 studies including 8137 cases and 9824 controls were involved in this meta-analysis. Overall, significantly elevated lung cancer risk was associated with ERCC2 Gln allele when all studies were pooled into the meta-analysis (Lys/Gln versus Lys/Lys: odds ratio (OR)=1.10, 95% confidence interval (CI)=1.03-1.19; Gln/Gln versus Lys/Lys: OR=1.20, 95% CI=1.06-1.35; dominant model: OR=1.13, 95% CI=1.05-1.20; and recessive model: OR=1.15, 95% CI=1.03-1.29). In the subgroup analysis by ethnicity, significantly increased risk was only found for Caucasians (Gln/Gln versus Lys/Lys: OR=1.25, 95% CI=1.08-1.45; dominant model: OR=1.10, 95% CI=1.00-1.22; and recessive model: OR=1.22, 95% CI=1.06-1.40). When stratified by study design, statistically significantly elevated risks were found in hospital-based studies (Lys/Gln versus Lys/Lys: OR=1.12, 95% CI=1.03-1.22; Gln/Gln versus Lys/Lys: OR=1.24, 95% CI=1.06-1.44; dominant model: OR=1.15, 95% CI=1.06-1.24; and recessive model: OR=1.19, 95% CI=1.03-1.37) and population-based studies (Gln/Gln versus Lys/Lys: OR=1.57, 95% CI=1.12-2.20 and recessive model: OR=1.50, 95% CI=1.08-2.07). In the subgroup analysis whether or not the studies were matched on smoking, significantly increased risk was found not in those matched studies but in the unmatched studies (Lys/Gln versus Lys/Lys: OR=1.11, 95% CI=1.03-1.19; Gln/Gln versus Lys/Lys: OR=1.22, 95% CI=1.07-1.40; dominant model: OR=1.13, 95% CI=1.05-1.22; and recessive model: OR=1.18, 95% CI=1.04-1.33). In conclusion, this meta-analysis suggests that the ERCC2 Lys751Gln polymorphism may contribute to lung cancer susceptibility among Caucasians.

[The association of XPD G312A polymorphism with lung cancer risk: a meta-analysis]

BACKGROUND AND OBJECTIVE

It has been proven that close relation was existed between XPD polymorphism G312A and lung cancer risk. However, some of the results are not consistent. The aim of this study is to explore the impact of DNA repair gene XPD polymorphism G312A on lung cancer risk.

METHODS

The literatures eligible from PUBMED, EMBASE, CNKI and WANGFANG database were enrolled in the meta-analysis. Heterogeneity among combined studies was assessed. The pooled OR and 95%CI were calculated. The sensitivity analysis and the publication bias were evaluated by RevMan 5.0 and STATA 11.0.

RESULTS

There were 6554 cases and 8322 controls from 18 studies included in the meta-analysis. In total, individuals with 312A allele and 312AA genotype showed increased lung cancer risk (A vs. G: OR = 1.06, 95% CI: 1.00-1.12; AA vs. AG+GG: OR = 1.20, 95% CI: 1.06-1.36; AA vs. GG: OR = 1.19, 95% CI: 1.04-1.36). In Asians, individuals with 312AA genotype showed 6.15 fold and 6.20 fold increased lung cancer risk in recessive genetic model and homogenous contrast respectively (AA vs. AG+GG: OR = 7.15, 95% CI: 1.90-26.94; AA vs. GG: OR = 7.20, 95% CI: 1.91-27.15). In Caucasians, individuals with 312AA genotype showed a 15% increased lung cancer risk (OR = 1.15, 95% CI: 1.01-1.31).

CONCLUSION

XPD 312A allele is risk allele for lung cancer. Individuals with AA genotype have higher risk of lung cancer, especially in Asians.

