Genetic polymorphisms of XRCC1 and risk of the esophageal cancer

Influence of Arg399Gln, Arg280His and Arg194Trp XRCC1 gene polymorphisms of Base Excision Repair pathway on the level of 8-oxo-guanine and risk of head and neck cancer in the Polish population

BACKGROUND

Reduced efficiency of DNA repair systems has long been a suspected factor in increasing the risk of cancer.

OBJECTIVE

In this work we investigate influence of three selected polymorphisms of DNA repair gene XRCC1 and level of oxidative damage (measured as level of 8-oxo-guanine) on modulation of the risk of HNSCC.

METHODS

In group of 359 patients with HNSCC (diagnosed with OSCC) the occurrence of polymorphic variants in Arg399Gln, Arg280His and Arg194Trp of XRCC1 were studied with TaqMan technique. In addition we determined level of 8-oxo-guanine with ELISA.

RESULTS

Arg399Gln polymorphism and Arg194Trp polymorphism of XRCC1 gene increases the risk of HNSCC. The coexistence of Arg399Gln and Arg194Trp simultaneously enhances this effect. At the same time, their coexistence with His280His raises the risk to a level higher than in the absence of such coexistence, although the His280His itself is not associated with an increased risk of HNSCC. Patients have higher levels of 8-oxo-guanine than control group, and His280His is polymorphism with highest mean value of 8-oxoG level among studied.

CONCLUSION

Patients with HNSCC not only have an increased level of 8-oxoguanine and the Arg399Gln and Arg/Trp of XRCC1 modulate risk of cancer, but there is also a relationship between these two phenomena, and it can be explained using intragenic combinations revealing that a high level of 8-oxoG could be a potential mechanism behind the modulation of HNSCC risk by the polymorphisms studied.

Effects of alcohol consumption, cigarette smoking, and betel quid chewing on upper digestive diseases: a large cross-sectional study and meta-analysis

Cigarette smoking is a well-known risk factor of upper digestive diseases. Findings on alcohol's effect on these diseases are inconsistent and with the exception of its association with esophageal cancer, little is known about betel quid chewing. This study investigated the association between use of these three substances and upper digestive diseases. We collected data from 9,275 patients receiving upper endoscopies between April 2008 and December 2013. Polynomial regressions were used to analyze the association between risk factors and diseases of the esophagus, stomach and duodenum. Meta-analysis for use of these substances and esophageal diseases was also performed. Participants who simultaneously consumed cigarettes, alcohol and betel quid had a 17.28-fold risk of esophageal cancer (95% CI = 7.59-39.33), 2.99-fold risk of Barrette's esophagus (95% CI = 2.40-4.39), 1.60-fold risk of grade A-B erosive esophagitis (95% CI = 1.29-2.00), 2.00-fold risk of gastric ulcer (95% CI = 1.52-2.63), 2.12-fold risk of duodenitis (95% CI = 1.55-2.89) and 1.29-fold risk of duodenal ulcer (95% CI = 1.01-1.65). Concurrent consumption of more substances was associated with significantly higher risk of developing these diseases. Meta-analysis also revealed use of the three substances came with a high risk of esophageal diseases. In conclusions, cigarette smoking, alcohol drinking and betel quid chewing were associated with upper digestive tract diseases.

Association and multiple interaction analysis among five XRCC1 polymorphic variants in modulating lung cancer risk in North Indian population

XRCC1 is a scaffold protein that provides for interaction of DNA polymerase, DNA ligase and damaged DNA. Genotyping was done for the five non-synonymous and synonymous variants of XRCC1 i.e. XRCC1, Arg¹⁹⁴Trp, Pro²⁰⁶Pro, Arg²⁸⁰His, Arg³⁹⁹Gln, Gln⁶³²Gln. Logistic regression analysis was used to analyze the association of XRCC1 with lung cancer, followed by data mining analysis which included both Multi-dimensionality reduction (MDR) and Classification and Regression tree (CART) analysis so as to find possible interaction between SNPs on XRCC1 gene. Statistical analysis revealed XRCC1 Gln⁶³²Gln (OR=2.67, p=<0.001) depicted an overall high risk towards lung cancer. Histological subdivision revealed carriers of mutant genotype in case of XRCC1 Arg³⁹⁹Gln imposed a protective effect towards SQCC subtype. Likewise, mutant genotype in XRCC1 Pro²⁰⁶Pro implied a protective effect for SCLC subtype (OR=0.29, p=0.0017) on the contrary XRCC1 Gln⁶³²Gln showed a high risk in SQCC diseased group (OR=4.16, p=<0.0001). Combination of XRCC1 Gln⁶³²Gln with other SNPs revealed XRCC1 Gln⁶³²Gln with Arg¹⁹⁴Trp (OR=2.10, p=0.03) and Pro²⁰⁶Pro (OR=5.6, p<0.0004) increased an overall risk towards lung cancer. Haplotype analysis illustrated haplotype block 11 (CGAGG) carrying minor allele for XRCC1 206 was associated with the highest risk towards lung cancer on the contrary block 4 (CAGAG) carrying mutant allele for XRCC1 399 significantly decreased the risk. Multi-dimensionality reduction (MDR) results showed the three factor model comprising XRCC1 206, 632, 280 as the best model (CVC=10, prediction error=0.34). Further Classification and Regression tree (CART) analysis revealed terminal node 1 carrying mutant of XRCC1 632 and wild type of XRCC1 280 represented the highest risk group. Our results demonstrated high order interaction between SNPs of XRCC1 gene. This study depicted a positive association of XRCC1 Gln⁶³²Gln towards lung cancer, however XRCC1 Arg³⁹⁹Gln, Arg¹⁹⁴Trp showed an overall no effect or protective effect.

Association of polymorphisms in X-ray repair cross complementing 1 gene and risk of esophageal squamous cell carcinoma in a Chinese population

OBJECTIVES

To investigate the association between three single nucleotide polymorphisms (SNPs) in the X-ray repair cross complementing 1 gene (XRCC1) and the risk of esophageal squamous cell carcinoma (ESCC) in Chinese population.

METHODS

A case-control study including 381 primary ESCC patients recruited from hospital and 432 normal controls matched with patients by age and gender from Chinese Han population was conducted. The genotypes of three XRCC1 polymorphisms at -77T>C (T-77C), codon 194 (Arg194Trp), and codon 399 (Arg399Gln) were studied by means of polymerase chain reaction-restriction fragment length polymorphism techniques (PCR-RFLP). Unconditional logistic regression model and haplotype analysis were used to estimate associations of these three SNPs in XRCC1 gene with ESCC risk.

RESULTS

Polymorphisms at these three sites in XRCC1 gene were not found to be associated with risk for developing ESCC; however the haplotype C(codon 194)G(codon 399)C(-77T>C) was significantly associated with reduced risk of ESCC (OR: 0.62, 95% CI: 0.40-0.96) upon haplotype analysis.

CONCLUSION

These results suggested that the gene-gene interactions might play vital roles in the progression on esophageal cancer in Chinese Han population and it would be necessary to confirm these findings in a large and multiethnic population.

XRCC1 R399Q polymorphism and colorectal cancer risk in the Chinese Han population: a meta-analysis

X-ray repair cross-complementing group 1 (XRCC1) plays a key role in DNA repair, genetic instability, and tumorigenesis. The XRCC1 R399Q polymorphism has been reported in some studies to influence the risk of colorectal cancer (CRC), though this remains controversial. We performed a meta-analysis to determine the association of XRCC1 R399Q polymorphisms with CRC risk in the Chinese Han population. A literature search was conducted using PubMed, EMBASE, and the China National Knowledge Infrastructure to identify eligible studies published before June 2014. The pooled odds ratio (OR) and corresponding 95% confidence interval (CI) were used to estimate the effect of XRCC1 R399Q polymorphisms on CRC risk. Eleven case-control studies with a total of 3194 CRC cases and 4472 controls were identified. No significant association between the XRCC1 R399Q polymorphism and CRC risk was observed in the Chinese Han population (Gln/Gln vs. Arg/Arg, OR = 1.26, 95% CI = 0.85-1.87, P OR = 0.242; Arg/Gln vs. Arg/Arg, OR = 0.95, 95% CI = 0.70-1.18, P OR = 0.651; dominant model, OR = 1.09, 95% CI = 0.86-1.38, P OR = 0.480; and recessive model, OR = 1.24, 95% CI = 0.91-1.70, P OR = 0.177). After excluding two studies that deviated from the Hardy-Weinberg equilibrium, there remained no significant association between XRCC1 R399Q and CRC risk. No publication bias was found using the funnel plot and Egger's test. Our meta-analysis results suggest that the XRCC1 R399Q polymorphism is not associated with increased risk of CRC in the Chinese Han population.

