Polymorphisms in DNA repair genes, smoking, and pancreatic adenocarcinoma risk

Overview of role of survivin in cancer: expression, regulation, functions, and its potential as a therapeutic target

Survivin holds significant importance as a member of the inhibitor of apoptosis protein (IAP) family due to its predominant expression in tumours rather than normal terminally differentiated adult tissues. The high expression level of survivin in tumours is closely linked to chemotherapy resistance, heightened tumour recurrence, and increased tumour aggressiveness and serves as a negative prognostic factor for cancer patients. Consequently, survivin has emerged as a promising therapeutic target for cancer treatment. In this review, we delve into the various biological characteristics of survivin in cancers and its pivotal role in maintaining immune system homeostasis. Additionally, we explore different therapeutic strategies aimed at targeting survivin.

Molecular Features and Clinical Management of Hereditary Pancreatic Cancer Syndromes and Familial Pancreatic Cancer

Hereditary pancreatic cancers are caused by several inherited genes. Familial pancreatic cancer is defined as pancreatic cancer arising in a patient with at least two first-degree relatives with pancreatic cancer in the absence of an identified genetic cause. Hereditary pancreatic cancer syndromes and familial pancreatic cancers account for about 10% of pancreatic cancer cases. Germline mutations in BRCA1, BRCA2, ATM, PALB2, CDKN2A, STK11, and TP53 and mismatch repair genes (MLH1, MSH2, MSH6, PMS2, and EPCAM) are among the well-known inherited susceptibility genes. Currently available targeted medications include poly (ADP-ribose) polymerase inhibitors (PARP) for cases with mutant BRCA and immune checkpoint inhibitors for cases with mismatch repair deficiency. Loss of heterozygosity of hereditary pancreatic cancer susceptibility genes such as BRCA1/2 plays a key role in carcinogenesis and sensitivity to PARP inhibitors. Signature 3 identified by whole genome sequencing is also associated with homologous recombination deficiency and sensitivity to targeted therapies. In this review, we summarize molecular features and treatments of hereditary pancreatic cancer syndromes and surveillance procedures for unaffected high-risk cases. We also review transgenic murine models to gain a better understanding of carcinogenesis in hereditary pancreatic cancer.

The Relationship Between GSTT1, GSTM1, GSTO1, GSTP1 and MTHFR Gene Polymorphisms and DNA Damage of BRCA1 and BRCA2 Genes in Arsenic-Exposed Workers

OBJECTIVE

To investigate the associations between genetic polymorphisms of GSTT1, GSTM1, GSTO1, GSTP1 and MTHFR genes and the DNA damage levels of BRCA1 and BRCA2 genes.

METHODS

Peripheral blood samples were used to measure DNA damage levels and genetic polymorphisms, and urine samples were collected to analyze arsenic metabolites in 79 arsenic-exposed workers and 24 non-arsenic-exposed workers.

RESULTS

The BRCA1 and BRCA2 damage levels in exposure group were significantly higher than that in control group. Significant associations were detected between GSTT1 and GSTO1 polymorphisms and DNA damage levels of BRCA1 and BRCA2 genes in subjects (P < 0.05).

CONCLUSIONS

Our findings suggest that the DNA damage levels of BRCA1 and BRCA2 genes may modulate by genetic variations of GSTT1 and GSTO1 when individuals are exposed to carcinogens, such as arsenic.

DNA damage response and repair in pancreatic cancer development and therapy

Pancreatic cancer (PC) is among fatal malignancies, with a dismal prognosis and a low survival rate of 5-10%. In both sporadic and inherited PC, gene alterations, such as BRCA1/2, PALB2, and ATM, can occur frequently. Currently, surgery, chemo- and radio-therapy are the most common therapeutic strategies for treating this cancer. DNA damage response (DDR) establishes multiple pathways that eliminate DNA damage sites to maintain genomic integrity. Various types of cancers and age-related diseases are associated with DDR machinery defects. According to the severity of the damage, DDR pathways respond appropriately to lesions through repairing damage, arresting the cell cycle, or apoptosis. Recently, novel agents, particularly those targeting DDR pathways, are being utilized to improve the response of many cancers to chemotherapy and radiotherapy. In this paper, we briefly reviewed DDR processes and their components, including DDR sensors, DDR mediators, and DDR transducers in the progression, prognosis, and treatment of PC.

Comprehensive assessment of the association between XPC rs2228000 and cancer susceptibility based on 26835 cancer cases and 37069 controls

Objectives In the present study, we examined available articles from online databases to comprehensively investigate the effect of the XPC (xeroderma pigmentosum complementation group C) rs2228000 polymorphism on the risk of different types of clinical cancer.

Methods We conducted a group of overall and subgroup pooling analyses after retrieving the data from four databases (updated till September 2019). The P-value of association, OR (odds ratios), and 95% CI (confidence interval) were calculated.

Results We selected a total of 71 eligible studies with 26835 cancer cases and 37069 controls from the 1186 retrieved articles. There is an enhanced susceptibility for bladder cancer cases under T vs. C [P=0.004; OR (95% CI) = 1.25 (1.07, 1.45)], TT vs. CC [P=0.001; 1.68 (1.25, 2.26)], CT+TT vs. CC [P=0.016; 1.26 (1.04, 1.53)], and TT vs. CC+ CT [P=0.001; 1.49 (1.18, 1.90)] compared with negative controls. Additionally, there is an increased risk of breast cancer under T vs. C, TT vs. CC and TT vs. CC+ CT (P<0.05, OR > 1). Nevertheless, there is a decreased risk of gastric cancer cases in China under T vs. C [P=0.020; 0.92 (0.85, 0.99)], CT vs. CC [P=0.001, 0.83 (0.73, 0.93)], and CT+TT vs. CC [P=0.003, 0.84 (0.76, 0.94)].

Conclusions The TT genotype of XPC rs2228000 may be linked to an increased risk of bladder and breast cancer, whereas the CT genotype is likely to be associated with reduced susceptibility to gastric cancer in the Chinese population.

Downregulation of the let-7 family of microRNAs may promote insulin receptor/insulin-like growth factor signalling pathways in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer type characterized by dysregulated cell signalling pathways and resistance to treatment. The insulin-like growth factor (IGF) signalling pathway has been identified to have a role in tumour progression and therapy resistance. However, its regulatory roles in PDAC have remained to be fully elucidated. In the present study, dysregulated microRNAs (miRNAs) in PDAC were explored with a focus on those that may be involved in regulating the insulin/IGF signalling pathway. A total of 208 patients were recruited, comprising 112 patients with PDAC, 50 patients with chronic pancreatitis (CP) and 46 subjects as a control group (CG). miRNA-specific quantitative PCR assays were used to measure 300 candidate miRNAs. The Student's t-test was applied to compare miRNA regulation between cancer patients and controls with a false discovery rate correction using Bonferroni-type comparison procedures. The DIANA-mirPath v.3 tool and HMDD v3.0 were used to identify miRNA-mRNA interactions within specific pathways. In patients with PDAC, 42 miRNAs were significantly upregulated and 42 were downregulated compared to the CG (P<0.01). In the PDAC vs. CP analysis, 16 significantly (P<0.01) upregulated and 16 downregulated miRNAs were identified. Of note, members of the let-7 family of miRNAs were downregulated and were indicated to target several components of the insulin receptor (INSR)/IGF pathway, including receptors and binding proteins, for upregulation and thus, may enable the activation of the pathway. Downregulation of the let-7 family may help promote the INSR/IGF pathway in PDAC. It may thus be an effective target for the development of INSR/IGF pathway-specific treatment strategies.