The association between XPD Asp312Asn polymorphism and lung cancer risk: a meta-analysis including 16,949 subjects

To derive a more precise estimation of the relationship between the xeroderma pigmentosum group D (XPD) Asp312Asn polymorphism and lung cancer risk, a meta-analysis was performed. PubMed, Medline, Embase, and Web of Science were searched. Crude ORs with 95% CIs were used to assess the strength of association between the XPD Asp312Asn polymorphism and lung cancer risk. The pooled ORs were performed with co-dominant model (Asp/Asn vs. Asp/Asp, Asn/Asn vs. Asp/Asp), dominant model (Asp/Asn + Asn/Asn vs. Asp/Asp), and recessive model (Asn/Asn vs. Asp/Asp+Asp/Asn), respectively. A total of 18 studies including 7,552 cases and 9,397 controls were involved in this meta-analysis. Overall, significantly elevated lung cancer risk was associated with XPD Asn allele when all studies were pooled into the meta-analysis (Asn/Asn vs. Asp/Asp: OR=1.158, 95% CI=1.018-1.317; recessive model: OR=1.161, 95% CI=1.029-1.311). In the subgroup analysis by ethnicity, significantly increased risks were found for both Caucasians (Asn/Asn vs. Asp/Asp: OR=1.164, 95% CI=1.003-1.351; recessive model: OR=1.169, 95% CI=1.016-1.345) and Asians (Asn/Asn vs. Asp/Asp: OR=8.056, 95% CI=2.420-26.817; recessive model: OR=7.956, 95% CI=2.391-26.477). When stratified by study design, statistically significantly elevated risk was noted in hospital-based studies (Asn/Asn vs. Asp/Asp: OR=1.315, 95% CI=1.110-1.558; recessive model: OR=1.290, 95% CI=1.099-1.513). In conclusion, this meta-analysis suggests that the XPD Asn allele is a low-penetrant risk factor for developing lung cancer.

Tobacco, Genetic Susceptibility and Lung cancer

Exposure to tobacco smoke is an established risk factor for lung cancer, although a possible role for genetic susceptibility in the development of lung cancer has been inferred from familial clustering of the disease and segregation analysis. Findings of familial aggregation and statistical evidence for a major susceptibility gene have led to the search for high penetrant, rare, single genes and low penetrant, high frequency susceptibility genes for lung cancer. The relatively small number of linkage studies conducted to date, have identified potential lung cancer susceptibility loci on chromosomes 6q, 12p, and 19q. A variety of studies have examined single nucleotide polymorphisms of several low penetrant, high frequency genes encoding for enzymes involved in the metabolism of carcinogens and DNA damage repair, as likely candidate susceptibility genes. These studies have produced somewhat conflicting findings and, when significant, only modest associations have been reported. Relatively few studies have looked for potential gene-environment interactions, explored associations between two or more genetic polymorphisms or evaluated interactions between genetic polymorphisms and endogenous risk factors. Few large scale genome wide association studies conducted recently have provided evidence that common variation on chromosome 15q25.1, 5p15.33 and 6p21.33 influences lung cancer risk and cancer types with strong environmental risk factors. It is hoped that newer research strategies, selecting candidate genes within pathways and genotype at multiple markers within a gene, employing new technologies, may allow complete coverage of the variation within candidate genes in multiple pathways and to unravel the genetic susceptibility to lung cancer. This knowledge could, in turn, be used to identify persons at risk, to individualize treatments such as chemoprevention, to personalize harms of smoking and to motivate cessation.

XPD codon 312 and 751 polymorphisms, and AFB1 exposure, and hepatocellular carcinoma risk

BACKGROUND

Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with risk of hepatocellular carcinoma (HCC) related to the exposure of aflatoxin B1 (AFB1). In this study, we have focused on the polymorphisms of xeroderma pigmentosum complementation group D (XPD) codon 312 and 751 (namely Asp312Asn and Lys751Gln), involved in nucleotide excision repair.

METHODS

We conducted a case-control study including 618 HCC cases and 712 controls to evaluate the associations between these two polymorphisms and HCC risk for Guangxi population by means of TaqMan-PCR and PCR-RFLP analysis.

RESULTS

We found that individuals featuring the XPD genotypes with codon 751 Gln alleles (namely XPD-LG or XPD-GG) were related to an elevated risk of HCC compared to those with the homozygote of XPD codon 751 Lys alleles [namely XPD-LL, adjusted odds ratios (ORs) were 1.75 and 2.47; 95% confidence interval (CIs) were 1.30-2.37 and 1.62-3.76, respectively]. A gender-specific role was evident that showed an higher risk for women (adjusted OR was 8.58 for XPD-GG) than for men (adjusted OR = 2.90 for XPD-GG). Interestingly, the interactive effects of this polymorphism and AFB1-exposure information showed the codon 751 Gln alleles increase the risk of HCC for individuals facing longer exposure years (Pinteraction = 0.011, OR = 0.85). For example, long-exposure-years (> 48 years) individuals who carried XDP-GG had an adjusted OR of 470.25, whereas long-exposure-years people with XDP-LL were at lower risk (adjusted OR = 149.12). However, we did not find that XPD codon 312 polymorphism was significantly associated with HCC risk.

