The codon 399 Arg/Gln XRCC1 polymorphism is associated with lung cancer in Indians

Association of RAD51, XRCC1, XRCC2, and XRCC3 Polymorphisms with Risk of Breast Cancer

Background: DNA repair genes are among the low-penetrance genes implicated in breast cancer. However variants of DNA repair genes may alter their protein function thus leading to carcinogenesis. Breast cancer is the most common cancer among women in India. The aim of the present study was to identify association, if any, of single nucleotide polymorphisms (SNP's) in four genes involved in DNA repair pathways including, RAD51 rs1801320, XRCC1 rs25487, XRCC2 rs3218536, and XRCC3 rs861539 with the risk of breast cancer. Materials and Methods: In this case-control study 611 female subjects (311 breast cancer patients and 300 healthy controls) were screened for four SNPs using polymerase chain reaction-restriction fragment length polymorphism analyses. Multifactor dimensionality reduction (MDR) analysis was performed to estimate the gene-gene interaction. Protein-protein interaction network analysis were studied using the STRING database. Results: The GC genotype (p = 0.018) and the combined GC+CC (p = 0.03) genotypes of RAD51 rs1801320 were significantly associated with reduced risk of breast cancer. The CT genotype (p = 0.0001), the combined CT+TT genotypes (p = 0.0002), and the T allele (p = 0.0019) of XRCC3 rs861539 polymorphism were associated with reduced risk of the breast cancer. No association of XRCC1 rs25487 and XRCC2 rs3218536 polymorphisms with breast cancer was observed. MDR analysis indicated a positive interaction between XRCC3 and XRCC2. String network analysis showed that the RAD51, XRCC1, XRCC2, and XRCC3 proteins are in strong interaction with each other and other breast cancer-related proteins such as BRCA2. Conclusion: RAD51 rs1801320 and XRCC3 rs861539 polymorphisms were associated with reduced risk of breast cancer. There is evidence of positive interactions among XRCC1, XRCC2, XRCC3, and RAD51.

Association of genetic polymorphisms in DNA repair genes ERCC2 Asp312Asn (rs1799793), ERCC2 Lys 751 Gln (rs13181), XRCC1 Arg399 Gln (rs25487) and XRCC3 Thr 241Met (rs861539) with the susceptibility of lung cancer in Saudi population

This study demonstrated the association of polymorphisms in ERCC2 (Asp312Asn) rs1799793, ERCC2 (Lys751Gln) rs13181, XRCC1 (Arg399Gln) rs25487 and XRCC3(Thr241Met) rs861539 polymorphisms with a susceptibility of lung cancer (LC) onset in the Saudi population. The study was performed on 134 LC patients and 270 controls. The data revealed that there was no significant association of LC with subtype squamous cell carcinoma (SCC), small cell lung cancer (SCLC) and adenocarcinoma with the ERCC2 rs1799793 polymorphism. The data showed that the CC genotype for ERCC2 rs13181, the AA genotype for XRCC1 rs25487, and the genotype TT for XRCC3 rs861539 were significantly associated with SCC susceptibility (p < 0.05). Similarly, the CC genotype for ERCC2 rs13181 and the AA genotype for XRCC1 rs25487 were significantly associated with adenocarcinoma susceptibility (p < 0.05). Whereas, the TT genotype for XRCC3 rs861539 was significantly associated with SCLC susceptibility (p = 0.005). In total, significant association of LC susceptibility was found in the following combination models of recessive genotypes: AC heterozygous for ERCC2 rs13181 + AA homozygous for XRCC1 rs25487, CC homozygous for ERCC2 rs13181 + GA heterozygous for rs25487, CC homozygous for rs13181 + AA homozygous for XRCC1 rs25487, CC homozygous for ERCC2 rs13181 + TT homozygous for XRCC3 rs861539, GA heterozygous for XRCC1 rs25487 + CT heterozygous for XRCC3 rs861539, GA heterozygous for XRCC1 rs25487 + TT homozygous for XRCC3 rs861539, AA homozygous for XRCC1 rs25487 + CT heterozygous for XRCC3 rs861539, AA homozygous for XRCC1 rs25487+ TT homozygous for XRCC3 rs861539. These data clearly demonstrated that the combination of recessive genotypes may be associated with susceptibility of LC onset (p < 0.05). In short, the data indicated that DNA repair genes increase LC risk via gene-gene interaction rather than independent variants.

