Genetic polymorphism of DNA base-excision repair genes (APE1, OGG1 and XRCC1) and their correlation with risk of lung cancer in a Chinese population

Impact of XRCC1 genetic variants on its tissue expression and breast cancer risk: A case-control study

X-ray repair cross-complementing group 1 (XRCC1), a coordinator protein of the DNA repair complex, is thought to be involved in cancer progression. This case-control study aimed to investigate the association of two biallelic single-nucleotide polymorphisms (SNPs; Arg399Gln, Arg194Trp) of the XRCC1 gene with its tissue expression level and breast cancer (BC) risk in Egyptian women. This study included 100 BC female patients (case group 1) and 100 healthy females (control group 2). The XRCC1 tissue expression was assessed by immunohistochemistry (IHC). Genotyping of the two XRCC1 SNPs (Arg399Gln, Arg194Trp) using real-time polymerase chain reaction (PCR) was also conducted. The XRCC1 expression level was significantly lower in cancerous tissues than adjacent non-cancerous tissues (p < .001). The XRCC1 399Gln/Gln genotype, 399Gln allele, the dominant, and recessive models were significantly associated with lower XRCC1 expression in breast cancerous tissues and increased risk for BC (3.390-, 1.965-, 2.241-, and 2.429-folds, respectively). The XRCC1 399Gln/Gln genotype was associated with lower incidence of advanced tumor grade (OR: 0.06; 95%CI: 0.01-0.74; p = .028). Conversely, the XRCC1 Arg194Trp polymorphism did not show any significant association with either XRCC1 expression in breast cancer tissues or BC risk in all genetic models. The XRCC1 haplotypes, 399Gln/194Arg and 399Gln/194Trp, were associated with 1.800- and 1.675-folds risk for BC, respectively. The XRCC1 gene polymorphism (Arg399Gln) is associated with reduced XRCC1 tissue expression and enhanced BC risk with a well-differentiated nature in Egyptian women. Moreover, XRCC1 haplotypes, 399Gln/194Arg and 399Gln/194Trp, were associated with increased BC risk.

The multifunctional APE1 DNA repair-redox signaling protein as a drug target in human disease

Apurinic/apyrimidinic (AP) endonuclease-reduction/oxidation factor 1 (APE1/Ref-1, also called APE1) is a multifunctional enzyme with crucial roles in DNA repair and reduction/oxidation (redox) signaling. APE1 was originally described as an endonuclease in the Base Excision Repair (BER) pathway. Further study revealed it to be a redox signaling hub regulating critical transcription factors (TFs). Although a significant amount of focus has been on the role of APE1 in cancer, recent findings support APE1 as a target in other indications, including ocular diseases [diabetic retinopathy (DR), diabetic macular edema (DME), and age-related macular degeneration (AMD)], inflammatory bowel disease (IBD) and others, where APE1 regulation of crucial TFs impacts important pathways in these diseases. The central responsibilities of APE1 in DNA repair and redox signaling make it an attractive therapeutic target for cancer and other diseases.

Association between apurinic/apyrimidinic endonuclease 1 rs1760944 T>G polymorphism and susceptibility of cancer: a meta-analysis involving 21764 subjects

BACKGROUND

Previous case-control studies have suggested that apurinic/apyrimidinic endonuclease 1 (APE1) rs1760944 T>G polymorphism may be associated with cancer risk. Here, we carried out an updated meta-analysis to focus on the correlation between APE1 rs1760944 T>G locus and the risk of cancer.

METHODS

We used the crude odds ratios (ORs) with their 95% confidence intervals (CIs) to evaluate the possible relationship between the APE1 rs1760944 T>G polymorphism and cancer risk. Heterogeneity, publication bias and sensitivity analysis were also harnessed to check the potential bias of the present study.

RESULTS

Twenty-three independent studies involving 10166 cancer cases and 11598 controls were eligible for this pooled analysis. We found that APE1 rs1760944 T>G polymorphism decreased the risk of cancer in four genetic models (G vs. T: OR, 0.87; 95% CI, 0.83-0.92; P<0.001; GG vs. TT: OR, 0.77; 95% CI, 0.69-0.86; P<0.001; GG/TG vs. TT: OR, 0.83; 95% CI, 0.77-0.89, P<0.001 and GG vs. TT/TG: OR, 0.85; 95% CI, 0.80-0.92, P<0.001). Results of subgroup analyses also demonstrated that this single-nucleotide polymorphism (SNP) modified the risk among lung cancer, breast cancer, osteosarcoma, and Asians. Evidence of publication bias was found in the present study. When we treated the publication bias with 'trim-and-fill' method, the adjusted ORs and CIs were not significantly changed.

CONCLUSION

In conclusion, current evidence highlights that the APE1 rs1760944 T>G polymorphism is a protective factor for cancer susceptibility. In the future, case-control studies with detailed risk factors are needed to confirm or refute our findings.

Architecture of The Human Ape1 Interactome Defines Novel Cancers Signatures

APE1 is essential in cancer cells due to its central role in the Base Excision Repair pathway of DNA lesions and in the transcriptional regulation of genes involved in tumor progression/chemoresistance. Indeed, APE1 overexpression correlates with chemoresistance in more aggressive cancers, and APE1 protein-protein interactions (PPIs) specifically modulate different protein functions in cancer cells. Although important, a detailed investigation on the nature and function of protein interactors regulating APE1 role in tumor progression and chemoresistance is still lacking. The present work was aimed at analyzing the APE1-PPI network with the goal of defining bad prognosis signatures through systematic bioinformatics analysis. By using a well-characterized HeLa cell model stably expressing a flagged APE1 form, which was subjected to extensive proteomics analyses for immunocaptured complexes from different subcellular compartments, we here demonstrate that APE1 is a central hub connecting different subnetworks largely composed of proteins belonging to cancer-associated communities and/or involved in RNA- and DNA-metabolism. When we performed survival analysis in real cancer datasets, we observed that more than 80% of these APE1-PPI network elements is associated with bad prognosis. Our findings, which are hypothesis generating, strongly support the possibility to infer APE1-interactomic signatures associated with bad prognosis of different cancers; they will be of general interest for the future definition of novel predictive disease biomarkers. Future studies will be needed to assess the function of APE1 in the protein complexes we discovered. Data are available via ProteomeXchange with identifier PXD013368.

Correlation analysis of mRNA expression and prognosis of hOGG1 gene polymorphism in patients with non-small cell lung cancer

Level of mRNA expression and gene polymorphism of human 8-hydroxyguanine glycosidase 1 (hOGG1) in patients with non-small cell lung cancer (NSCLC) were investigated. A polymorphism analysis of hOGG1 gene rs1052133 locus in 182 NSCLC patients (NSCLC group) surgically treated in Xiang Yang No. 1 People's Hospital, Hubei University of Medicine from January 2008 to January 2012 and 200 healthy individuals (control group) was performed. The expression level of hOGG1 was compared between cancer tissues and adjacent tissues of NSCLC patients, and the survival rate was analyzed. The expression level of hOGG1 was significantly higher in cancer tissues than that in adjacent tissues (P<0.001). Taqman probe method was used to detect the genotypes of hOGG1 polymorphism locus rs1052133, with the genotype distribution frequencies of NSCLC group (P=0.411) and control group (P=0.354) consistent with the Hardy-Weinberg equilibrium. The proportion of C/C gene was significantly higher in NSCLC group than that in control group (P=0.008, OR=2.2, 95%, CI=1.27–4.52). The median value of the hOGG1 expression level in detection results as the boundary, NSCLC patients were divided into hOGG1 high expression group (≥3.61) with 91 cases and hOGG1 low expression group (<3.61) with 91 cases. The 1-, 2- and 3-year survival rates of patients in hOGG1 low expression group were significantly higher than those in hOGG1 high expression group (P=0.007). The 3-year survival rate in hOGG1 low expression group is significantly higher than that in hOGG1 high expression group (P=0.007). The sensitivity, specificity and AUC of hOGG1 to patient survival prediction were 83.33%, 64.29%, and 0.816, respectively. In conclusion, hOGG1 is highly expressed in NSCLC tissues. Compared to S/S and S/C genotypes, the C/C gene was found to be more common in NSCLC group than in control group. Thus, hOGG1 has a high predictive value for patient survival.