ERCC1 single nucleotide polymorphism C8092A, but not its expression is associated with survival of esophageal squamous cell carcinoma patients from Fujian province, China

Esophageal carcinoma is one of the world's deadliest cancers. Esophageal squamous cell carcinoma (ESCC) is more frequent than adenocarcenoma (AC) in China. Platinum-based chemotherapy with surgical resection is a common treatment approach for ESCC; however, the treatment response is uncertain. Evidence suggests polymorphisms in genes encoding excision repair cross-complementing group 1 (ERCC1), a protein involved in nuclear excision repair (NER), may help predict response to cisplatin and other platinum-based chemotherapeutics. Multiple ERCC1 single nucleotide polymorphisms (SNPs) have been associated with platinum chemotherapy response. Two common SNPs occur at the C8092A and C118T loci. Our study aimed to determine if 1) an association exists between ERCC1 tumor expression and patient survival, 2) whether adjuvant therapy influence on survival is related to histological ERCC1 presence in tumor cell nuclei, and 3) whether other clinicopathological characteristics in a cohort of patients following surgery for various stages of ESCC are associated with tumor ERCC1 expression. One hundred eight patients were included in the study, and tumor biopsy was collected for genotyping and immunohistochemical analysis of ERCC1. Sixty-seven patients (62%) received no adjuvant therapy, and the rest had either platinum-based chemotherapy (28.5%), radiotherapy (6.5%) or both treatments (2.8%). Log-rank analysis revealed no significant connection between tumor ERCC1 expression (P = 0.12) or adjuvant therapy (P = 0.56) on patient survival. Also, non-parametric Mann-Whitney analysis showed no significant link between tumor size or nodus tumor formation and ERCC1 presence in patients in the study. Interestingly, C8092A SNP showed significant association with patient survival (P = 0.01), with patients homozygous for the mutant allele showing the most significantly reduced survival (P = 0.04) compared to those homozygous for the dominant allele (CC). Our results provide novel insight into the genotypic variation of patients from Quanzhou, Fujian province China.

Association between the XRCC1 Arg194Trp polymorphism and risk of cancer: evidence from 201 case-control studies

The Arg194Trp polymorphism in the X-ray cross-complementing group 1 (XRCC1) had been implicated in cancer susceptibility. The previous published data on the association between XRCC1 Arg194Trp polymorphism and cancer risk remained controversial. Hence, we performed a meta-analysis to investigate the association between cancer susceptibility and XRCC1 Arg194Trp (59,227 cases and 81,587 controls from 201 studies) polymorphism in different inheritance models. We used odds ratios with 95 % confidence intervals to assess the strength of the association. Overall, significantly increased cancer risk was found (recessive model: (odds ration [OR] = 1.18, 95% confidence interval [CI] = 1.09-1.27; homozygous model: OR = 1.21, 95% CI = 1.10-1.33; additive model: OR = 1.05, 95% CI = 1.01-1.09) when all eligible studies were pooled into the meta-analysis. In further stratified and sensitivity analyses, significantly increased glioma risk was found among Asians, significantly decreased lung cancer risk was found among Caucasians, and significant increased breast cancer risk was found among hospital-based studies. In summary, this meta-analysis suggests that Arg194Trp polymorphism may be associated with increased breast cancer risk, Arg194Trp polymorphism is associated with increased glioma risk among Asians, and Arg194Trp polymorphism is associated with decreased lung cancer risk among Caucasians. In addition, our work also points out the importance of new studies for Arg194Trp association in some cancer types, such as gastric, pancreatic, prostate, and nasopharyngeal cancers, where at least some of the covariates responsible for heterogeneity could be controlled, to obtain a more conclusive understanding about the function of the XRCC1 Arg194Trp polymorphism in cancer development (I (2) > 75%).

XPF-673C>T polymorphism effect on the susceptibility to esophageal cancer in Chinese population

Purpose

Xeroderma pigmentsum group F (XPF) plays a pivotal role in DNA nucleotide excision repair and has been linked to the development of various cancers. This study aims to assess the association of XPF genetic variants with the susceptibility to esophageal squamous cell carcinoma (ESCC) in Chinese population.

Methods

This two-stage case-control study was conducted in a total of 1524 patients with ESCC and 1524 controls. Genotype of XPF -673C>T and 11985A>G variants were determined by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP). Logistic regression analysis was performed to estimate odd ratios (ORs) and 95% confidence intervals (95% CI).

Results

Our case-control study showed that XPF -673TT genotype was associated with a decreased risk of ESCC compared with CC genotype in both case-control sets (Tangshan set: OR = 0.58; 95%CI = 0.34–0.99, P = 0.040; Beijing set: OR = 0.66; 95%CI = 0.46–0.95, P = 0.027). Stratified analyses revealed that a multiplicative interaction between -673C>T variant and age, sex or smoking status was evident (Gene-age: P_interaction = 0.002; Gene-sex: P_interaction = 0.002; Gene-smoking: P_interaction = 0.002). For XPF 11985A>G polymorphism, there was no significant difference of genotype distribution between ESCC cases and controls.

Conclusion

These findings indicated that genetic variants in XPF might contribute to the susceptibility to ESCC.

Deoxyribonucleic acid repair gene X-ray repair cross-complementing group 1 polymorphisms and non-carcinogenic disease risk in different populations: A meta-analysis

PURPOSE

This study aims to assess a meta-analysis of the association of X-ray repair cross-complementing group 1 (XRCC1) polymorphisms with the risk of various non-carcinogenic diseases in different population.

MATERIALS AND METHODS

This meta-analysis was performed by critically reviewing reveals 38 studies involving 10043 cases and 11037 controls. Among all the eligible studies, 14 focused on Arg194Trp polymorphism, 33 described the Arg399Gln and three articles investigated on Arg280His. Populations were divided into three different ethnic subgroups include Caucasians, Asians and other (Turkish and Iranian).

RESULTS

Pooled results showed no correlation between Arg194Trp and non-carcinogenic disease. There was only weak relation in the recessive (odds ratio [OR] =1.11, 95% confidence interval [CI]: 0.86-1.44) model in Asian population and dominant (OR = 1.04, 95% CI: 0.66-1.63) model of other populations. In Arg399Gln polymorphism, there was no relation with diseases of interest generally. In the pooled analysis, there were weak relation in the dominant (OR = 1.08, 95% CI: 0.86-1.35) model of Asian population and quite well-correlation with recessive (OR = 1.49, 95% CI: 1.19-1.88), dominant (OR = 1.23, 95% CI: 0.94-1.62), and additive (OR = 1.23, 95% CI: 0.94-1.62) models of other subgroup. For Arg280His, there was a weak relation only in the dominant model (OR = 1.06, 95% CI: 0.74-1.51).

CONCLUSION

The present meta-analysis correspondingly shows that Arg399Gln variant to be associated with increased non-carcinogenic diseases risk through dominant and recessive modes among Iranian and Turkish population. It also suggests a trend of dominant and recessive effect of Arg280His variant in all population and its possible protective effect on non-carcinogenic diseases.