A comprehensive meta-analysis and a case-control study give insights into genetic susceptibility of lung cancer and subgroups

Reports of genetic association of polymorphisms with lung cancer in the Indian subcontinent are often conflicting. To summarise and replicate published evidence for association with lung cancer and its subgroups. We performed a meta-analysis of candidate associations on lung cancer, its histological subtypes and smoking status in the Indian subcontinent following PRISMA guidelines. Multiple testing corrections were done by the Benjamini-Hochberg method through assessment of significance at a false discovery rate of 10%. We genotyped and investigated rs1048943/CYP1A1 in a case-control sample from eastern India, followed by its global meta-analysis using a similar protocol. Meta-analysis of 18 variants of 11 genes reported in 39 studies (7630 cases and 8169 controls) showed significant association of rs1048943/CYP1A1 [2.07(1.49-2.87)] and rs4646903/CYP1A1 [1.48(1.93-1.95)] with overall lung cancer risk at 10% FDR, while nominal association (p < 0.05) was observed for del1/GSTT1, del2/GSTM1, rs1695/GSTP1 and rs17037102/ DKK2. Subtype analysis showed a significant association of del1/GSTT1 with adenocarcinoma, rs4646903/CYP1A1 with squamous carcinoma, and rs1048943/CYP1A1 with both. Association of rs4646903/CYP1A1 in smokers and effect modification by meta-regression analysis was observed. Genotyping of rs1048943/CYP1A1 that presented significant heterogeneity (p < 0.1) revealed an association with adenocarcinoma among eastern Indian smokers, while a global meta-analysis in 10458 cases and 10871 controls showed association with lung cancer and its subgroups. This study identified the susceptibility loci for lung cancer and its covariate-subgroups.

Higher order genes interaction in DNA repair and cytokine genes polymorphism and risk to lung cancer in North Indians

Context

Lung cancer pathological process involves cumulative effects exerted by gene polymorphism(s), epigenetic modifications, and alterations in DNA repair machinery. Further, DNA damage due to oxidative stress, chronic inflammation, and the interplay between genetic and environmental factors is also an etiologic milieu of this malignant disease.

Aims

The present study aims to assess the prognostic value of DNA repair, cytokines, and GST gene polymorphism in lung cancer patients who had not received any neoadjuvant therapy.

Materials and Methods

In this case-control study, 127 cases and 120 controls were enrolled. DNA from the blood samples of both patients and controls was used to genotype XRCC1Arg399Gln, XPDLys751Gln, and interleukin-1 (IL-1β) genes by polymerase chain reaction (PCR)-restriction fragment length polymorphism method, whereas multiplex PCR was performed to genotype GSTT1 and GSTM1.

Results

Binary logistic regression analysis showed that XRCC1Arg399Gln-mutant genotype (Gln/Gln, odds ratio [OR] = 4.6, 95% confidence interval [CI]: 2.2-9.6) and GSTT1 null (OR = 2.7, 95% CI: 1.6-4.5) were linked to cancer susceptibility. Generalized multidimensional reduction analysis of higher order gene-gene interaction using cross-validation testing (CVT) accuracy showed that GSTT1 (CVT 0.62, P = 0.001), XPD751 and IL-1β (CVT 0.6, P = 0.001), and XRCC1399, XPD751, and interleukin-1 receptor antagonists (IL-1RN) (CVT 0.98, P = 0.001) were single-, two-, and three-factor best model predicted, respectively, for lung cancer risk. Classification and regression tree analysis results showed that terminal nodes which contain XRCC1399-mutant genotype (AA) had increased the risk to lung cancer.

Conclusion

The present study demonstrated that XRCC1399 (Gln/Gln), GSTT1, and IL-1RN allele I, I/II served as the risk genotypes. These genes could serve as the biomarkers to predict lung cancer risk.

Association of XRCC1, XRCC2 and XRCC3 Gene Polymorphism with Esophageal Cancer Risk

Aim

The X-ray repair cross-complementing (XRCC) gene polymorphisms influence esophageal carcinogenesis by altering the DNA repair capacity. The present study was designed to screen five single nucleotide polymorphisms (SNPs) of XRCC genes for their susceptibility to esophageal cancer (EC) risk. There is no previous report on these polymorphisms for EC from India, where EC frequency is high.

Methods

The present study included 497 subjects (213 EC patients and 284 healthy controls). The polymorphisms were screened using the PCR-RFLP method and allele and genotype distribution were compared using chi-square test. Association analysis was done by haplotype analysis and linkage disequilibrium (LD) analysis. Gene–gene interactions were identified using multifactor dimensionality reduction (MDR). The risk was calculated using binary logistic regression.

Results

For XRCC1 p.Arg399Gln, a decreased risk for EC was associated with the AA genotype [OR (95% CI): 0.53 (0.3–0.95), p=0.03] even after adjusting for various covariates [OR (95% CI): 0.49 (0.26–0.9), p=0.024] and with the recessive model [OR (95% CI): 0.49 (0.27–0.8), p=0.016]. The GA genotype of p.Arg280His was associated with an increased risk for EC [OR (95% CI): 1.7 (1.0–2.82), p= 0.045] after adjustments. The two XRCC1 polymorphisms, p.Arg399Gln and p.Arg194Trp were in slight LD among EC patients (D̍́=0.845, r²=0.042). XRCC2 and XRCC3 polymorphisms were not associated with EC risk.