OGG1 rs1052133 Polymorphism and Genetic Susceptibility to Chronic Myelogenous Leukaemia

Background:

In some cancer cells, the OGG1 gene is somatically mutated and highly populated. This study was conducted to examine whether OGG1 rs1052133 polymorphism is associated with the genetic background of chronic myelogenous leukaemia (CML) in Sudan.

Methods:

A total of 332 CML patients and 70 healthy controls were included in this study. Overall, the genotypes (P=0.0000) and allele (C vs. G, P=0.0007) differed considerably in the frequencies of OGG1 rs1052133 polymorphism between CML patients and controls. Our study is the first to evaluate the association of polymorphism with CML risk with OGG1 rs1052133.

Results:

A statistically significant association was observed between the genotype distribution of OGG1 rs1052133 polymorphism and CML (P=0.0000) patients. A similar result was also observed in the allele distribution (C vs. G, P=0.0007) compared with healthy controls when compared OGG1 rs1052133 genotypes with CML stages.

Results:

Genotype and allele frequencies of OGG1 rs1052133 among CML patients. A statistically significant association was observed between the genotype distribution of the OGG1 rs1052133 polymorphism and CML patients (P=0.0000). A similar result was also observed in the allele distribution (C vs. G, P=0.0007) compared with healthy controls with stages of CML in OGG1 rs1052133 genotypes.

Conclusion:

The results suggest that single nucleotide polymorphism in the gene involved in the restoration of DNA base excision (OGG1 rs1052133) can play a key role in the risk of appearance of CML. To clarify the role of OGG1 in the genetic basis of CML, further case control with larger sample sizes and fine-mapping is required.

Evaluation of the exposure to coal dust and prevalence of pneumoconiosis in underground mining in three Colombian departments

Introduction: Coal workers’ pneumoconiosis is a chronic and irreversible disease representing a public health problem. Objective: To estimate the prevalence of pneumoconiosis and its associated factors among underground coal miners in the Colombian departments of Boyacá, Cundinamarca and Norte de Santander. Materials and methods: We conducted a cross-sectional study of 476 miners to measure the prevalence of pneumoconiosis and its associated factors such as coal dust and silica levels, as well as the occupational conditions. The medical assessment and a chest x-ray were performed according to the International Labor Organization criteria, along with spirometry and the identification of glutathione S-transferase and repair enzyme polymorphisms.The associations were explored using Cox regression models. Results: We performed a total of 479 environmental monitoring sessions in 31 companies and we evaluated 476 workers with 10 to 57 years of mining work experience. The prevalence of pneumoconiosis was 33.8% (95% CI: 27.0 - 41.3%). In the Cox multivariate regression model with a constant risk time, pneumoconiosis was significantly associated with working in medium-sized companies (PR=2.00, 95% CI: 0.995 - 2.690; p=0.052), the level of severe exposure to coal dust (PR=2.055, 95% CI: 1.043 - 4.048; p=0.038), and working in underground mining for 25 years or more (for those with 25.0-29.9 years: PR=2.199, 95% CI: 1.449 - 3.338; p=0.001). Conclusions: The prevalence of pneumoconiosis was very high and was found to be associated with severe exposure to coal dust, work exposure for 25 years or more and working in medium-sized enterprises

Evaluating the OGG1 rs1052133 and rs293795 polymorphisms in a sample of rural workers from Central Brazil population: a comparative approach with the 1000 Genomes Project

Brazilian population is one of the largest consumers of pesticides in the world, especially the Central Brazil population. Thus, the aim of this study was to evaluate the frequency of genotypes, alleles, haplotypes, and the linkage disequilibrium (DL) of the OGG1 gene in rural workers from Central Brazil, comparing with the populations of the 1000 genome. Three hundred thirty healthy individuals not related and randomly selected were included in this study. We obtained genomic DNA from peripheral blood lymphocytes. The 748-bp OGG1 gene was amplified by PCR and sequenced. Of the 330 individuals, 215 (65%) were males and 115 (35%) were females. There were no differences in the distribution of the rs1052133 and rs293795 with age and sexes. Haplotypes containing only conserved T/C alleles were the most common in our population. The frequency of the mutant alleles of rs1052133 and rs293795, in our population, was 20% and 30%, respectively, and it is noteworthy, worldwide, that mutant alleles are commonly associated to an increased risk for the development of cancer, specially due to direct or indirect contact to pesticides, as occurs in rural workers of Central Brazil population.

Polymorphisms of DNA repair genes are associated with colorectal cancer in patients with Lynch syndrome

BACKGROUND

DNA repair genes are crucial for maintaining genomic stability by preventing mutagenesis and carcinogenesis. The present retrospective cohort study aimed at investigating whether MLH1, APEX1, MUTYH, OGG1, NUDT1, XRCC5, XPA, and ERCC2 single nucleotide polymorphisms (SNPs) are associated with colorectal cancer (CRC) in Chinese population with Lynch syndrome.

METHODS

From Amsterdam criteria family registry, we identified 270 patients with Lynch syndrome. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between DNA repair SNPs and CRC were calculated using a weighted Cox proportional hazard regression model.

RESULTS

Heterozygous variants of rs1799832 in NUDT1 (HR = 2.97, 95% CI = 1.51-5.83) and rs13181 in ERCC2 (HR = 2.69, 95% CI = 1.10-6.55) were significantly associated with an increased risk of CRC compared with wild-type homozygous CC and TT genotypes, respectively. However, the variant CG+GG genotype of MUTYH rs3219489 was associated with a decreased risk of CRC (HR = 0.49, 95% CI = 0.26-0.91) compared with the homozygous CC wild-type counterparts.

CONCLUSION

Our findings revealed that polymorphisms of DNA repair genes that include NUDT1, ERCC2, and MUTYH are associated with CRC in patients with Lynch syndrome in Chinese population. Further studies with large sample size are needed to confirm our findings.

Human 8-oxoguanine DNA glycosylase gene polymorphism (Ser326Cys) and cancer risk: updated meta-analysis

Genetic polymorphism of human 8-oxoguanine glycosylase 1 (hOGG1) has been reported to have a relationship with the risk of the development of various cancers. Many studies have described the influence of Ser326Cys polymorphism of the hOGG1 gene on cancer susceptibility. However, the results have remained inconclusive and controversial. Therefore, we performed a meta-analysis to more precisely determine the relationship between the hOGG1 polymorphism and the development of cancer.Electronic databases including PubMed, Embase, Google Scholar, and the Korean Studies Information Service System (KISS) were searched. The odds ratio (OR), 95% confidence interval (CI), and p value were calculated to assess the strength of the association with the risk of cancer using Comprehensive Meta-analysis software (Corporation, NJ, USA). The 127 studies including 38,757 cancer patients and 50,177 control subjects were analyzed for the meta-analysis.Our meta-analysis revealed that G allele of Ser326Cys polymorphism of the hOGG1 gene statistically increased the susceptibility of cancer (all population, OR = 1.092, 95% CI = 1.051-1.134, p < 0.001; in Asian, OR = 1.095, 95% CI = 1.048-1.145, p < 0.001; in Caucasian, OR = 1.097, 95% CI = 1.033-1.179, p = 0.002). Also, other genotype models showed significant association with cancer (p < 0.05, respectively).The present meta-analysis concluded that the G allele was associated with an increased risk of cancer. It suggested that the hOGG1 polymorphism may be a candidate marker of cancer.