Association between the c.910A>G genetic variant of the XRCC1 gene and susceptibility to esophageal cancer in the Chinese Han population

Esophageal cancer (EC) is a common malignancy worldwide. The X-ray repair cross-complementing 1 gene (XRCC1) is one of the most important candidate genes for influencing susceptibility to EC. This study aimed to investigate the effect of XRCC1 genetic variants on susceptibility to EC. A total of 383 EC patients (males: 239, females: 144, mean age: 56.62) and 387 cancer-free controls (males: 251, females: 136, mean age: 58.23) were enrolled in this study. The c.910A>G genetic variant of the XRCC1 gene was determined by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing methods. The allele and genotype frequencies indicated statistical differences between EC patients and cancer-free controls. The c.910A>G genetic variant was statistically associated with increased susceptibility to EC [GG vs AA: odds ratio (OR)=1.79, 95% confidence interval (CI)=1.12-2.86, P=0.014; GG vs AG/AA: OR=1.76, 95%CI=1.13-2.75, P=0.013; G vs A: OR=1.25, 95%CI=1.01-1.55, P=0.041]. The allele G and genotype GG could contribute to the increased susceptibility to EC. Our findings suggest that the c.910A>G genetic variant is associated with susceptibility to EC in the Chinese Han population, and might be used as a molecular marker for detecting susceptibility to EC.

Meta-analysis of genetic polymorphisms and ophthalmologic disease risk in Asian populations: a case of DNA repair XRCC1 gene

This study aimed to assess a meta-analysis of the association of XRCC1 polymorphisms with the risk of various ophthalmologic diseases in Asian population. This meta-analysis was performed by critically reviewing reveals 38 studies involving 1373 cases and 1745 controls. Among all the eligible studies, one focused on Arg194Trp polymorphism, nine described the Arg399Gln and no article investigated on Arg280His. There was a large between-study heterogeneity in ORs of individual studies of the dominant model (chi2 = 74.18, I2 = 58.9%, p = 0.013) and the additive (chi2 = 56.18, I2 = 41.4%, p = 0.091) models, but a moderate heterogeneity in the recessive model (chi2 = 72.27, I2 = 78.8%, p = 0.000) was observed. So, we pooled the results using the random-effect analysis and found that Arg399Gln has a weak relation with ophthalmologic disease in the recessive (OR = 0.96, 95% CI: 0.64-1.44), the dominant (OR = 1.05, 95% CI: 0.82-1.33) and the additive (OR = 1.15, 95% CI: 0.77-1.70) and models. The present meta-analysis correspondingly shows that comprising diverse population is very important since susceptibility loci might vary indifferent ethnic groups. To ratify our findings, widespread studies with enlarged sample size and various populations are essential to explain the role of all polymorphism of XRCC1 genes in the pathogenesis of ophthalmologic diseases. Finally, our meta-analysis showed Arg399Gln variant was not associated with increased ophthalmologic diseases risk via dominant and recessive modes among Asian population.

DNA repair gene polymorphisms and risk of head and neck cancer in the Tunisian population

Altered activity of DNA repair enzymes may be involved in modulating cancer susceptibility and pathogenesis of head and neck cancer (HNC). We conducted a case-control study to test the association between three common single-nucleotide polymorphisms of XRCC1, ERCC2, and ERCC3 genes with HNC risk in Tunisian patients. To the best of our knowle dge, this is the first report on polymorphisms in XRCC1, ERCC2, and ERCC3 and susceptibility to HNC in our population. The genotype analyses of XRCC1 Arg399Gln, ERCC2 Lys751Gln, and ERCC3 7122 A>G polymorphisms for 169 HNC patients, and 261 controls were performed using the PCR-based restriction fragment length polymorphism. Stratification of the populations according to smoking and drinking habits and occupational exposure highlighted the importance of tobacco, alcohol, and toxic substance as three risk co-factors for the development of HNC. Our study suggests that only the XRCC1 Arg399Gln polymorphism was associated with the risk of HNC in the Tunisian population (OR = 2.04; P = 0.001). Furthermore, the risk of HNC was associated with XRCC1 Arg399Gln polymorphism stratified by occupational exposure status (OR = 2.29; P = 0.024). However, no statistically significant association was observed between the risk of developing HNC and the ERCC2 Lys751Gln and ERCC3 A>G polymorphisms. These data suggest that the XRCC1 Arg399Gln polymorphism is associated with an increased risk of developing HNC, because it correlates with occupational exposure in Tunisian population.

XRCC1 Arg399Gln, Arg194Trp, and Arg280His polymorphisms in esophageal cancer risk: a meta-analysis

BACKGROUND

The X-ray repair cross-complementation group 1 (XRCC1) protein plays an important role in base excision repair.

AIM

To elucidate the role of XRCC1 Arg399Gln, Arg194Trp and Arg280His genotypes in esophageal cancer risk, all available studies were considered in the present meta-analysis.

METHODS

Eligible studies were identified by searching several electronic databases for relevant reports published before June 2012.

RESULTS

According to the inclusion criteria and exclusion criteria, a total of 21 eligible studies were included in the pooled analyses. Among the 21 studies, 18 focused on Arg399Gln polymorphism, 11 described the Arg194Trp, and 4 articles investigated on Arg280His. Our analysis suggested that there was no evidence of significant association between XRCC1 Arg399Gln polymorphism and esophageal cancer risk in any genetic model. In the stratified analysis by ethnicity for Arg399Gln polymorphism and esophageal cancer, the results showed that Arg399Gln polymorphism was not associated with esophageal cancer risk. Only 4 studies analyzed the relationship between XRCC1 Arg280His polymorphism and the risk of esophageal cancer. The Arg/His and His/His genotypes were not significantly associated with increased risk of EC. A similar negative association was maintained in dominant and recessive models. However, for XRCC1 Arg194Trp polymorphism, our study showed individuals carrying the variant genotype Trp/Trp had a significant increased risk of esophageal cancer (OR = 1.295, 95 % CI 1.053-1.591, P = 0.014). In addition, increased associations were found in recessive model (OR = 1.332, 95 % CI 1.093-1.624, P = 0.005).

CONCLUSIONS

Our meta-analysis suggested that Arg194Trp Trp allele might act as a risk allele in its association with esophageal cancer.

XRCC1 Polymorphisms and Pancreatic Cancer: A Meta-Analysis

OBJECTIVE

To assess the association between X-ray repair cross-complementating group 1 (XRCC1) polymorphisms and pancreatic cancer.

METHODS

We searched MEDLINE, Web of Science and HuGE Navigator at June 2010, and then quantitatively summarized associations of the XRCC1 polymorphisms with pancreatic cancer risk using meta-analysis.

RESULTS

Four studies with 1343 cases and 2302 controls were included. Our analysis found: at codon 194, the Trp allele did not decrease pancreatic cancer risk (Arg/Arg versus Trp/Trp: OR=0.97; 95% CI: 0.48-1.96; P=0.97; Arg/Arg versus Arg/Trp: OR=0.89; 95% CI: 0.70-1.13; P=0.55; Arg/Trp versus Trp/Trp: OR=1.06; 95% CI: 0.52-2.16; P=0.90); at codon 280, only a study showed a nonsignificant association between single nucleotide polymorphism with pancreatic cancer risk; at codon 399, the Gln allele also showed no significant effect on pancreatic cancer compared to Arg allele (Arg/Arg versus Gln/Gln: OR=0.94; 95% CI: 0.74-1.18; Arg/Arg versus Arg/Gln: OR=0.97; 95% CI: 0.83-1.13; Arg/Gln versus Gln/Gln: OR=0.97; 95% CI: 0.77-1.22). The shape of the funnel plot and the Egger's test did not detect any publication bias.

CONCLUSION

There is no evidence that XRCC1 polymorphisms (Arg194Trp, Arg280His, and Arg399Gln) are associated with pancreatic cancer risk.

