Meta-analysis of two ERCC2 (XPD) polymorphisms, Asp312Asn and Lys751Gln, in breast cancer

Contribution of ERCC2 rs13181 (Lys751Gln) and rs1799793 (Asp312Asn) polymorphisms to the risk of bladder cancer in Bangladesh

BACKGROUND

Human Excision Repair Cross-Complementation Group 2 (ERCC2) proteins play a vital role in the nucleotide excision repair pathway through ATP-dependent helicase activity. Several studies found that polymorphisms in the ERCC2 gene are associated with susceptibility to different cancers, although the outcomes were confusing.

OBJECTIVE

As a result, in this retrospective study, we investigated the relationship between genetic polymorphisms of the ERCC2 gene at codons 312 (rs1799793) and 751 (rs13181) and bladder cancer susceptibility in Bangladesh, as well as the disease's aggressiveness.

METHODS

Genetic polymorphisms of ERCC2 were assayed by the polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) method with 121 bladder cancer patients and 130 healthy controls.

RESULTS

Patients who had the Gln/Gln polymorphism of ERCC2 at codon 751 (OR=3.27; 95% CI=1.19-8.67; p<0.05) and Asp/Asn at codon 312 (OR=2.14; 95% CI=1.03-4.29; p<0.05) were significantly associated with a higher risk of developing bladder cancer. Again, Gln/Gln polymorphisms in bladder cancer (p<0.05) were more likely to be present in individuals with cancer in the family.

CONCLUSIONS

This study reveals that susceptibility and bladder cancer aggressiveness are associated with polymorphisms at codon 751 and Asp/Asn at codon 312 of the ERCC2 gene.

The link of ERCC2 rs13181 and ERCC4 rs2276466 polymorphisms with breast cancer in the Bangladeshi population

BACKGROUND

Breast cancer (BC) is the most common disease in women and the leading cause of death from cancer globally. Epidemiological studies examined that nucleotide excision repair genes ERCC2 (rs13181) and ERCC4 (rs2276466) SNPs might increase cancer risk. Based on the previous investigation, this study was conducted to explore the correlation between these polymorphisms and BC susceptibility in Bangladeshi women.

METHODS AND RESULTS

Between January 2019 and January 2020, 140 blood samples were collected from female patients histologically diagnosed with BC, and 111 female controls were recruited from non-cancer subjects. Genotyping was performed applying the PCR-RFLP method, and all statistical analyzes were conducted using SPSS, version 25.0. Comparison of characteristics and clinicopathological features between ERCC2 rs13181 and ERCC4 rs2276466 carriers and non-carriers showed no significant link with BC. Analysis of ERCC2 rs13181 with the risk of BC showed that the GG genotype and G allele carriers showed a fourfold and 1.78-fold higher risk (OR 4.00, P = 0.001 and OR 1.78, P = 0.002) that are statistically significant. In addition, the patients with combined TG+GG genotype revealed a 2.09-fold increased chance (OR 2.09, P = 0.020) BC development. Analysis of recessive model (GG vs. TT+TG) also depicted 2.74-times significantly higher risk (OR 2.74, P = 0.002). On the other hand, ERCC4 rs2276466 polymorphism did not show any significant association with BC (P > 0.05).

CONCLUSIONS

Our findings show that ERCC2 rs13181 is linked to an elevated risk of BC. Our study also shows that ERCC4 rs2276466 polymorphism has no substantial risk of BC in the Bangladeshi population.

Polymorphism of the DNA repair gene XDP increases the risk of systemic lupus erythematosus but not multiple sclerosis in the Iranian population

BACKGROUND

Xeroderma pigmentosum group D ( XPD ) is an essential component of the nucleotide excision repair (NER) pathway, which can play a major role in DNA repair processes. A deficiency in this pathway was suggested as a causative factor of autoimmune diseases. Therefore, the current study aimed to investigate the relationship between XPD Lys751Gln polymorphism (rs13181) as one of the most common XDP polymorphisms and the risk of two important auto-immune diseases,namely systemic lupus erythematosus (SLE) and multiple sclerosis (MS) in the Iranian population.

METHODS

165 SLE patients and 165 age- and gender-matched healthy controls, and 150 MS patients and 150 age- and gender-matched healthy controls were genotyped for XPD rs13181 A/C polymorphism using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

The results of the present study have indicated that both C allele frequency ( P = 0.012; odds ratio: 1.5; 95% confidence interval: 1.1-2.07) and CC genotype ( P = 0.007; odds ratio: 2.46; 95% confidence interval: 1.2-4.7) in SLE patient were significantly higher than those in control group. Furthermore, there were no significant differences between MS patients and normal subjects concerning the genotype and the allele frequencies.

CONCLUSION

Our findings suggested that XPD rs13181 A/C polymorphism may be a crucial risk factor for the development of SLE but not MS in Iranian patients.

Breast cancer in an 18-year-old female: A fatal case report and literature review

Breast cancer (BC) is the most frequent malignancy in both pre- and postmenopausal women. However, it is exceedingly rare in very young patients, and especially in adolescents. Herein, we report a case of an 18-year-old female diagnosed with invasive BC. The proband had been found to be negative for BC in close family members. A common BC genetic screening test for the Polish population did not detect any known founder mutations in the BRCA1 gene. Further evaluation identified a p.Ile157Thr (I157T) mutation in the CHEK2 gene, a p.Ala1991Val (A1991V) variant of unknown significance in the BRCA2 gene, p.Lys751Gln (K751Q) variant in the XPD (ERCC2) gene, and a homozygous p.Glu1008Ter (E1008*) mutation in the NOD2 gene. No other mutation had been found by next generation sequencing in major BC high-risk susceptibility genes BRCA1, BRCA2, as well as 92 other genes. To date, all these found alterations have been considered as low to moderate risk factors in the general population and moderate risk factors in younger women (<35 years of age). There are no previous articles relating low and moderate risk gene mutations to very young onset (below 20 years) BC with a fatal outcome. In our patient, a possible cumulative or synergistic risk effect for these 4 alterations, and a mutation in the NOD2 gene in particular, of which both presumably healthy parents were found to be carriers, is suggested.