Association between the APEX1 Asp148Glu polymorphism and prostate cancer, especially among Asians: a new evidence-based analysis

Background

Prostate cancer (Pca) is a serious disease associated with considerable morbidity and mortality. As a causative factor, the Asp148Glu polymorphism has been identified in the apurinic/apyrimidinic endonuclease (APEX1) gene. However, the association among Asians is considered controversial.

Methods

Evidence for this association was obtained from the PubMed, Embase, HuGENet and Chinese National Knowledge Infrastructure (CNKI) databases. In the analysis, four models were applied. Associations between the APEX1 polymorphism and the invasiveness of Pca based on the Gleason score, prostate-specific antigen expression and clinical status were also evaluated.

Results

Seven articles were included in the analysis. Positive results were not only discovered in the pooled analysis, but also among patients of mixed descentand Asian descent. However, after considering the Hardy-Weinberg equilibrium (HWE), we observed only a 1.557-fold increase in Pca risk for subjects of Asian descent(GG vs. TT: OR=1.557, 95%CI=1.069-2.268) under the co-dominant model. Additionally, we did not also find any relationship between the APEX1 Asp148Glu polymorphism and invasive Pca risk.

Conclusion

On the basis of the function of the APEX1 Asp148Glu polymorphism, recent studies, and our results, we suggest that the APEX1 Asp148Glu polymorphism might be important in stimulating the development of Pca rather than its invasiveness in various populations, especially for Asians.

Contribution of DNA repair xeroderma pigmentosum group D genotypes to pancreatic cancer risk in the Chinese Han population

This study aimed to determine the association between the polymorphisms and haplotypes in the xeroderma pigmentosum group D (XPD) gene and the risk of pancreatic cancer in the Chinese Han population. SNaPshot was used for genotyping six SNP sites of the XPD gene. Comparisons of the correlations between different genotypes in combination with smoking and the susceptibility to pancreatic cancer were performed. Individual pancreatic cancer risk in patients who carry mutant C alleles (AC, CC, and AC+CC) at rs13181 increased (p < 0.05). Taking non-smoking individuals who carry the AA genotype as a reference, and non-smoking individuals who carry mutant allele C (AC+CC), the risk of pancreatic cancer increased by 3.343 times in individuals who smoked ≥ 20 cigarettes daily, 3.309 times in individuals who smoked ≥ 14 packs per year, 5.011 times in individuals who smoked ≥ 24 packs per year, and 4.013 times in the individuals who smoked ≥ 37 packs per year (P < 0.05). In addition, haplotype analysis revealed that haplotype AGG, which comprised rs13181, rs3916874 and rs238415, was associated with a 1.401-fold increase in pancreatic cancer risk (p < 0.05). We conclude that the polymorphism of XPD Lys751Gln (rs13181) in combination with smoking contributes to increased risk of pancreatic cancer in the Chinese Han population. Haplotype AGG might be a susceptibility haplotype for pancreatic cancer.

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.

The association analysis of hOGG1 genetic variants and gastric cancer risk in a Chinese population

Human 8-oxoguanine DNA glycosylase (hOGG1) is known to play an important role in the prevention of carcinogenesis, including gastric cancer (GC). We performed a case-control study to investigate whether single nucleotide polymorphisms (SNPs) of hOGG1 are associated with GC risk in a Chinese population. Two potential functional tagSNPs (rs159153 and rs1052133) and a previously reported risk SNP (rs125701) were genotyped in 1,275 GC patients and 1,436 controls. We found that SNP rs125701 G > A was significantly associated with the increased GC risk [adjusted odds ratio (OR) = 1.38, 95% confidence interval (CI) = 1.05-1.79 in additive model]. Besides, the functional studies demonstrated that the minor A allele of rs125701 significantly reduced the transcriptional activity of hOGG1 promoter and enhanced the methylation level of CpG site of cg15357639. In conclusion, our results suggested that the SNP rs125701 in hOGG1 promoter was associated with the elevated GC risk, which could act as a new potential biomarker for GC susceptibility. Further functional verification of rs125701 in GC pathogenesis is warranted.

Association between the OGG1 Ser326Cys Polymorphism and Cancer Risk: Evidence from 152 Case-Control Studies

Although it has been suggested that the 8-oxoguanine DNA glycosylase (OGG1) gene Ser326Cys polymorphism may be a risk factor for cancer, the conclusions from previous studies are inconsistent. Thus, we conducted an updated meta-analysis to estimate the effect of OGG1 variant genotypes on cancer susceptibility. We searched the PubMed for all eligible studies published in English for the period ending September 2014. We found the association between OGG1 Ser326Cys polymorphism and cancer susceptibility based on 152 case-control studies in different genetic model comparisons (dominant model: OR = 1.053, P = 0.018; recessive model: OR = 1.108, P < 0.001; homozygote: OR = 1.135, P < 0.001; additive model: OR = 1.059, P < 0.001). However, the results from the subgroup analyses based on types of cancer, health population as controls or studies with relatively large sample size did not support the conclusion. Although the overall results of this meta-analysis showed a positive association between OGG1 variant genotypes and cancer susceptibility, the subgroup analyses by cancer type, sample size, and source of controls presented inconsistent results. Therefore, the current evidence from the meta-analysis did not support the hypothesis of OGG1 Ser326Cys polymorphism as a risk factor of cancer.

Association of DNA Repair Gene APE1 Asp148Glu Polymorphism with Breast Cancer Risk

OBJECTIVE

The aim of this study was to investigate the role of APE1 Asp148Glu polymorphism in breast cancer progression in Saudi population.

METHODS

We examined the genetic variations (rs1130409) in the DNA base excision repair gene APE1 at codon 148 (Asp148Glu) and its association with breast cancer risk using genotypic assays and in silico structural as well as functional predictions. In silico structural analysis was performed with Asp148Glu allele and compared with the predicted native protein structure. The wild and mutant 3D structures of APE1 were compared and analyzed using solvent accessibility models for protein stability confirmation.

RESULTS

Genotypic analysis of APE1 (rs1130409) showed statistically significant association of Asp148Glu with elevated susceptibility to breast cancer. The in silico analysis results indicated that the nsSNP Asp148Glu may cause changes in the protein structure and is associated with breast cancer risk.

CONCLUSION

Taken together, this is the first report that established that Asp148Glu variant has structural and functional effect on the APE1 and may play an important role in breast cancer progression in Saudi population.