Association of XRCC1, XRCC3, and XPD genetic polymorphism with an increased risk of hepatocellular carcinoma because of the hepatitis B and C virus

OBJECTIVE

The south-east Asian and sub-Saharan African populations are the most susceptible to hepatocellular carcinoma (HCC). We aimed to establish whether XRCC1, XRCC3, and XPD are associated with liver cancer in Pakistan and to examine the interaction of hepatitis B virus (HBV) or hepatitis C virus (HCV) with repaired genes in the occurrence of liver cancer.

MATERIALS AND METHODS

We enrolled 74 healthy individuals, 75 had either HBV or HCV, and 50 were HCC patients. The characteristic information of all the study participants were collected through a standard interviewer-administered questionnaire. The PCR-RFLP was used to identify the genotype of the patients.

RESULTS

The results of our study indicated that the patients infected with HBV or HCV had a four or three-fold greater risk of developing liver cancer. Patients older than 55 years of age had a significantly higher risk of developing cancer compared with younger patients. The homozygous wild types Arg/Arg for 280 and Thr/Thr for 241 were more frequent in the controls than in the cases. The allelic frequency of mutant 280His and 399Gln was more pronounced among HCC cases than the controls or the HBV-infected patients.

CONCLUSION

The frequency of the XPD gene in the controls was in Hardy-Weinberg equilibrium, indicating that the gene played a protective role in the Pakistani population. XRCC1 or XRCC3 was associated with liver cancer in the Pakistani population; however, the XPD gene played a vital role in the repair of DNA damage.

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

Many studies have examined the association between the XRCC3 Thr241Met gene polymorphism and lung cancer risk in various populations, but their results have been inconsistent. To assess this relationship more precisely, a meta-analysis was performed. The PubMed, Embase, Web of Science, and CNKI database was searched for case–control studies published up to July 2012. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated.

Ultimately, 17 studies, comprising 4123 lung cancer cases and 5597 controls were included. Overall, for T allele carriers (TC + TT) versus the wild-type homozygotes (CC), the pooled OR was 0.95 (95% CI = 0.87-1.04 P = 0.228 for heterogeneity), for TT versus CC the pooled OR was 0.99 (95% CI = 0.86-1.15 P = 0.315 for heterogeneity). In the stratified analysis by ethnicity, histological types of lung cancer and smoking status, no any significantly risks were found for (C/T + T/T) vs C/C or T/T vs C/C. No publication bias was found by using the funnel plot and Egger's test.

Overall, there is no evidence showing a significant correlation between XRCC3 Thr241Met polymorphism and lung cancer risk stratified analysis by ethnicity, histology and smoking status.

Association between XRCC1 and XRCC3 polymorphisms and colorectal cancer risk: a meta-analysis of 23 case-control studies

Several potential functional polymorphisms in the DNA repair gene X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln (rs25487), Arg194Trp (rs1799782), Arg280His (rs25489) and X-ray repair cross-complementing group 3 (XRCC3) T241M (rs861539) have been implicated in colorectal cancer (CRC) risk, but the results are conflicting. Here, we performed a meta-analysis of 23 published case control datasets and assessed genetic heterogeneity between those datasets. All the case-control studies published from January 2000 to June 2012 on the association between those polymorphisms and CRC risk were identified by searching the electronic literature Medline. Statistical analysis was performed with the software programs Review Manager (version 4.2). For overall CRC, no significant association was observed, the pooled odds ratios for XRCC1 Arg399Gln, Arg194Trp, Arg280His, and XRCC3 T241M were 1.02 (95 % CI: 0.93, 1.12), 1.03 (95 % CI: 0.94, 1.14), 0.98 (95 % CI: 0.85, 1.13) and 1.03 (95 % CI: 0.85, 1.26), respectively. Furthermore, no significant association was observed in subgroup analyses based on ethnicity. The results suggested that these four SNPs evaluated are not associated with risk of CRC.

Association between XPD gene polymorphisms and esophageal squamous cell carcinoma

Single nucleotide polymorphisms (SNPs) of Xeroderma pigmentosum group D (XPD) are associated with various types of cancer. However, previous studies of correlations between SNPs in this gene and esophageal squamous cell carcinoma (ESCC) have generated conflicting results. In the present study, we investigated the potential relationship between SNPs in two key regions of XPD, codons 312 and 751 and ESCC in a Chinese population. Polymerase chain reaction‑restriction fragment length polymorphism was used to analyze genotypes at codons 312 and 751 of XPD in 400 ESCC patients (case group) and 400 healthy individuals (control group). Logistic regression was used to analyze the relationship between genotypes and ESCC. No statistically significant difference was observed for the genotype or allele frequencies of codon 312 between case and control groups (P>0.05). However, a statistically significant difference was observed in the genotype and allele frequencies of codon 751 between the case and control groups (P<0.05). Specifically, compared with the AA genotype at codon 751, a significant increase in risk of ESCC was detected for individuals with the CC genotype (OR=1.600; 95% CI, 1.137‑2.253; P=0.007). Therefore, XPD polymorphism at codon 312 is not correlated with ESCC, while polymorphism at codon 751 is associated with ESCC and the CC genotype may confer increased susceptibility to the disease.

Genetic variability in DNA repair proteins in age-related macular degeneration

The pathogenesis of age-related macular degeneration (AMD) is complex and involves interactions between environmental and genetic factors, with oxidative stress playing an important role inducing damage in biomolecules, including DNA. Therefore, genetic variability in the components of DNA repair systems may influence the ability of the cell to cope with oxidative stress and in this way contribute to the pathogenesis of AMD. However, few reports have been published on this subject so far. We demonstrated that the c.977C>G polymorphism (rs1052133) in the hOGG1 gene and the c.972G>C polymorphism (rs3219489) in the MUTYH gene, the products of which play important roles in the repair of oxidatively damaged DNA, might be associated with the risk of AMD. Oxidative stress may promote misincorporation of uracil into DNA, where it is targeted by several DNA glycosylases. We observed that the g.4235T>C (rs2337395) and c.–32A>G (rs3087404) polymorphisms in two genes encoding such glycosylases, UNG and SMUG1, respectively, could be associated with the occurrence of AMD. Polymorphisms in some other DNA repair genes, including XPD (ERCC2), XRCC1 and ERCC6 (CSB) have also been reported to be associated with AMD. These data confirm the importance of the cellular reaction to DNA damage, and this may be influenced by variability in DNA repair genes, in AMD pathogenesis.

No association between polymorphisms of the DNA repair geneXRCC1 and cervical neoplasm risk

OBJECTIVES

To investigate the association between genetic polymorphisms ofX-ray repair crosscomplementing group 1 (XRCC1) codons 194, 280, and 399 and cervical neoplasm susceptibility.

METHODS

A community-based nested case-control study was conducted. The study population consisted of women living in Chiayi City, located in southwestern Taiwan, who had received pap smear screening between October, 1999, and December, 2000 (n=32,466). The potential cases were women having lesions greater than cervical intraepithelium neoplasm II (C1N2) reconfirmed by cervical biopsy. The potential controls (case: control=1∶2) were age matched (±2 yrs) and residency matched women who had had normal pap smears. In total, 100 cases (39 C1N2, 12 C1N3, 46 carcinoma in situ (CIS), and 3 invasive cancer) and 196 controls had the information on both questionnaire and data ofXRCC1 polymorphisms.

RESULTS

The frequency ofArg/Arg, Arg/Gln, andGln/Gln in codon 399 among cases and controls was 54% (54/100), 38% (38/100), and 8% (8/100) and 58% (114/196), 37% (73/196), and 5% (9/196), respectively, which were not significantly different. No associations were also observed betweenXRCC1 codon 194 and 280 genotypes and cervical neoplasm. While dichotomized by age (<40 vs. ≥40 yrs), smoking status (active and passive smokers vs. non-smokers), and disease status (C1N2 and C1N3 vs. CIS and invasive cancer), the results remained insignificant.

CONCLUSIONS

The present findings suggest thatXRRC1 codon 194, 280 and 399 genotypes may not influence cervical neoplasm risk in the Taiwanese population.