Identification of a novel DNA repair-related prognostic signature predicting survival of patients with hepatocellular carcinoma

Purpose

Hepatocellular carcinoma (HCC) is the sixth most lethal neoplasm worldwide. Traditional biomarkers often exploit the relationship between a certain gene and cancer progression, but they cannot predict patient survival or prognosis accurately. We aim to construct a new DNA repair-related gene signature that combines several genes to improve prognosis prediction in HCC.

Methods

We selected an HCC mRNA sequencing (mRNA-seq) dataset (n=365) from The Cancer Genome Atlas (TCGA), and gene set enrichment analysis (GSEA) was used to explore bioinformatics information and further screen genes. We then built a gene signature based on the Cox proportional hazards regression model.

Results

GSEA revealed that the hallmark DNA repair gene set was significantly upregulated in the tumor phenotype. A set of seven genes, namely, ADA, FEN1, POLR2G, SAC3D1, SEC61A1, SF3A3, and UPF3B, were significantly a ssociated with overall survival (OS) and used to form a gene signature. The signature risk score was calculated and used to divide patients into high‐ and low‐risk groups. The high-risk group showed worse prognosis (log-rank test p<0.0001). Univariate and multivariate Cox regression analysis showed that the prognostic performance of this risk score signature was robust in different subgroups based on clinicopathological features, with p-values <0.05 (HR=2.38, 95% CI (confidence interval) =1.355–4.184), indicating that it can serve as an independent prognostic indicator.

Conclusion

We developed and identified a seven‐gene signature related to the DNA repair process that can predict survival in HCC. It can be used as an effective classification tool and to guide clinical treatment.

Genetic polymorphisms and pancreatic cancer risk: A PRISMA-compliant systematic review and meta-analysis

BACKGROUNDS

Previous investigations yielded inconsistent results for the associations between pancreatic cancer (PC) risk and genetic polymorphisms. The study aimed to perform a systematic review and meta-analysis of studies exploring association of some genetic polymorphisms and PC risk.

METHODS

We systematically searched on PubMed and Web of Science for association of genetic polymorphisms and PC risk published from 1969 to January 2019. We computed the multivariate odd ratio (OR) and 95% confidence intervals (CI), comparing different genetic types.

RESULTS

The present meta-analysis showed significant associations between deoxyribonucleic acid (DNA) repair gene (X-ray repair cross-complementing group 1 (XRCC1) Arg399GIn and Arg194Trp, excision repair cross complementation 1 (ERCC1) rs11615 and rs3212986, ERCC2 rs13181) polymorphisms and PC risk.

CONCLUSIONS

Because of the limited sample size and ethnicity enrolled in the present meta-analysis, further larger scaled studies should be performed to demonstrate the association.

Associations of mRNA expression of DNA repair genes and genetic polymorphisms with cancer risk: a bioinformatics analysis and meta-analysis

A systematical bioinformatics and meta-analysis were carried out to establish our understanding of possible relationships between DNA repair genes and the development of cancer. The bioinformatics analysis confirmed that lower XPA and XPC levels and higher XPD, XPF, and WRN levels were observed in 19 types of cancer, and subsequently results indicated that elevated XPA and XPC had a better impact on overall survival, however, higher XPD, XPF, and WRN showed worse influence on cancer prognosis. The meta-analysis included 58 eligible studies demonstrated that harboring XPA rs10817938, XPD rs238406 increased overall cancer risk, however, XPA rs2808668 SNP in overall cancer analysis and XPF rs3136038 in the digestive system remarkably reduced the cancer risk. Moreover, no correlation was investigated for XPC rs1870134, WRN rs1346044 and rs1801195. These suggest that the DNA repair gene was associated with carcinogenesis, and contribute to the prognosis, and the critical SNPs further involved in affecting cancer risk.

Interaction of polymorphisms in xeroderma pigmentosum group C with cigarette smoking and pancreatic cancer risk

The aim of the present study was to evaluate the association between xeroderma pigmentosum group C (XPC) polymorphisms and pancreatic cancer (PC) risk. A total of 7 XPC tagging SNPs (tag-SNPs) were selected from the International HapMap Project Databases (rs2228001A/C, rs2470353G/C, rs2228000C/T, rs3731114C/G, rs3729587G/C, rs2607775C/G and rs3731055G/A) and were genotyped in 205 patients with PC and 230 non-cancer control subjects using a SNaPshot assay. The C allelic gene frequency of rs2470353 was higher in patients with PC compared with that in the control group (P=0.003). Compared with the GG gene type, PC risk was increased in subjects with GC and GC+CC gene types (P=0.012 and P=0.006, respectively). PC risk increased 3.505-fold for the subjects who were heavy smokers (tobacco, ≥25 packets/year) with the GC+CC gene type (P=0.008). The G allelic gene frequency of rs2607775 was higher in PC patients compared with that in the control group (P=0.003). Compared with the CC gene type, PC risk increased in subjects with CG and CG+GG gene types (P=0.013 and P=0.005, respectively). Furthermore, PC risk increased 3.950-fold in subjects who were heavy smokers (tobacco, ≥25 packets/year) with the CG+GG gene type (P=0.001). Haplotype analysis further revealed that the CCC haplotype of rs2228000, rs3731114 and rs3729587 increased PC risk (odds ratio, 1.610; 95% confidence interval, 1.035–2.481; P=0.034). The present study revealed that XPC gene polymorphisms could increase the risk of PC in the study population, particularly among heavy smokers.

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 Polymorphisms of X-Ray Repair Cross Complementing Group 1 Gene and Pancreatic Cancer Risk: a Systematic Review with Meta-Analysis

Emerging evidences have shown that common genetic polymorphisms in X-ray repair cross complementing group 1 (XRCC1) gene may be associated with the development of pancreatic cancer, but individually published studies and previous meta-analyses revealed inconclusive results. The aim of our study was to investigate the association between polymorphisms in XRCC1 gene and pancreatic cancer risk. We conducted a search of PubMed, Embase, the Cochrane Library and Web of Science databases. Odds ratios (ORs) with 95% confidence intervals (CIs) were determined as measures of the strength of association between polymorphisms of XRCC1 and pancreatic cancer risk. Sensitivity analysis and publication bias were evaluated. All analyses were undertaken using the STATA 13.0. A total of 10 studies were included in this systematic review. Five common functional single-nucleotide polymorphisms (SNPs) in XRCC1 gene were found, including Arg399Gln G > A (rs25487), Arg194Trp C > T (rs1799782), Arg280His G > A (rs25489), c.1517G > C, c.1471G > A. Results from our stratified analysis based on Hardy-Weinberg equilibrium (HWE) showed that there was a robust significant association between Arg280His polymorphism and pancreatic cancer risk (allelic model, OR 0.743, 95% CI 0.576-0.958, P = 0.022; heterozygous model, OR 0.701, 95% CI 0.525-0.936, P = 0.016; dominant model, OR 0.710, 95% CI 0.537-0.939, P = 0.016). We also found a statistically significant association between c.1517G > C polymorphism and pancreatic cancer risk (Allelic model, OR 1.252, 95% CI 1.064-1.473, P = 0.007). No significant results were obtained for Arg399Gln, Arg194Trp and c.1471G > A polymorphisms. The present meta-analysis suggested that Arg280His and c.1517G > C polymorphisms in XRCC1 gene were associated with pancreatic cancer risk.

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.

Association between ERCC2 Lys751Gln polymorphism and the risk of pancreatic cancer, especially among Asians: evidence from a meta-analysis

Single nucleotide polymorphisms (SNPs) of Excision repair cross-complementing group 2 (ERCC2) gene are suspected to affect the risk of pancreatic cancer. Many studies have reported the association between ERCC2 Lys751Gln polymorphism (rs13181) and the susceptibility to pancreatic cancer, but the outcomes remained controversial. To comprehensively determine this association, we conducted a meta-analysis based on a total of eight studies. Evidence for this association was obtained from the PubMed, EMBASE, Web of Science and Chinese National Knowledge Infrastructure (CNKI) databases. In general, a significant association was found between ERCC2 rs13181 polymorphism and the susceptibility to pancreatic cancer in four genetic models [CC vs. AA: OR = 1.56, (95% CI: 1.28-1.90), P = 0.470; AC/CC vs. AA: OR=1.20, (95% CI: 1.06-1.36), P = 0.396; CC vs.