CONCLUSION

These findings suggest that XPD Lys751Gln polymorphism is an important modulator of AFB1 related-HCC development in Guangxi population.

DNA repair gene polymorphisms and prostate cancer risk in South Australia--results of a pilot study

OBJECTIVE

Single nucleotide polymorphisms (SNPs) in DNA repair genes may impact on DNA damage, and cancer risk. To elucidate the role of SNPs in DNA repair genes in prostate cancer (PC) we conducted a case-control study comprising of 118 Caucasian men affected with late onset PC and 132 age-matched healthy controls from South Australia.

METHODS AND MATERIALS

We examined the association between PC risk with nonsynonymous SNPs (nsSNPs) in 5 genes involved in 3 DNA-repair pathways: (1) base excision repair (BER): hOGG1 C1245G (Ser326Cys) and XRCC1 G28152A (Arg399Gln); (2) nucleotide excision repair (NER): XPD G23591A (Asp312Asn); (3) homologous recombination repair: RAD51 G135C (in 5' untranslated region) and XRCC3 C18067T (Thr241Met).

RESULTS

Prostate cancer risk was significantly increased only for carriers of the G allele of the C1245G polymorphism in the hOGG1 gene (OR = 2.28; 95% CI = 1.36-3.83; P = 0.002).

CONCLUSION

Our results suggest that this common nsSNP in a gene involved in repair of oxidative damage to DNA may contribute to PC susceptibility in South Australian men.

Statistically significant association of the single nucleotide polymorphism (SNP) rs13181 (ERCC2) with predisposition to Squamous Cell Carcinomas of the Head and Neck (SCCHN) and Breast cancer in the north Indian population

Background

Non-synonymous single nucleotide polymorphisms (SNPs) within vital DNA repair genes may cause reduction of activity leaving the genome unrepaired resulting in genomic instability and cancer.

Materials and methods

The present endeavour involved study on the association of the SNP rs13181 (Lys751Gln/A18911C) in the Nucleotide Excision Repair (NER) pathway gene ERCC2 (excision repair cross-complementing rodent repair deficiency, complementation group 2) with the risks of Squamous Cell Carcinomas of the Head and Neck (SCCHN) and Breast cancer using a case-control based association study among 685 (400 controls and 285 SCCHN-affected cases) and 395 (227 normal healthy female controls and 168 breast cancer cases) ethnically-matched samples, respectively from north India using Polymerase Chain Reaction followed by Restriction Fragment Length Polymorphism (PCR-RFLP) analysis.

Results

Results showed significant association of rs13181 homozygous mutant (CC) [Odds Ratio (OR) 4.412, 95% Confidence Interval (CI) 2.413 to 8.068], heterozygous (AC) (OR 2.086, 95% CI 1.246 to 3.492) and combined mutant (AC + CC) (OR 2.672, 95% CI 1.647 to 4.334) genotypes with predisposition to Breast cancer. Statistically significant increase in SCCHN risk was also associated with the mutant genotypes of rs13181 (ERCC2), viz. homozygous mutant (CC) (OR 1.680, 95% CI 1.014 to 2.784), heterozygous (AC) (OR 1.531, 95% CI 1.092 to 2.149) and combined mutant (AC + CC) (OR 1.560, 95% CI 1.128 to 2.158) genotypes.

Conclusion

The results of this case-control study indicate that the polymorphism rs13181 might be a risk factor for predisposition towards SCCHN and breast cancer among north Indian subpopulations.

Nucleotide excision repair genes and risk of lung cancer among San Francisco Bay Area Latinos and African Americans