Multiple pathway-based genetic variations associated with tobacco related multiple primary neoplasms

BACKGROUND

In order to elucidate a combination of genetic alterations that drive tobacco carcinogenesis we have explored a unique model system and analytical method for an unbiased qualitative and quantitative assessment of gene-gene and gene-environment interactions. The objective of this case control study was to assess genetic predisposition in a biologically enriched clinical model system of tobacco related cancers (TRC), occurring as Multiple Primary Neoplasms (MPN).

METHODS

Genotyping of 21 candidate Single Nucleotide Polymorphisms (SNP) from major metabolic pathways was performed in a cohort of 151 MPN cases and 210 cancer-free controls. Statistical analysis using logistic regression and Multifactor Dimensionality Reduction (MDR) analysis was performed for studying higher order interactions among various SNPs and tobacco habit.

RESULTS

Increased risk association was observed for patients with at least one TRC in the upper aero digestive tract (UADT) for variations in SULT1A1 Arg²¹³His, mEH Tyr¹¹³His, hOGG1 Ser³²⁶Cys, XRCC1 Arg²⁸⁰His and BRCA2 Asn³⁷²His. Gene-environment interactions were assessed using MDR analysis. The overall best model by MDR was tobacco habit/p53(Arg/Arg)/XRCC1(Arg³⁹⁹His)/mEH(Tyr¹¹³His) that had highest Cross Validation Consistency (8.3) and test accuracy (0.69). This model also showed significant association using logistic regression analysis.

CONCLUSION

This is the first Indian study on a multipathway based approach to study genetic susceptibility to cancer in tobacco associated MPN. This approach could assist in planning additional studies for comprehensive understanding of tobacco carcinogenesis.

XRCC1 and base excision repair balance in response to nitric oxide

Inflammation associated reactive oxygen and nitrogen species (RONs), including peroxynitrite (ONOO(-)) and nitric oxide (NO), create base lesions that potentially play a role in the toxicity and large genomic rearrangements associated with many malignancies. Little is known about the role of base excision repair (BER) in removing these endogenous DNA lesions. Here, we explore the role of X-ray repair cross-complementing group 1 (XRCC1) in attenuating RONs-induced genotoxicity. XRCC1 is a scaffold protein critical for BER for which polymorphisms modulate the risk of cancer. We exploited CHO and human glioblastoma cell lines engineered to express varied levels of BER proteins to study XRCC1. Cytotoxicity and the levels of DNA repair intermediates (single-strand breaks; SSB) were evaluated following exposure of the cells to the ONOO(-) donor, SIN-1, and to gaseous NO. XRCC1 null cells were slightly more sensitive to SIN-1 than wild-type cells. We used small-scale bioreactors to expose cells to NO and found that XRCC1-deficient CHO cells were not sensitive. However, using a molecular beacon assay to test lesion removal in vitro, we found that XRCC1 facilitates AAG-initiated excision of two key NO-induced DNA lesions: 1,N(6)-ethenoadenine and hypoxanthine. Furthermore, overexpression of AAG rendered XRCC1-deficient cells sensitive to NO-induced DNA damage. These results show that AAG is a key glycosylase for BER of NO-induced DNA damage and that XRCC1's role in modulating sensitivity to RONs is dependent upon the cellular level of AAG. This demonstrates the importance of considering the expression of other components of the BER pathway when evaluating the impact of XRCC1 polymorphisms on cancer risk.

XRCC1 genetic polymorphism Arg399Gln and hepatocellular carcinoma risk: a meta-analysis

BACKGROUND

Studies investigating the association between X-ray repair cross-complementing group 1 (XRCC1) genetic polymorphism Arg399Gln and hepatocellular carcinoma (HCC) risk report conflicting results. The aim of this study was to quantitatively summarize the evidence for such a relationship.

METHODS

Two investigators independently searched the Medline, Embase, CNKI and Chinese Biomedicine Database. Summary odds ratios (ORs) and 95% confidence intervals (95% CIs) for XRCC1 polymorphism and HCC were calculated in a fixed-effects model (the Mantel-Haenszel method) and a random-effects model (the DerSimonian and Laird method) when appropriate. The pooled ORs were performed for a codominant model (Gln/Gln vs. Arg/Arg, Arg/Gln vs. Arg/Arg), a dominant model (Gln/Gln+Arg/Gln vs. Arg/Arg) and a recessive model (Gln/Gln vs. Arg/Gln+Arg/Arg).

RESULTS

This meta-analysis included 11 case-control studies, which included 2208 HCC cases and 3265 controls. Overall, the variant genotypes (Gln/Gln and Arg/Gln) of Arg399Gln were not associated with HCC risk when compared with the wild-type Arg/Arg homozygote (Gln/Gln vs. Arg/Arg, OR=1.01, 95% CI=0.79-1.28; Arg/Gln vs. Arg/Arg, OR=1.09, 95% CI=0.81-1.45). Similarly, no associations were found in the dominant and recessive models (dominant model, OR=1.12, 95% CI=0.85-1.47; recessive model, OR=0.99, 95% CI=0.79-1.25). Limiting the analysis to the studies within Hardy-Weinberg equilibrium, the results were persistent and robust. When stratifying for ethnicity, country/region and source of controls, no evidence of a significant association was observed in any subgroup. No publication bias was found in the present study.

CONCLUSION

No association is found between the XRCC1 polymorphism Arg399Gln and the risk of HCC.

A genetic variation in APE1 is associated with gastric cancer survival in a Chinese population

Altered DNA repair can be associated with aggressive tumor biology and impact on survival of cancer patients. We investigated whether genetic variation of human apurinic/apyrimidinic (AP) endonuclease, a key multifunctional gene involved in the base excision repair pathway, would play a role in gastric cancer survival outcomes. We genotyped APE1 rs1760944 by the TaqMan method in 925 gastric cancer patients. Analyses of association between the polymorphism and survival outcomes were carried out using the Kaplan-Meier method, Cox proportional hazards models, and the log-rank test. Survival analyses for all patients showed that the differences in median survival time between gastric cancer carriers with APE1 rs1760944 TT (55 months) and those with GT/GG (78 months), were statistically significant (P = 0.025, log-rank test). Kaplan-Meier survival estimates revealed that gastric cancer patients carrying the GT/GG genotypes had a higher survival than TT, and this protective effect was also more pronounced among subgroups with tumor size >5 cm (hazard ratio = 0.66, 95% confidence interval = 0.49-0.88), diffuse-type gastric cancer (0.76, 0.60-0.97), T3 depth of invasion (0.73, 0.57-0.93), lymph node metastasis (0.73, 0.58-0.92), no distant metastasis (0.81, 0.66-0.99), and TNM stage III and IV (0.75, 0.58-0.99 for stage III; 0.50, 0.29-0.88 for stage IV). Our results showed that the genetic variant rs1760944 in APE1 was associated with gastric cancer survival in a Chinese population. Larger studies are needed to verify our findings in different populations.

Polymorphisms of DNA repair and xenobiotic genes predispose to CpG island methylation in non-neoplastic gastric mucosa

BACKGROUND

Genetic factors, related to DNA repair or xenobiotic pathways might confer different degrees of susceptibility to gastric carcinogenesis. CpG island hyper methylation (CIHM) is a major event in gastric carcinogenesis. We evaluated the association between XRCC1, GSTP1, GSTT1 and GSTM1 polymorphisms with CIHM status in non-neoplastic gastric mucosa.

METHODS

XRCC1 Arg399Gln, and Arg194Trp, GSTP1 Ile104Val, and GSTT1, GSTM1 null polymorphisms were genotyped in 415 cancer free subjects, in relation to four candidate CpG (p14, p16, DAP-kinase and CDH1) loci, assessed by Methylation-Specific-Polymerase Chain Reaction (MSP). CIHM high was defined as two or more CpG islands methylated.

