An association between DNA repair gene polymorphisms and survival in patients with resected non-small cell lung cancer

XRCC2 driven homologous recombination subtypes and therapeutic targeting in lung adenocarcinoma metastasis

Lung adenocarcinoma (LUAD) is a leading cause of cancer mortality, with many patients facing poor prognosis, particularly those with metastatic or drug-resistant tumors. Homologous recombination genes (HRGs) are crucial in tumor progression and therapy resistance, but their clinical significance in LUAD is not well understood. In this study, we systematically characterize key HRGs in LUAD patients, identifying two distinct HR subtypes associated with different outcomes and biological functions. We establish a 5-gene scoring system (XRCC2, RAD51, BRCA1, FANCA, and CHEK1) that reliably predicts patient outcomes and immunotherapy responses in LUAD. Bioinformatics analysis and clinical validation highlight XRCC2 as a crucial biomarker in LUAD. Functional investigations through in vivo and in vitro experiments reveal the role of XRCC2 in promoting lung cancer migration and invasion. Mechanistically, XRCC2 stabilizes vimentin (VIM) protein expression through deubiquitylation. We predict c-MYC as a potential regulator of XRCC2 and demonstrate that inhibiting c-MYC with compound 10058-F4 reduces XRCC2 and VIM expression. Preclinical studies show the synergistic inhibition of metastasis in vivo when combining 10058-F4 with doxorubicin (Dox). Our findings present a potential personalized predictive tool for LUAD prognosis, identifying XRCC2 as a critical biomarker. The c-Myc-XRCC2-VIM axis emerges as a promising therapeutic target for overcoming lung metastasis. This study provides valuable insights into LUAD, proposing a prognostic tool for further clinical validation and unveiling a potential therapeutic strategy for combating lung metastasis by targeting c-Myc-XRCC2-VIM.

XPA: DNA Repair Protein of Significant Clinical Importance

The nucleotide excision repair (NER) pathway is activated in response to a broad spectrum of DNA lesions, including bulky lesions induced by platinum-based chemotherapeutic agents. Expression levels of NER factors and resistance to chemotherapy has been examined with some suggestion that NER plays a role in tumour resistance; however, there is a great degree of variability in these studies. Nevertheless, recent clinical studies have suggested Xeroderma Pigmentosum group A (XPA) protein, a key regulator of the NER pathway that is essential for the repair of DNA damage induced by platinum-based chemotherapeutics, as a potential prognostic and predictive biomarker for response to treatment. XPA functions in damage verification step in NER, as well as a molecular scaffold to assemble other NER core factors around the DNA damage site, mediated by protein–protein interactions. In this review, we focus on the interacting partners and mechanisms of regulation of the XPA protein. We summarize clinical oncology data related to this DNA repair factor, particularly its relationship with treatment outcome, and examine the potential of XPA as a target for small molecule inhibitors.

Intronic polymorphisms in genes LRFN2 (rs2494938) and DNAH11 (rs2285947) are prognostic indicators of esophageal squamous cell carcinoma

Background

Genome wide association study (GWAS) has become the major means to screen for the genetic variants associated with risk and prognosis of different diseases. A recent GWAS has discovered three novel intronic single nucleotide polymorphisms in genes LRFN2 (rs2494938), DNAH11 (rs2285947) and PLCXD2 (rs2399395) that are associated with altered risk of esophageal squamous cell carcinoma (ESCC) among Han Chinese populations. However, the prognostic significance of these variations in ESCC remains unclear.

Methods

To investigate the association of three novel single nucleotide polymorphisms (rs2494938, rs2285947, rs2399395) with the prognosis of ESCC patients, we recruited 287 ESCC patients treated with surgical resection and evaluated the potential significance of the three polymorphisms through Kaplan-Meier survival analysis, log-rank test, and Cox proportional hazards regression models.

Results

The ESCC patients carrying genotype AA at rs2494938 had worse survival and genotype GG at 2285947 had better prognosis (Log-rank P = 0.003 and Log-rank P = 0.037, respectively). In addition, rs2494938 at 6p21.1 was independently associated with overall survival of ESCC patients in recessive model [AA vs. GG/GA, HR = 3.12, 95% CI = 1.43–6.83, P = 0.004], rs2285947 at 7p15.3 was independently associated with overall survival of ESCC patients in both dominant model [AA/GA vs. GG, HR = 1.59, 95% CI = 1.02–2.49, P = 0.042] and additive model [AA vs. GA vs. GG, HR = 1.45, 95% CI = 1.05–2.01, P = 0.025].