Predictive value of excision repair cross-complementing group 2 gene Lys751Gln and Asp312Asn polymorphisms in melanoma risk

Epidemiological studies have assessed the association between excision repair cross-complementing group 2 (ERCC2) Lys751Gln and Asp312Asn polymorphisms and melanoma risk with conflicting results. Relevant articles were searched from PubMed, Embase, and Web of Science with a time limit of 3 September 2016. Pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of the association. We performed this meta-analysis with 12 studies including 6157 cases and 8873 controls for Lys751Gln and nine studies including 5037 cases and 7542 controls for Asp312Asn polymorphism. Overall, no significant associations were found under all the models for Lys751Gln polymorphism, and significant associations were found for Asp312Asn polymorphism for AA versus GG (OR=1.12, 95% CI=1.00-1.26) and for the recessive model (OR=1.11, 95% CI=1.00-1.24). In the stratification analyses by source of control: for Lys751Gln polymorphism, significant associations were found for CC versus AA (OR=1.19, 95% CI=1.04-1.36) and the recessive model (OR=1.15, 95% CI=1.02-1.30); for Asp312Asn polymorphism, significant associations were found for AA versus GG (OR=1.31, 95% CI=1.11-1.53) and the recessive model (OR=1.29, 95% CI=1.11-1.50). This meta-analysis suggested that both the Lys751Gln and Asp312Asn polymorphisms were risk factors for melanoma risk in population-based subgroup.

Significant association between ERCC2 and MTHR polymorphisms and breast cancer susceptibility in Moroccan population: genotype and haplotype analysis in a case-control study

Background

Genetic determinants of breast cancer (BC) remained largely unknown in the majority of Moroccan patients. The purpose of this study was to explore the association of ERCC2 and MTHFR polymorphisms with genetic susceptibility to breast cancer in Moroccan population.

Methods

We genotyped ERCC2 polymorphisms (rs1799793 (G934A) and rs13181 (A2251C)) and MTHFR polymorphisms (rs1801133 (C677T) and rs1801131 (A1298C)) using TaqMan SNP Genotyping Assays. Genotypes were compared in 151 BC cases and 156 population-matched controls. Allelic, genotypic and haplotype associations with the risk and clinicopathological features of BC were assessed using logistic regression analyses.

Results

ERCC2-rs1799793-AA genotype was associated with high risk of BC compared to wild type genotype (recessive model: OR: 2.90, 95% CI: 1.34–6.26, p = 0.0069) even after Bonferroni correction (p < 0,0125). MTHFR rs1801133-TT genotype was associated with increased risk of BC (recessive model, OR: 2.49, 95% CI: 1.17–5.29, p = 0.017) but the association turned insignificant after Bonferroni correction. For the rest of SNPs, no statistical associations to BC risk were detected.

Significant association with clinical features was detected for MTHFR-rs1801133-TC genotype with early age at diagnosis and familial BC. Following Bonferroni correction, only association with familial BC remained significant. MTHFR-rs1801131-CC genotype was associated with sporadic BC. ERCC2-rs1799793-AA genotype correlated with ER+ and PR+ breast cancer. ERCC2-rs13181-CA genotype was significantly associated large tumors (T ≥ 3) in BC patients. None of these associations passed Bonferroni correction.

Haplotype analysis showed that ERCC2 A-C haplotype was significantly associated with increased BC risk (OR: 3.71, 95% CI: 1.7–8.12, p = 0.0002 and p = 0.0008 before and after Bonferroni correction, respectively) and positive expression of ER and PR in BC patients. ERCC2 G-C haplotype was correlated with PR negative and larger tumor (T4). We did not find any MTHFR haplotypes associated with BC susceptibility. However, the less common haplotype MTHFR T-C was more frequent in young patients and in familial breast cancer, while MTHFR C-C haplotype was associated with sporadic BC form.

Conclusions

Our findings are a first observation of association between ERCC2 SNPs and breast cancer in Moroccan population. The results suggested that ERCC2 and MTHFR polymorphisms may be reliable for assessing risk and prognosis of BC in Moroccan population.

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.

Nucleotide excision repair pathway gene polymorphisms are linked to breast cancer risk in a Chinese population

Polymorphisms in nucleotide excision repair (NER) pathway genes are associated with the risk of breast cancer, but the relevance of these associations appeared to vary according to the ethnicity of the subjects. To systemically evaluate the potential associations between NER polymorphisms and breast cancer risk in a Chinese population, we carried out a case-control study on 450 breast cancer patients and 430 healthy controls. Sequenom MassARRAY was used for genotyping, and immunohistochemistry was performed to detect estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) expression in tumor tissue. Our results showed that ERCC1 rs11615 (additive model: ORadjusted: 1.36, 95% CI: 1.08-1.71, p = 0.009), XPC rs2228000 (additive model: ORadjusted: 1.39, 95% CI: 1.13-1.72, p = 0.002) and ERCC2/XPD rs50872 (additive model: ORadjusted: 1.32, 95% CI: 1.04-1.67, p = 0.021) were associated with an increased risk of breast cancer. Stratified analysis revealed three polymorphisms (rs11615, rs1800975, and rs50872) to be associated with breast cancer in menopausal females. Three polymorphisms were associated with specific breast cancer grades (rs11615 with grade 3, rs2228000 and rs50872 with grade 1-2). Two polymorphisms (rs2228001 and rs50872) were associated with the risk of breast cancer with negative lymph node involvement. rs1800975 and rs50872 were associated with the risk of ER- and PR- breast cancer, whereas rs11615 was associated with the risk of ER+ and PR+ breast cancer. We found that carriers of the T allele of ERCC1 rs11615, XPC rs2228000 and rs50872, particularly in postmenopausal females, have an increased risk of breast cancer.

Exploratory analysis of ERCC2 DNA methylation in survival among pediatric medulloblastoma patients

AIM

Medulloblastoma is the most frequent malignant pediatric brain tumor. While survival rates have improved due to multimodal treatment including cisplatin-based chemotherapy, there are few prognostic factors for adverse treatment outcomes. Notably, genes involved in the nucleotide excision repair pathway, including ERCC2, have been implicated in cisplatin sensitivity in other cancers. Therefore, this study evaluated the role of ERCC2 DNA methylation profiles on pediatric medulloblastoma survival.

METHODS

The study population included 71 medulloblastoma patients (age <18years at diagnosis) and recruited from Texas Children's Cancer Center between 2004 and 2009. DNA methylation profiles were generated from peripheral blood samples using the Illumina Infinium Human Methylation 450 Beadchip. Sixteen ERCC2-associated CpG sites were evaluated in this analysis. Multivariable regression models were used to determine the adjusted association between DNA methylation and survival. Cox regression and Kaplan-Meier curves were used to compare 5-year overall survival between hyper- and hypo-methylation at each CpG site.