RESULTS

 Significant association between XRCC1 codon 399 Gln/Gln genotype and reduced susceptibility to CIHM of DAP-kinase (adjusted OR = 0.30, 95%CI = 0.13-0.71, p = .0055) and CIHM high (OR = 0.42, 95%CI = 0.19-0.97, p = .04). XRCC1 codon 399 Gin/Gln genotype also presented lower number of CIHM when compared with both Arg/Gln, and Arg/Arg + Arg/Gln genotypes (p = .02, .046, respectively) When subjects were divided according to age (>50 and <50), an association was found between GSTM1 null genotype and increased susceptibility to CIHM high in the 50 years and older generations (OR = 1.63, 95%CI = 1.01-2.62, p = .045).

CONCLUSION

XRCC1 codon 399 Gln/Gln genotype is associated with reduced susceptibility to CIHM especially DAP-kinase. GSTM1 null genotype may increase the susceptibility to CIHM especially in older patients. Genetic factors, related to DNA repair or xenobiotic pathways may have a role in CIHM-related gastric carcinogenesis.

Polymorphism in the DNA repair enzyme XRCC1: utility of current database and implications for human health risk assessment

Genetic polymorphisms are increasingly recognized as sources of variability not only in toxicokinetic but also in toxicodynamic response to environmental agents. XRCC1 is involved in base excision repair (BER) of DNA; it has variant genotypes that are associated with modified repair function. This analysis focuses on four polymorphisms: three in the coding region that affect protein structure and one in an upstream regulatory sequence that affects gene expression. The Arg399Gln variant is the most widely studied with evidence supporting a quantitative effect of genotype on phenotype. The homozygous variant (Gln/Gln) can have 3-4-fold diminished capacity to remove DNA adducts and oxidized DNA damage. This variant is relatively common in Caucasians and Asians where approximately 10% are homozygous variant. In contrast, the Arg194Trp variant appears to protect against genotoxic effects although the degree to which DNA repair is enhanced by this polymorphism is uncertain. The homozygous variant is rare in Caucasians and African Americans but it is present at 7% in Asians. A third coding region polymorphism at codon 280 appears to decrease repair function but additional quantitative information is needed and the homozygous variant is rare across populations studied. A polymorphism in an upstream promoter binding sequence (-77T>C) appears to lower XRCC1 levels by decreasing gene expression. Based upon genotype effect on phenotype and allele frequency, the current analysis finds that the codon 399 and upstream (-77) polymorphisms have the greatest potential to affect the toxicodynamic response to DNA damaging agents. However, the implications for risk assessment are limited by the likelihood that polymorphisms in multiple BER genes interact to modulate DNA repair.

Association between polymorphisms in the XRCC1 and GST genes, and CpG island methylation status in colonic mucosa in ulcerative colitis

CpG island hypermethylation (CIHM) is frequently observed in the colonic mucosa in ulcerative colitis (UC) and is deeply involved in UC-associated colorectal carcinogenesis. We evaluated the influence of common polymorphisms related to DNA repair or xenobiotic pathway (XRCC1, GSTP1, GSTT1, and GSTM1) on the individual susceptibility to CIHM status in the non-neoplastic rectal mucosa in UC patients. XRCC1 Arg399Gln and Arg194Trp, GSTP1 Ile104Val, and GSTT1, GSTM1 null polymorphisms were genotyped in 84 UC patients without neoplastic lesions, in relation to CIHM in the rectal mucosa of three candidate CpG loci (p14, p16, and CDH1) assessed by methylation-specific polymerase chain reaction. XRCC1 codon 399 Arg/Gln genotype (odds ratio (OR) = 0.31, 95%CI = 0.12-0.81, p = 0.017) and 399 Gln carrier (GlnGln+Arg/Gln: OR = 0.30, 95%CI = 0.12-0.76, p = 0.01) were significantly associated with reduced susceptibility to CIHM of the CDH1 promoter. GSTP1 Val carrier (Ile Val+Val/Val) also held a significantly lower susceptibility to CIHM of the p16 promoter (OR = 0.26, 95%CI = 0.08-0.86, p = 0.028). In contrast, GSTT1 present genotype (OR = 3.16, 95%CI = 1.27-7.89, p = 0.01) was significantly associated with increased susceptibility to CIHM of the same gene. XRCC1 codon 399 Gln/Gln genotype was significantly associated with lower mean number of CIHM when compared to the Arg/Arg genotype (1.53 ± 1.01 vs. 0.63 ± 1.06, p = 0.024). In addition, the GSTP1 Ile/Val carrier (Ile/Val+Val/Val) was also significantly associated with lower mean number of CIHM (1.43 ± 1.03 vs. 0.84 ± 1.07, p = 0.03). XRCC1 Arg399Gln and GSTP1 Ile104Val polymorphisms may influence the CIHM status in the rectal mucosa of UC patients and may be substantially involved in UC-associated carcinogenesis.

Effects of cigarette smoking, XRCC1 genetic polymorphisms, and age on basal DNA damage in human blood mononuclear cells

The aim of this study was to investigate the effects of smoking, polymorphisms of XRCC1 codons 194 and 399, and age on levels of basal DNA damage (as measured by an alkaline comet assay) on mononuclear cells in 122 healthy Japanese workers. In the whole group of 122 individuals, the tail moment (TM) values of current smokers (P < 0.001) or former smokers (P = 0.03) were significantly higher than those of nonsmokers. Individuals bearing the XRCC1 399Gln variant allele showed significant increases in TM values in all subjects or in referent subgroups stratified by age or smoking status except in the current smokers group; in contrast, the TM values of individuals bearing the XRCC1 194Trp variant allele were significantly lower than those of individuals bearing wild-type Arg/Arg genotypes. Furthermore, older subjects (> or =47 years old) had significantly higher TM values than younger subjects (<47 years old) in all subjects (P = 0.008). Multiple regression analysis indicated that smoking habits, polymorphisms of XRCC1 codons 194 and 399, and age were important variables affecting individuals basal DNA damage.

DNA repair gene XRCC1 polymorphisms and non-Hodgkin lymphoma risk in a Chinese population

Genetic polymorphism in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with cancer risks. This hospital-based case-control study examined whether polymorphism in the DNA repair gene x-ray repair cross-complementing groups 1 (XRCC1 Arg194Trp [C-->T], Arg280His [G-->A], and Arg399Gln [G-->A]) played a role in susceptibility to non-Hodgkin's lymphoma (NHL) in the Chinese population. We genotyped these polymorphisms for 221 histopathologically confirmed NHL cases and 254 age- and sex-matched healthy control cases in China. No studied polymorphism alone was shown to be related to the risk of NHL or each histologic subtype of NHL. When stratified by smoking status, however, the XRCC1Arg399Gln variant genotypes (homozygotes and heterozygotes) were associated with a 3.0-fold risk of follicular lymphoma among heavy smokers (95% confidence interval: 1.16-7.82; P = 0.02). Further large-scale studies would confirm this association and clarify marginally significant trends in XRCC1 polymorphism combinations for an increased risk for NHL.

Functional characterization of a promoter polymorphism in APE1/Ref-1 that contributes to reduced lung cancer susceptibility

Apurinic/apyrimidinic endonuclease 1/redox effector factor-1 (APE1/Ref-1) is a ubiquitous multifunctional protein that possesses both DNA-repair and redox regulatory activities. Although it was originally identified as a DNA-repair enzyme, accumulating evidence supports a role of APE1/Ref-1 in tumor development. To investigate association between APE1/Ref-1 polymorphisms and lung cancer risk in Chinese populations, we first genotyped three variants of APE1/Ref-1 and found a -141 T-to-G variant (rs1760944) in the promoter associated with decreased risk of lung cancer [odds ratio (OR) = 0.62 for GG; P=0.043]. Similar results were obtained in a follow-up replication study. Combined data from the two studies comprising a total of 1072 lung cancer patients and 1064 cancer-free control participants generated a more significant association (P=0.002). We observed lower APE1/Ref-1 mRNA levels in the presence of the protective G allele in human peripheral blood mononuclear cells and normal lung tissues. The -141G-allele-promoter construct exhibited decreased luciferase reporter gene expression. Electrophoretic mobility shift assays and surface plasmon resonance analysis showed that the -141G allele impaired the binding affinity of some transcription factor, accounting for lower APE1/Ref-1-promoter activity. Supershift assays further revealed that the protein of interest was octamer-binding transcription factor-1 (Oct-1). Chromatin immunoprecipitation reconfirmed binding of Oct-1 to the APE1/Ref-1 -141-promoter region. We also found that Oct-1 conferred attenuated transactivation capacity toward the -141G variant by exogenously introducing Oct-1. These data indicate that genetic variations in APE1/Ref-1 may modify susceptibility to lung cancer and provide new insights into an unexpected effect of APE1/Ref-1 on lung carcinogenesis.