Conclusions

This study demonstrated that the polymorphisms rs2494938 at 6p21.1 and rs2285947 at 7p15.3 may serve as independent prognostic biomarkers for ESCC, implying the potential biological role of their related genes (LRFN2 and DNAH11) in the process of ESCC development.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0796-9) contains supplementary material, which is available to authorized users.

XPG polymorphisms and their association with lung cancer susceptibility, overall survival and response in North Indian patients treated with platinum-based doublet chemotherapy

AIM

The study investigates association of XPG polymorphism with lung cancer susceptibility, overall survival and clinical outcomes in North Indian population.

RESULTS

A significant protective effect was observed for 2228959 C/A polymorphism with lung cancer and its histological subtypes. An increased hazard ratio (HR) was observed in 17655 G/C variant among small-cell lung carcinoma patients with mutant genotype (HR: 2.55; p = 0.05). Individuals treated with irinotecan-cisplatin/carboplatin regimen showed a longer survival time (HR¹: 0.04; median survival time [MST]: 32.5 months). Subjects treated with pemetrexed-cisplatin/carboplain regimen were associated with higher mortality rate in lung cancer patients (HR¹: 1.83;  MST: 9.13 months).

CONCLUSION

2228959 C/A polymorphism contributes to protective effect in lung cancer patients. 2228959 C/A polymorphism might be associated with favorable prognosis in lung cancer risk.

XRCC2 Polymorphisms and Environmental Factors Predict High Risk of Colorectal Cancer

Background

This case-control study aimed to analyze the association of XRCC2 polymorphisms (rs3218408 and rs3218384) with colorectal cancer (CRC) risk. The interaction of XRCC2 polymorphisms with environmental factors was investigated as well.

Material/Methods

We enrolled 147 CRC patients and 114 healthy individuals into the study. Polymerase chain reaction (PCR)-sequencing method was performed to detect rs3218408 and rs3218384 polymorphisms. Hardy-Weinberg equilibrium (HWE) was checked in the control group. Odds ratio (OR) with 95% confidence interval (CI) represented the risk of CRC. Cross-table method was used in analyzing the interaction effects.

Results

Compared to the control group, the frequency of smokers was much higher in the case group (P<0.001). A similar result was observed in drinkers (55.8% vs. 40.4%, P=0.013). Dietary habits of all subjects were investigated as well, showing that CRC patients ate fewer vegetables than did healthy controls (P<0.001). In the analysis of polymorphisms, rs3218408 appeared to be an independent risk factor of CRC (GG: OR=2.048, 95%CI=1.032–4.061; G allele: OR=1.445, 95%CI=1.019–2.049). There were 68 (76.4%) C allele carriers (rs3218384) among smokers, which was higher than the number of G allele carriers (P<0.001). A similar outcome was observed for alcohol drinkers (P=0.048), which suggests a relationship of rs3218384 with smoking and drinking. Further analysis indicated that interaction of rs3218384 with smoking increased the risk of CRC (GG and smoking: OR=3.250, 95%CI=1.235–8.556; GC+CC and smoking: OR=2.167, 95%CI=1.175–3.996).

Conclusions

We found that rs3218408 was related with increased risk of CRC, and the interaction of rs3218384 with smoking increased the risk of CRC.

Association of XPA Polymorphisms Towards Lung Cancer Susceptibility and its Predictive Role in Overall Survival of North Indians

The present study investigated the role of Xeroderma pigmentosum group A (XPA) polymorphism (A23G and G709A) with lung cancer risk and its association with overall survival in North Indians. 370 cases and 370 controls were investigated to evaluate association between XPA polymorphism (A23G and G709A) with lung cancer risk using logistic regression analysis. A follow-up study was also conducted for 291 lung cancer cases illustrating correlation between overall survival in lung cancer patients and XPA variants. GG genotype showed an increased lung cancer risk (p = 0.0007) for A23G polymorphism whereas G709A polymorphism was associated with significant protective effect in heterozygous (AG) subjects (p = 0.001). When stratified according to smoking status an increased risk for lung cancer was observed for GG genotype in A23G polymorphism (p = 0.0002). A poor survival in females carrying variant genotype (GG) was observed (p = 0.001; MST = 4.16 months) for A23G polymorphism. Adenocarcinoma patients with heterozygous genotype showed an increased hazard ratio (p = 0.02) for A23G polymorphism. G709A was associated with a reduced hazard ratio marking a better survival among mutant females (HR 0.17; p = 0.05; MST = 18.63 months). It can be concluded that A23G polymorphism might contribute to increased lung cancer risk in North Indian population emphasizing on poor survival among females. G709A polymorphism might result in protective effect in lung cancer subjects. The present study had a low sample size but it could act as reference for the large sample studies in future.