Few studies on the association between nucleotide excision repair (NER) variants and lung cancer risk have included Latinos and African Americans. We examine variants in 6 NER genes (ERCC2, ERCC4, ERCC5, LIG1, RAD23B and XPC) in association with primary lung cancer risk among 113 Latino and 255 African American subjects newly diagnosed with primary lung cancer from 1998 to 2003 in the San Francisco Bay Area and 579 healthy controls (299 Latinos and 280 African Americans). Individual single nucleotide polymorphism and haplotype analyses, multifactor dimensionality reduction (MDR) and principal components analysis (PCA) were performed to assess the association between 6 genes in the NER pathway and lung cancer risk. Among Latinos, ERCC2 haplotype CGA (rs238406, rs11878644, rs6966) was associated with reduced lung cancer risk [odds ratio (OR) of 0.65 and 95% confidence interval (CI): 0.44-0.97], especially among nonsmokers (OR = 0.29; 95% CI: 0.12-0.67). From MDR analysis, in Latinos, smoking and 3 SNPs (ERCC2 rs171140, ERCC5 rs17655 and LIG1 rs20581) together had a prediction accuracy of 67.4% (p = 0.001) for lung cancer. Among African Americans, His/His genotype of ERCC5 His1104Asp (rs17655) was associated with increased lung cancer risk (OR = 1.78; 95% CI: 1.09-2.91), and LIG1 haplotype GGGAA (rs20581, rs156641, rs3730931, rs20579 and rs439132) was associated with reduced lung cancer risk (OR = 0.61; 95% CI: 0.42-0.88). Our study suggests different elements of the NER pathway may be important in the different ethnic groups resulting either from different linkage relationship, genetic backgrounds and/or exposure histories.

ERCC1 and ERCC2 polymorphisms and risk of idiopathic azoospermia in a Chinese population

The ERCC1 (excision repair cross complementation group 1) and ERCC2 (excision repair cross complementation group 2) genes are important in repairing DNA damage and genomic instability in germ cells, and are essential for normal spermatogenesis. It has been verified that polymorphisms of these two genes could alter DNA repair capacity in some phenotypic studies. However, little information is available on these polymorphisms in male infertility. This study was designed to examine whether ERCC1 polymorphisms 3 UTR (C8092A), Asn118Asn (G19007A) and ERCC2 polymorphisms Asp312Asn (G-->A), Lys751Gln (A-->C), which have been reported to contribute to some cancers, are associated with idiopathic azoospermia in the Chinese population. The four polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism assay in a hospital-based case-control study, comprising 202 infertile patients with idiopathic azoospermia and 187 fertile controls. It was found that the ERCC1 8092 CA + AA genotypes were significantly associated with an increased risk of idiopathic azoospermia (OR = 1.750, 95% CI = 1.170-2.618), while other polymorphisms appeared to show no significant differences between cases and controls. Further studies are needed to confirm the roles of these polymorphisms in idiopathic azoospermia.

Pharmacogenetically relevant polymorphisms in Portugal

OBJECTIVE

Most drugs are developed based on data from European-derived 'reference' populations; however, clinically relevant DNA polymorphisms often demonstrate population-specific patterns of allele frequencies. Given that the knowledge of the frequency distribution of functional polymorphisms in a population may guide national planning for selection of therapeutic options, in the present study we examined the allele frequencies of enzymes responsible for drug disposition in Portugal.

PATIENTS & METHODS

Using PCR- and Pyrosequencing-based methods, the current study assessed the frequencies of 15 key polymorphisms from genes encoding enzymes involved in Phases I, II and III of drug metabolism, DNA repair and intracellular metabolism in 135 healthy individuals from Portugal.

RESULTS

Allele frequencies were derived for cytochrome P450 (CYP)2C9*2 (13.2%), CYP2C9*3 (8%), CYP2C19*2 (14%), CYP3A4*1B (7%), CYP3A5*3C (87.5%), glutathione S-transferase (GST)M1*0 (77.9%), GSTP1 313A>G (33%), inosine triphosphatase 94C>A (7%), UDP-glucuronosyltransferase (UGT)1A1*28 (28%), UGT1A1 -3156G>A (23%), ATP-binding cassette (ABC)B1 1236C>T (46%), ABCB1 2677G>A/T (2 and 42%), ABCG2 421C>A (8%), excision repair cross-complementing rodent repair deficiency 2 2251A>C (3%) and thymidylate synthetase 1494del (31%).

CONCLUSION

Although, on the whole, the frequency distributions among the Portuguese fitted the patterns commonly found in other Europeans well, evidence for some degree of African influence was observed. This is the most comprehensive study on pharmacogenetically relevant variations in Portugal to date, and the baseline of pharmacogenetic data might be important for determining policy guidelines for cancer prevention and drug treatments in the Portuguese population.