Conclusion

XRCC1 p.Arg399Gln plays a protective role in the development of the EC. The study is the first report from India, providing baseline data about genetic polymorphisms in DNA repair genes XRCC1, XRCC2 and XRCC3 modulating overall EC risk.

Multiple logistic regression analysis predicts cancer risk among tobacco usage with glutathione S-transferase p1 genotyping in patients with head and neck cancer

INTRODUCTION

Numerous studies have been investigated to understand the association between glutathione S-transferase P1 (GSTP1) polymorphism and risk of head and neck cancer (HNC) but yielded contradictory results, and no studies could confirm polymorphism in GSTP1 and that tobacco usage increases the risk of HNCs. Therefore, this study aimed to understand the association of GSTP1 Ile105Val polymorphism with or without tobacco usage in carcinogenesis and clinicopathological characteristics of patients with HNC.

MATERIALS AND METHODS

Binary logistic regression analysis was performed to predict HNC risk with tobacco use and GSTP1 genotyping. Five predictor variables such as gender, age, tobacco usage, familial, and GSTP1 genotypes were included in the model.

RESULTS

The results of the logistic regression analysis show that the full model which considered all the five independent variables together was statistically significant, log-likelihood = -111.820, and all slopes are zero: G = 74.297, degree of freedom (DF) = 5, P = 0.000. The strongest predictor in this model is tobacco usage (odds ratio = Z = -5.16, P = 0.000).

CONCLUSION

The study concludes that multiple logistic regression analysis model could predict the risk factors in case-control studies where control samples are compromised.

Efficient Single-Strand Break Repair Requires Binding to Both Poly(ADP-Ribose) and DNA by the Central BRCT Domain of XRCC1

XRCC1 accelerates repair of DNA single-strand breaks by acting as a scaffold protein for the recruitment of Polβ, LigIIIα, and end-processing factors, such as PNKP and APTX. XRCC1 itself is recruited to DNA damage through interaction of its central BRCT domain with poly(ADP-ribose) chains generated by PARP1 or PARP2. XRCC1 is believed to interact directly with DNA at sites of damage, but the molecular basis for this interaction within XRCC1 remains unclear. We now show that the central BRCT domain simultaneously mediates interaction of XRCC1 with poly(ADP-ribose) and DNA, through separate and non-overlapping binding sites on opposite faces of the domain. Mutation of residues within the DNA binding site, which includes the site of a common disease-associated human polymorphism, affects DNA binding of this XRCC1 domain in vitro and impairs XRCC1 recruitment and retention at DNA damage and repair of single-strand breaks in vivo.

Association of 12 polymorphic variants conferring genetic risk to lung cancer in Indian population: An extensive meta-analysis

Candidate gene as well as genome-wide association studies identified several polymorphic variants to be associated with lung cancer worldwide including in India. However, contradictory results have failed to estimate the overall effect of the polymorphic variants on the disease. Textmining was conducted on PubMed following specific search strings to gather all the publications related to genetic association with lung cancer in India. Out of 211 PubMed hits only 30 studies were selected for meta-analysis following specific inclusion criteria. Heterogeneity between studies was calculated by Cochran's Q-test (P < 0.05) and heterogeneity index (I² ). Publication bias was visualized by funnel plots and Egger's regression test. For each variant, following a fixed-effect model, summary odds ratio (OR) along with 95% confidence interval (CI) was estimated. The meta-analysis revealed three polymorphic variants viz. 'deletion polymorphism (del1) (OR = 1.39, 95% CI = 1.03-1.87, P = 0.027) in GSTT1', 'deletion polymorphism (del2) (OR = 1.30, 95% CI = 1.01-1.67, P = 0.038) in GSTM1' and 'rs1048943 (OR = 1.98, 95% CI = 1.27-3.10, P = 0.002) in CYP1A1' to be associated with lung cancer. However, after multiple testing correction, only rs1048943 was found to be significantly associated (P value = 0.0321) with lung cancer. None of the polymorphic variants showed any evidence of heterogeneity between studies or of publication bias. Our meta-analysis revealed strong association of rs1048943 in CYP1A1, but a suggestive association of deletion polymorphisms in GSTT1 and GSTM1 with lung cancer, which provides a comprehensive insight on the overall effect of the polymorphic variants, reported in various case-control studies on Indian population, on the risk of lung cancer development. Environ. Mol. Mutagen. 58:688-700, 2017. © 2017 Wiley Periodicals, Inc.