Genetic Investigation of Polymorphic OGG1 and MUTYH Genes Towards Increased Susceptibility in Lung Adenocarcinoma and its Impact on Overall Survival of Lung Cancer Patients Treated with Platinum Based Chemotherapy

Genes OGG1 and MUTYH are the two primary genes in Base excision repair pathway. OGG1 hydrolyzes the sugar phosphate backbone and remove the damaged base creating abasic site. MUTYH complements OGG1 as it particularly remove adenine mispaired with 8-oxo-G. Both OGG1 and MUTYH act as a check for the mis-incorporation of bases may be due to damages incurred on DNA. DNA isolation for 326 lung cancer cases and 330 controls was followed by genotyping making use of PCR-RFLP. Logistic regression was done to analyze the risk towards lung cancer. Patients were followed through telephonic conversation. Kaplan meier and Cox-regression were used for survival analysis. OGG1 presented a high risk towards lung cancer (CG: OR = 2.44, p = 0.0003; CG + GG: OR = 1.88, p = 0.0093). On the same lines adenocarcinoma for OGG1 were potent risk factors towards lung cancer (CG: OR = 4.72, p = 0.0002; CG + GG: OR = 3.63, p = 0.0018). Single allelic carriers for MUTYH gene imposed a high risk towards overall lung susceptibility and for all the three histology. Stratified analysis for chemotherapeutic drugs revealed administration of Cisplatin/Carboplatin + Pemtrexed for OGG1Ser ³²⁶ Cys showed a better survival (MST CG vs. CC: 9.1 vs. 0.56, p = <0.0001; HR =0.051, p = 0.0025). Whereas, MUTYH Gln³²⁴His showed a smaller survival for mutant genotype (CC) (MST CC vs. GG: 4.0 vs. 9.4, p = 0.05; HR = 1.75, p = 0.26). Single allelic carriers for both OGG1 and MUTYH were risk factors towards lung cancer. The risk was amplified on combining both OGG1 and MUTYH.

XPG genetic polymorphisms and clinical outcome of patients with advanced non-small cell lung cancer under platinum-based treatment: a meta-analysis of 12 studies

PURPOSE

A number of studies on the relationship between xeroderma pigmentosum group G (XPG) polymorphisms and clinical outcomes in non-small cell cancer (NSCLC) have led to inconclusive results. This meta-analysis evaluates the predictive value of XPG polymorphisms on the treatment response rate and overall survival of patients with NSCLC.

METHODS

To measure the correlative strength of the relationship between XPG polymorphisms and outcomes of patients with NSCLC, we searched electronic databases, including PubMed and China National Knowledge Infrastructure, to retrieve studies up to August 2016. We also employed pooled odds ratios (ORs) and hazard ratios (HRs) corresponding to 95% confidence intervals (95% CIs).

RESULTS

Twelve studies involving 2877 patients with NSCLC were included: 8 studies involving 1473 patients examined the correlation between XPG polymorphisms and tumor response rate and 7 studies involving 2329 patients reported on the correlation of XPG polymorphisms with overall survival. None of the XPG His1104Asp(C>G)/His46His(C>T) polymorphisms exhibited a correlation with treatment response rate or overall survival. However, in a further stratified analysis by ethnicity, carriers of the 1104G allele were associated with good response among Asians in the homozygote model (GG vs. CC: OR = 1.57, 95% CI: 1.05-2.34, P = 0.027). Meanwhile, further stratified by ethnicity, His46His polymorphism was not associated with RR and OS in any genetic models.

CONCLUSIONS

No strong evidence was found to support the use of XPG polymorphisms as tumor response and prognostic factors of patients with NSCLC receiving a platinum-based treatment regimen, which is attributed to marginal association. Studies with large-scale and multiple ethnicities need to be conducted to verify the conclusion.