Germline variations of apurinic/apyrimidinic endonuclease 1 (APEX1) detected in female breast cancer patients

Apurinic/apyrimidinic endonuclease 1 (APEX1) is a multifunctional protein which plays a central role in the BER pathway. APEX1 gene being highly polymorphic in cancer patients and has been indicated to have a contributive role in Apurinic/apyrimidinic (AP) site accumulation in DNA and consequently an increased risk of cancer development. In this case-control study, all exons of the APEX1 gene and its exon/intron boundaries were amplified in 530 breast cancer patients and 395 matched healthy controls and then analyzed by single-stranded conformational polymorphism followed by sequencing. Sequence analysis revealed fourteen heterozygous mutations, seven 5'UTR, one 3 'UTR, two intronic and four missense. Among identified mutations one 5'UTR (rs41561214), one 3'UTR (rs17112002) and one missense mutation (Ser129Arg, Mahjabeen et al., 2013) had already been reported while the remaining eleven mutations. Six novel mutations (g.20923366T>G, g.20923435G>A, g.20923462G>A, g.20923516G>A, 20923539G>A, g.20923529C>T) were observed in 5'UTR region, two (g.20923585T>G, g.20923589T>G) in intron1 and three missense (Glu101Lys, Ala121Pro, Ser123Trp) in exon 4. Frequencues of 5'UTR mutations; g.20923366T>G, g.20923435G>A and 3'UTR (rs17112002) werecalculated as 0.13, 0.1 and 0.1 respectively. Whereas, the frequency of missense mutations Glu101Lys, Ser123Trp and Ser129Arg was calculated as 0.05. A significant association was observed between APEX1 mutations and increased breast cancer by ~9 fold (OR=8.68, 95%CI=2.64 to 28.5) with g.20923435G>A (5'UTR) , ~13 fold (OR= 12.6, 95%CI=3.01 to 53.0) with g.20923539G>A (5'UTR) and~5 fold increase with three missense mutations [Glu101Lys (OR=4.82, 95%CI=1.97 to 11.80), Ser123Trp (OR=4.62, 95%CI=1.7 to 12.19), Ser129Arg (OR=4.86, 95%CI=1.43 to 16.53)]. The incidence of observed mutations was found higher in patients with family history and with early menopause. In conclusion, our study demonstrates a significant association between germ line APEX1 mutations and breast cancer patients in the Pakistani population.

OGG1 Mutations and Risk of Female Breast Cancer: Meta-Analysis and Experimental Data

In first part of this study association between OGG1 polymorphisms and breast cancer susceptibility was explored by meta-analysis. Second part of the study involved 925 subjects, used for mutational analysis of OGG1 gene using PCR-SSCP and sequencing. Fifteen mutations were observed, which included five intronic mutations, four splice site mutations, two 3'UTR mutations, three missense mutations, and a nonsense mutation. Significantly (p < 0.001) increased (~29 fold) breast cancer risk was associated with a splice site variant g.9800972T>G and 3'UTR variant g.9798848G>A. Among intronic mutations, highest (~15 fold) increase in breast cancer risk was associated with g.9793680G>A (p < 0.009). Similarly ~14-fold increased risk was associated with Val159Gly (p < 0.01), ~17-fold with Gly221Arg (p < 0.005), and ~18-fold with Ser326Cys (p < 0.004) in breast cancer patients compared with controls, whereas analysis of nonsense mutation showed that ~13-fold (p < 0.01) increased breast cancer risk was associated with Trp375STOP in patients compared to controls. In conclusion, a significant association was observed between OGG1 germ line mutations and breast cancer risk. These findings provide evidence that OGG1 may prove to be a good candidate of better diagnosis, treatment, and prevention of breast cancer.

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.

Updated assessment of the association of the XRCC1 Arg399Gln polymorphism with lung cancer risk in the Chinese population

BACKGROUND

Published studies have reported relationships between X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln polymorphism and lung cancer risk in Chinese population. However, the epidemiological results remained controversial. The objective of this study was to clarify the association of XRCC1 Arg399Gln polymorphism with lung cancer risk in the Chinese population.

MATERIALS AND METHODS

Systematic searches were performed through the database of Medline/Pubmed, Web of Science, Embase, CNKI and WanFang Medical Online. Odds ratios (ORs) with 95% confidence interval (95%CI) were calculated to estimate the strength of the association.

RESULTS

Overall, we observed an increased lung cancer risk among subjects carrying XRCC1 codon 399 Gln/Gln genotype (OR=1.36, 95%CI: 1.09-1.71) in the Chinese population on the basis of 19 studies with 5,416 cases and 5,782 controls. We did not observe any association between XRCC1 codon 399 Arg/Gln and Arg/Gln+Gln/Gln polymorphisms and lung cancer risk (OR=1.00, 95%CI: 0.92-1.08 and OR=1.05, 95%CI: 0.97- 1.13, respectively). Limiting the analysis to studies with controls in agreement with Hardy-Weinberg equilibrium (HWE), we observed an increased lung cancer risk among subjects carrying XRCC1 codon 399 Gln/Gln genotype (OR=1.18, 95%CI: 1.01-1.38). When stratified by source of control, we observed an increased lung cancer risk among subjects carrying XRCC1 codon 399 Arg/Gln+Gln/Gln genotype on the basis of hospitalized patient-based controls (OR=1.21, 95%CI: 1.04-1.42) and among subjects carrying XRCC1 codon 399 Gln/Gln genotype on the basis of healthy subject-based controls (OR=1.22, 95%CI: 1.04-1.43).

CONCLUSIONS

Our findings indicated that certain XRCC1 Arg399Gln variants might affect the susceptibility of lung cancer in Chinese population. Larger sample size studies are required to confirm our findings.

Potential anti-cancer effect of curcumin in human lung squamous cell carcinoma

Background

To explore the molecular mechanisms of the anti-cancer effect of curcumin in human lung squamous cell carcinoma (LSQCC) SK-MES-1 cells.

Methods

Cell viability was determined using MTT assay. Ribonucleic acid sequencing was performed to measure expression levels of transcripts in LSQCC cells treated with 15 μmol/L curcumin (treatment groups) or an equal amount of dimethylsulfoxide (control). Cuffdiff software was used to identify differentially expressed genes (DEGs) in treatment groups, followed by enrichment analysis of DEGs using the Database for Annotation, Visualization and Integration Discovery. The protein-protein interaction (PPI) networks for up and downregulated DEGs were constructed by Cytoscape software using Search Tool for the Retrieval of Interacting Genes data to identify hub nodes.

Results

Curcumin significantly reduced cell viability in LSQCC cells. In total, 380 DEGs including 154 upregulated and 126 downregulated genes were found in the treatment groups. The upregulated genes were enriched in base excision repair (BER, such as PCNA, POLL, and MUTYH) and Janus kinase-signal transducer and activator of transcription (JAT-STAT) signaling pathways (such as AKT1 and STAT5A), while the downregulated genes were enriched in nine pathways, including the vascular endothelial growth factor (VEGF) signaling pathway (such as PTK2, VEGFA, MAPK1, and MAPK14) and mitogen-activated protein kinase (MAPK) signaling pathway (ARRB2, MAPK1, MAPK14, and NFKB1). PCNA and AKT1 were the hub nodes in the PPI network of upregulated genes while MAPK1, MAPK14, VEGFA, and NFKB1 were the hub nodes in the PPI network of downregulated genes.

Conclusions

Curcumin might exert anti-cancer effects on LSQCC via regulating BER, JAT-STAT, VEGF, and MAPK signaling pathways.

Association of DNA base-excision repair XRCC1, OGG1 and APE1 gene polymorphisms with nasopharyngeal carcinoma susceptibility in a Chinese population

BACKGROUND

Numerous carcinogens and reactive oxygen species (ROS) may cause DNA damage including oxidative base lesions that lead to risk of nasopharyngeal carcinoma. Genetic susceptibility has been reported to play a key role in the development of this disease. The base excision repair (BER) pathway can effectively remove oxidative lesions, maintaining genomic stability and normal expression, with X-ray repair crosscomplementing1 (XRCC1), 8-oxoguanine glycosylase-1 (OGG1) and apurinic/apyimidinic endonuclease 1 (APE1) playing important roles.

AIMS

To analyze polymorphisms of DNA BER genes (OOG1, XRCC1 and APE1) and explore their associations, and the combined effects of these variants, with risk of nasopharyngeal carcinoma.