Prognostic importance of DNA repair gene polymorphisms of XRCC1 Arg399Gln and XPD Lys751Gln in lung cancer patients from India

PURPOSE

Inter individual variation in lung cancer susceptibility may be modulated in part through genetic polymorphisms in the DNA repair genes, especially the genes involved in the Base Excision Repair (BER) and nucleotide excision repair (NER) pathway. Two of the genetic polymorphisms, XRCC1Arg399Gln and XPD Lys751Gln have been extensively studied in the association with lung cancer risk, although published studies have been inconclusive.

METHODS

In order to verify the role of the common variant alleles in the XPD gene, we have genotyped 211 lung cancer patients and 211 healthy controls using PCR-RFLP assays in a hospital based, case-control study in an Indian population. Logistic regression models were fit to examine the relationship between the log odds of lung cancer and each covariate. Overall Survival in relation to various genotypes and clinicopathological factors were analyzed using Kaplan Meier estimates and hazard ratios were calculated using Cox Regression analysis.

RESULTS

The carriers of XRCC1 399 AA genotypes were at higher risk of lung cancer (OR = 2.1, 95% CI:1.224-3.669, P = 0.007) than carriers of GG genotype. Subjects carrying 751 AC genotype were at an increased risk of carcinoma of the lung (OR = 1.8; 95% CI:1.233-2.807, P = 0.003) than subjects with AA genotypes. Compared to the XRCC1 399 GG/ XPD 751 AA reference genotype, the combined variants, XRCC1 399 GG/ XPD 751 AC+CC (OR = 1.9, 95% CI: 1.037-3.481), P = 0.03), XRCC1 399 GA+AA/ XPD 751 AA (OR = 1.7, 95% CI: 1.020-2.833, P = 0.04), XRCC1 399 GA+AA/XPD 751 AC+CC (OR = 2.7, 95% CI: 1.582-4.864, P = 0.01), had significantly higher odds ratios. Increasing numbers of either XPD or XRCC1 variant alleles were associated with shorter overall survival, the risk being significant for the XRCC1 gene polymorphism (P = 0.01 by log-rank test). The hazard of dying was significant for the XRCC1 399 AA genotype (HR = 3.04, 95%CI: 1.393-6.670, P = 0.005). Higher tumour stage also came out as significant predictors of patient death.

CONCLUSIONS

These findings suggest that genetic polymorphisms in the DNA repair genes may modulate overall lung cancer susceptibility and that pathological stage and XRCC1 Arg399Gln independently predicted overall survival among Indian lung cancer patients.

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

BACKGROUND

Polymorphisms 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.

METHODS

A 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.

RESULTS

Borderline 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).

CONCLUSION

In 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.

Polymorphism of XRCC1 predicts overall survival of gastric cancer patients receiving oxaliplatin-based chemotherapy in Chinese population

Pharmacogenetic advances in cancer chemotherapy have the potential to predict clinical benefit to particular regimens. Platinum agents have shown to be effective in the treatment of gastric cancer. We assessed whether single nucleotide polymorphisms (SNPs) in xeroderma pigmentosum group D (XPD), X-ray repair cross complementing group 1 (XRCC1) and glutathione S-transferase P1 (GSTP1) predicted overall survival in gastric cancer patients receiving oxaliplatin-based chemotherapy in Chinese population. SNPs of XPD-751, XRCC1-399 and GSTP1-105 in 62 gastric cancer patients were evaluated using the TaqMan 5' nuclease assay. Genotypes were correlated to survival. The median overall survival time was 322 days (range: 56-2058 days). The median survival times for patients with Arg/Arg or Arg/Gln genotypes of XRCC1 gene were significantly longer than others (P=0.03). For 58 patients with ECOG PS (Eastern Cooperative Oncology Group performance status)<or=2, more obvious significance was demonstrated (P=0.002). Patients with XRCC1-399 Gln/Gln genotype demonstrated a significant worse survival. No significant association was found between SNPs of XPD-751, GSTP1-105 and survival (P=0.125, 0.475, respectively). XRCC1 genotyping might make tailor chemotherapy possible for gastric cancer patients treated with oxaliplatin-based chemotherapy.