RESULTS

In total, 12.7% (n=9) of the patient population died within five years of diagnosis. In our population, methylation of the cg02257300 probe (Hazard Ratio=9.33; 95% Confidence Interval: 1.17-74.64) was associated with death (log-rank p=0.01). This association remained suggestive after correcting for multiple comparisons (FDR p<0.2). No other ERCC2-associated CpG site was associated with survival in this population of pediatric medulloblastoma patients.

CONCLUSION

These findings provide the first evidence that DNA methylation within the promoter region of the ERCC2 gene may be associated with survival in pediatric medulloblastoma. If confirmed in future studies, this information may lead to improved risk stratification or promote the development of novel, targeted therapeutics.

Identification and Functional Testing of ERCC2 Mutations in a Multi-national Cohort of Patients with Familial Breast- and Ovarian Cancer

The increasing application of gene panels for familial cancer susceptibility disorders will probably lead to an increased proposal of susceptibility gene candidates. Using ERCC2 DNA repair gene as an example, we show that proof of a possible role in cancer susceptibility requires a detailed dissection and characterization of the underlying mutations for genes with diverse cellular functions (in this case mainly DNA repair and basic cellular transcription). In case of ERCC2, panel sequencing of 1345 index cases from 587 German, 405 Lithuanian and 353 Czech families with breast and ovarian cancer (BC/OC) predisposition revealed 25 mutations (3 frameshift, 2 splice-affecting, 20 missense), all absent or very rare in the ExAC database. While 16 mutations were unique, 9 mutations showed up repeatedly with population-specific appearance. Ten out of eleven mutations that were tested exemplarily in cell-based functional assays exert diminished excision repair efficiency and/or decreased transcriptional activation capability. In order to provide evidence for BC/OC predisposition, we performed familial segregation analyses and screened ethnically matching controls. However, unlike the recently published RECQL example, none of our recurrent ERCC2 mutations showed convincing co-segregation with BC/OC or significant overrepresentation in the BC/OC cohort. Interestingly, we detected that some deleterious founder mutations had an unexpectedly high frequency of > 1% in the corresponding populations, suggesting that either homozygous carriers are not clinically recognized or homozygosity for these mutations is embryonically lethal. In conclusion, we provide a useful resource on the mutational landscape of ERCC2 mutations in hereditary BC/OC patients and, as our key finding, we demonstrate the complexity of correct interpretation for the discovery of “bonafide” breast cancer susceptibility genes.

Approximately 5–10% of breast/ovarian cancer (BC/OC) cases have inherited an increased risk of developing this malignancy. However, mutations in the two major breast cancer susceptibility genes BRCA1 and BRCA2 explain only 15–20% of all familial BC/OC cases. With the emergence of the high throughput NGS-technology, the number of proposed novel candidate genes for breast cancer predisposition continuously increases. However, a “bonafide” proof of cancer susceptibility requires a detailed characterization of candidate mutations, which we addressed in the current study. Using the DNA repair gene ERCC2 as an example, we performed a comprehensive multi-center approach, analyzing ERCC2 mutations in 1000+ patients with hereditary BC/OC. We identified 25 potential candidate mutations for cancer breast cancer susceptibility, some of them affecting ERCC2 functional activity in appropriate cell-culture based assays. However, a more dissected analysis showed no convincing co-segregation with BC/OC and there was no longer a significant overrepresentation in BC/OC when compared to regionally matched controls instead of the global ExAc variant data base, pointing to the relevance of founder-mutations. In conclusion, we provide a useful resource on the mutational landscape of ERCC2 mutations in hereditary BC/OC patients and, as our key finding, we highlight the complexity of correct interpretation for the discovery of “bonafide” breast cancer susceptibility genes.

Single nucleotide polymorphisms in DNA repair genes and putative cancer risk

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

Different patterns of allelic imbalance in sporadic tumors and tumors associated with long-term exposure to gamma-radiation

The study aimed to reveal cancer related mutations in DNA repair and cell cycle genes associated with chronic occupational exposure to gamma-radiation in personnel of the Siberian Group of Chemical Enterprises (SGCE). Mutations were analyzed by comparing genotypes of malignant tumors and matched normal tissues of 255 cancer patients including 98 exposed to external gamma-radiation (mean dose 128.1±150.5mSv). Also a genetic association analysis was carried out in a sample of 149 cancer patients and 908 healthy controls occupationally exposed to gamma-radiation (153.2±204.6mSv and 150.5±211.2mSv, respectively). Eight SNPs of genes of DNA excision repair were genotyped (rs13181, rs1052133, rs1042522, rs2305427, rs4244285, rs1045642, rs1805419 and rs1801133). The mutation profiles in heterozygous loci for selected SNP were different between sporadic tumors and tumors in patients exposed to radiation. In sporadic tumors, heterozygous genotype Arg/Pro of the rs1042522 SNP mutated into Arg/0 in 15 cases (9.6%) and 0/Pro in 14 cases (8.9%). The genotype Lys/Gln of the rs13181 SNP mutated into Lys/0 and 0/Gln in 9 and 4 cases, respectively. In tumors of patients exposed to low-level radiation, the rs1042522 Arg/0 mutated genotype was found in 12 cases (12.1%), while in 2 cases (2%) 0/Pro mutation was observed. Finally, the rs13181 0/Gln mutated genotype was observed in 15 cases (16,5%) . Thus, our study showed the difference in patterns of allelic imbalance in tumors appeared under low-level radiation exposure and spontaneous tumors for selected SNPs. This suggests different mechanisms of inactivation of heterozygous genotypes in sporadic and radiation-induced tumors.