Association between polymorphisms in DNA repair gene XRCC1 and non-melanoma skin cancer risk: a meta-analysis

Objective

Non-melanoma skin cancer (NMSC) is the most common malignancy with annually rising incidence. The aim of this study was to estimate the association between three coding polymorphisms (Arg399Gln, Arg194Trp, and Arg280His) of the DNA repair gene X-ray repair cross-complementing group 1 (XRCC1) and NMSC susceptibility.

Methods

Online databases were searched to retrieve case–control studies published between January 2000 and November 2016. Pooled odds ratio (OR) and 95% confidence interval (CI) were employed to assess the strength of association. Overall, 10 relevant studies were finally included for analysis, including 3,143 NMSC patients and 3,540 controls. For each polymorphism of XRCC1 gene, there were 3,050 cases and 3,463 controls for Arg399Gln, 914 cases and 1,182 controls for Arg194Trp, and 279 cases and 413 controls for Arg280His.

Results

Our results showed that these three polymorphisms in the XRCC1 coding region were not associated with increased risk of NMSC in the total studied population. However, subgroup analysis by ethnicities demonstrated that Gln/Arg genotype of Arg399Gln polymorphism was associated with increased risk of NMSC under the heterogeneous model in Asian populations (Gln/Arg vs Arg/Arg: OR =1.39, 95% CI =1.04–1.87, P=0.03); subgroup analysis by tumor types showed that Trp/Trp genotype of Arg194Trp was positively associated with decreased cancer risk in squamous-cell skin cancer (SCC) type under the homogeneous model (Trp/Trp vs Arg/Arg: OR =0.38, 95% CI =0.16–0.92, P=0.03).

Conclusion

Our results suggested that Arg399Gln variant of XRCC1 gene might be a risk factor for NMSC in Asian populations, and Arg194Trp variant of XRCC1 gene might be a protective factor for patients with SCC. In addition, future case–control studies are still needed to further evaluate the effect of XRCC1 polymorphisms in NMSC risk.

Genetic Variant Arg399Gln G>A of XRCC1 DNA Repair Gene Enhanced Cancer Risk Among Indian Population: Evidence from Meta-analysis and Trial Sequence Analyses

The X-ray repair cross-complementation group 1 (XRCC1) gene plays an important role in base excision repair pathway. Several studies have reported contradictory results for XRCC1 exon 10 (Arg399Gln, G23990A, rs25487) gene polymorphism and cancer risk in Indian population, making it difficult to interpret them. Therefore, we have conducted a meta-analysis to evaluate the more precise association between XRCC1 exon 10 G>A gene polymorphism and risk of cancer by published studies. We searched PubMed (Medline) and Google scholar web databases to cover all studies published on association between XRCC1 exon 10 G>A gene polymorphism and cancer risk until August 2016. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to appraise the strength of association. Heterogeneity, publication bias and sensitivity analysis were also assessed. Twenty-five published studies had fulfilled the inclusion criteria comprising 4131 confirmed cancer cases and 5013 controls. When all studies were polled together, overall significant association was found between XRCC1 exon 10 G>A polymorphism and cancer risk in variant allele carrier (A vs. G: OR 1.217, 95% CI 1.056-1.402, p = 0.007), homozygous (AA vs. GG: OR 1.359, 95% CI 1.036-1.783, p = 0.027), dominant (AA+AG vs. GG OR 1.208, 95% CI 1.006-1.450, p = 0.043) and recessive (AA vs. AG+GG: OR 1.315, 95% CI 1.029-1.680, p = 0.029) genetic models. Further sensitivity analysis supported the stability of our result by showing similar ORs before and after removal of a single study. The present meta-analysis suggested that the XRCC1 exon 10 G>A polymorphism contribute cancer risk in Indian population, and supports that individuals with risk allele A and AA genotype are at higher risk of developing cancer.

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 TNFα-308, IFNγ+874, and IL10-1082 gene polymorphisms and the risk of non-small cell lung cancer in the population of the South Indian state of Telangana

BACKGROUND

Cytokine-mediated inflammation is important in the pathogenesis of non-small cell lung cancer (NSCLC). Genetic polymorphisms in cytokine genes and their association with lung cancer in the Indian population have not been reported.

METHODS

For the first time, we analyzed genetic polymorphisms of TNFα ^-308, IFNγ ⁺⁸⁷⁴, and IL10 ^-1082 genes in 246 NSCLC patients and 250 healthy controls in the South Indian population from Telangana using ARMS PCR.