MATERIALS AND METHODS

We detected SNPs of XRCC1 (Arg399Gln), OGG1 (Ser326Cys), APE1 (Asp148Glu and -141T/G) using the polymerase chain reaction (PCR) with peripheral blood samples from 231 patients with NPC and 300 healthy people, furtherly analyzing their relations with the risk of NPC in multivariate logistic regression models.

RESULTS

After adjustment for sex and age, individuals with the XRCC1 399Gln/Gln (OR=1.96; 95%CI:1.02- 3.78; p=0.04) and Arg/Gln (OR=1.87; 95%CI:1.29-2.71; p=0.001) genotype variants demonstrated a significantly increased risk of nasopharyngeal carcinoma compared with those having the wild-type Arg/Arg genotype. APE1- 141G/G was associated with a significantly reduced risk of NPC (OR=0.40;95%CI:0.18-0.89) in the smoking group. The OR calculated for the combination of XRCC1 399Gln and APE1 148Gln, two homozygous variants ,was significantly additive for all cases (OR=2.09; 95% CI: 1.27-3.47; p=0.004).

CONCLUSION

This is the first study to focus on the association between DNA base-excision repair genes (XRCC1, OGG1 and APE1) polymorphism and NPC risk. The XRCC1 Arg399Gln variant genotype is associated with an increased risk of NPC. APE1- 141G/G may decrease risk of NPC in current smokers. The combined effects of polymorphisms within BER genes of XRCC1 399Gln and APE1 148Gln may contribute to a high risk of nasopharyngeal carcinoma.

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.

Single nucleotide polymorphisms of DNA base-excision repair genes (APE1, OGG1 and XRCC1) associated with breast cancer risk in a Chinese population

Altered DNA repair capacity can result in increased susceptibility to cancer. The base excision repair (BER) pathway effectively removes DNA damage caused by ionizing radiation and reactive oxidative species (ROS). In the current study, we analyzed the possible relation of polymorphisms in BER genes, including 8-oxoguanine DNA glycosylase (OGG1), apurinic/apyrimidinic endonuclease 1 (APE1), and X-ray repair cross-complementing group 1 protein (XRCC1), with breast cancer risk in Chinese Han women. This case-control study examined 194 patients with breast cancer and 245 cancer-free hospitalized control subjects. Single nucleotide polymorphisms (SNPs) of OGG1 (Ser326Cys), XRCC1 (Arg399Gln), and APE1 (Asp148Glu and -141T/G) were genotyped and analyzed for their association with breast cancer risk using multivariate logistic regression models. We found that XRCC1 Arg399Gln was significantly associated with an increased risk of breast cancer. Similarly, the XRCC1 Gln allele was significantly associated with an elevated risk in postmenopausal women and women with a high BMI (≥ 24 kg/m2). The OGG1 Cys allele provided a significant protective effect against developing cancer in women with a low BMI (< 24 kg/m2). When analyzing the combined effects of these alleles on the risk of breast cancer, we found that individuals with ≥ 2 adverse genotypes (XRCC1 399Gln, APE1 148Asp, and OGG1 326Ser) were at a 2.18-fold increased risk of breast cancer (P = 0.027). In conclusion, our data indicate that Chinese women with the 399Gln allele of XRCC1 have an increased risk of breast cancer, and the combined effects of polymorphisms of BER genes may contribute to tumorigenesis.

Increased oxidative DNA damage and decreased expression of base excision repair proteins in airway epithelial cells of women who cook with biomass fuels

To investigate whether biomass burning causes oxidative DNA damage and alters the expression of DNA base excision repair (BER) proteins in airway cells, sputum samples were collected from 80 premenopausal rural biomass-users and 70 age-matched control women who cooked with liquefied petroleum gas. Compared with control the airway cells of biomass-users showed increased DNA damage in alkaline comet assay. Biomass-users showed higher percentage of cells expressing oxidative DNA damage marker 8-oxoguanine and lower percentages of BER proteins OGG1 and APE1 by immunocytochemical staining. Reactive oxygen species (ROS) generation was doubled and level of superoxide dismutase was depleted significantly among biomass-users. The concentrations of particulate matters were higher in biomass-using households which positively correlated with ROS generation and negatively with BER proteins expressions. ROS generation was positively correlated with 8-oxoguanine and negatively with BER proteins suggesting cooking with biomass is a risk for genotoxicity among rural women in their child-bearing age.

Human AP endonuclease 1: a potential marker for the prediction of environmental carcinogenesis risk

Human apurinic/apyrimidinic endonuclease 1 (APE1) functions mainly in DNA repair as an enzyme removing AP sites and in redox signaling as a coactivator of various transcription factors. Based on these multifunctions of APE1 within cells, numerous studies have reported that the alteration of APE1 could be a crucial factor in development of human diseases such as cancer and neurodegeneration. In fact, the study on the combination of an individual's genetic make-up with environmental factors (gene-environment interaction) is of great importance to understand the development of diseases, especially lethal diseases including cancer. Recent reports have suggested that the human carcinogenic risk following exposure to environmental toxicants is affected by APE1 alterations in terms of gene-environment interactions. In this review, we initially outline the critical APE1 functions in the various intracellular mechanisms including DNA repair and redox regulation and its roles in human diseases. Several findings demonstrate that the change in expression and activity as well as genetic variability of APE1 caused by environmental chemical (e.g., heavy metals and cigarette smoke) and physical carcinogens (ultraviolet and ionizing radiation) is likely associated with various cancers. These enable us to ultimately suggest APE1 as a vital marker for the prediction of environmental carcinogenesis risk.

The interaction of APEX1 variant with polycyclic aromatic hydrocarbons on increasing chromosome damage and lung cancer risk among male Chinese

Polycyclic aromatic hydrocarbons (PAHs) are the most significant contributors to tobacco-induced lung carcinogenesis. Apurinic/apyrimidinic endonuclease 1 (APE1) is a central enzyme in the removal of apurinic/apyrimidinic sites caused by DNA damaging agents. This study aimed to investigate the potential interaction of APEX1 polymorphisms and PAHs on genetic damage and lung cancer risk among male Chinese. We recruited an occupational cohort of 922 male coke oven workers and determined their DNA damage levels by calculating the lymphocytic micronucleus (MN) frequencies. Two well-studied APEX1 polymorphisms (-307A > C and Asp148Glu) and their associations with MN frequencies were examined. The impact of MN-related single nucleotide polymorphism (SNP) on lung cancer risk was further investigated in two case-control studies including 1634 male lung cancer patients and 1678 controls. It was shown that, the APEX1 148Glu allele was associated with significantly higher MN frequencies than 148Asp allele, with strongest associations among the highest PAH-exposure workers (P = 0.008). The APEX1 148Glu allele was also associated with increased lung cancer risk among male smokers, especially among heavy smokers in both case-control studies (odd ratio: 4.40, 95%CI: 3.29-5.72). In addition, APEX1 148Glu variant interacts with smoking in increasing male lung cancer risk, as measured by the attributable proportion due to interaction, which was 0.23 (95%CI: 0.06-0.39). This study showed evidence on interaction between APEX1 148Glu variant and cigarette smoking in increasing lung cancer susceptibility among male Chinese, which may be due to the synergistic effects of APEX1 148Glu and PAHs in increasing chromosome damage levels. The results provide a new insight into gene-interactions in lung carcinogenesis.

APE1 polymorphisms are associated with colorectal cancer susceptibility in Chinese Hans

AIM: To study the association between four base excision repair gene polymorphisms and colorectal cancer risk in a Chinese population.