A haplotype encompassing the variant allele of DNA repair gene polymorphism ERCC2/XPD Lys751Gln but not the variant allele of Asp312Asn is associated with risk of lung cancer in a northeastern Chinese population

The effect of the polymorphism of the DNA repair gene ERCC2/XPD Asp312Asn on the risk of lung cancer was investigated in a northeastern Chinese population. A hospital-based case-control study consisted of 201 lung cancer cases and 171 cancer-free controls matched to age, sex, and ethnicity. A polymerase chain reaction-restriction fragment length polymorphism method was used for genotyping. Frequency of the variant C-allele of ERCC2 Asp312Asn was 0.006 among the controls in present study, which differs markedly from previous reports both in European ancestry populations and in other Chinese populations (all P < 0.001). The polymorphism was not associated with risk of lung cancer. Haplotype analysis including three previously studied polymorphisms (ERCC1 Asn118Asn, ERCC2 Arg156Arg, and ERCC2 Lys751Gln) revealed that a haplotype consisting of ERCC1Asn118Asn(G)-ERCC2 Arg156Arg(C)-ERCC2 Asp312Asn(G)-ERCC2 Lys751Gln(C) was marginally associated with an increased risk of lung cancer (OR = 3.61, 95% CI = 1.00-13.06, P = 0.04). Our data suggest that the polymorphism ERCC2 Lys751Gln or a haplotype encompassing the variant allele is associated with risk of lung cancer in this population. Studies including larger sample sizes are needed to elucidate the effects of these polymorphisms on lung cancer risk in this northeastern Chinese population.

XPA A23G, XPC Lys939Gln, XPD Lys751Gln and XPD Asp312Asn polymorphisms, interactions with smoking, alcohol and dietary factors, and risk of colorectal cancer

Polymorphisms in the XPD and the XPC gene have been associated with a lower DNA repair capacity. We determined the risk of colorectal cancer in association with the four polymorphisms XPA A23G, XPC Lys939Gln, XPD Lys751Gln and XPD Asp312Asn, and interactions between the polymorphisms and the environmental factors: smoking intensity, intake of alcohol, red meat, processed meat, fish and poultry, fruits and vegetables and dietary fibres, in relation to development of colorectal cancer in a study population of 405 colorectal cancer cases and a comparison group of 810 persons, nested within the Danish prospective cohort, Diet, Cancer and Health, of 57053 cohort members. No association was found between the XPC Lys939Gln, XPA A23G, XPD Lys751Gln, and XPD Asp312Asn polymorphisms and risk of colorectal cancer. The association of the XPD Lys751Gln polymorphism was statistically significantly different between genders, with a lower risk of colorectal cancer among women carrying the variant allele. We observed a statistically significant interaction between the XPC Lys939Gln polymorphism and consumption of red meat, with a 3.7-fold increase in colorectal cancer risk per 100g red meat intake per day among carriers of the homozygous variant, but virtually no effect of red meat intake among carriers of the wild type allele. In the light of the multiple comparisons being made, this result may be a chance finding. The results showed no interaction between the XPD Lys751Gln, XPA A23G, and XPD Asp312Asn polymorphisms and the environmental factors for the development of colorectal cancer. Overall, the results of the present study indicate that the four polymorphisms are not of major importance in colorectal cancer carcinogenesis.

Polymorphisms in the thymidylate synthase promoter and the DNA repair genes XRCC1 and XPD in a Brazilian population

Polymorphisms in genes responsible for maintaining genomic integrity are potential modifiers of disease risk. Since considerable interindividual and interethnic variation in DNA repair capacity has been associated with polymorphic alleles, we evaluated the frequency of the 2R/3R variants in the TS promoter, Arg194Trp and Arg399Gln in the XRCC1 gene, and Asp312Asn and Lys751Gln in the XPD gene in 364 healthy individuals from a Brazilian population separated by ethnicity (European ancestry and African ancestry). The genotypes were determined by PCR (TS) or by PCR-RFLP (XRCC1 and XPD). The frequency of the TS 3R allele was 0.56 for whites and 0.51 for nonwhites. In the case of the XRCC1 MspI polymorphism, the allele frequencies were 0.09 for 194Trp in both nonwhites and whites and 0.27 and 0.28 for 399Gln in nonwhites and whites, respectively. For the XPD 312Asn allele, we found a frequency of 0.25 in white individuals, which was significantly different (P = 0.025) from that seen in nonwhites (0.15). Similarly, the 751Gln polymorphic allele of the XPD gene was significantly more frequent (P < 0.002) in whites (0.30) than in nonwhites (0.20). The genotype frequencies were within Hardy-Weinberg equilibrium. We concluded that the genotype and allele frequencies of XPD gene polymorphism differed between white and nonwhite Brazilians, and that the frequencies of the XPD 312Asn and XRCC1 399Gln alleles in this Brazilian population showed ethnic variability when compared with those observed in other populations.