XPD Lys751Gln and Asp312Asn polymorphisms and hepatocellular carcinoma susceptibility: A meta-analysis of 11 case-control studies in an Asian population

This meta-analysis was performed to evaluate the association between xeroderma pigmentosum complementary group D (XPD) Lys751Gln and Asp312Asn polymorphisms and susceptibility to hepatocellular carcinoma (HCC). PubMed, Embase, Google Scholar and the Chinese National Knowledge Infrastructure and the Chinese Biomedicine databases were systematically searched to identify relevant studies published up to June 1, 2014. Statistical analyses were performed using Stata version 12.0 software. A total of 11 case-control studies, comprising 2,852 cases and 2,936 controls, were included. The results of the meta-analysis revealed that a significant association between the risk of HCC and variant genotypes of the XPD Lys751Gln and Asp312Asn polymorphisms was evident in the homozygote comparison [Gln/Gln versus Lys/Lys: Odds ratio (OR), 1.831; 95% confidence interval (CI), 1.001-3.349], heterozygote comparison (Lys/Gln versus Lys/Lys: OR, 1.486; 95% CI, 1.044-2.114), dominant model (Gln/Gln + Lys/Gln versus Lys/Lys: OR, 1.540; 95% CI, 1.054-2.249) and allelic contrast (Gln-allele versus Lys-allele: OR, 1.453; 95% CI, 1.032-2.046) for the Lys751Gln polymorphism and the homozygote comparison for the Asp312Asn polymorphism (Asn/Asn versus Asp/Asp: OR, 1.352; 95% CI, 1.010-1.808). By contrast, no significant association was observed in the recessive model for the Lys751Gln polymorphism (Gln/Gln versus Lys/Gln + Lys/Lys: OR, 1.603; 95% CI, 0.924-2.779), or for the heterozygote comparison (Asn/Asp versus Asp/Asp: OR, 1.229; 95% CI, 0.857-1.762), dominant model (Asn/Asn + Asp/Asn versus Asp/Asp: OR, 1.249; 95% CI, 0.910-1.715), recessive model (Asn/Asn versus Asp/Asn + Asp/Asp: OR, 1.250; 95% CI, 0.940-1.663) or allelic contrast (Asn-allele versus Asp-allele: OR, 1.226; 95% CI, 0.965-1.557) for the Asp312Asn polymorphism. The present meta-analysis has indicated that the XPD Lys751Gln polymorphism could be a potential biomarker of HCC susceptibility and that the XPD Lys751Gln and Asp312Asn polymorphisms could be risk factors for HCC susceptibility in an Asian population; however, further large-scale and well-designed studies are required to reach a more precise and comprehensive conclusion.

Association of the Asp312Asn and Lys751Gln polymorphisms in the XPD gene with the risk of non-Hodgkin's lymphoma: evidence from a meta-analysis

Polymorphisms in DNA repair genes may alter DNA repair capacity and, consequently, lead to genetic instability and carcinogenesis. Several studies have investigated the association of the Asp312Asn and Lys751Gln polymorphisms in the xeroderma pigmentosum complementation group D (XPD) gene with the risk of non-Hodgkin's lymphoma (NHL), but the conclusions have been inconsistent. Therefore, we performed this meta-analysis to more precisely estimate these relationships. A systematic literature search was performed using the PubMed, Embase, and Chinese Biomedical (CBM) databases. Ultimately, 6 studies of Asp312Asn, comprising 3,095 cases and 3,306 controls, and 7 studies of Lys751Gln, consisting of 3,249 cases and 3,676 controls, were included. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of each association. Overall, no association was observed between the Asp312Asn polymorphism and NHL risk (homozygous: OR = 1.11, 95% CI = 0.94-1.32; heterozygous: OR = 1.00, 95% CI = 0.89-1.11; recessive: OR = 1.12, 95% CI = 0.95-1.31; dominant: OR = 1.02, 95% CI = 0.92-1.13; and allele comparison: OR = 1.04, 95% CI = 0.96-1.12) or between the Lys751Gln polymorphism and NHL risk (homozygous: OR = 0.97, 95% CI = 0.83-1.15; heterozygous: OR = 0.96, 95% CI = 0.86-1.06; recessive: OR = 1.00, 95% CI = 0.86-1.16; dominant: OR = 0.96, 95% CI = 0.87-1.06; and allele comparison: OR = 0.98, 95% CI = 0.91-1.05). Furthermore, subgroup analyses did not reveal any association between these polymorphisms and ethnicity, the source of the controls, or the NHL subtype. These results indicated that neither the Asp312Asn nor Lys751Gln XPD polymorphism was related to NHL risk. Large and well-designed prospective studies are required to confirm this finding.

Crystal structure of the Rad3/XPD regulatory domain of Ssl1/p44

The Ssl1/p44 subunit is a core component of the yeast/mammalian general transcription factor TFIIH, which is involved in transcription and DNA repair. Ssl1/p44 binds to and stimulates the Rad3/XPD helicase activity of TFIIH. To understand the helicase stimulatory mechanism of Ssl1/p44, we determined the crystal structure of the N-terminal regulatory domain of Ssl1 from Saccharomyces cerevisiae. Ssl1 forms a von Willebrand factor A fold in which a central six-stranded β-sheet is sandwiched between three α helices on both sides. Structural and biochemical analyses of Ssl1/p44 revealed that the β4-α5 loop, which is frequently found at the interface between von Willebrand factor A family proteins and cellular counterparts, is critical for the stimulation of Rad3/XPD. Yeast genetics analyses showed that double mutation of Leu-239 and Ser-240 in the β4-α5 loop of Ssl1 leads to lethality of a yeast strain, demonstrating the importance of the Rad3-Ssl1 interactions to cell viability. Here, we provide a structural model for the Rad3/XPD-Ssl1/p44 complex and insights into how the binding of Ssl1/p44 contributes to the helicase activity of Rad3/XPD and cell viability.

Polymorphisms in DNA repair genes and breast cancer risk in Russian population: a case-control study

Genetic variation in DNA repair genes can alter an individual's capacity to repair damaged DNA and influence the risk of cancer. We tested seven polymorphisms in DNA repair genes XRCC1, ERCC2, XRCC3, XRCC2, EXOI and TP53 for a possible association with breast cancer risk in a sample of 672 case and 672 control Russian women. An association was observed for allele A of the polymorphism XRCC1 (R399Q) rs25487 (co-dominant model AA vs. GG: OR 1.76, P = 0.003; additive model OR 1.28, P = 0.005; dominant model: OR 1.29, P = 0.03; recessive model OR 1.63, P = 0.008). Allele T of the polymorphism ERCC2 (D312N) rs1799793 was also associated with breast cancer risk (co-dominant model TT vs. CC: OR 1.43, P = 0.04; additive model OR 1.21, P = 0.02; dominant model: OR 1.30, P = 0.02), but the association became insignificant after applying Bonferroni correction. No association with breast cancer was found for the remaining SNPs. In summary, our study provides evidence that polymorphisms in DNA repair genes may play a role in susceptibility to breast cancer in the population of ethnical Russians.