METHODS: Two hundred forty-seven colorectal cancer (CRC) patients and three hundred cancer-free controls were enrolled in this study. Four polymorphisms (OGG1 Ser326Cys, APE1 Asp148Glu, -141T/G in the promoter region, and XRCC1 Arg399Gln) in components of the base excision repair pathway were determined in patient blood samples using polymerase chain reaction with confronting two-pair primers. The baseline information included age, gender, family history of cancer, and three behavioral factors [smoking status, alcohol consumption, and body mass index (BMI)]. χ² tests were used to assess the Hardy-Weinberg equilibrium, the distributions of baseline characteristics, and the four gene polymorphisms between the cases and controls. Multivariate logistic regression analyses were conducted to analyze the correlations between the four polymorphisms and CRC risk, adjusted by the baseline characteristics. Likelihood ratio tests were performed to analyze the gene-behavior interactions of smoking status, alcohol consumption, and BMI on polymorphisms and CRC susceptibility.

RESULTS: The APE1 148 Glu/Glu genotype was significantly associated with an increased risk of colorectal cancer (OR = 2.411, 95%CI: 1.497-3.886, P < 0.001 relative to Asp/Asp genotype). There were no associations between OGG1, XRCC1, or APE1 promoter polymorphisms and CRC risk. A multivariate analysis including three behavioral factors showed that the APE1 148 Glu/Glu genotype was associated with an increased risk for CRC among both smokers and non-smokers, non-drinkers and individuals with a BMI ≥ 25 kg/m² (ORs = 2.356, 3.299, 2.654, and 2.581, respectively). The XRCC1 399 Arg/Gln genotype was associated with a decreased risk of CRC among smokers and drinkers (OR = 0.289, 95%CI: 0.152-0.548, P < 0.001, and OR = 0.327, 95%CI: 0.158-0.673, P < 0.05, respectively). The APE1 promoter polymorphism -141 T/G genotype was associated with a reduced risk of colorectal cancer among subjects with a BMI < 25 kg/m² (OR = 0.214, 95%CI: 0.069-0.660, P < 0.05 relative to T/T genotype). There were significant gene-behavior interactions between smoking status and XRCC1 Arg399Gln, as well as BMI and APE1 -141T/G polymorphism (all P < 0.05).

CONCLUSION: APE1 Asp148Glu is associated with increased CRC risk and smoking alters the association between XRCC1 Arg399Gln and CRC risk in the Chinese Han population.

Association of DNA base excision repair genes (OGG1, APE1 and XRCC1) polymorphisms with outcome to platinum-based chemotherapy in advanced nonsmall-cell lung cancer patients

Polymorphism of DNA base excision repair (BER) genes affects DNA repair capacity and may alter sensitivity to platinum-based chemotherapy regimens. This study investigated polymorphisms of OGG1 Ser326Cys, APE1 Asp148Glu APE1-141T/G and XRCC1 Arg399Gln for association with clinical outcome in 235 advanced inoperable nonsmall-cell lung cancer (NSCLC) patients after treatment with platinum-based chemotherapy. The multivariate analysis showed that OGG1 326 GC was associated with poor PFS [hazard ratio (HR) 1.730, p = 0.005], while XRCC1 399 GA, or GA+AA, was associated with poor OS in short-term period (HR 1.718, p = 0.003; HR 1.691, p = 0.003, respectively). Patients with OGG1 326/XRCC1 399 variant alleles had a higher risk to die early in short-term period (HR 1.929, p < 0.001). Furthermore, patients with XRCC1 399 variant allele (GA+AA) had higher risk of hematologic toxicity (p = 0.009), whereas patients carrying the OGG1 326 variant (GG), or the APE1-141 GG variant, had reduced risk of gastrointestinal toxicity (p = 0.015 and p = 0.023, respectively). The data from the current study provide evidence that OGG1 Ser326Cys, XRCC1 Arg399Gln, APE1 Asp148Glu, and APE1-141T/G polymorphisms may be useful in predicting clinical outcomes in patients with advanced inoperable NSCLC that will undergo platinum-based chemotherapy.

Association between APE1 Single Nucleotide Polymorphism (rs1760944) and Cancer Risk: a Meta-Analysis Based on 6,419 Cancer Cases and 6,781 Case-free Controls

Apurinic/apyrimidinic endonuclease 1 (APE1) is an essential enzyme in the base excision repair pathway. Epidemiological studies have suggested associations between APE1 rs1760944 polymorphism and cancer risk. This study was aimed to evaluate the relationship between APE1 rs1760944 polymorphism and cancer risk. We searched Pubmed, ISI Web of Knowledge, Embase, Chinese National Knowledge Infrastructure (CNKI) databases until September 2013 to identify eligible studies. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to estimate the strength of the associations. 12 studies from 11 articles on APE1 rs1760944 genotypes and cancer risk were identified, including a total of 6,419 cancer cases and 6,781 case-free controls. Overall, APE1 rs1760944 polymorphism was significantly associated with the decreased risk of cancer in any genetic models (G vs. T: OR = 0.86, 95% CI = 0.82-0.90; homozygote comparison: OR = 0.74, 95% CI = 0.67-0.82; heterozygote comparison: OR =0.88, 95%CI = 0.81-0.95; dominant model TG+GG vs. TT: OR = 0.82, 95% CI = 0.76-0.89; recessive model GG vs. TT+TG: OR = 0.81, 95%CI = 0.75-0.88). In the stratified analysis by populations, the effect was remain in studies of Asian population (homozygote comparison: OR = 0.71, 95%CI = 0.63-0.79; heterozygote comparison: OR = 0.86, 95 %CI = 0.79- 0.94; dominant model: OR = 0.80, 95% CI = 0.74 -0.87 and recessive model: OR = 0.78, 95%CI = 0.71-0.86). Moreover, a significantly decreased risk was found in lung cancer studies (homozygote comparison: OR = 0.68, 95% CI = 0.59-0.79; heterozygote comparison: OR = 0.86, 95%CI = 0.77- 0.98; dominant model: OR = 0.80, 95%CI = 0.72-0.90 and recessive model: OR= 0.77, 95% CI= 0.68-0.87). These findings support that APE1 rs1760944 polymorphism has a possible protective effect on cancer susceptibility particularly among Asians. Further studies based on different ethnicity and various cancer types are warranted to verify our findings.

hOGG1 Ser326Cys polymorphism and lung cancer susceptibility: a meta-analysis

The Ser326Cys polymorphism in the human 8-oxogunaine glycosylase (hOGG1) gene with lung cancer susceptibility had been investigated by the approaches of PCR-RFLP, PCR-SSCP and ASA. Due to limited specimen and different approaches the conclusion was drawn toughly. To evaluate this correlation comprehensively, a meta-analysis was performed based on 30 case-control studies, including 10,327 cases and 12,148 controls. The random-effects model was used to estimate the odds ratios and 95 % confidence interval for various contrasts of this polymorphism. The combined results suggested that the hOGG1 Ser326Cys polymorphism was not associated with lung cancer susceptibility in different genetic models. Similarly, in the stratified analyses by ethnicity and source of control, no risk was observed between all the genetic models and lung cancer risk. Our meta-analysis revealed that there was little correlation between the hOGG1 Ser326Cys polymorphism and the risk of lung cancer.

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

OBJECTIVE

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

RESEARCH DESIGN AND METHODS

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

MAIN OUTCOME MEASURES AND RESULTS

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

CONCLUSIONS

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

APEX nuclease (multifunctional DNA repair enzyme) 1 gene Asp148Glu polymorphism and cancer risk: a meta-analysis involving 58 articles and 48903 participants

BACKGROUND

Polymorphisms in the APEX nuclease (multifunctional DNA repair enzyme) 1 gene (APEX1) may be involved in the carcinogenesis by affecting DNA repair. We aimed to summarize available data on the association of the APEX1 Asp148Glu (rs1130409) polymorphism with risk of multiple types of cancer via a meta-analysis.