RESULTS

IFNγ⁺⁸⁷⁴ A/T and IL10^-1082 G/G gene polymorphisms were found to be significantly associated with NSCLC with 1.56- and 1.68-fold disease risk, respectively. There was no association between the risk of NSCLC and TNFα^-308 polymorphism. Gene polymorphisms stratified according to smoking revealed that IFNγ⁺⁸⁷⁴ A/T polymorphisms in smokers increased the disease risk by 2.91 fold. IL10^-1082 G/G polymorphisms showed 2-fold increased risk among patients who were smokers when compared to the controls. However, there was no association between TNFα^-308, IFNγ⁺⁸⁷⁴, and IL10^-1082 gene polymorphism and the stage of the NSCLC patients. The overall risk associated with the combination of these polymorphisms indicated that the TNFα^-308 G/A + IFNγ⁺⁸⁷⁴ A/T + IL10^-1082 G/G genotype increased the risk by 1.5 fold.

CONCLUSIONS

The results of our study indicate an association between cytokine gene polymorphisms and the risk of NSCLC in an Indian population.

Arg194–Arg399 haplotype of XRCC1 gene is susceptible to lung cancer in the Han population

Objective:

Lung cancer is still one of the most frequently diagnosed cancers all over the world, especially in developing countries. The aim of this study was to investigate the relationship between two well-characterized non-synonymous polymorphisms (Arg194Trp and Arg399Gln) in X-ray repair cross-complementing group 1 ( XRCC1) gene and the risk of lung carcinoma in the Han population.

Methods:

This study was hospital-based in design and included 159 participants (63 patients with lung carcinoma and 96 cancer-free controls) of Chinese Han descent. Genomic DNA from blood samples was extracted for PCR studies, followed by direct sequencing to determine the variants of the XRCC1 gene.

Results:

Carriers with Arg194–Arg399 haplotype of XRCC1 gene conferred a 189.3% increased risk compared to the non-carriers (95% confidence interval [CI], 1.195–2.998; P = 0.006). And single-locus analysis (both allele and genotype distributions of polymorphism Arg194Trp and Arg399Gln) identified neither association with cancer risk nor with clinico-pathological parameters of lung carcinoma in the Han population.

Conclusions:

Arg194–Arg399 haplotype of XRCC1 gene might increase lung cancer susceptibility and serve as a risk factor for lung cancer in the Han population.

Association of DNA repair and xenobiotic pathway gene polymorphisms with genetic susceptibility to gastric cancer patients in West Bengal, India

Gastric cancer is one of the most common malignancies in India. DNA repair gene or xenobiotic pathway gene polymorphisms have recently been shown to affect individual susceptibility to gastric cancer. Here, the possible interaction between common polymorphisms in X-ray repair cross complementing group I (XRCC1) gene and glutathione S-transferase (GST) genes (GSTM1, GSTT1 and GSTP1), smoking and alcohol consumption and overall survival in gastric cancer patients were evaluated. In this population-based case control study, 70 gastric cancer patients and 82 healthy controls were enrolled. The epidemiological data were collected by a standard questionnaire, and blood samples were collected from each individual. XRCC1 Arg194Trp, Arg280His and Arg399Gln polymorphisms were determined by polymerase chain reaction and direct DNA sequencing. GSTM1 and GSTT1 null polymorphisms and GSTP1 Ile105Val polymorphism were identified by multiplex polymerase chain reaction and restriction fragment length polymorphism (RFLP), respectively. The risk of gastric cancer was significantly elevated in individuals with XRCC1 Arg/Gln +Gln/Gln (p = 0.031; odds ratio = 2.32; 95 % confidence interval (CI) 1.07-5.06) and GSTP1 Val/Val genotype (p = 0.009; odds ratio = 8.64; 95 % CI 1.84-40.55). An elevated risk for GC was observed in smokers and alcohol consumers carrying GSTP1 Ile/Val +Val/Val genotype (p = 0.041; odds ratio = 3.71; 95 % CI 0.98-14.12; p = 0.002; odds ratio = 12.31; 95 % CI 1.71-88.59). These findings suggest that XRCC1 rs25487 and GSTP1 rs1695 can be considered as a risk factor associated with gastric cancer and might be used as a molecular marker for evaluating the susceptibility of the disease.

Association of MDR1 gene (C3435T) polymorphism and gene expression profiling in lung cancer patients treated with platinum-based chemotherapy

INTRODUCTION

Chemotherapy is the standard and recommended treatment for lung cancer apart from surgery and radiotherapy. Chemotherapy is administered as mono-agents or as combination therapy. In this study, we examined the role of MDR1 C3435T polymorphisms in lung cancer patients undergoing chemotherapy.