Polymorphism of the DNA repair gene ERCC2 Lys751Gln and risk of lung cancer in a northeastern Chinese population

The ERCC2 gene (excision repair cross-complementing rodent repair deficiency, complementation group 2 [xeroderma pigmentosum D]) (previously XPD), encoding a DNA repair protein, is involved in nucleotide excision repair and basal transcription. To test the effect of the polymorphism ERCC2 Lys751Gln on the risk of lung cancer in a northeastern Chinese population, a hospital-based case-control study was designed consisting of 147 newly diagnosed and previously untreated subjects with lung cancer and 145 cancer-free control subjects matched on age (+/-3 years), gender, and ethnicity. Among the controls, the allele frequency of the C-allele of ERCC2 Lys751Gln was 0.02. The C-allele of ERCC2 Lys751Gln was significantly overrepresented among lung cancer cases (C versus A: adjusted odds ratio OR(adj) = 2.61, 95% CI = 1.12-6.05, P = 0.03). The carriers of AC genotype were at 2.78-fold (OR(adj) = 2.78, 95% CI = 1.12-6.93) higher risk of lung cancer than carriers of the AA genotype. Subdivided by tumor type, carriers of AC genotype had a 4.65-fold higher risk of squamous cell carcinoma of lung compared with carriers of AA genotype (OR(adj) = 4.65, 95% CI = 1.67-12.98, P = 0.003); similar, but not statistically significant estimates were found for adenocarcinoma of lung. In conclusion, our results suggest that ERCC2 Lys751Gln(C) allele is a potential risk marker for lung cancer in this northeastern Chinese population.

Importance of xeroderma pigmentosum group D polymorphisms in susceptibility to ovarian cancer

The purpose of this study was to evaluate the role of XPD genotypes as genetic indicator of susceptibility to ovarian cancer. We have used a case-control study. We analysed DNA samples from 141 ovarian cancer patients and 202 control subjects, for three XPD polymorphisms using PCR-RFLP. We observed that Asn312Asn XPD genotype carriers have increased susceptibility of ovarian cancer (OR=2.46 95% CI 1.20-5.06; P=0.015). Furthermore, we found that carriers of Gln751Gln XPD genotype have an increased susceptibility of ovarian cancer (OR=3.40 95% CI 1.61-7.15; P=0.001). Asn312Asn and Gln751Gln are particularly associated with an early-stage of disease. Our results suggest an important role for Asn312Asn and Gln751Gln XPD polymorphisms in the susceptibility to ovarian cancer.

Lack of association between DNA repair gene ERCC1 polymorphism and risk of lung cancer in a Chinese population

The ERCC1 (Excision Repair Cross Complementation Group 1) gene is involved in the nucleotide excision repair pathway. This study was designed to examine whether ERCC1 Asn118Asn (G19007A) polymorphism, which has been associated with risk of some cancers among Caucasians, may be associated with risk of lung cancer in a Chinese population. ERCC1 Asn118Asn (G19007A) genotypes were determined in DNA samples from 151 cases and 143 controls. The distribution of genotypes between cases and controls was not associated with an increased risk of lung cancer (AA versus GG: adjusted OR (odds ratio) = 1.41, 95% CI (confidence interval) = 0.76-2.59; AG versus GG: adjusted OR = 0.78, 95% CI = 0.47-1.29; and AA + AG versus GG: adjusted OR = 0.93, 95% CI = 0.73-1.19). The frequency A (0.20) of the A-allele was significantly lower among these Chinese controls than in the Caucasian control populations (A = 0.54-0.65) (All P < 0.001). No statistically significant effects of age, histological subtype or smoking were found. These findings suggest that ERCC1 Asn118Asn (G19007A) polymorphism may play a limited role for lung cancer in this Chinese population.