AC/CC

OR = 1.50; (95% CI: 1.24-1.81), P = 0.530; C vs. A: OR=1.22, (95%CI:1.11-1.34), P = 0.159]. Furthermore, stratified analyses by ethnicity indicated a significant association only in the Asian population. Our results indicate that the ERCC2 Lys751Gln polymorphism might be important in stimulating the development of pancreatic cancer, especially for Asians.

TGF-β1 polymorphisms -509 C>T and +915 G>C and risk of pancreatic cancer

BACKGROUND

Ninety percent of pancreatic cancer patients have less than 5-year overall survival and approximately 50% of cases were diagnosed with metastasis in the time of admission. Previous evidences have demonstrated the strong association between TGF-β1 variations and cancer susceptibility so far.

METHODS

A total of 78 patients with pancreatic cancer and 94 healthy controls were enrolled in this case- control study between 2007 and 2012. Genomic DNA was isolated from peripheral blood samples according to phenol chloroform extraction. The genotypes of TGF-β1 rs rs1800469 and rs1800471 were determined using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

The mean age of cases and the control group were 64.50 ± 13.718 and 40.12 ± 16.001, respectively. For polymorphism -509 C>T, the frequency of TT genotype were 31 (33.0), CT, 47(50) and CC, 16 (17) in control and 19 (24.4), 45 (57.7) and 14 (17.9) in cases respectively. In position +915 G>C, the frequency of GG genotype was 84 (89.4) and GC, 10 (10.6) in control and 71 (91.0) and 7 (9) in cases, respectively. We did not observe any significant differences in the genotype and allele frequencies of the TGF-β1-509 C>T (rs1800469) and codon +915 G>C (rs1800471) between the two study groups (P>0.05).

CONCLUSION

we found that TGF-β1 gene polymorphisms rs1800469 and rs1800471 might not play a role in pancreatic cancer susceptibility in Iranian population.

Analysis of DNA Repair Genes Polymorphisms in Breast Cancer

Genetic polymorphisms in the DNA repair genes may be associated with increased cancer risk. The purpose of this study was to evaluate the association of the DNA repair genes polymorphisms with the risk of breast cancer development. The study included 200 breast cancer patients and 200 healthy controls. The following polymorphisms were studied: C/G (Ser326Cys, rs1052133) of the hOGG1, A/C (IVS5 + 33, rs3212961) of the ERCC1, A/C (Lys939Gln, rs2228001) of the XPC, C/T (Thr241Met, rs861539) of the XRCC3, G/T (Leu787Leu, rs1800392) of the WRN and G/T (Ser307Ser, rs1056503) of the XRCC4 gene. Presented study showed statistically significant increase in the breast cancer development risk of the G/G hOGG1 genotype (OR 8.13; 95 % CI, 4.37-15.14; p < 0.001) and for the G hOGG1 allele (OR 5.11; 95 % CI, 3.69-7.06; p < 0.001), as well as for the C/C ERCC1 genotype (OR 10.61; 95 % CI, 5.72-19.69; p < 0.001) and the C ERCC1 allele (OR 4.66; 95 % CI, 3.43-6.34; p < 0.001) in patients with breast cancer in comparison with healthy control group. We also observed positive association of the C/C XPC genotype (OR 3.80; 95 % CI, 2.27-6.38; p < 0.001) as well as the C XPC allele occurrence with an increased breast cancer development risk (OR 2.65; 95 % CI, 1.98-3.55; p < 0.001). Furthermore, we found an association of the G/T WRN gene polymorphism with increased risk of carcinoma. The hOGG1, ERCC1, XPC and WRN genes polymorphisms may be related to development of breast cancer.

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 and Intragenic Single-Nucleotide Polymorphism Interactions of the XRCC1 Polymorphisms for Pancreatic Cancer Susceptibility

OBJECTIVES

X-ray repair cross-complementing group 1 (XRCC1) gene is an important candidate gene for influencing human cancer risks. This study examined the main and interactive effect of 9 single-nucleotide polymorphisms (SNPs) (Arg194Trp, Arg280His, Arg399Gln, c.1254C>T, c.1517G>C, c.1471G>A, C310T, 539del542, and T1915C) of XRCC1 in contribution to pancreatic cancer (PC).

METHODS

A total of 298 PC patients and 298 healthy controls were enrolled. Selected SNPs in XRCC1 were genotyped. The generalized multifactor dimensionality reduction method investigated gene-gene interactions.

RESULTS

Single-locus analyses showed that, in the codominant model, the GO genotype of 539del542 might have a higher risk for PC (odds ratio [OR], 1.47; 95% confidence interval [95% CI], 1.05-2.08). For T1915C polymorphism, the TC and CC genotypes both had a higher risk for PC (OR, 1.76; 95% CI, 1.25-2.48; OR, 1.83; 95% CI, 1.05-3.19, respectively); and a similar result was observed in the dominant model (OR, 1.77; 95% CI, 1.28-2.46). A tendency of association between Arg280His and PC was also detected in the dominant model (OR, 0.70; 95% CI, 0.48-1.00). Furthermore, the generalized multifactor dimensionality reduction method showed that the 4-locus model was significant, involving Arg280His, 539del542, T1915C, and c.1517G>C (P < 0.05).

CONCLUSIONS

Thus, XRCC1 polymorphisms may contribute to the risk of PC independently or in an interactive manner.

Risk Factors for Early-Onset and Very-Early-Onset Pancreatic Adenocarcinoma: A Pancreatic Cancer Case-Control Consortium (PanC4) Analysis

OBJECTIVES

While pancreatic cancer (PC) most often affects older adults, to date, there has been no comprehensive assessment of risk factors among PC patients younger than 60 years.

METHODS

We defined early-onset PC (EOPC) and very-early-onset PC (VEOPC) as diagnosis of PC in patients younger than 60 and 45 years, respectively. We pooled data from 8 case-control studies, including 1954 patients with EOPC and 3278 age- and sex-matched control subjects. Logistic regression analysis was performed to identify associations with EOPC and VEOPC.

RESULTS

Family history of PC, diabetes mellitus, smoking, obesity, and pancreatitis were associated with EOPC. Alcohol use equal to or greater than 26 g daily also was associated with increased risk of EOPC (odds ratio, 1.49; 95% confidence interval, 1.21-1.84), and there appeared to be a dose- and age-dependent effect of alcohol on risk. The point estimate for risk of VEOPC was an odds ratio of 2.18 (95% confidence interval, 1.17-4.09).

CONCLUSIONS

The established risk factors for PC, including smoking, diabetes, family history of PC, and obesity, also apply to EOPC. Alcohol intake appeared to have an age-dependent effect; the strongest association was with VEOPC.

Essential Metals Zinc, Selenium, and Strontium Protect against Chromosome Damage Caused by Polycyclic Aromatic Hydrocarbons Exposure

Essential metals play important roles in maintaining cellular homeostasis, but the effects of their interaction with the environmental pollutants are still not very well-known in human subjects. The aim of this study was to evaluate the roles of essential metals and their interactions with polycyclic aromatic hydrocarbons (PAHs) on chromosome damage, an early carcinogenic event. A total of 1245 male workers were included in this study and the levels of 11 urinary essential metals, 12 urinary PAH metabolites, plasma concentrations of benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts, and lymphocyte micronucleus (MN) frequencies were monitored. We found that zinc (Zn), selenium (Se), and strontium (Sr) have significant inverse dose-response relationships with MN frequencies (all P < 0.05). Furthermore, the protective roles of Zn, Se, and Sr were mainly shown among subjects with high levels of BPDE-Alb adducts. Significant effect modification of BPDE-Alb adducts on the associations of Zn, Se, and Sr with MN frequencies was observed (all Pinteraction < 0.05). Our study showed evidence that Zn, Se, and Sr play protective roles in reducing chromosome damage, and these effects can be modified by PAH exposure levels. These findings add potential evidence for the preventive effects of Zn, Se, and Sr against carcinogenesis in human subjects.