METHODS AND RESULTS

We genotyped 126 cases with lung cancer and 111 healthy controls, using the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP). Frequencies of MDR1 C3435C, C3435T and T3435T genotypes were 61, 16 and 23 % in lung cancer patients and 86, 9 and 5 % in the controls, respectively. The T3435T genotypes had a 5.23-fold increased risk for lung cancer. (OR 5.23; 95 % CI 2.082-13.146; p = 0.0004). Patients with TT genotypes were more frequent in stage IV and were significantly associated with the disease (p = 0.05). Habitual smoker lung cancer patients were 50 % CC genotypes whereas TT genotypes were 34 %. The non-smokers had 46 % CC genotypes and 23 % TT genotypes. Furthermore, we collected tissue biopsy samples for expression analysis from 20 patients (for controls we used the non-cancerous region of the same tissue). The present study showed mRNA expression of MDR1 was up-regulated in 80 % of the cancer group in comparison with the control group (p = 0.0002). We also correlated the association between MDR1 genotypes with different combinations of chemotherapy. The combinations and genotype distributions in the group receiving paclitaxel + cisplatin were as follows: CC (67 %), CT (24 %) and TT (9 %) genotypes, respectively, and the group receiving carboplatin + gemcitabine CC (46 %), CT (19 %) and TT (35 %) genotypes, respectively. We found that MDR1 (rs1045642) C3435T polymorphism and gene expression was significantly associated with the clinical outcome in lung carcinoma patients.

CONCLUSION

In conclusion, it is suggested that MDR1 TT genotypes had higher risk for the development of lung cancer. Also, this polymorphism could be used as a genetic marker for predicting the clinical outcome of lung cancer patients.

Radiosensitization effect of overexpression of adenovirus-mediated SIRT6 on A549 non-small cell lung cancer cells

OBJECTIVE

To explore the radiosensitization effect of overexpression of silent information regulator 6 (SIRT6) on A549 non-small cell lung cancer (NSCLC) cells.

METHODS

Adenovirus vector Ad-SIRT6 causing overexpression of SIRT6 was established. Western blotting and MTT assay were adopted to detect the level of SIRT6 protein and the inhibitory rate of A549 cell proliferation after different concentrations of adenovirus transduction (0, 25, 100, 200, and 400 pfu/cell) for 24 h. Control group, Ad-null group and Ad-SIRT6 group were designed in this experiment and virus concentration of the latter two groups was 200 pfu/cell. Colony formation assays were employed to test survival fraction (SF) of the 3 groups after 0, 2, 4, 6, 8, 10 X-ray irradiation. Flow cytometry was used to detect the status of cell cycle of 3 groups after 48 h of 4 Gy X-ray irradiation and Western blotting was used to determine the expression of apoptosis-related genes of 3 groups after 48 h of 4 Gy X-ray irradiation.

RESULTS

In the range of 25 ~ 400 pfu/cell, the inhibitory rate of A549 cell proliferation increased as adenovirus concentration raised. The inhibitory rates under the concentrations of 0, 25, 100, 200, and 400 pfu/cell were 0%, 4.23 ± 0.34%, 12.7 ± 2.57%, 22.6 ± 3.38%, 32.2 ± 3.22%, 38.7 ± 4.09% and 47.8 ± 5.58% and there were significantly differences among groups (P < .05). SF in Ad-SIRT6 group was lower than Ad-null and control groups after 4 ~ 10 Gy X-ray irradiation (P < 0.05) and the sensitization enhancement ratio (SER) was 1.35 when compared with control group. Moreover, after 48 h of 4 Gy X-ray irradiation, there appeared a significant increase in G1-phase cell proportion, up-regulated expression of the level of apoptosis-promoting genes (Bax and Cleaved caspase-3), but a obvious decline in S-phase and G2-phase cell proportion and a significant decrease of the level of apoptosis- inhibiting gene (Bal-2) in the Ad-SIRT6 group (P<0.05).

CONCLUSION

The over-expression of adenovirus-mediated SIRT6, which has radiosensitization effect on A549 cells of NSCLC, can inhibit the proliferation of A549 cells and cause G0/G1 phase retardation as well as induce apoptosis of cells.

Expression of ERCC1, RRM1 and LRP in non-small cell lung cancers and their influence on chemotherapeutic efficacy of gemcitabine concomitant with nedaplatin

OBJECTIVE

To explore the clinical efficacy of gemcitabine concomitant with nedaplatin and drug resistance in the treatment of non-small cell lung cancer (NSCLC) and associated molecular predicators.

MATERIALS AND METHODS

A total of 68 patients diagnosed with NSCLC by histology served as the study objects and were randomly divided into an observation group treated with gemcitabine concomitant with nedaplatin and a control group with cisplatin concomitant with gemcitabine, 34 cases for each group. Short-term and long-term efficacies, adverse responses as well as the expression of nucleotide excision repair cross complementing 1 (ERCC1), ribonucleotide reductase subunit M1 (RRM1) and lung resistance-related protein (LRP) in NSCLC tissues in both groups were assessed.