The genetic variations in DNA repair genes ERCC2 and XRCC1 were associated with the overall survival of advanced non-small-cell lung cancer patients

It was reported that DNA repair can confer cancer cell resistance to therapeutic treatments by activating antiapoptotic cellular defense. We hypothesized that genetic variants of DNA repair genes may be associated with lung cancer prognosis. Seventeen tagging single‐nucleotide polymorphism (tagSNPs) selected from 12 DNA repair genes were genotyped in 280 advanced non‐small‐cell lung cancer (NSCLC) patients by TaqMan assay. The associations of these SNPs and overall survival of advanced NSCLC patients were investigated. Advanced NSCLC patients carrying ERCC2 rs50872 CT+TT genotypes had significantly longer median survival time (MST) and decreased death risk than patients with rs50872 CC genotype [log‐rank P = 0.031; adjusted HR(95% CI) = 0.73 (0.55–0.98), P = 0.033]. These effects were mainly seen among younger patients (≤65 years old) [HR(95% CI) = 0.57 (0.37–0.87), P = 0.010], patients without surgery [HR(95% CI) = 0.68 (0.47–0.98), P = 0.036] but with chemotherapy [HR(95% CI) = 0.64 (0.46–0.91), P = 0.012] or radiotherapy [HR(95% CI) = 0.58 (0.38–0.89), P = 0.013]. Meanwhile, compared to advanced NSCLC patients with rs25487 GG genotype, patients carrying XRCC1 rs25487 GA+AA genotypes had significantly shorter MST (MST = 11.7 vs. 16.7, log‐rank P = 0.048). In addition, advanced NSCLC patients carrying the ERCC2 rs50872 CC in combination with XRCC1 rs25487 GA+AA genotype had the shortest MST (11.2 month) and highest death risk [HR(95% CI) = 1.70 (1.15–2.52), P = 0.008] when compared with those carrying rs50872 CT+TT and rs25487 GG genotype (MST = 22.0 month). The ERCC2 rs50872 T allele was associated with favorable but XRCC1 rs25487 A allele with bad survival for advanced NSCLC in Chinese population, which may offer novel biomarkers for predicting clinical outcomes.

Single nucleotide polymorphisms in DNA repair genes and putative cancer risk

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

Association of CDC25 phosphatase family polymorphisms with the efficacy/toxicity of platinum-based chemotherapy in Chinese advanced NSCLC patients

AIM

To explore relationships between single nucleotide polymorphisms (SNPs) of the CDC25 protein family and the survival and chemotherapy responses of patients with advanced non-small-cell lung cancer (NSCLC).

METHODS & MATERIALS

We genotyped 14 SNPs of the CDC25 family in 663 Chinese patients with advanced NSCLC who were treated with first-line platinum-based chemotherapy and, in evaluable patients, analyzed relationships between the CDC25 family and the efficacy of platinum-based chemotherapy.

RESULTS

CDC25A rs3731513 and rs1380053, CDC25C rs6861656, CDC25A haplotype T/A/A/A/C and CDC25C haplotype A/G/G/G/C were significantly associated with the patients' progression-free survival. In addition, CDC25B rs3761218 and haplotype G/T/G/G were associated with the occurrence of severe toxicity with platinum-based chemotherapy, especially gastrointestinal and hematological toxicity.

CONCLUSION

These findings reveal a relationship between genetic variations of the CDC25 family and the efficacy and toxicity of platinum-based chemotherapy in patients with advanced NSCLC, especially in those with non-squamous-cell carcinoma.

Associations of LIG4 and HSPB1 genetic polymorphisms with risk of radiation-induced lung injury in lung cancer patients treated with radiotherapy