Association between XPD Lys751Gln and Asp312Asn polymorphisms and hepatocellular carcinoma risk: a systematic review and meta-analysis

Genetic polymorphisms of xeroderma pigmentosum group D (XPD) in the nucleotide excision repair pathway may influence cancer susceptibility by affecting the capacity for DNA repair. Studies investigating the association between XPD Lys751Gln and Asp312Asn polymorphisms and hepatocellular carcinoma (HCC) risk reported inconsistent results. The aim of this study was to quantitatively summarize the evidence for such an association. Eligible studies were identified by searching electronic databases including PubMed, Embase, Cochrane library, and CBM, Chinese Biomedical Literature Database, for the period up to October 2014. The association of XPD Lys751Gln and Asp312Asn polymorphisms and HCC risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs). Finally, a total of 11 studies with 4322 cases and 4970 controls were included for XPD Lys751Gln polymorphism and 6 studies with 2223 cases and 2441 controls were available for XPD Asp312Asn polymorphism. With respect to XPD Lys751Gln polymorphism, statistically significant increased HCC risk was found when all studies were pooled into the meta-analysis (Gln/Gln vs Lys/Lys: OR = 1.363, 95% CI 1.065-1.744, P = 0.014; Lys/Gln vs Lys/Lys: OR = 1.205, 95% CI 1.099-1.321, P = 0.000; Gln/Gln+Lys/Gln vs Lys/Lys: OR = 1.300, 95% CI 1.141-1.480, P = 0.000). In subgroup analyses by ethnicity, source of control, Hardy-Weinberg equilibrium (HWE) in controls, hepatitis B virus (HBV) infection, and statistically significant increase of HCC risk was found in East Asians, population-based studies, studies consistent with HWE, and HBV-positive subjects, but not in mixed/other populations, hospital-based studies, studies deviating from HWE, and HBV-negative subjects. With respect to XPD Asp312Asn polymorphism, no significant association with HCC risk was found in the overall and subgroup analyses. The results suggest that the XPD Lys751Gln polymorphism contributes to increased HCC susceptibility, especially in East Asian populations. Further, large and well-designed studies are required to validate this association.

Association between the XPD/ERCC2 Lys751Gln polymorphism and risk of cancer: evidence from 224 case-control studies

Genetic variations in the xeroderma pigmentosum group D (XPD) gene may increase cancer susceptibility by affecting the capacity for DNA repair. A lot of studies have reported the association of XPD Lys751Gln polymorphism with risk of cancer, but the results remained controversial. Hence, we performed a systematic review and conducted a meta-analysis to explore association of the XPD Lys751Gln polymorphism with risk of cancer (78,398 cases and 103,178 controls from 224 studies). Overall, a significantly increased cancer risk was found in all genetic models (dominant model: odds ratio (OR) = 1.10, 95% confidence interval (CI) = 1.06-1.14; recessive model: OR = 1.10, 95% CI = 1.05-1.15; homozygous model: OR = 1.14, 95% CI = 1.08-1.21; heterozygous model: OR = 1.09, 95% CI = 1.05-1.12; additive model: OR = 1.08, 95% CI= 1.05-1.11) when all eligible studies were pooled into the meta-analysis. In further stratified and sensitivity analyses, the elevated risk of cancer remained for subgroups of breast cancer, esophageal cancer, hepatocellular cancer, leukemia, lung cancer, and melanoma. In summary, this meta-analysis suggests the XPD Lys751Gln polymorphism is a genetic susceptibility for some cancer types. Moreover, ethnicity, histological type of cancer, and smokers seem to contribute to varying expressions of the Lys751Gln on some cancer risk. In addition, our work also points out the importance of new studies for Lys751Gln association in endometrial cancer and ovarian cancer, where at least some of the covariates responsible for heterogeneity could be controlled, to obtain a more conclusive understanding about the function of the Lys751Gln polymorphism in cancer development.

Polymorphisms in the DNA repair gene ERCC2/XPD and breast cancer risk: a HapMap-based case-control study among Han Women in a Chinese less-developed area

AIMS

Genetic variations in DNA repair genes may impact repair functions, DNA damage, and breast cancer risk. This study is aimed to assess the associations of genetic polymorphisms in excision repair cross-complementing group 2 (ERCC2) with the risk of developing breast cancer.

MATERIALS AND METHODS

In total, 101 histopathologically confirmed breast cancer cases and 101 age/region-matched healthy controls were genotyped for rs 3916840, rs 1799793, and rs 238416 in ERCC2 by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The rs 238416 heterozygous GA genotype combined with the rs 238416 genotypes (GA+AA) showed a significant association with breast cancer susceptibility (corrected p<0.01, odds ratio [OR]=0.29, 95% confidence interval [CI]=0.15-0.54; corrected p<0.01, OR=0.31, 95% CI=0.17-0.56, respectively). The rs 238416 GA genotype carriers had a decreased risk of breast cancer. However, we observed no significant association between the rs 3916840 and rs 1799793 polymorphisms in ERCC2 and breast cancer risk. Moreover, haplotype analysis showed that the ACG haplotype was associated with a significantly decreased risk of breast cancer, whereas the GCG haplotype was associated with a significantly increased risk of breast cancer (corrected p=0.004 and p=0.002, respectively). Multifactor dimensionality reduction analysis demonstrated that the interactions between rs 3916840 and rs 238416 were significantly synergistic.

CONCLUSION

To the best of our knowledge, this study is the first to demonstrate that the rs 238416 heterozygous genotype likely has a higher DNA repair capacity and, thus, can be protective against breast cancer in Chinese Han women.