RESULTS

The short-term objective response rate (ORR) and disease control rate (DCR) were 35.3% (12/34) and 76.5% (26/34) in the observation group and 38.2% (13/34) and 85.3% (29/34) in the control group, respectively, the differences not being statistically significant. The time to progression (TTP) in both groups were 1~12 months, while the median TTP was 135 d and 144 d, respectively. Though the survival was slightly higher in the control group, there were no significant differences in TTP and survival time. The rates of decreased hemoglobin, vomiting and nausea as well as renal toxicity were evidently lower in the observation group, while other adverse responses demonstrated no significant difference. The positive expression rates of ERCC1, RRM1 and LRP were 47.1% (16/34), 61.8% (21/34) and 64.7% (22/34) in the observation group, respectively. Compared with negative ERCC1 expression, ORR had decreasing trend and the overall survival time (OS) decreased significantly in patients with positive ERCC1 expression, which were markedly decreased by the positive expressions of RRM1 and LRP.

CONCLUSIONS

Gemcitabine concomitant with nedaplatin has significant effects in the treatment of NSCLC, with an adverse response rate obviously lower than for cisplatin concomitant with gemcitabine, suggesting that wider use in the clinic is warranted. Additionally, the positive expressions of ERCC1, RRM1 and LRP may increase patient drug resistance, so they can be applied as the chemotherapeutic predicators to guide individualized therapy of NSCLC patients.

The role of base excision repair in the development of primary open angle glaucoma in the Polish population

Glaucoma is a leading cause of irreversible blindness in developing countries. Previous data have shown that progressive loss of human TM cells may be connected with chronic exposure to oxidative stress. This hypothesis may suggest a role of the base excision repair (BER) pathway of oxidative DNA damage in primary open angle glaucoma (POAG) patients. The aim of our study was to evaluate an association of BER gene polymorphism with a risk of POAG. Moreover, an association of clinical parameters was examined including cup disk ratio (c/d), rim area (RA) and retinal nerve fiber layer (RNFL) with glaucoma progression according to BER gene polymorphisms. Our research included 412 patients with POAG and 454 healthy controls. Gene polymorphisms were analyzed by PCR-RFLP. Heidelberg Retinal Tomography (HRT) clinical parameters were also analyzed. The 399 Arg/Gln genotype of the XRCC1 gene (OR 1.38; 95% CI 1.02-1.89 p = 0.03) was associated with an increased risk of POAG occurrence. It was indicated that the 399 Gln/Gln XRCC1 genotype might increase the risk of POAG progression according to the c/d ratio (OR 1.67; 95% CI 1.07-2.61 P = 0.02) clinical parameter. Moreover, the association of VF factor with 148 Asp/Glu of APE1 genotype distribution and POAG progression (OR 2.25; 95% CI 1.30-3.89) was also found. Additionally, the analysis of the 324 Gln/His MUTYH polymorphism gene distribution in the patient group according to RNFL factor showed that it might decrease the progression of POAG (OR 0.47; 95% CI 0.30-0.82 P = 0.005). We suggest that the 399 Arg/Gln polymorphism of the XRCC1 gene may serve as a predictive risk factor of POAG.

Note of clarification of data in the paper titled X-ray repair cross-complementing group 1 codon 399 polymorphism and lung cancer risk: an updated meta-analysis

We read with great interest the paper titled "X-ray repair cross-complementing group 1 codon 399 polymorphism and lung cancer risk: an updated meta-analysis" published by Wang et al in Tumor Biology, 2014, 35:411-418. Their results suggest that codon 399 polymorphism of XRCC1 gene might contribute to individual's susceptibility to lung cancer in Asian population and especially in nonsmoking Chinese women. The result is encouraging. Nevertheless, several key issues are worth noticing.

The influence of XRCC1 genetic variants on lung cancer susceptibility in Chinese Han population

Growing evidence suggests that genetic variants of X-ray repair cross-complementing group 1 proteins (XRCC1) contribute to genetic effects on the development of lung cancer. This case-control study aims to evaluate the genetic effects of XRCC1 c.482C>T and c.1686C>G single nucleotide polymorphisms (SNPs) on lung cancer susceptibility. 391 lung cancer patients and 398 cancer-free controls were enrolled in this study. The genotypes of c.482C>T and c.1686C>G genetic variants were detected by the created restriction site-polymerase chain reaction (CRS-PCR), PCR-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing methods. The genetic effects on lung cancer susceptibility were evaluated using association analyses by the unconditional logistic regression model. Our data indicated that there were significant differences in the distribution of allelic and genotypic frequencies between lung cancer patients and cancer-free controls. The XRCC1 c.482C>T and c.1686C>G genetic variants were significantly associated with the susceptibility to lung cancer (for c.482C>T, TT versus (vs.) CC: OR=2.14, 95% CI 1.31-3.48, P=0.002; T vs. C: OR=1.37, 95% CI 1.10-1.69, P=0.004; for c.1686C>G, GG vs. CC: OR=2.53, 95% CI 1.46-4.38, P=0.001; G vs. C: OR=1.33, 95% CI 1.06-1.65, P=0.012). These preliminary results suggested that the XRCC1 c.482C>T and c.1686C>G genetic variants might play genetic effects on the susceptibility to lung cancer in the studied population.