METHODS AND RESULTS

In total, 58 qualified articles including 22,398 cancer patients and 26,505 controls were analyzed, and the data were extracted independently by two investigators. Analyses of the full data set indicated a marginally significant association of the APEX1 Asp148Glu polymorphism with cancer risk under allelic (odds ratio (OR)=1.05; 95% confidence interval (95% CI): 0.99-1.11; P=0.071), dominant (OR=1.09; 95% CI: 1.01-1.17; P=0.028), and heterozygous genotypic (OR=1.08; 95% CI: 1.01-1.16; P=0.026) models, with significant heterogeneity and publication bias. In subgroup analyses by cancer type, with a Bonferroni corrected alpha of 0.05/6, significant association was observed for gastric cancer under both dominant (OR=1.74; 95% CI: 1.2-2.51; P=0.003) and heterozygous genotypic (OR=1.66; 95% CI: 1.2-2.31; P=0.002) models. In subgroup analysis by ethnicity, risk estimates were augmented in Caucasians, especially under dominant (OR=1.11; 95% CI: 1.0-1.24; P=0.049) and heterozygous genotypic (OR=1.11; 95% CI: 0.99-1.24; P=0.063) models. By study design, there were no significant differences between population-based and hospital-based studies. In subgroup analysis by sample size, risk estimates were remarkably overestimated in small studies, and no significance was reached in large studies except under the heterozygous genotypic model (OR=1.23; 95% CI: 1.06-1.43; P=0.006, significant at a Bonferroni corrected alpha of 0.05/2). By quality score, the risk estimates, albeit nonsignificant, were higher in low-quality studies than in high-quality studies. Further meta-regression analyses failed to identify any contributory confounders for the associated risk estimates.

CONCLUSIONS

Our findings suggest that APEX1 Asp148Glu polymorphism might be a genetic risk factor for the development of gastric cancer. Further investigations on large populations are warranted.

The association of APE1 Asp148Glu gene polymorphisms and lung cancer risk: an updated meta-analysis

Many studies have examined the association between APE1 Asp148Glu (rs3136820) polymorphism gene polymorphisms and lung cancer risk in various populations, but their results have been inconsistent. To assess this relationship more precisely, a meta-analysis was performed. PubMed and CNKI databases were searched for case-control studies published up to October 2013. Data were extracted, and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated. Ultimately, 14 studies, comprising 4,165 lung cancer cases and 5,438 controls were included. Overall, for Glu carriers (Asp/Glu + Glu/Glu) versus wild-type homozygotes (Asp/Asp), the pooled OR was 1.05 (95% CI = 0.96-1.15 P = 0.000 for heterogeneity); for Glu/Glu versus Asp/Asp, the pooled OR was 1.07 (95% CI = 0.95-1.21 P = 0.007 for heterogeneity). In the stratified analysis by ethnicity, the significantly risks were not found among Asians or Caucasians. This updated meta-analysis suggests that the APE1 Asp148Glu polymorphisms are not associated with lung cancer risk among Asians or Caucasians.

Smoking and hOGG1 Ser326Cys polymorphism contribute to lung cancer risk: evidence from a meta-analysis

The human 8-oxoguanine DNA glycosylase (hOGG1) gene plays an important role in the repair of oxidatively damaged DNA base lesions and its functional single nucleotide polymorphisms (SNPs) may alter DNA repair capacity and thus contributes to cancer susceptibility. Numerous studies have investigated the association between hOGG1 Ser326Cys polymorphism and lung cancer susceptibility; however, the conclusions are still inconclusive. We searched eligible publications from MEDLINE, EMBASE, and CBM and performed a meta-analysis to assess the associations between hOGG1 Ser326Cys polymorphism and lung cancer risk. Pooled odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated to estimate risk associations, and false-positive report probability (FPRP) analysis was also carried out to evaluate significant findings. A total of 31 investigations with 10,220 cases and 12,284 controls were identified. When all studies were pooled, a significantly increased overall lung cancer risk was found (Cys/Cys vs. Ser/Ser: OR = 1.24, 95 % CI = 1.05-1.47, P = 0.013; recessive model: OR = 1.22, 95 % CI = 1.05-1.41, P = 0.008, and Cys vs. Ser: OR = 1.11, 95 % CI = 1.02-1.21, P = 0.022), and further stratification analysis showed that the association was stronger in Asians, never smokers, and more-cigarette takers. These results were confirmed by FPRP analysis. Despite some limitations, this meta-analysis provides solid evidence that hOGG1 Ser326Cys polymorphism may contribute to lung cancer risk, particularly for Asian populations, never smokers, and more-cigarette takers. Nevertheless, these findings warrant further validation in single large investigations.

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

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

Association between the hOGG1 Ser326Cys polymorphism and lung cancer susceptibility: a meta-analysis based on 22,475 subjects

Objectives

The Ser326Cys polymorphism in the human 8-oxogunaine glycosylase (hOGG1) gene with lung cancer susceptibility had been investigated, but results were inconsistent and underpowered. The aim of this study was to conduct a meta-analysis assessing the association of hOGG1 Ser326Cys polymorphism with risk of lung cancer.

Materials and methods

Relevant studies were identified through a search of MEDLINE, PubMed, Web of Science, EMBASE, and Chinese Biomedical Literature database (CBM) using terms “lung cancer”, “hOGG1” or “OGG1”, “polymorphism” or “variation” and the last search updated on May 1, 2013. In this meta-analysis, we assessed 30 published studies involving 22,475 subjects that investigated the association between the hOGG1 Ser326Cys polymorphism and lung cancer susceptibility.

Results

Overall, the hOGG1 Ser326Cys polymorphism was not associated with lung cancer susceptibility in different genetic models (dominant model comparison: OR = 0.133; 95% CI = 0.111–0.161; P_{heterogeneity} = 0.000), and recessive model: OR = 0.543; 95% CI = 0.399–0.739; P_{heterogeneity} = 0.000). Similarly, in the stratified analyses by ethnicity, significantly increased risks were found among Asians for homozygote comparison (OR = 0.850; 95% CI = 0.732 0.986; P_{heterogeneity} = 0.064), and dominant model (OR = 0.160; 95% CI = 0.137–0.187; P_{heterogeneity} = 0.001), and Caucasians for dominant model (OR = 1.35; 95% CI = 1.03–1.77; P_{heterogeneity} = 0.015), and recessive model (OR = 1.35; 95% CI = 1.03–1.77; P_{heterogeneity} = 0.015). In population-based populations, marginally significant increased risks were found in dominant model (OR = 0.143; 95% CI = 0.111 0.184; P_{heterogeneity} = 0.000) and recessive model (OR = 0.429; 95% CI = 0.261–0.705; P_{heterogeneity} = 0.000). We also found a significant difference between hOGG1 Ser326Cys genotype and lung cancer susceptibility in studies with hospital-based controls for homozygote model (OR = 0.798; 95% CI = 0.649–0.982; P_{heterogeneity} = 0.007),dominant model (OR = 0.122; 95% CI = 0.091–0.163; P_{heterogeneity} = 0.000).