Ethnic background and genetic variation in the evaluation of cancer risk: a systematic review

The clinical use of genetic variation in the evaluation of cancer risk is expanding, and thus understanding how determinants of cancer susceptibility identified in one population can be applied to another is of growing importance. However there is considerable debate on the relevance of ethnic background in clinical genetics, reflecting both the significance and complexity of genetic heritage. We address this via a systematic review of reported associations with cancer risk for 82 markers in 68 studies across six different cancer types, comparing association results between ethnic groups and examining linkage disequilibrium between risk alleles and nearby genetic loci. We find that the relevance of ethnic background depends on the question. If asked whether the association of variants with disease risk is conserved across ethnic boundaries, we find that the answer is yes, the majority of markers show insignificant variability in association with cancer risk across ethnic groups. However if the question is whether a significant association between a variant and cancer risk is likely to reproduce, the answer is no, most markers do not validate in an ethnic group other than the discovery cohort's ancestry. This lack of reproducibility is not attributable to studies being inadequately populated due to low allele frequency in other ethnic groups. Instead, differences in local genomic structure between ethnic groups are associated with the strength of association with cancer risk and therefore confound interpretation of the implied physiologic association tracked by the disease allele. This suggest that a biological association for cancer risk alleles may be broadly consistent across ethnic boundaries, but reproduction of a clinical study in another ethnic group is uncommon, in part due to confounding genomic architecture. As clinical studies are increasingly performed globally this has important implications for how cancer risk stratifiers should be studied and employed.

MnSOD rs4880 and XPD rs13181 polymorphisms predict the survival of breast cancer patients treated with adjuvant tamoxifen

The enzyme manganese superoxide dismutase (MnSOD) defends against oxidative stress caused by reactive oxygen species (ROS), whereas Xeroderma pigmentosum group D (XPD) protein is involved in DNA repair. Polymorphisms in these genes have previously been associated with the outcome of breast cancer.

MATERIAL AND METHODS

Two gene polymorphisms, the MnSOD Val16Ala (rs4880A>G) and the XPD Lys751Gln (rs13181A>C), were analyzed in a cohort of 396 Finnish breast cancer patients by using PCR-RFLP-based methods in a prospective case-control study. The overall survival (OS), breast cancer-specific survival (BCSS), and relapse-free survival (RFS), assessed by using Kaplan-Meier survival analysis and multivariate Cox regression analysis, were evaluated according to the adjuvant treatments and the rs4880 and rs13181 genotypes.

RESULTS

In the combined analysis of rs4880 and rs13181 genotypes for patients treated with adjuvant tamoxifen (TAM) an increasing number of low-risk genotypes (rs4880 AA, rs4880 AG, or rs13181 AA) was significantly associated with better RFS, BCSS, and OS (n=64). In addition, there was improved BCSS and RFS among TAM-treated patients carrying the wild-type rs4880 A allele as compared with the other genotypes (n=64). The wild-type rs13181 AA genotype was similarly associated with better RFS and BCSS in the TAM-treated population (n=65).

CONCLUSION

This is the first study to show that the MnSOD rs4880 and XPD rs13181 polymorphisms may influence the outcome of breast cancer patients receiving adjuvant TAM monotherapy. Patients carrying the rs4880 A allele or rs13181 AA genotype may have a reduced ability to scavenge ROS and repair the DNA damage generated by TAM treatment.

The effect of XPD polymorphisms on digestive tract cancers risk: a meta-analysis

Background

The Xeroderma pigmento-sum group D gene (XPD) plays a key role in nucleotide excision repair. Single nucleotide polymorphisms (SNP) located in its functional region may alter DNA repair capacity phenotype and cancer risk. Many studies have demonstrated that XPD polymorphisms are significantly associated with digestive tract cancers risk, but the results are inconsistent. We conducted a comprehensive meta-analysis to assess the association between XPD Lys751Gln polymorphism and digestive tract cancers risk. The digestive tract cancers that our study referred to, includes oral cancer, esophageal cancer, gastric cancer and colorectal cancer.

Methods

We searched PubMed and EmBase up to December 31, 2012 to identify eligible studies. A total of 37 case-control studies including 9027 cases and 16072 controls were involved in this meta-analysis. Statistical analyses were performed with Stata software (version 11.0, USA). Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association.

Results

The results showed that XPD Lys751Gln polymorphism was associated with the increased risk of digestive tract cancers (homozygote comparison (GlnGln vs. LysLys): OR = 1.12, 95% CI = 1.01–1.24, P = 0.029, P_{heterogeneity} = 0.133). We found no statistical evidence for a significantly increased digestive tract cancers risk in the other genetic models. In the subgroup analysis, we also found the homozygote comparison increased the susceptibility of Asian population (OR = 1.28, 95% CI = 1.01–1.63, P = 0.045, P_{heterogeneity} = 0.287). Stratified by cancer type and source of control, no significantly increased cancer risk was found in these subgroups. Additionally, risk estimates from hospital-based studies and esophageal studies were heterogeneous.

Conclusions

Our meta-analysis suggested that the XPD 751Gln/Gln genotype was a low-penetrate risk factor for developing digestive tract cancers, especially in Asian populations.

The effect of XPD/ERCC2 Lys751Gln polymorphism on acute leukemia risk: a systematic review and meta-analysis

AIMS

Epidemiological studies have assessed the association between xeroderma pigmentosum group D (XPD) Lys751Gln and acute leukemia risk with conflicting results. We performed this meta-analysis to derive a more precise estimation of the relationship. Pooled odds ratio (OR) with 95% confidence interval (95% CI) was used to assess the strength of the association.

RESULTS

Ten published case-control studies including a total of 1494 cases and 2259 controls were identified. Overall, significant risk effects of Lys751Gln genotype was found under the dominant model (OR=1.16; 95% CI=1.01-1.34; P=0.032). When stratified by clinical types, the variant genotype was associated with the acute myeloid leukemia (AML) risk under the heterozygote comparison (OR=1.20; 95% CI=1.00-1.43; P=0.048), the homozygote comparison (OR=1.35; 95% CI=1.05-1.74; P=0.019) and the dominant model (OR=1.23; 95% CI=1.04-1.45; P=0.015), respectively. Furthermore, significantly increased risks were also pronounced in Caucasian AML patients (the homozygote comparison: OR=1.38; 95% CI=1.07-1.78; P=0.013; the dominant model: OR=1.23; 95% CI=1.03-1.46; P=0.020; and the recessive model: OR=1.26; 95% CI=1.00-1.60; P=0.050). No evident heterogeneities were observed for the overall data under all genetic models. In addition, no statistical evidence for publication bias was found using the method of Begg's and Egger's tests.

CONCLUSION

This meta-analysis suggested that XPD Lys751Gln polymorphism might be a risk factor for AML and Caucasian acute leukemia patients.