Association of single nucleotide polymorphisms of DNA repair genes in NER pathway and susceptibility to pancreatic cancer

In our study, we conducted a case-control study to investigate the association of ERCC1, ERCC2, ERCC3, ERCC4, ERCC5, XPA, XPC and DDB2 gene polymorphisms in the risk of pancreatic cancer. Between May 2012 and May 2014, a total of 246 patients with who were newly diagnosed with histopathologically confirmed primary pancreatic cancer and 246 controls were selected into our study. Genotyping of ERCC1 rs3212986 and rs11615, ERCC2 rs13181, ERCC3 rs4150441, ERCC4 rs6498486, ERCC5 rs873601, XPA rs2808668, XPC rs2228000, XPC rs2228001 and DDB2 rs2029298 were analyzed using polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism (RFLP). By conditional logistic regression analysis, individuals carrying with TT genotype of ERCC1 rs3212986 and GG genotype of ERCC2 rs13181 were associated with increased risk of pancreatic cancer when compared with wide-type genotype, and the adjusted ORs (95% CI) were 2.40 (1.29-4.52) and 2.27 (1.26-4.15), respectively. We found that individuals carrying with GT+TT genotype of ERCC1 rs3212986 and TG+GG genotype of ERCC2 rs1318 gene polymorphisms were correlated with higher risk of pancreatic cancer in smokers when compared with non-smokers, and the adjusted ORs (95% CI) were 1.89 (1.05-3.40) and 1.88 (1.06-3.34), respectively. In conclusion, our study suggests that ERCC1 rs3212986 and ERCC2 rs1318 gene polymorphisms contribute to the development of pancreatic cancer, especially in smokers.

Common variation at 2p13.3, 3q29, 7p13 and 17q25.1 associated with susceptibility to pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer death in the developed world. Both inherited high-penetrance mutations in BRCA2 (ref. 2), ATM, PALB2 (ref. 4), BRCA1 (ref. 5), STK11 (ref. 6), CDKN2A and mismatch-repair genes and low-penetrance loci are associated with increased risk. To identify new risk loci, we performed a genome-wide association study on 9,925 pancreatic cancer cases and 11,569 controls, including 4,164 newly genotyped cases and 3,792 controls in 9 studies from North America, Central Europe and Australia. We identified three newly associated regions: 17q25.1 (LINC00673, rs11655237, odds ratio (OR) = 1.26, 95% confidence interval (CI) = 1.19-1.34, P = 1.42 × 10(-14)), 7p13 (SUGCT, rs17688601, OR = 0.88, 95% CI = 0.84-0.92, P = 1.41 × 10(-8)) and 3q29 (TP63, rs9854771, OR = 0.89, 95% CI = 0.85-0.93, P = 2.35 × 10(-8)). We detected significant association at 2p13.3 (ETAA1, rs1486134, OR = 1.14, 95% CI = 1.09-1.19, P = 3.36 × 10(-9)), a region with previous suggestive evidence in Han Chinese. We replicated previously reported associations at 9q34.2 (ABO), 13q22.1 (KLF5), 5p15.33 (TERT and CLPTM1), 13q12.2 (PDX1), 1q32.1 (NR5A2), 7q32.3 (LINC-PINT), 16q23.1 (BCAR1) and 22q12.1 (ZNRF3). Our study identifies new loci associated with pancreatic cancer risk.

XPC Ala499Val and XPG Asp1104His polymorphisms and digestive system cancer risk: a meta-analysis based on model-free approach

Many studies have reported the association between XPC Ala499Val and XPG Asp1104His polymorphisms and digestive system cancer susceptibility, but the results were inconclusive. We performed a meta-analysis, using a comprehensive strategy based on the allele model and a model-free approach, to derive a more precise estimation of the relationship between XPC Ala499Val and XPG Asp1104His polymorphisms with digestive system cancer risk. For XPC Ala499Val, no significant cancer risk was found in the allele model (OR = 0.98, 95% CI: 0.86-1.11) and with model-free approach (ORG = 0.97, 95% CI: 0.83-1.13). For XPG Asp1104His, there was also no association between this polymorphism and cancer risk in the allele model (OR = 1.03, 95% CI: 0.96-1.11) and with the model-free approach (ORG = 1.04, 95% CI: 0.95-1.14). Therefore, this meta-analysis suggests that the XPC Ala499Val and XPG Asp1104His polymorphisms were not associated with digestive system cancer risk. Further large and well-designed studies are needed to confirm these findings.

Lack of association between XPF polymorphisms and gastric cancer risk: a meta-analysis

BACKGROUND

Xeroderma pigmentosum complementation group F (XPF or ERCC4) plays a key role in DNA repair that protects against genetic instability and carcinogenesis. Several epidemiological studies have examined associations between XPF polymorphisms and gastric cancers risk, but the findings remain inconclusive. Therefore, we conducted the present meta-analysis to obtain the most reliable estimate of the association.

METHODS

PubMed, Embase, Web of Science, and Wanfang were searched. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were extracted and pooled to assess the strength of the association between 3 commonly studied polymorphisms of XPF (rs744154, rs6498486, rs1799801) and gastric cancer risk. The pooled ORs were performed for the co-dominant model (homozygous and heterozygous), dominant model, and recessive model. 3 studies on rs744154, 3 studies on rs6498486, and 4 studies on rs1799801 were included in our meta-analysis.

RESULTS

Our results show that the genotype distribution of the 3 polymorphisms was not associated with risk of gastric cancer in all genetic models.

CONCLUSION

This meta-analysis suggests that the 3 common XPF polymorphisms rs744154, rs6498486, and rs1799801 are not associated with gastric cancer risk. However, large-sample and representative population-based studies with homogeneous gastric cancer patients and well-matched controls are warranted to confirm this finding.

The hOGG1 Ser326Cys polymorphism contributes to digestive system cancer susceptibility: evidence from 48 case-control studies

The Ser326Cys polymorphism in the human 8-oxogunaine DNA glycosylase (hOGG1) gene had been implicated in cancer susceptibility. Studies investigating the associations between the Ser326Cys polymorphism and digestion cancer susceptibility showed conflicting results. Therefore, a meta-analysis was performed to derive a more precise estimation of the relationship. We conducted a meta-analysis of 48 studies that included 12,073 cancer cases and 19,557 case-free controls. We assessed the strength of the association using odds ratios (ORs) with 95% confidence intervals (CIs). In our analysis, the hOGG1 Ser326Cys polymorphism was significantly associated with the risk of digestive system cancers (Cys/Cys vs. Ser/Ser: OR = 1.17, 95% CI = 1.00-1.35, P < 0.001; Cys/Cys vs. Cys/Ser + Ser/Ser: OR = 1.14, 95% CI = 1.00-1.29, P < 0.001). In subgroup analyses by cancer types, we found that the hOGG1 Ser326Cys polymorphism may increase hepatocellular cancer and colorectal cancer risks, but decrease the risk of oral cancer. These findings supported that hOGG1 Ser326Cys polymorphism may contribute to the susceptibility of digestive cancers.