Genetic variations in esophageal cancer risk and prognosis

Investigations into inherited genetic variations in the DNA code (known as polymorphisms) in the field of oncology have provided preliminary support for an association with cancer risks and outcomes. Early studies have highlighted several genes with this potential predictive and prognostic power. However, these studies have had methodological limitations and have produced inconsistent results, making impractical as yet the routine evaluation of such genetic polymorphisms in general clinical practice. Continued research in this area is essential if we are to be able to soon use genetic polymorphisms to better select patients for targeted anticancer interventions. This review discusses the role of genetic polymorphisms and their association with esophageal cancer risk and prognosis. The article also highlights future directions in this new, emerging field of molecular epidemiology.

Polymorphism of DNA repair gene XRCC1 and hepatitis-related hepatocellular carcinoma risk in Indian population

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the life-threatening malignancies worldwide with hepatitis B and C virus infection as the major risk factor. The risk of HCC might also increase because of the hereditary genetic defects in DNA repair genes. In this regard, X-ray cross-complementing group 1 gene (XRCC1) is a major DNA repair gene involved in base excision repair (BER).

AIM

The present study was designed with an aim to find out any possible association between XRCC1 (codons 194, 280, and 399) polymorphisms and the risk of developing hepatitis virus-related HCC in Indian population.

METHODS

A total of 407 subjects comprising (170 controls, 174 chronic viral hepatitis, and 63 HCC subjects) were included in the study. PCR-RFLP was used for the genotyping of the three codons of XRCC1.

RESULTS

The study revealed that two genotypes Arg194Trp and Arg280His increased the risk of HCC by 2.27- (95% CI = 1.01-5.08; P < 0.001) and 4.95-folds (95% CI = 2.48-9.89; P < 0.001), respectively. Interestingly, the risk for HCC was further enhanced by 35.96 (95% CI = 11.64-110.91; P < 0.001) and 5.28 times (95% CI = 2.81-9.09; P < 0.001) when the genotype Arg280His was found in association with Arg194Trp and Arg399Gln, respectively.

CONCLUSION

These preliminary results suggest a positive association of XRCC1 genotypes and risk of hepatitis virus-related HCC in India.

Polymorphisms of the NER pathway genes, ERCC1 and XPD are associated with esophageal adenocarcinoma risk

PURPOSE

Functional variation in DNA repair capacity through single nucleotide polymorphisms (SNPs) of key repair genes is associated with a higher risk of developing various types of cancer. Studies have focused on the nucleotide excision repair (NER) and base excision repair (BER) pathways. We investigated whether variant alleles in seven SNPs within these pathways increased the risk of esophageal adenocarcinoma.

METHODS

DNA was extracted from prospectively collected blood specimens. The samples were genotyped for SNPs in NER genes (XPD Lys751Gln, XPD Asp312Asn, ERCC1 8092C/A, and ERCC1 118C/T), and BER genes (XRCC1 Arg399Gln, APE1 Asp148Glu, and hOGG1 Ser326Cys). The presence of variant alleles was correlated with risk of esophageal adenocarcinoma both individually and jointly.

RESULTS

Variant alleles in NER SNPs XPD Lys751Gln (AOR = 1.50, 95% CI 1.1-2.0), ERCC1 8092 C/A (AOR = 1.44, 95% CI 1.1-1.9), and ERCC1 118C/T (AOR = 1.42, 95% CI 1.0-1.9) were individually associated with esophageal adenocarcinoma risk. An increasing number of variant alleles in NER SNPs showed a significant trend with esophageal adenocarcinoma risk (p = 0.007).

CONCLUSIONS

The presence of variant alleles in NER genes increases risk of esophageal adenocarcinoma. There is evidence of an additive role for SNPs along a common DNA repair pathway. Future larger studies of esophageal adenocarcinoma etiology should evaluate entire biological pathways.

Association between polymorphisms in DNA base excision repair genes XRCC1, APE1, and ADPRT and differentiated thyroid carcinoma

PURPOSE

DNA BER pathway is related with carcinogenesis. We hypothesized that functional polymorphisms of three BER genes, XRCC1, apurinic/apyrimidinic endonuclease (APE1), and ADPRT, confer risks for DTC and its progression.

EXPERIMENTAL DESIGN

Five common nonsynonymous single nucleotide polymorphisms (Arg194Trp, Arg280His, and Arg399Gln for XRCC1; Asp148Glu for APE1; and Val762Ala for ADPRT) were genotyped in Chinese DTC cases and controls.

RESULTS

The XRCC1-194Trp/Trp genotype showed a significantly increased risk for DTC (odds ratio, 1.85; 95% confidence interval, 1.11-3.07; P = 0.018). Subset analysis based on regional LN metastasis showed that the genetic effect came primarily from the subjects with LN metastasis (odds ratio, 4.54; 95% confidence interval, 2.11-9.79; P = 0.0001), but no significant association for subjects without LN metastasis. The other four single nucleotide polymorphisms did not show significant results. Haplotype analysis of XRCC1 polymorphisms yielded a significant result (P = 0.004), especially in the subjects with LN metastasis (P = 0.0002). Moreover, we found that XRCC1-194Trp and ADPRT-762Ala variants collectively contributed to an increased risk of the disease and LN metastasis, with the combined variant homozygotes exhibiting the highest 3.18-fold risk for DTC (P = 0.046) and 9.25-fold risk for DTC with LN metastasis (P = 0.004).

CONCLUSIONS

The XRCC1 polymorphisms, especially the 194Trp allele, may have an effect on DTC development and progression. This variant can interact with ADPRT-762Ala variant to further substantially increase susceptibility to the disease and regional LN metastasis. Identifying these risk genetic markers could provide more insight into the DTC pathogenesis and may also provide information to develop better prevention and therapeutic strategies.

Genetic polymorphisms and head and neck cancer outcomes: a review

Head and neck cancer (HNC) patients have variable prognoses even within the same clinical stage and while receiving similar treatments. The number of studies of genetic polymorphisms as prognostic factors of HNC outcomes is growing. Candidate polymorphisms have been evaluated in DNA repair, cell cycle, xenobiotic metabolism, and growth factor pathways. Polymorphisms of XRCC1, FGFR, and CCND1 have been consistently associated with HNC survival in at least two studies, whereas most of the other polymorphisms have either conflicting data or were from single studies. Heterogeneity and lack of description of patient populations and lack of accounting for multiple comparisons were common problems in a significant proportion of studies. Despite a large number of exploratory studies, large replication studies in well-characterized HNC populations are warranted.

Polymorphisms of inflammatory and metalloproteinase genes, Helicobacter pylori infection and the risk of oesophageal adenocarcinoma

Helicobacter pylori (HP) infection appears protective against oesophageal adenocarcinoma (EA) risk. Matrix metalloproteinases (MMPs) are released in the presence of HP infection. In MMP2 wild-type individuals, HP was significantly protective of EA risk (adjusted odds ratio: 0.29; 95% confidence interval=0.1-0.7). Matrix metalloproteinases may modulate the EA-HP relationship.