Objective. This study aims to explore the correlations of genetic polymorphisms in LIG4 and HSPB1 genes with the radiation-induced lung injury (RILI), especially radiation pneumonitis (RP), in lung cancer patients. Methods. A total of 160 lung cancer patients, who were diagnosed with inoperable lung cancer and received radiotherapy, were included in the present study from September 2009 to December 2011. TaqMan Real-Time PCR (RT-PCR) was used to verify the SNPs of LIG4 and HSPB1 genes. Chi-square criterion was used to compare the differences in demographic characteristics, exposure to risk factors, and SNPs genotypes. Crude odds ratios (ORs) with 95% confidence intervals (95% CI) were calculated by logistic regression analysis. All statistical analyses were conducted in SPSS 18.0. Results. A total of 32 (20.0%) lung cancer patients had RP after receiving radiotherapy. Of the 32 cases, 4 cases were of grade 2, 24 cases were of grade 3, and 4 cases were of grade 4. However, our results indicated that the general condition and treatment of all patients had no significant difference with RP risk (P > 0.05). Meanwhile, our results revealed that there was no significant association between the frequencies of LIG4 rs1805388 and HSPB1 rs2868371 genotype distribution and the risk of RP (P > 0.05). Conclusion. In conclusion, we demonstrated that the genetic polymorphisms in LIG4 rs1805388 and HSPB1 rs2868371 were not obviously correlated with the risk of RP and RILI of lung cancer.

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.

si-RNA-mediated knockdown of PDLIM5 suppresses gastric cancer cell proliferation in vitro

Gastric cancer is the second most prominent cause of cancer mortality in the world. This study was designed to identify the possible use of si-RNA-mediated PDLIM5 gene silencing as a therapeutic tool for gastric cancer. Expression levels of PDLIM5 were detected in several gastric cancer cell lines using Western blot and qRT-PCR. We found PDLIM5 is highly expressed in all cultured gastric cancer cell lines. Small interfering RNA (si-RNA) was then employed to knock down PDLIM5 expression in MGC80-3 gastric cancer cells. Knockdown of PDLIM5 significantly inhibited cell proliferation and colony formation. Moreover, the absence of PDLIM5 in MGC80-3 cells led to S phase cell cycle arrest and apoptosis. This study highlights the critical role of PDLIM5 in gastric cancer cell growth and suggests that si-RNA-mediated silencing of PDLIM5 might serve as a potential therapeutic approach for the treatment of gastric cancer.

XRCC2 gene polymorphisms and its protein are associated with colorectal cancer susceptibility in Chinese Han population

XRCC2 is an essential part of the homologous recombination repair pathway. However, relatively little is known about the effect of XRCC2 gene C41657T and G4234C polymorphisms on the individual susceptibility to colorectal cancer (CRC). The purpose of this study was to investigate the association between XRCC2 gene C41657T and G4234C polymorphisms and CRC and to explore the relationship among the polymorphisms and clinicopathologic parameters and protein expression levels of XRCC2. A hospital-based case-control study was conducted with 246 CRC cases and 262 healthy controls. The genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. XRCC2 protein was analyzed by immunohistochemistry for the paraffin sections of 120 CRC cases. The study data showed that the C41657T genotypes were associated with the risk of CRC. The CT/TT genotypes and T allele were overrepresented among the CRC cases. Compared with CC, CT/TT enhanced the risk of CRC (odds ratio = 1.646, 95 % confidence interval = 1.127-2.404, P = 0.010). XRCC2 protein expression of CRC patients with CT/TT genotypes was significantly higher than that of the patients with CC genotype (χ (2) = 4.887, P = 0.027). XRCC2 gene G4234C polymorphisms have no relevance to the risk of CRC. Our findings suggest that XRCC2 C41657T polymorphism may adjust the XRCC2 expression and might influence susceptibility of CRC.

Inter-individual variation in DNA repair capacity: a need for multi-pathway functional assays to promote translational DNA repair research

Why does a constant barrage of DNA damage lead to disease in some individuals, while others remain healthy? This article surveys current work addressing the implications of inter-individual variation in DNA repair capacity for human health, and discusses the status of DNA repair assays as potential clinical tools for personalized prevention or treatment of disease. In particular, we highlight research showing that there are significant inter-individual variations in DNA repair capacity (DRC), and that measuring these differences provides important biological insight regarding disease susceptibility and cancer treatment efficacy. We emphasize work showing that it is important to measure repair capacity in multiple pathways, and that functional assays are required to fill a gap left by genome wide association studies, global gene expression and proteomics. Finally, we discuss research that will be needed to overcome barriers that currently limit the use of DNA repair assays in the clinic.