Conclusion

Our data showed that the hOGG1 Ser326Cys polymorphism contributed to the risk of lung cancer.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/3842531131031605

Polymorphisms of DNA repair genes XPD, XRCC1, and OGG1, and lung adenocarcinoma susceptibility in Chinese population

Lung adenocarcinoma (ADC) is one of the major histological types of lung cancer. Genetic polymorphism in DNA repair genes and lung ADC susceptibility is well documented. In this case-control study, the association between the polymorphic sites of DNA repair genes XPD-751, XRCC1-399, and OGG1-326, and lung ADC susceptibility in ethnic Han Chinese population has been investigated. Genomic DNA was isolated from the peripheral blood of 201 healthy controls and 82 lung ADC patients from the people of Hunan Province, China. Polymorphisms of the investigated genes were analyzed by using polymerase chain reaction-restriction fragment length polymorphism. There was no significant difference between the samples from lung ADC patients and healthy controls about the genotype frequencies of XPD-751, XRCC1-399, and OGG1-326 sites. However, multifactor dimensionality reduction analysis showed that the genetic polymorphisms of the three-loci models of DNA repair genes (XPD-751/XRCC1-399/OGG1-326) are associated with lung ADC. Thus, this study reveals that a three-order interaction among the polymorphic sites of XPD-751, XRCC1-399, and OGG1-326 is associated with lung ADC risk in the studied population, although polymorphism in individual gene was not associated.

DNA repair genes polymorphism and lung cancer risk with the emphasis to sex differences

Polymorphisms in nucleotide and base excision repair genes are associated with the variability in the risk of developing lung cancer. In the present study, we investigated the polymorphisms of following selected DNA repair genes: XPC (Lys939Gln), XPD (Lys751Gln), hOGG1 (Ser326Cys) and XRCC1 (Arg399Gln), and the risks they present towards the development of lung cancer with the emphasis to gender differences within the Slovak population. We analyzed 761 individuals comprising 382 patients with diagnosed lung cancer and 379 healthy controls. Genotypes were determined by polymerase chain reaction/restriction fragment length polymorphism method. We found out statistically significant increased risk for lung cancer development between genders. Female carrying XPC Gln/Gln, XPC Lys/Gln+Gln/Gln and XRCC1 Arg/Gln, XRCC1 Arg/Gln+Gln/Gln genotypes had significantly increased risk of lung cancer corresponding to OR = 2.06; p = 0.04, OR = 1.66; p = 0.04 and OR = 1.62; p = 0.04, OR = 1.69; p = 0.02 respectively. In total, significantly increased risk of developing lung cancer was found in the following combinations of genotypes: XPD Lys/Gln+XPC Lys/Lys (OR = 1.62; p = 0.04), XRCC1 Gln/Gln+hOGG1 Ser/Ser (OR = 2.14; p = 0.02). After stratification for genders, the following combinations of genotype were found to be significant in male: XPD Lys/Gln+XPC Lys/Lys (OR = 1.87; p = 0.03), XRCC1 Arg/Gln+XPC Lys/Lys (OR = 4.52; p = 0.0007), XRCC1 Arg/Gln+XPC Lys/Gln (OR = 5.44; p < 0.0001). In female, different combinations of the following genotypes were found to be significant: XRCC1 Arg/Gln+hOGG1 Ser/Ser (OR = 1.98; p = 0.04), XRCC1 Gln/Gln+hOGG1 Ser/Ser (OR = 3.75; p = 0.02), XRCC1 Arg/Gln+XPC Lys/Gln (OR = 2.40; p = 0.04), XRCC1 Arg/Gln+XPC Gln/Gln (OR = 3.03; p = 0.04). We found out decreased cancer risk in genotype combinations between female patients and healthy controls: XPD Lys/Lys+XPC Lys/Gln (OR = 0.45; p = 0.02), XPD Lys/Gln+XPC Lys/Lys (OR = 0.32; p = 0.005), XPD Lys/Gln+XPC Lys/Gln (OR = 0.48; p = 0.02). Our results did not show any difference between pooled smokers and non-smokers in observed gene polymorphisms in the association to the lung cancer risk. However, gender stratification indicated the possible effect of heterozygous constitution of hOGG1 gene (Ser/Cys) on lung cancer risk in female non-smokers (OR = 0.20; p = 0.01) and heterozygous constitution of XPC gene (Lys/Gln) in male smokers (OR = 2.70; p = 0.01).

Association between the OGG1 Ser326Cys and APEX1 Asp148Glu polymorphisms and lung cancer risk: a meta-analysis

The previous published data on the association between the 8-oxo-guanine glycosylase-1 (OGG1) and apurinic/apyrimidinic-endonuclease-1 (APEX1/APE1) polymorphisms and lung cancer risk remained controversial. Several polymorphisms in the OGG1 and APEX1 gene have been described, including the commonly occurring Ser326Cys in OGG1 and Asp148Glu in APEX1. This meta-analysis of literatures was performed to derive a more precise estimation of the relationship. A total of 37 studies were identified to the meta-analysis, including 9,203 cases and 10,994 controls for OGG1 Ser326Cys (from 25 studies) and 3,491 cases and 4,708 controls for APEX1 Asp148Glu (from 12 studies). When all the eligible studies were pooled into the meta-analysis of OGG1 Ser326Cys polymorphism, significantly increased lung cancer risk was observed in recessive model (OR = 1.17, 95 % CI = 1.03-1.33) and in additive model (OR = 1.21, 95 % CI = 1.03-1.42). In the stratified analysis, significantly increased risk of lung cancer was also observed on the population-based studies (recessive model: OR = 1.26, 95 % CI = 1.08-1.46, additive model: OR = 1.42, 95 % CI = 1.06-1.73) and non-smokers (dominant model: OR = 1.20, 95 % CI = 1.02-1.42, recessive model: OR = 1.20, 95 % CI = 1.02-1.40, additive model: OR = 1.35, 95 % CI = 1.08-1.68). Additionally, when one study was deleted in the sensitive analysis, the results of OGG1 Ser326Cys were changed in Asians (recessive model: OR = 1.16, 95 % CI = 1.06-1.27, additive model: OR = 1.23, 95 % CI = 1.09-1.38). When all the eligible studies were pooled into the meta-analysis of APEX1 Asp148Glu polymorphism, there was no evidence of significant association between lung cancer risk and APEX1 Asp148Glu polymorphism in any genetic model. In the stratified analysis, significantly decreased lung adenocarcinoma risk was observed in recessive model (OR = 0.68, 95 % CI = 0.48-0.97, P (h) = 0.475, I(2) = 0.0 %). Additionally, when one study was deleted in the sensitive analysis, the results of APEX1 Asp148Glu were changed in Asians (recessive model: OR = 1.21, 95 % CI = 1.03-1.43) and smokers (dominant model: OR = 1.62, 95 % CI = 1.08-2.44, additive model: OR = 1.37, 95 % CI = 1.02-1.84). In summary, this meta-analysis indicates that OGG1 Ser326Cys show an increased lung cancer risk in Asians and non-smokers, APEX1 Asp148Glu polymorphism may be associated with decreased lung adenocarcinoma risk, and APEX1 Asp148Glu polymorphism show an increased lung cancer risk in Asians and smokers. However, a study with the larger sample size is needed to further evaluated gene-environment interaction on OGG1 Ser326Cys and APEX1 Asp148Glu polymorphisms and lung cancer risk.

The hOGG1Ser326Cys polymorphism and increased lung cancer susceptibility in Caucasians: an updated meta-analysis

hOGG1 encodes a DNA repair enzyme responsible for the excision of reactive oxygen species (ROS) in damaged DNA. Previous studies have obtained inconsistent results. To validate the association between the hOGG1Ser326Cys polymorphism and lung cancer risk, we performed an updated meta-analysis of 20 studies (8739 cases and 10385 controls) using STATA version 11.1. With this approach, we tested the overall and subgroup association between the SNP and lung cancer susceptibility stratified by ethnicity, control sources, cell histotypes, and smoking status. We demonstrated a novel, significant correlation between the hOGG1 Ser326Cys polymorphism and increased lung cancer susceptibility in Caucasians. Our findings indicate a need for larger-scale studies to verify the association of this SNP with lung cancer risk in Caucasians.