Associations of ERCC4 rs1800067 polymorphism with cancer risk: an updated meta-analysis

BACKGROUND

RESULTS from previous studies concerning the association of ERCC4 rs1800067 polymorphism with risk of cancer were inconsistent. To explore the exact relation with susceptibility, we conducted the present meta-analysis.

MATERIALS AND METHODS

Literature of electronic databases including PubMed, Web of Science, EMBASE, Wanfang and Chinese National Knowledge Infrastructure (CNKI) were systematically searched. ORs and their 95%CIs were used to assess the strength of associations between ERCC4 polymorphism and cancer risk.

RESULTS

There was no significant association between ERCC4 rs1800067 AA or AG genotypes and overall risk of cancer (AA vs. GG: OR=0.998, 95%CI=0.670-1.486, P=0.992; AG vs. GG: OR=0.970, 95%CI=0.888- 1.061, P=0.508). A dominant genetic model also did not demonstrate significant association of (AA+AG) genotype carriers with altered risk of overall cancer (OR=0.985, 95%CI=0.909-1.068, P=0.719). In addition, no significant association was observed between A allele of ERCC4 rs1800067 A/G polymorphism and altered cancer risk compared with G allele (OR=0.952, 95%CI=0.851-1.063, P=0.381). Subgroup analysis suggested that AA genotype carriers were significantly associated with decreased risk of glioma compared with wild-type GG genotype individuals (OR=0.523, 95%CI=0.275-0.993, P=0.048). For subgroup of lung cancer, A allele of ERCC4 rs1800067 A/G polymorphism was significantly associated with decreased risk of lung cancer compared with G allele (OR=0.806, 95%CI=0.697-0.931, P=0.003).

CONCLUSIONS

This meta-analysis indicated that ERCC4 rs1800067 A/G polymorphism might not be associated with risk of overall cancer. However, individuals with the AA genotype were associated with significantly reduced risk of glioma compared with wild-type GG genotype; The A allele was associated with significantly reduced risk of lung cancer compared with G allele. Future large- scale studies performed in multiple populations are warranted to confirm our results.

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

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

Combined effect of tobacco and DNA repair genes polymorphisms of XRCC1 and XRCC2 influence high risk of head and neck squamous cell carcinoma in northeast Indian population

Tobacco consumption in various forms is one of the major risk factor for the development of head and neck squamous cell carcinoma. Polymorphisms in XRCC1 and XRCC2 genes may alter an individual's susceptibility to tobacco-related cancers. Here, we have investigated the interaction of XRCC1 (Arg399Gln) and XRCC2 (Arg188His) polymorphism and tobacco exposure in the progression of HNSCC in northeast Indian population. The population-based case-control study includes 110 HNSCC patients and 140 controls. The polymorphisms of XRCC1 and XRCC2 were studied by means of PCR-RFLP, and the results were confirmed by DNA sequencing. Smokers and tobacco-betel quid chewers were significantly higher in cases (P = 0.045 and 0.033). The variant homozygote AA genotype of XRCC1 Arg399Gln and heterozygote GA genotype of XRCC2 Arg188His has an increased risk toward HNSCC (OR 2.43; P = 0.031 and OR 3.29; P < 0.01, respectively). The interaction between tobacco-betel quid chewing and variant genotypes of XRCC1 and XRCC2 resulted in several fold increase the risk of HNSCC, when compared to non-chewers. Heavy smokers carrying XRCC1 AA and XRCC2 GA genotypes had a significantly higher risk of HNSCC compared to never smokers (P = 0.017 and 0.003, respectively). Upon gene-gene interaction analysis, individuals carrying both XRCC1 GA (Arg/Gln) and XRCC2 GA (Arg/His) genotypes had the highest risk of HNSCC (P = 0.001).Our finding suggests that interaction of tobacco and polymorphisms of XRCC1 and XRCC2 increases the risk of HNSCC. Furthermore, cross talk between these two DNA repair genes might modulate susceptibility toward HNSCC.

Association between OGG1 gene single nucleotide polymorphisms and risk of pancreatic cancer in Chinese

Previous studies have suggested that the 8-oxoguanine DNA glycosylase gene (OGG1) has potentially influenced the risk of pancreatic cancer. The objective of this study was to assess the association between single nucleotide polymorphisms (SNPs) of OGG1 gene and risk of pancreatic cancer. A case-control study has been conducted in 370 pancreatic cancer patients and 395 healthy controls. Genotypes were determined using the polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing methods. The association analysis was evaluated by the unconditional logistic regression test. Our data suggested that the distributions of alleles and genotypes were statistically different between pancreatic cancer patients and healthy controls. The c.307G>C SNP was associated with the decreased risk of pancreatic cancer (C vs. G: OR 0.73, 95 % CI 0.59-0.91, P = 0.006). As for c.828A>G SNP, the significantly decreased risk of pancreatic cancer was detected (G vs. A: OR 0.74, 95 % CI 0.59-0.92, P = 0.006). The allele C of c.307G>C and allele G of c.828A>G SNPs might be associated with a protection from pancreatic cancer. Findings from this study indicate that OGG1 SNPs are associated with pancreatic cancer risk in Chinese Han population and could be useful molecular biomarkers for assessing the risk of pancreatic cancer.

Association between the XPG Asp1104His and XPF Arg415Gln polymorphisms and risk of cancer: a meta-analysis

BACKGROUND

The XPG (xeroderma pigmentosum type G) Asp1104His and XPF (xeroderma pigmentosum type F) Arg415Gln polymorphisms had been implicated in cancer susceptibility. The previous published data on the association between XPG Asp1104His and XPF Arg415Gln polymorphisms and cancer risk remained controversial.

METHODOLOGY/PRINCIPAL FINDINGS

To derive a more precise estimation of the association between the XPG Asp1104His and XPF Arg415Gln polymorphisms and overall cancer risk, we performed a meta-analysis to investigate the association between cancer susceptibility and XPG Asp1104His (32,162 cases and 39,858 controls from 66 studies) and XPF Arg415Gln polymorphisms (17,864 cases and 20,578 controls from 32 studies) in different inheritance models. We used odds ratios with 95% confidence intervals to assess the strength of the association. Overall, significantly elevated cancer risk was found when all studies were pooled into the meta-analysis of XPG Asp1104His (dominant model: OR = 1.05, 95% CI = 1.00-1.10; Asp/His vs. Asp/Asp: OR = 1.06, 95% CI = 1.01-1.11). In the further stratified and sensitivity analyses, significantly decreased lung cancer risk was found for XPF Arg415Gln (dominant model: OR = 0.82, 95% CI = 0.71-0.96; Arg/Gln versus Arg/Arg: OR = 0.83, 95% CI = 0.71-0.97; additive model: OR = 0.83, 95% CI = 0.72-0.95) and significantly increased other cancer risk was found among hospital-based studies for XPG Asp1104His (dominant model: OR = 1.23, 95% CI = 1.02-1.49).

CONCLUSIONS/SIGNIFICANCE

In summary, this meta-analysis suggests that XPF Arg415Gln polymorphism may be associated with decreased lung cancer risk and XPG Asp1104His may be a low-penetrant risk factor in some cancers development. And larger scale primary studies are required to further evaluate the interaction of XPG Asp1104His and XPF Arg415Gln polymorphisms and cancer risk in specific populations.

Opportunities for translation: targeting DNA repair pathways in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) remains one of the poorest prognosis neoplasms. It is typified by high levels of genomic aberrations and copy-number variation, intra-tumoural heterogeneity and resistance to conventional chemotherapy. Improved therapeutic options, ideally targeted against cancer-specific biological mechanisms, are urgently needed. Although induction of DNA damage and/or modulation of DNA damage response pathways are associated with the activity of a number of conventional PDAC chemotherapies, the effectiveness of this approach in the treatment of PDAC has not been comprehensively reviewed. Here, we review chemotherapeutic agents that have shown anti-cancer activity in PDAC and whose mechanisms of action involve modulation of DNA repair pathways. In addition, we highlight novel potential targets within these pathways based on the emerging understanding of PDAC biology and their exploitation as targets in other cancers.