Genetic polymorphisms in XPG could predict clinical outcome of platinum-based chemotherapy for advanced non-small cell lung cancer

We conducted a prospective study to investigate the role of four single nucleotide polymorphisms (SNPs) of XPG on the clinical outcome of advanced non-small cell lung cancer (NSCLC) treated with platinum-based doublets chemotherapy. In total, 277 patients with histologically confirmed NSCLC were mainly from December 2007 and December 2008. The genotypes of rs2296147T>C, rs1047768C>T, rs873601G>A, and rs17655G>C were determined by polymerase chain reaction-restriction fragment length polymorphism. By univariate analysis, a shorter survival was associated with older age, sex, and higher disease stage. By multivariate Cox regression analysis, patients carrying rs2296147 TT genotype and T allele were prognostic factors of progression-free survival (PFS) and overall survival (OS). Similarly, patients carrying rs873601 GG genotype and G allele were marginally significantly associated with favorable outcome for PFS and OS. We found that individuals carrying both rs2296147 T allele and rs873601 G allele were associated with better PFS and OS. However, rs1047768C>T and rs17655G>C polymorphisms did not influence the PFS and OS of advanced NSCLC. In summary, our study provided statistical evidence that XPG rs2296147T>C and rs873601G>A polymorphisms may be used as surrogate markers toward individualizing NSCLC treatment strategies.

Role of ERCC5 promoter polymorphisms in response to platinum-based chemotherapy in patients with advanced non-small-cell lung cancer

The ERCC5 gene plays an important role in the nucleotide excision repair pathway that recognizes and removes platinum-DNA adducts. We aimed to examine whether ERCC5 promoter polymorphisms contribute toward intervariations in the platinum treatment response in patients with advanced non-small-cell lung cancer (NSCLC). We evaluated the association between three tag-single nucleotide polymorphisms in the ERCC5 promoter region (rs2094258, rs751402, and rs2296147, respectively) and the efficacy of chemotherapy in 228 advanced NSCLC patients. We found that the rs751402 AA genotype was associated with a better treatment response [AA vs. AG+GG: odds ratio (OR)=2.74, 95% confidence interval (CI) 1.04-7.26, P=0.036) in all NSCLC patients, which was more evident in the subgroup of patients with squamous cell carcinoma (AA vs. GG: OR=6.40, 95% CI 1.15-35.50, P=0.043; AA vs. AG+GG: OR=6.12, 95% CI 1.15-32.52, P=0.019). No statistically significant association was found between rs2094258 and rs2296147 polymorphisms and treatment response. Our results suggested that the ERCC5 rs751402 AA genotype increased the chemotherapy response in advanced NSCLC, especially in patients with squamous cell carcinoma. Further and larger scale studies are still required to provide more comprehensive information on ERCC5 promoter variations in the clinical outcome of NSCLC patients treated with platinum regimens.

XRCC3 gene polymorphism is associated with survival in Japanese lung cancer patients

We focused on OGG1 Ser326Cys, MUTYH Gln324His, APEX1 Asp148Glu, XRCC1 Arg399Gln, and XRCC3 Thr241Met and examined the relationship between the different genotypes and survival of Japanese lung cancer patients. A total of 99 Japanese lung cancer patients were recruited into our study. Clinical data were collected, and genotypes of the target genes were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Survival analysis to verify the impact of these gene polymorphisms on the clinical outcome of lung cancer showed that lung squamous cell carcinoma patients with the Thr/Met genotype at XRCC3 had a significantly shorter survival time than those with the Thr/Thr genotype (13 months versus 48 months; log-rank test, p < 0.0001). Cox regression analysis showed that the carriers of XRCC3 genotypes were at a significantly higher risk [adjusted hazard ratio (HR) = 9.35, 95% confidence interval (CI) = 2.52-34.68, p = 0.001; adjusted HR = 9.05, 95% CI = 1.89-44.39, p = 0.006]. Our results suggest that XRCC3 Thr241Met may act as a favorable prognostic indicator for lung squamous cell carcinoma patients.

A functional polymorphism in XRCC1 is associated with glioma risk: evidence from a meta-analysis