XPD Asp312Asn and Lys751Gln polymorphisms and breast cancer susceptibility: a meta-analysis

The association between xeroderma pigmentosum complementation group D (XPD) Asp312Asn and Lys751Gln gene polymorphisms and breast cancer risk has been widely reported, but the results were inconsistent. In order to derive a more precise estimation of the relationship, a meta-analysis was performed. A comprehensive search strategy was conducted towards the electronic databases including Medline, PubMed, Web of Science, Embase, and Chinese Biomedical Literature Database (Chinese). The association between the XPD polymorphism and breast cancer risk was conducted by odds ratios (ORs) and 95 % confidence intervals (95 % CIs). A total of 22 studies with 18,136 cases and 18,351 controls were included in our meta-analysis. Among these, 12 studies with 7,667 cases and 7,480 controls for Asp312Asn polymorphism and 20 studies with 10,469 cases and 10,871 controls for Lys751Gln polymorphism. With regard to Asp312Asn polymorphism, no significantly associated was found with breast cancer risk. However, significant association was found between Lys751Gln polymorphism and breast cancer risk under all genetic models in overall populations (C vs. A—OR = 1.10, 95 % CI = 1.04–1.17, P = 0.002; CC vs. AA—OR = 1.17, 95 % CI = 1.06–1.30, P = 0.003; AC vs. AA—OR = 1.06, 95 % CI = 1.01–1.12, P = 0.032; CC vs. AC/AA—OR = 1.17, 95 % CI = 1.04–1.32, P = 0.009; CC/AC vs. AA—OR = 1.07, 95 % CI = 1.02–1.12, P = 0.005). In subgroup analysis base on ethnicity, significance was found in Caucasians and mix. The results suggest that XPD Asp312Asn polymorphism was not associated with breast cancer. The XPD Lys751Gln polymorphism significantly increased breast cancer risk, especially for Caucasian and mix.

Polymorphisms of excision repair gene XPD Lys751Gln and hOGG1 Ser326Cys might not be associated with hepatocellular carcinoma risk: a meta-analysis

The xeroderma pigmentosum group D (XPD) and human 8-oxoguanine glycosylase 1 (hOGG1) genes have been suggested to play an important role in the pathogenesis of hepatocellular carcinoma (HCC). However, the results have been inconsistent. In this study, we performed a meta-analysis to clarify the associations of polymorphisms of XPD and hOGG1 genes with HCC risk. Published literature from PubMed, EMBASE, and Chinese National Knowledge Infrastructure were retrieved. Pooled odds ratio (OR) with 95 % confidence interval (CI) was calculated using a fixed- or random-effects model. Seven studies (1,955 HCC cases and 2,023 controls) for XPD Lys751Gln polymorphism and six studies (1,470 HCC cases and 1,541 controls) for hOGG1 Ser326Cys polymorphism were included in the final meta-analysis. For XPD Lys751Gln polymorphism, no significant association was found under all genetic models (Gln/Gln vs Lys/Lys OR = 1.09, 95 % CI = 0.28-4.18; Gln/Lys vs Lys/Lys OR = 1.41, 95 % CI = 0.81-2.44; dominant model OR = 1.40, 95 % CI = 0.77-2.57; recessive model OR = 1.02, 95 % CI = 0.33-3.23). For hOGG1 Ser326Cys polymorphism, there was a significant association of this polymorphism with HCC risk under heterogeneous codominant model (OR = 1.38, 95 % CI = 1.01-1.88) and dominant model (OR = 1.57, 95 % CI = 1.14-2.16). The sensitivity analysis indicated that the significant association between hOGG1 Ser326Cys polymorphism and HCC risk was not robust. The present meta-analysis has limited evidence to support the association of XPD Lys751Gln and hOGG1 Ser326Cys polymorphisms with HCC risk. Further, large-scale studies with the consideration for gene-gene/gene-environment interactions should be conducted to investigate the association.

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

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

XPD Asp312Asn polymorphism is a risk factor for prostate cancer

PURPOSE

The association between Asp312Asn and Lys751Gln polymorphisms of Xeroderma pigmentosum Group D (XPD) and prostate cancer risk are still inconclusive. For better understanding of the effects of these two polymorphisms on prostate cancer risk, a meta-analysis was performed.

METHODS

An extensive search was performed to identify all case-control studies investigating such association. The strength of association between these two polymorphisms and prostate cancer risk was assessed by odds ratio (OR) with the corresponding 95 % confidence interval (95 % CI).

RESULTS

A total of seven case-control studies were identified, among which five studies (1,257 cases and 1,956 controls) were eligible for Asp312Asn polymorphism and six studies (1,451 cases and 2,375 controls) were eligible for Lys751Gln polymorphism. Asp312Asn polymorphism was associated with an increased risk of prostate cancer in additive and recessive genetic models (additive model: OR = 1.68, 95 % CI = 1.28-2.22, P = 0.00; recessive model: OR = 1.65, 95 % CI = 1.27-2.15, P = 0.00). In the subgroup analysis, Asp312Asn polymorphism was associated with an increased risk of prostate cancer among Asians in all three genetic models (additive model: OR = 2.09, 95 % CI = 1.39-3.14, P = 0.00; dominant model: OR = 1.49, 95 % CI = 1.12-1.98, P = 0.01; recessive model: OR = 1.93, 95 % CI = 1.31-2.83, P = 0.00). However, no significant associations were found between Lys751Gln polymorphism and prostate cancer risk in the overall analyses or the subgroup analyses by ethnicity.

CONCLUSIONS

The results of this meta-analysis indicate that the XPD Asp312Asn polymorphism is a risk factor for prostate cancer development.

Impact of two common xeroderma pigmentosum group D (XPD) gene polymorphisms on risk of prostate cancer

Background

DNA repair genes (eg: xeroderma pigmentosum group D, XPD) may affect the capacity of encoded DNA repair enzymes to effectively remove DNA adducts or lesions, which may result in enhanced cancer risk. The association between XPD gene polymorphisms and the susceptibility of prostate cancer (PCa) was inconsistent in previous studies.