Contribution of environment and genetics to pancreatic cancer susceptibility

Several risk factors have been identified as potential contributors to pancreatic cancer development, including environmental and lifestyle factors, such as smoking, drinking and diet, and medical conditions such as diabetes and pancreatitis, all of which generate oxidative stress and DNA damage. Oxidative stress status can be modified by environmental factors and also by an individual's unique genetic makeup. Here we examined the contribution of environment and genetics to an individual's level of oxidative stress, DNA damage and susceptibility to pancreatic cancer in a pilot study using three groups of subjects: a newly diagnosed pancreatic cancer group, a healthy genetically-unrelated control group living with the case subject, and a healthy genetically-related control group which does not reside with the subject. Oxidative stress and DNA damage was evaluated by measuring total antioxidant capacity, direct and oxidative DNA damage by Comet assay, and malondialdehyde levels. Direct DNA damage was significantly elevated in pancreatic cancer patients (age and sex adjusted mean ± standard error: 1.00 ± 0.05) versus both healthy unrelated and related controls (0.70 ± 0.06, p<0.001 and 0.82 ± 0.07, p = 0.046, respectively). Analysis of 22 selected SNPs in oxidative stress and DNA damage genes revealed that CYP2A6 L160H was associated with pancreatic cancer. In addition, DNA damage was found to be associated with TNFA -308G>A and ERCC4 R415Q polymorphisms. These results suggest that measurement of DNA damage, as well as select SNPs, may provide an important screening tool to identify individuals at risk for development of pancreatic cancer.

Genome-wide analysis of the role of copy-number variation in pancreatic cancer risk

Although family history is a risk factor for pancreatic adenocarcinoma, much of the genetic etiology of this disease remains unknown. While genome-wide association studies have identified some common single nucleotide polymorphisms (SNPs) associated with pancreatic cancer risk, these SNPs do not explain all the heritability of this disease. We hypothesized that copy number variation (CNVs) in the genome may play a role in genetic predisposition to pancreatic adenocarcinoma. Here, we report a genome-wide analysis of CNVs in a small hospital-based, European ancestry cohort of pancreatic cancer cases and controls. Germline CNV discovery was performed using the Illumina Human CNV370 platform in 223 pancreatic cancer cases (both sporadic and familial) and 169 controls. Following stringent quality control, we asked if global CNV burden was a risk factor for pancreatic cancer. Finally, we performed in silico CNV genotyping and association testing to discover novel CNV risk loci. When we examined the global CNV burden, we found no strong evidence that CNV burden plays a role in pancreatic cancer risk either overall or specifically in individuals with a family history of the disease. Similarly, we saw no significant evidence that any particular CNV is associated with pancreatic cancer risk. Taken together, these data suggest that CNVs do not contribute substantially to the genetic etiology of pancreatic cancer, though the results are tempered by small sample size and large experimental variability inherent in array-based CNV studies.

Lack of association of XRCC1 rs1799782 genetic polymorphism with risk of pancreatic cancer: a meta-analysis

Emerging evidence suggests that genetic polymorphisms in X-ray repair cross-complementation group 1 (XRCC1) gene could be associated with pancreatic cancer risk. However, previous published studies on the association between XRCC1 rs1799782 genetic polymorphism and pancreatic cancer risk reported inconsistent results. For better understanding of the effects of XRCC1 rs1799782 genetic polymorphism on pancreatic cancer risk, we conducted a meta-analysis of previous published studies by calculating the pooled odds ratio (OR) with a 95% confidence interval (95% CI). A total of five eligible studies with 1,144 pancreatic cancer cases and 2,925 controls were eventually enrolled. Overall, we found that the XRCC1 rs1799782 genetic polymorphism was not associated with pancreatic cancer risk in total population under all genetic models (TT vs. CC: OR = 1.11, 95% CI 0.76-1.63, P = 0.583; CT vs. CC: OR = 1.39, 95% CI 0.92-2.10, P = 0.118; TT/CT vs. CC: OR = 1.39, 95% CI 0.92-2.10, P = 0.121; TT vs.

CT/CC

OR = 1.07, 95% CI 0.73-1.55, P = 0.743; T vs. C: OR = 1.31, 95% CI 0.93-1.86, P = 0.125). In the subgroup analysis based on ethnicity, there was no statistically significant association between XRCC1 rs1799782 genetic polymorphism and pancreatic cancer risk in Asians/Caucasians under all genetic models (all P values > 0.05). No publication bias was detected in this study. Our meta-analysis suggests that the XRCC1 rs1799782 genetic polymorphism is not significantly associated with pancreatic cancer risk. Considering the limited sample size and ethnicity enrolled in this meta-analysis, further larger scaled studies are needed to provide a more precise estimation on the association.

Association of OGG1 Ser326Cys polymorphism and pancreatic cancer susceptibility: evidence from a meta-analysis

The 8-oxoguanine DNA glycosylase (OGG1) gene has been considered to be associated with cancer susceptibility. The OGG1 Ser326Cys polymorphism has been reported to be associated with pancreatic cancer (PC), but the published studies have yielded inconsistent results. For better understanding of the effect of OGG1 Ser326Cys polymorphism on PC susceptibility, a meta-analysis was performed. All eligible studies were identified through a search of PubMed, Excerpta Medica Database (Embase), Elsevier Science Direct, and Chinese Biomedical Literature Database before May 2013. The association between the OGG1 Ser326Cys polymorphism and PC risk was conducted by odds ratios (ORs) and 95 % confidence intervals (CIs). A total of five case–control studies with 1,690 cases and 3,650 controls were eventually collected. Overall, we found that OGG1 Ser326Cys polymorphism was not associated with PC susceptibility (Cys/Cys vs. Ser/Ser: OR = 0.95, 95 % CI = 0.80–1.14; Cys/Cys vs. Ser/Ser + Ser/Cys: OR = 0.95, 95 % CI = 0.78–1.14; Cys/Cys + Ser/Cys vs. Ser/Ser (OR = 1.00, 95 % CI = 0.89–1.12)). In the subgroup analysis based on ethnicity, source of control, sample size, and genotyping method, no significant association was found in any genetic models. This meta-analysis suggests that the OGG1 Ser326Cys polymorphism may not associated with PC susceptibility. Considering the limited sample size and ethnicity included in the meta-analysis, further larger scaled and well-designed studies are needed to confirm our results.

Associations of Lys939Gln and Ala499Val polymorphisms of the XPC gene with cancer susceptibility: a meta-analysis

XPC polymorphisms may alter DNA repair capacity, thus leading to genetic instability and carcinogenesis. Numerous studies have investigated the associations of XPC Lys939Gln (rs2228001) and Ala499Val (rs2228000) polymorphisms with cancer susceptibility; however, the findings are inconclusive. We searched literature from MEDLINE and EMBASE for eligible publications that assessed the associations between these two polymorphisms and cancer risk. We also assessed genotype-mRNA expression correlation data from HapMap for rs2228001 and rs2228000 in normal cell lines derived from 270 subjects with different ethnicities. The final analysis included 62 published studies of 25,708 cases and 30,432 controls for the Lys939Gln and 34 studies with 14,877 cases and 17,888 controls for the Ala499Val. Overall, Lys939Gln was significantly associated with an increased overall cancer risk (Gln/Gln vs. Lys/Lys: OR = 1.16, 95% CI = 1.07 - 1.25, p < 0.001; recessive model: OR = 1.14, 95% CI = 1.06 - 1.22, p < 0.001; dominant model: OR = 1.06, 95% CI = 1.01 - 1.11, p = 0.015 and Gln vs. Lys: OR = 1.07, 95% CI = 1.03 - 1.10, p < 0.001) and further stratifications showed an increased risk for bladder, lung and colorectal cancer, Asian populations and population-based studies. Likewise, Ala499Val was also significantly associated with an increased overall cancer risk (Val/Val vs. Ala/Ala: OR = 1.21, 95% CI = 1.07 - 1.36, p = 0.003 and recessive model: OR = 1.20, 95% CI = 1.08 - 1.34, p = 0.001) and further stratification showed an increased risk for breast and bladder cancer, particularly in Asian populations. Interestingly, significantly correlation between XPC genotypes and mRNA expression was found only for Asian populations as well. Despite some limitations, this meta-analysis established some solid statistical evidence for an association between XPC polymorphisms and cancer risk, which warrants further validation in single large studies.