Previous studies show that X-ray cross-complementing group 1 (XRCC 1) Arg399Gln may result in variations in repair efficiency of DNA damage, and this repair deficit may eventually cause individual susceptibility to glioma. However, published data regarding the association between XRCC 1 Arg399Gln polymorphism and glioma risk was contradictory. The aim of this study was to derive a more precise estimation of the association of XRCC 1 Arg399Gln polymorphism with glioma risk by performing a meta-analysis of eligible studies. Odds ratios (ORs) and 95 % confidence intervals (95 %CIs) were used to assess the strength of the association. We performed a meta-analysis of eleven published studies that included 2,808 glioma cases and 3,114 controls. Overall, there was a significant association between XRCC1 Arg399Gln polymorphism and glioma risk in two genetic models (for ArgGln vs ArgArg: OR = 1.30, 95 % CI 1.01-1.68; for GlnGln/ArgGln vs ArgArg: OR = 1.28, 95 % CI 1.01-1.62). In the stratified analysis by ethnicity, the XRCC1 Arg399Gln polymorphism had a higher risk of glioma development among Asians (for Gln vs Arg: OR = 1.34, 95 % CI 1.12-1.61; for GlnGln vs ArgArg: OR = 1.72, 95 % CI 1.18-2.51; for ArgGln vs ArgArg: OR = 1.31, 95 % CI 1.01-1.71; for GlnGln/ArgGln vs ArgArg: OR = 1.41, 95 % CI 1.10-1.80; for GlnGln vs ArgArg/ArgGln: OR = 1.48, 95 % CI 1.05-2.09)., but not among Caucasians. In conclusion, the results suggest that the XRCC 1 Arg399Gln polymorphism may contribute to the susceptibility of glioma in Asians.

An interethnic variability and a functional prediction of DNA repair gene polymorphisms: the example of XRCC3 (p.Thr241>Met) and XPD (p.Lys751>Gln) in a healthy Tunisian population

Genetic polymorphisms in DNA repair genes might influence the repair activities of the enzymes predisposing individuals to cancer risk. Owing to the presence of these genetic variants, interethnic differences in DNA repair capacity have been observed in various populations. The present study was undertaken to determine the allele and genotype frequencies of two common non-synonymous SNPs, XRCC3 p.Thr241>Met (C > T, rs861539) and XPD p.Lys751>Gln (T > G, rs13181) in a healthy Tunisian population and to compare them with HapMap ( http://www.hapmap.org/ ) populations. Also, we predicted their eventual functional effect based on bioinformatics tools. The genotypes of 154 healthy and unrelated individuals were determined by PCR-RFLP procedure. Our findings showed a close relatedness with Caucasians from European ancestry which might be explained by the strategic geographic location of Tunisia in the Mediterranean, thus allowing exchanges with Europeans countries. The in silico predictions showed that p.Thr241>Met substitution in XRCC3 protein was predicted as possibly damaging, indicating that it is likely to have functional consequences as well. To the best of our knowledge, this is the first study in this regard in Tunisia. So, these data could provide baseline database and help us to explore the relationship of XRCC3 and XPD polymorphisms with both cancer risk and DNA repair variability in our population.

Influence of DNA repair gene polymorphisms on prognosis in inoperable non-small cell lung cancer patients treated with radiotherapy and platinum-based chemotherapy

Polymorphisms in DNA repair genes may modulate not only an individual DNA repair capacity, DNA damage levels and cancer risk but also clinical outcome after DNA damage-inducing anticancer therapy. In this study, we analyzed the association between the XPA -4G>A, XPD Asp312Asn, hOGG1 Ser326Cys, XRCC1 Arg399Gln, XRCC2 -4234G>C, XRCC3 -4541A>G and Thr241Met polymorphisms and prognosis in 250 inoperable non-small cell lung cancer (NSCLC) patients treated with radiotherapy and platinum-based chemotherapy. In univariate model, the XPA-4A and XRCC1 399Gln alleles alone and in combination influenced survival only in stage III group. In multivariate analysis, the XPA-4 GA/AA was associated with poor survival (HR 1.55, p = 0.011 overall and HR 1.72, p = 0.008 in stage III). In chemoradiotherapy group, the XPA-4A carriers were at increased risk of death and progression (HR 1.73, p = 0.013 and HR 1.65, p = 0.016, respectively), especially in stage III (p = 0.008). Moreover, individuals with ≥ 2 XPA/XRCC1 adverse alleles showed a higher risk of death (HR 1.46, p = 0.036 overall; HR 1.85, p = 0.004 in stage III and HR 1.71, p = 0.022 in chemoradiotherapy group) and progression (HR 1.75, p = 0.011 overall and HR 1.93, p = 0.005 in stage III). The XPA-4 GA/AA genotype individually and together with the XRCC1 399Gln was an independent unfavorable prognostic factor in our study. Thus, our findings indicate a prognostic potential of the XPA-4G>A in unresected NSCLC treated with radiotherapy and chemoradiotherapy. The results require validation in an independent population.