Interaction of XRCC1 and XPD gene polymorphisms with lifestyle and environmental factors regarding susceptibility to lung cancer in a high incidence population in North East India

BACKGROUND

This study aimed to explore the role of XRCC1 (Arg399Gln) and XPD (Lys751Gln) gene polymorphisms, lifestyle and environmental factors as well as their possible interactions in propensity to develop lung cancer in a population with high incidence from North East India.

MATERIALS AND METHODS

A total of 272 lung cancer cases and 544 controls were collected and XRCC1 (Arg399Gln) and XPD (Lys751Gln) genotypes were analyzed using a polymerase chain reaction based restriction fragment length polymorphism assay. Conditional multiple logistic regression analysis was used to calculate adjusted odds ratios and 95% confidence intervals after adjusting for confounding factors.

RESULTS

The combined Gln/Gln genotype of XRCC1 and XPD genes (OR=2.78, CI=1.05-7.38; p=0.040) was significantly associated with increased risk for lung cancer. Interaction of XRCC1Gln/Gln genotype with exposure of wood combustion (OR=2.56, CI=1.16-5.66; p=0.020), exposure of cooking oil fumes (OR=3.45, CI=1.39-8.58; p=0.008) and tobacco smoking (OR=2.54, CI=1.21-5.32; p=0.014) and interaction of XPD with betel quid chewing (OR=2.31, CI=1.23-4.32; p=0.009) and tobacco smoking (OR=2.13, CI=1.12-4.05; p=0.022) were found to be significantly associated with increased risk for lung cancer.

CONCLUSIONS

Gln/Gln alleles of both XRCC1 and XPD genes appear to amplify the effects of household exposure, smoking and betel quid chewing on lung cancer risk in the study population.

Allele and genotype distributions of DNA repair gene polymorphisms in South Indian healthy population

Various DNA repair pathways protect the structural and chemical integrity of the human genome from environmental and endogenous threats. Polymorphisms of genes encoding the proteins involved in DNA repair have been found to be associated with cancer risk and chemotherapeutic response. In this study, we aim to establish the normative frequencies of DNA repair genes in South Indian healthy population and compare with HapMap populations. Genotyping was done on 128 healthy volunteers from South India, and the allele and genotype distributions were established. The minor allele frequency of Xeroderma pigmentosum group A (XPA) G23A, Excision repair cross-complementing 2 (ERCC2)/Xeroderma pigmentosum group D (XPD) Lys751Gln, Xeroderma pigmentosum group G (XPG) His46His, XPG Asp1104His, and X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln polymorphisms were 49.2%, 36.3%, 48.0%, 23.0%, and 34.0% respectively. Ethnic variations were observed in the frequency distribution of these polymorphisms between the South Indians and other HapMap populations. The present work forms the groundwork for cancer association studies and biomarker identification for treatment response and prognosis.

Association of single nucleotide polymorphisms of ERCC1 and XPF with colorectal cancer risk and interaction with tobacco use

We investigated the association between polymorphisms in excision repair cross-complementation group 1 (ERCC1) (rs3212986, rs2298881 and rs11615) and xeroderma pigmentosum-complementation group F (XPF) (rs2276466 and rs6498486) and risk of colorectal cancer. A 1:1 matched case-control study was conducted. Conditional regression analysis indicated that individuals carrying the ERCC1 rs3212986 TT genotype and T allele had a marginally increased risk of colorectal cancer when compared with subjects with the GG genotype. Similarly, subjects carrying the rs11615 TT genotype and T allele had a marginally increased risk of colorectal cancer when compared with those with the CC genotype. Stratified analysis revealed that individuals with rs3212986 TT who were current or former smokers had a significantly increased risk of colorectal cancer, and a significant interaction was found between this SNP and cigarette smoking. In conclusion, our study suggests that rs3212986 and rs11615 polymorphisms are associated with risk of colorectal cancer in a Chinese population, particularly in smokers. This finding could be useful in revealing the genetic characteristics of colorectal cancer, and suggests more effective strategies for prevention and treatment.