Dietary antioxidants and the aetiology of pancreatic cancer: a cohort study using data from food diaries and biomarkers

OBJECTIVE

To investigate whether the dietary antioxidants vitamins C and E, selenium and zinc decrease the risk of developing pancreatic cancer, for the first time using 7-day food diaries, the most accurate dietary methodology in prospective work.

DESIGN

23,658 participants, aged 40-74 years, recruited into the EPIC-Norfolk Study completed 7-day food diaries which recorded foods, brands and portion sizes. Nutrient intakes were calculated in those later diagnosed with pancreatic cancer and in 3970 controls, using a computer program with information on 11,000 foods. Vitamin C was measured in serum samples. The HRs of developing pancreatic cancer were estimated across quartiles of intake and thresholds of the lowest quartile (Q1) against a summation of the three highest (Q2-4).

RESULTS

Within 10 years, 49 participants (55% men), developed pancreatic cancer. Those eating a combination of the highest three quartiles of all of vitamins C and E and selenium had a decreased risk (HR=0.33, 95% CI 0.13 to 0.84, p<0.05). There were threshold effects (Q2-4 vs Q1) for selenium (HR=0.49, 95% CI 0.26 to 0.93, p<0.05) and vitamin E (HR=0.57, 95% CI 0.29 to 1.09, p<0.10). The HRs of quartiles for antioxidants, apart from zinc, were <1, but not statistically significant. For vitamin C, there was an inverse association with serum measurements (HR trend=0.67, 95% CI 0.49 to 0.91, p=0.01), but the threshold effect from diaries was not significant (HR=0.68, 95% CI 0.37 to 1.26).

CONCLUSION

The results support measuring antioxidants in studies investigating the aetiology of pancreatic cancer. If the association is causal, 1 in 12 cancers might be prevented by avoiding the lowest intakes.

Genotoxic effect of exposure to metal(loid)s. A molecular epidemiology survey of populations living and working in Panasqueira mine area, Portugal

Previous studies investigating the exposure to metal(loid)s of populations living in the Panasqueira mine area of central Portugal found a higher internal dose of elements such as arsenic, chromium, lead, manganese, molybdenum and zinc in exposed individuals. The aims of the present study were to evaluate the extent of genotoxic damage caused by environmental and occupational exposure in individuals previously tested for metal(loid) levels in different biological matrices, and the possible modulating role of genetic polymorphisms involved in metabolism and DNA repair. T-cell receptor mutation assay, comet assay, micronucleus (MN) test and chromosomal aberrations (CA) were performed in a group of 122 subjects working in the Panasqueira mine or living in the same region. The modifying effect of polymorphisms in GSTA2, GSTM1, GSTP1, GSTT1, XRCC1, APEX1, MPG, MUTYH, OGG1, PARP1, PARP4, ERCC1, ERCC4, and ERCC5 genes was investigated. Significant increases in the frequency of all biomarkers investigated were found in exposed groups, however those environmentally exposed were generally higher. Significant influences of polymorphisms were observed for GSTM1 deletion and OGG1 rs1052133 on CA frequencies, APEX1 rs1130409 on DNA damage, ERCC1 rs3212986 on DNA damage and CA frequency, and ERCC4 rs1800067 on MN and CA frequencies. Our results show that the metal(loid) contamination in the Panasqueira mine area induced genotoxic damage both in individuals working in the mine or living in the area. The observed effects are closely associated to the internal exposure dose, and are more evident in susceptible genotypes. The urgent intervention of authorities is required to protect exposed populations.

Association of XRCC1 gene single nucleotide polymorphisms and susceptibility to pancreatic cancer in Chinese

The human X-ray repair cross-complementing group 1 gene (XRCC1) is an important candidate gene for affecting pancreatic cancer (PC) risk. The objective of this study was to detect whether the c.1471G > A and c.1686C > G polymorphisms of XRCC1 gene influence PC risk. The association of XRCC1 genetic variants with PC risk was analyzed in 328 PC patients and 350 controls by the polymerase chain reaction-restriction fragment length polymorphism and created restriction site-polymerase chain reaction method. Our data suggested that the genotypes and alleles from these two genetic variants were statistically associated with PC risk. For c.1471G > A, the AA genotype was associated with the decreased risk of developing PC compared to GG wild genotype (odds ratio (OR) = 0.43, 95% confidence intervals (CI) 0.26-0.70, chi-squared (χ(2)) = 11.91, P = 0.001). For c.1686C > G, the risk of PC was significantly lower for GG genotype in comparing to CC wild genotype (OR = 0.48, 95% CI 0.29-0.81, χ(2) = 7.98, P = 0.005). The A allele of c.1471G > A and G allele of c.1686C > G genetic variants could contribute to decrease the risk of PC (for c.1471G > A: A vs G, OR = 0.65, 95% CI 0.52-0.82, χ(2) = 13.71, P < 0.001, for c.1686C > G: G vs C, OR = 0.70, 95% CI 0.55-0.88, χ(2) = 9.42, P = 0.002). Our findings indicate that the c.1471G > A and c.1686C > G polymorphisms of XRCC1 gene are associated with PC risk in Chinese population.

Association between polymorphisms of XRCC1 Arg399Gln and XPD Lys751Gln genes and prognosis of colorectal cancer in a Chinese population

We conducted this study to detect associations between XRCC1 Arg399Gln and XPD Lys751Gln genotypes and survival of colorectal cancer patients treated with 5-FU/oxalipatin chemotherapy. We included 289 Chinese patients with advanced colorectal cancer, who had received 5-FU/oxalipatin chemotherapy as first-line treatment from January 2005 to January 2007. All patients were followed up till Nov. 2011. Genotyping for XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms was based upon duplex polymerase-chain-reaction with the PCR-RFLP method. In our study, we found the XRCC1 399 Gln/Gln genotype to confer significantly higher rates of response to chemotherapy when compared to the Arg/Arg genotype [OR (95% CI)=2.56(1.57-2.55)]. patients with the XPD 751 Gln/Gln genotype had significantly higher rates of response to chemotherapy [OR (95% CI)=1.54(0.87-2.65)] and those with the XRCC1 399 Gln/Gln genotype had a longer average survival time and significantly lower risk of death than did those with the Arg/Arg genotype [HR (95% CI)=0.66(0.36-0.95)]. Similarly, those carrying the XPD 751Gln/Gln genotype had 0.51-fold the risk of death of those with XPD 751Lys/Lys [HR (95% CI)=0.51(0.33-0.94)]. In conclusion, it is suggested that the XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms should be routinely assessed to determine colorectal patients who are more likely to benefit from 5-FU/oxalipatin chemotherapy.