Association between polymorphisms in XRCC1 gene and clinical outcomes of patients with lung cancer: a meta-analysis

Background

X-ray repair cross-complementing group 1 (XRCC1) protein plays an important role in the repair of DNA damage and adducts. Single nucleotide polymorphisms (SNPs) of XRCC1 are suspected to have some relationship with response to chemotherapy and overall survival of lung cancer. This meta-analysis aimed to summarize published data on the association between the commonest SNPs of XRCC1 (Arg194Trp, C > T, rs1799782 and Arg399Gln, G > A, rs25487) and clinical outcome of lung cancer patients.

Methods

We retrieved the relevant articles from PubMed, EMBASE and the China National Knowledge Infrastructure (CNKI) databases. Studies were selected using specific inclusion and exclusion criteria. Primary outcomes included objective response (i.e., complete response + partial response vs. progressive disease + stable disease) and overall survival (OS). Odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI) were estimated. All analyses were performed using the Stata software.

Results

Twenty-two articles were included in the present analysis. XRCC1 Arg194Trp and Arg399Gln polymorphisms were significantly associated with response to treatment in lung cancer patients. Patients with C/T genotype, T/T genotype and minor variant T allele at Arg194Trp were more likely to respond to platinum-based chemotherapy compared with those with C/C genotype (C/T vs. C/C: OR, 2.54; 95%CI, 1.95-3.31; T/T vs. C/C: OR, 2.06; 95%CI, 1.39-3.06; C/T+T/T vs. C/C: OR, 2.42; 95% CI, 1.88-3.10). For XRCC1 Arg399Gln, G/A genotype, A/A genotype and minor variant A allele were associated with objective response in all patients (G/A vs. G/G: OR, 0.67; 95%CI, 0.50-0.90; A/A vs. G/G: OR, 0.43; 95%CI, 0.25-0.73; A/A+G/A vs. G/G: OR, 0.63; 95%CI, 0.49-0.83). Both G/A and A/A genotypes of XRCC1 Arg399Gln could influence overall survival of lung cancer patients (G/A vs. G/G: HR, 1.23; 95%CI, 1.06-1.44; A/A vs. G/G: HR, 2.03; 95%CI, 1.20-3.45). Interaction analysis suggested that compared with the patients carrying C/T+T/T genotype at XRCC1 194 and G/G genotype at XRCC1 399, the patients carrying 194 C/C and 399 G/A+A/A or 194 C/C and 399 G/G genotype showed much worse objective response.

Conclusions

Genetic polymorphisms in XRCC1 gene might be associated with overall survival and response to platinum-based chemotherapy in lung cancer patients.

The determination of relationship between "excision repair cross-complementing group 1" (ERCC1) gene T19007C and C8092A single nucleotide polymorphisms and clinicopathological parameters in non-small cell lung cancer

DNA repair plays a key role in prevention of carcinogenesis and one of the most important DNA repair mechanisms is nucleotide excision repair (NER) pathway. This pathway includes a number of genes such as excision repair cross-complementing group 1 (ERCC1) gene which are responsible for the 5' incision of damaged DNA. A reduced DNA repair capacity associated with ERCC1 mRNA level has been observed in lung carcinogenesis. Two single nucleotide polymorphisms (SNPs) in ERCC1 gene, T19007C (rs11615) and C8092A (rs3212986), reportedly predict to affect the mRNA of ERCC1 in non-small cell lung cancer (NSCLC). To examine the role of two common SNPs in ERCC1 gene further, we conducted this study where 80 cases histopatologically diagnosed as NSCLC were genotyped. Genomic DNA was extracted from formalin-fixed, paraffin embedded tissues and two SNPs were analyzed using real-time PCR. The distributions of TT, TC, and CC genotypes of the T19007C SNP were 40, 44 and 16%, respectively. Significantly increased frequency of the patients carrying at least one 19007C allele was observed in early stage compared to advanced stage (P=0.002). And also, the frequency of TC and CC genotypes significantly increased in younger patients compared to older patients (P=0.035). Regarding C8092A SNP, the distribution of CC, CA, and AA genotypes was 38, 51 and 11%, respectively. There was no significant difference in the genotype distribution between C8092A SNP and clinicopathological parameters. This study indicated that harboring at least one 19007C allele may have protective effect in NSCLC.