Genetic polymorphisms and esophageal cancer risk

The aim of this paper is to review and evaluate, in a comprehensive manner, the published data regarding the contribution of genetic polymorphisms to risk of esophageal cancer, including squamous cell carcinoma (SCC) and adenocarcinoma, in humans. All relevant studies available in MEDLINE and published before February 2007 were identified. Studies carried out in humans and that compared esophageal cancer patients with at least 1 standard control group were considered for analysis. One-hundred studies and 3 meta-analyses were identified. Eighty (80%) studies were conducted in Asian countries, particularly China including Taiwan (60 (60%) studies). The most intensively examined genes were those encoding carcinogen metabolic enzymes. The most widely studied gene was GSTM1 (15 studies), followed by ALDH2 (11 studies). ALDH2, MTHFR C677T, CYP1A1 Ile/Val, CYP1A1MspI, CYP2E1, GSTP1, GSTM1 and GSTT1 were examined by meta-analyses and significant relations were found between ALDH2*1*2 and the CYP1A1 Val allele and increased risk of esophageal cancer. In addition, increased risk of esophageal SCC was consistently associated with the ADH2*1*2 and the p53 codon 72 Pro/Pro genotypes. Cohort studies that simultaneously consider multiple genetic and environmental factors possibly involved in esophageal carcinogenesis are needed to ascertain not only the relative contribution of these factors to tumor development but also the contributions of their putative interactions.

XRCC1 codon 399 and ERCC2 codon 751 polymorphism, smoking, and drinking and risk of esophageal squamous cell carcinoma in a North Indian population

XRCC1 (X-ray cross-complementing group 1) codon 399 and ERCC2 (excision repair cross-complementing group 2) codon 751 polymorphisms were studied in esophageal squamous cell carcinoma (ESQCC) in a North Indian population. Peripheral blood samples of 120 cases and 160 age-and-gender matching controls were collected from North India and the two polymorphisms were studied by means of polymerase chain reaction-restriction fragment length polymorphism techniques. The data were analyzed with a logistic regression model. The XRCC1 codon 399 Gln/Gln genotype was significantly associated with reduced risk of ESQCC (OR = 0.31, 95% CI = 0.12-0.78, P = 0.01). In smokers, the XRCC1 Arg/Gln genotype was marginally and statistically nonsignificantly (OR = 1.5) associated with increased risk of this cancer. In drinkers, the XRCC1 Gln/Gln genotype was significantly protective (OR = 0.06, 95% CI = 0.007-0.605, P = 0.03), whereas ERCC2 (Lys/Gln-Gln/Gln) was marginally associated with increased risk (OR = 2.1, 95% CI = 0.46-9.44). Upon analysis of gene-gene interaction, a relationship was observed, although statistically nonsignificant, between combined genotypes of XRCC1 (Arg/Gln-Gln/Gln)-ERCC2 Gln/Gln (OR = 0.33, 95% CI = 0.09-1.16) and XRCC1 (Gln/Gln)-ERCC2 (Lys/Gln) (OR = 0.36, 95% CI = 0.11-1.17) and reduced risk of ESQCC in the North Indian population. These observations suggest that the Gln/Gln genotype of XRCC1 might play an important role in DNA repair in ESQCC.

Relationship between XRCC1 polymorphisms and susceptibility to prostate cancer in men from Han, Southern China

AIM

To investigate the association among XRCC1 polymorphisms, smoking, drinking and the risk of prostate cancer (PCa) in men from Han, Southern China.

METHODS

In a case-control study of 207 patients with PCa and 235 cancer-free controls, frequency-matched by age, we genotyped three XRCC1 polymorphisms (codons 194, 280 and 399) using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RELP) method.

RESULTS

Among the three polymorphisms, we found that the XRCC1 Arg399Gln variant allele was associated with increased PCa risk (adjusted odd ratio [OR]: 1.67, 95% confident interval [CI]: 1.11-2.51), but the XRCC1 Arg194Trp variant allele had a 38% reduction in risk of PCa (adjusted OR: 0.62, 95% CI: 0.41-0.93). However, there was no significant risk of PCa associated with Arg280His polymorphism. When we evaluated the three polymorphisms together, we found that the individuals with 194Arg/Arg wild-type genotype, Arg280His and Arg399Gln variant genotypes had a significantly higher risk of PCa (adjusted OR: 4.31; 95% CI: 1.24-14.99) than those with three wild-type genotypes. In addition, we found that Arg399Gln variant genotypes had a significant risk of PCa among heavy smokers (adjusted OR: 2.04; 95% CI: 1.03-4.05).

CONCLUSION

These results suggest that polymorphisms of XRCC1 appear to influence the risk of PCa and may modify risks attributable to environmental exposure.

Contrasting impact of DNA repair gene XRCC1 polymorphisms Arg399Gln and Arg194Trp on the risk of lung cancer in the north-Indian population

DNA repair forms the most effective defense system against DNA damage. The XRCC1 gene product is implicated in single-strand and base-excision repair mechanisms. Our main aim was to investigate the relationship between the XRCC1 gene with lung cancer on the north-Indian population. Blood samples from 225 North-Indian subjects including 103 newly diagnosed cases and 122 population-based healthy persons were collected. XRCC1 genotypes were detected using a PCR-RFLP technique. The data were analyzed by logistic regression analysis. XRCC1 polymorphisms at codon 399 were found to be protective in the development of lung cancer (OR--0.6, 95% CI--0.46-0.80, p-0.0008). The codon 194 Trp/Trp genotype was associated with a slightly increased risk of lung cancer. When assessed in nonsmokers, only the Arg/Trp genotype of XRCC1 codon 194 was positively associated with lung cancer (OR--2.3, 95% CI--0.77-7.20). Smoking also seemed to significantly interact with the combined genotypes of XRCC1 codon 399 Arg/Gln/Gln/Gln. In conclusion, the results have suggested that the XRCC1 gene might be the risk genotype for lung cancer in this population.

The nonsynonymous single nucleotide polymorphisms of DNA repair geneXRCC1and susceptibility to the development of cervical carcinoma and high-risk human papillomavirus infection

To evaluate contribution of single nucleotide polymorphisms (SNPs) of X-ray repair cross-complementing group 1 (XRCC1) gene to the risk of cervical carcinoma, we conducted a case-control study of 1012 patients including 539 carcinoma and 473 cervical intraepithelial neoplasia (CIN) and 800 normal women controls and genotyped three XRCC1 SNPs (Arg194Trp, Arg280His, and Arg399Gln). We found that compared with the Arg399Gln (GG), subjects carrying the homozygous Gln399Gln (AA) genotype had a significantly 2.32-fold increased risk of cervical carcinoma (95% CI 1.47-3.65), heterozygous Arg399Gln (GA) genotype were also associated with a significantly increased risk of cervical carcinoma, with the adjusted odds ratio (OR) being 1.58 (95% CI 1.24-2.00). Similarly, compared with Arg194Arg (CC) wild-type genotype, elevated risks were associated with the Trp194Trp (TT) for carcinoma (ORs and 95% CIs being 2.09 [1.45-3.02]) but not for heterozygote Arg194Trp (CT). In addition, three common haplotypes were found to be associated with an increased risk of cervical carcinoma. Using 194Arg-280Arg-399Arg as the reference, the OR and 95% confidence interval for 194Arg-280Arg-399Gln, 194Arg-280His-399Arg, 194Trp-280Arg-399Arg were 2.30 (1.86-2.85), 1.85 (1.41-2.41), 1.98 (1.62-2.40), respectively. The significantly increased risk associated with the haplotypes was also observed in squamous cell carcinoma (SCC) for all three common haplotypes using 194Arg-280Arg-399Arg as the reference. Neither difference was found for adenocarcinoma and CIN. All three SNPs and haplotypes did not confer more risk of high-risk human papillomavirus infection in carcinoma, CIN, and normal subgroup. Our findings suggest that XRCC1 polymorphisms including genotypes and haplotypes contribute to susceptibility to the development of cervical SCC, and the increased susceptibility is probably not through increasing susceptibility to human papillomavirus infection.