Association between X-ray repair cross-complementation group 1 rs25487 polymorphism and pancreatic cancer risk

Previous published studies suggested that genetic polymorphisms in DNA repair genes could modify the DNA repair capacity and could be associated with pancreatic cancer risk. However, previous studies on the association between X-ray repair cross-complementation group 1 (XRCC1) rs25487 (Arg399Gln) polymorphism and pancreatic cancer risk reported inconsistent results. To obtain a more precise estimation of the association between XRCC1 rs25487 polymorphism and pancreatic cancer risk, we performed a meta-analysis of previous published studies by calculating the pooled odds ratio (OR) with a 95% confidence interval (95% CI). Eight individual studies with 5,542 subjects from six publications were finally included into this meta-analysis. The meta-analysis of total eight studies showed that there was no association between XRCC1 rs25487 polymorphism and pancreatic cancer risk in total population under all four genetic models (Gln versus Arg: OR = 1.10, 95% CI 0.95-1.28, P = 0.199; GlnGln versus ArgArg: OR = 1.15, 95% CI 0.93-1.41, P = 0.191; GlnGln/ArgGln versus ArgArg: OR = 1.10, 95% CI 0.97-1.25, P = 0.127; GlnGln versus ArgArg/ArgGln: OR = 1.12, 95% CI 0.92-1.36, P = 0.253). Subgroup analysis showed that there was no association between XRCC1 rs25487 polymorphism and pancreatic cancer risk in Caucasians, but XRCC1 rs25487 polymorphism was associated with pancreatic cancer risk in Asians (GlnGln/ArgGln versus ArgArg: OR = 1.24, 95% CI 1.01-1.53, P = 0.040). Therefore, the meta-analysis suggests that XRCC1 rs25487 polymorphism is associated with pancreatic cancer risk in Asians. Further studies with more participants are needed to provide a more precise estimation on the association above.

Comprehensive study on associations between nine SNPs and glioma risk

AIM

Glioma cancer is the most common type of adult brain tumor. Recent genome-wide association studies (GWAS) have identified various new susceptibility regions and here we conducted an extensive analysis of associations between 12 single nucleotide polymorphisms (SNPs) and glioma risk.

METHODS

A total of 197 glioma cases and 197 health controls were selected, and 9 SNPs in 8 genes were analyzed using the Sequenom MassARRAY platform and Sequenom Assay Design 3.1 software.

RESULTS

We found the MAF among selected controls were consistent with the MAF from the NCBI SNP database. Among 9 SNPs in 8 genes, we identified four significant SNP genotypes associated with the risk of glioma, C/C genotype at rs730437 and T/T genotype at rs1468727 in ERGF were protective against glioma, whereas the T/T genotype at rs1799782 in XRCC1 and C/C genotype at rs861539 in XRCC3 conferred elevated risk.

CONCLUSION

Our comprehensive analysis of nine SNPs in eight genes suggests that the rs730437 and rs1468727 in ERGF, rs1799782 in XRCC1 gene, and rs861539 in XRCC3 gene are associated with glioma risk. These findings indicate that genetic variants of various genes play a complex role in the development of glioma.

Receptivity and preferences of pancreatic cancer family members for participating in lifestyle programs to reduce cancer risk

Background

Cancer is a shared family experience that might provide an opportunity for lifestyle change among at-risk family members. The purpose of this study was to assess receptivity and preferences for cancer risk reduction programs among at-risk family members with two or more relatives affected with pancreas cancer.

Methods

We surveyed 401 at-risk family members in an existing pancreatic cancer family registry. Participants completed a mailed survey which examined demographic, medical, and psychosocial correlates of willingness to participate in lifestyle cancer risk reduction programs. Multivariable generalized estimating equation approaches were used to model preferences.

Results

Overall, 85% (n = 342) of at-risk family members were receptive to lifestyle cancer risk reduction programs. Participant preferred programs focused on nutrition (36%, n = 116) and weight management (33%, n = 108), with Web/Internet (46%, n = 157) being the most preferred delivery channel. Most respondents preferred to participate in programs with their family or friends (74%, n = 182), rather than alone (25%, n = 85). In multivariable analysis, younger age (p = 0.008) and higher perceived likelihood of developing cancer (p = 0.03) were associated with willingness to participate in lifestyle programs.

Conclusions

Family members of those with pancreatic cancer are receptive to cancer risk reduction programs focusing on nutrition and weight management delivered via the internet. Further research is indicated to determine how to best incorporate a family-based approach when designing lifestyle intervention programs.

XRCC1 Polymorphisms and Pancreatic Cancer: A Meta-Analysis

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Association of two ERCC4 tagSNPs with susceptibility to atrophic gastritis and gastric cancer in Chinese

Genetic polymorphisms in excision repair cross-complementing group 4 (ERCC4) may contribute to the risk of cancer development. However, there are few reports regarding to susceptibility to gastric cancer (GC) or its precursor, atrophic gastritis (AG). Thereby, we investigated the association between two tag single nucleotide polymorphisms (tagSNPs) rs6498486 and rs254942, which represents the majority of common SNPs of ERCC4 gene, and the risks of GC and AG development in a sex- and age-matched case-control designed study. We found that rs6498486 polymorphism was associated with a reduced AG risk in total population (for AC vs. AA: OR=0.69, 95%CI=0.52-0.94, P=0.016; for AC/CC vs. AA: OR=0.68, 95%CI=0.51-0.92, P=0.010) as well as in the subpopulation of youngers (age<60years) (for AC/CC vs. AA: OR=0.67, 95%CI=0.45-0.99, P=0.048). For the rs254942 polymorphism, compared with the common TT genotype, the genotypes of CT and CT/CC were only observed to reduce AG risk in the subgroups of males (for CT vs. TT: OR=0.64, 95%CI=0.45-0.90, P=0.012; for CT/CC vs. TT: OR=0.66, 95%CI=0.47-0.92, P=0.016) and youngers (for CT vs. TT: OR=0.72, 95%CI=0.53-0.97, P=0.035; for CT/CC vs. TT: OR=0.74, 95%CI=0.55-0.99, P=0.045). However, no significant statistical association of the two SNPs with GC susceptibility was observed in the total population. Only rs6498486 AC and AC/CC genotypes were found to be marginally associated with a reduced GC risk in the subgroup of males (for AC vs. AA: OR=0.69, 95%CI=0.49-0.99, P=0.043; for AC/CC vs. AA: OR=0.71, 95%CI=0.50-0.99, P=0.046). Our findings suggested that the ERCC4 rs6498486 and rs254942 may be associated with AG risk. Further validation of our results in larger populations and additional studies evaluating their molecular function are required.

Diabetes and risk of pancreatic cancer: a pooled analysis from the pancreatic cancer cohort consortium

PURPOSE

Diabetes is a suspected risk factor for pancreatic cancer, but questions remain about whether it is a risk factor or a result of the disease. This study prospectively examined the association between diabetes and the risk of pancreatic adenocarcinoma in pooled data from the NCI pancreatic cancer cohort consortium (PanScan).

METHODS

The pooled data included 1,621 pancreatic adenocarcinoma cases and 1,719 matched controls from twelve cohorts using a nested case-control study design. Subjects who were diagnosed with diabetes near the time (<2 years) of pancreatic cancer diagnosis were excluded from all analyses. All analyses were adjusted for age, race, gender, study, alcohol use, smoking, BMI, and family history of pancreatic cancer.

RESULTS

Self-reported diabetes was associated with a forty percent increased risk of pancreatic cancer (OR = 1.40, 95 % CI: 1.07, 1.84). The association differed by duration of diabetes; risk was highest for those with a duration of 2-8 years (OR = 1.79, 95 % CI: 1.25, 2.55); there was no association for those with 9+ years of diabetes (OR = 1.02, 95 % CI: 0.68, 1.52).

CONCLUSIONS

These findings provide support for a relationship between diabetes and pancreatic cancer risk. The absence of association in those with the longest duration of diabetes may reflect hypoinsulinemia and warrants further investigation.