Polymorphisms of DNA repair gene XPD and DNA damage of workers exposed to vinylchloride monomer

Vinyl chloride monomer (VCM) is a human carcinogen. However, the exact mechanism of carcinogenesis remains unclear. 2-Chloroethylene oxide (CEO) and 2-chloroacetaldehyde (CAA), the metabolic intermediates of VCM, induce DNA damage which is mainly repaired by the nucleotide excision repair (NER) pathway. The XPD gene product and the related XPB protein are DNA helicases that are involved in transcription and NER. Polymorphisms of XPD have been implicated in chemical exposure-related health effects. In order to explore the mechanism of VCM-related health effects, a special matched case-control design (exposed workers with DNA damage and without damage) was used to investigate the association between the gene polymorphisms of XPD and DNA damage in 106 male and 44 female workers occupationally exposed to VCM. Exposure and anthropometrics information was collected through in-person interview. Such information was then used to calculate cumulative exposure doses of the workers. DNA damage in peripheral lymphocytes was measured by the single cell gel electrophoresis (SCGE) assay that identified DNA strand breaks. Genomic DNA from lymphocytes was used in genotyping assays. Genotypes of XPD Ile199Met, XPD Asp312Asn, and XPD Lys751Gln were identified by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) procedure. The results indicate that the genotypes of XPD 751Lys/Gln and Gln/Gln were significantly associated with the expression of DNA damages (OR 2.21, P<0.05, 95% CI 1.01-5.13). An interesting observation is the reduction of DNA damage for workers with high VCM exposure and possessing the XPD Asp/Asn and Asn/Asn genotypes (OR 0.33, 95% CI 0.11-0.95). Polymorphisms of XPD may therefore be a major reason of genetic susceptibility in VCM-induced DNA damage and health consequences.

ERCC1 and ERCC2 polymorphisms and adult glioma

ERCC2 and ERCC1 are important in DNA nucleotide excision repair and lie on chromosome 19q13.3 near a putative glioma suppressor region. We genotyped constitutive variants ERCC1 C8092A and ERCC2 K751Q and R156R in approximately 450 adults with glioma and 500 controls from two independent population-based series, uniformly reviewed patients' tumors to determine histopathologic category, and determined a variety of tumor markers among astrocytic tumors. Odds ratios (ORs) for glioblastoma for those carrying two ERCC1 A alleles versus none or one were 1.67 in series 1 and 1.64 in series 2, which yielded a combined OR of 1.67 (95% CI, 0.93-3.02; P = 0.09), adjusted for age, gender, ethnicity, and series. Odds ratios for the ERCC2 variants were not consistently elevated or reduced for the two series in all cases versus controls. However, among whites, for those with ERCC2 K751Q genotype QQ versus QK/KK, the OR for nonglioblastoma histologies versus controls was 1.82 (95% CI, 0.97-3.44; P = 0.06). Also, among whites, glioma patients were significantly more likely than controls to be homozygous for variants in both ERCC1 C8092A and ERCC2 K751Q (OR, 3.2; 95% CI, 1.1-9.3). Given the numbers of comparisons made, these findings could be due to chance. However, the results might warrant clarification in additional series in conjunction with the nearby putative glioma suppressor genes (GLTSCR1 and GLTSCR2).

A common polymorphism in the 3'UTR of cyclooxygenase 2/prostaglandin synthase 2 gene and risk of lung cancer in a Chinese population

Cyclooxygenases (COXs) are key enzymes that convert arachidonic acid to prostaglandins. Overexpression of COX-2, one of the COX isozymes, has been shown to be an early event in lung carcinogenesis and may play an important role in lung cancer development. A common single nucleotide polymorphism, T8473C, located within a potential functional region in the 3'UTR of COX-2 gene was identified and we hypothesized that this COX-2 variant is associated with lung cancer risk. To test this hypothesis, we genotyped this variant in a case-control study of 322 histologically-confirmed lung cancer patients and 323 age and sex frequency-matched cancer-free controls in a Chinese population. The results showed that the frequencies of variant genotypes 8473CT/CC were significantly less common in the cases (27.3%) than in the controls (35.3%) (P=0.034), suggesting that the 8473C allele was protective against lung cancer. Multivariate logistic regression analyses revealed that the COX-2 variant genotypes (8473CT/CC) were associated with a significantly decreased risk of lung cancer compared with the 8473TT wild-type homozygotes (OR=0.64, 95% CI=0.45-0.92). When we defined the reference group as non-smokers having the 8473CT/CC variant genotypes, the smokers with the 8473TT wild-type genotype had the greatest risk (adjusted OR=5.28, 95% CI=3.10-9.00). These findings indicate that the COX-2 T8473C polymorphism may contribute to lung cancer susceptibility in the Chinese population. Further larger molecular epidemiological studies are warranted to confirm these findings.