Methodology/Principal Findings

A meta-analysis based on 9 independent case-control studies involving 3165 PCa patients and 3539 healthy controls for XPD Gln751Lys SNP (single nucleotide polymorphism) and 2555 cases and 3182 controls for Asn312Asp SNP was performed to address this association. Meanwhile, odds ratio (OR) and 95% confidence intervals (CIs) were used to evaluate this relationship. Statistical analysis was performed with STATA10.0. No significant association was found between XPD Gln751Lys SNP and PCa risk. On the other hand, in subgroup analysis based on ethnicity, associations were observed in Asian (eg. Asn vs. Asp: OR = 1.34, 95%CI = 1.16–1.55; Asn/Asn+Asn/Asp vs. Asp/Asp: OR = 1.23, 95%CI = 1.07–1.42) and African (eg. Asn vs. Asp: OR = 1.31, 95%CI = 1.01–1.70; Asn/Asn vs. Asp/Asp: OR = 1.71, 95%CI = 1.03–7.10) populations for Asn312Asp SNP. Moreover, similar associations were detected in hospital-based controls studies; the frequency of Asn/Asn genotype in early stage of PCa men was poorly higher than those in advanced stage of PCa men (OR = 1.45, 95%CI = 1.00–2.11).

Conclusion/Significance

Our investigations demonstrate that XPD Asn312Asp SNP not the Gln751Lys SNP, might poorly increase PCa risk in Asians and Africans, moreover, this SNPs may associate with the tumor stage of PCa. Further studies based on larger sample size and gene-environment interactions should be conducted to determine the role of XPD gene polymorphisms in PCa risk.

Is there evidence of involvement of DNA repair polymorphisms in human cancer?

DNA suffers from a wide range of damage, both from extracellular agents and via endogenous mechanisms. Damage of DNA can lead to cancer and other diseases. Therefore, it is plausible that sequence variants in DNA repair genes are involved in cancer development. A recent systematic review and meta-analysis, based on the "Venice criteria", showed that out of 241 associations investigated, only three resulted to have a strong grade of cumulative evidence. These associations were: two SNPs rs1799793 and rs13181 in the ERCC2 gene and lung cancer (recessive model) and rs1805794 in the NBN gene and bladder cancer (dominant model). An update of this meta-analysis has been performed in the present paper, and we found partially inconsistent results. Inconsistencies in the literature are thus far not easy to explain. In addition, none of the cancer genome-wide association studies (GWAs) published so far showed highly statistically significant associations for any of the common DNA repair gene variants, in such a way as to place DNA repair genes among the top 10-20 hits identified in GWAs. Though this suggests that it is unlikely that DNA repair gene polymorphisms per se play a major role, a clarification of the discrepancies in the literature is needed. Also, gene/environment and gene/lifestyle interactions for the carcinogenic mechanisms involving DNA repair should be investigated more systematically and with less classification error. Finally, the combined effect of multiple SNPs in several genes in one or more relevant DNA repair pathways could have a greater impact on pathological phenotypes than SNPs in single genes, but this has been investigated only occasionally.

Association between the ERCC5 Asp1104His polymorphism and cancer risk: a meta-analysis

BACKGROUND

Excision repair cross complementing group 5 (ERCC5 or XPG) plays an important role in regulating DNA excision repair, removal of bulky lesions caused by environmental chemicals or UV light. Mutations in this gene cause a rare autosomal recessive syndrome, and its functional single nucleotide polymorphisms (SNPs) may alter DNA repair capacity phenotype and cancer risk. However, a series of epidemiological studies on the association between the ERCC5 Asp1104His polymorphism (rs17655, G>C) and cancer susceptibility generated conflicting results.

METHODOLOGY/PRINCIPAL FINDINGS

To derive a more precise estimation of the association between the ERCC5 Asp1104His polymorphism and overall cancer risk, we performed a meta-analysis of 44 published case-control studies, in which a total of 23,490 cases and 27,168 controls were included. To provide additional biological plausibility, we also assessed the genotype-gene expression correlation from the HapMap phase II release 23 data with 270 individuals from 4 ethnic populations. When all studies were pooled, we found no statistical evidence for a significantly increased cancer risk in the recessive genetic models (His/His vs. Asp/Asp: OR = 0.99, 95% CI: 0.92-1.06, P = 0.242 for heterogeneity or His/His vs. Asp/His + Asp/Asp: OR = 0.98, 95% CI: 0.93-1.03, P = 0.260 for heterogeneity), nor in further stratified analyses by cancer type, ethnicity, source of controls and sample size. In the genotype-phenotype correlation analysis from 270 individuals, we consistently found no significant correlation of the Asp1104His polymorphism with ERCC5 mRNA expression.

CONCLUSIONS/SIGNIFICANCE

This meta-analysis suggests that it is unlikely that the ERCC5 Asp1104His polymorphism may contribute to individual susceptibility to cancer risk.

Associations between XPD Asp312Asn polymorphism and risk of head and neck cancer: a meta-analysis based on 7,122 subjects

Background

To investigate the association between XPD Asp312Asn polymorphism and head and neck cancer risk through this meta-analysis.

Methods

We performed a meta-analysis of 9 published case-control studies including 2,670 patients with head and neck cancer and 4,452 controls. An odds ratio (OR) with a 95% confidence interval (CI) was applied to assess the association between XPD Asp312Asn polymorphism and head and neck cancer risk.

Results

Overall, no significant association between XPD Asp312Asn polymorphism and head and neck cancer risk was found in this meta-analysis (Asn/Asn vs. Asp/Asp: OR = 0.95, 95%CI = 0.80–1.13, P = 0.550, P_{heterogeneity} = 0.126; Asp/Asn vs. Asp/Asp: OR = 1.11, 95%CI = 0.99–1.24, P = 0.065, P_{heterogeneity} = 0.663; Asn/Asn+Asp/Asn vs. Asp/Asp: OR = 1.07, 95%CI = 0.97–1.19, P = 0.189, P_{heterogeneity} = 0.627; Asn/Asn vs. Asp/Asp+Asp/Asn: OR = 0.87, 95%CI = 0.68–1.10, P = 0.243, P_{heterogeneity} = 0.089). In the subgroup analysis by HWE, ethnicity, and study design, there was still no significant association detected in all genetic models.

Conclusions

This meta-analysis demonstrates that XPD Asp312Asn polymorphism may not be a risk factor for developing head and neck cancer.

Association of ERCC2/XPD polymorphisms and interaction with tobacco smoking in lung cancer susceptibility: a systemic review and meta-analysis

The association of the two ERCC polymorphisms, Asp312Asn and Lys751Gln, with lung cancer risk remains controversial and inconclusive. To better evaluate the potential role of the two polymorphisms and interaction with tobacco smoking in lung cancer susceptibility presented in diverse populations, we have conducted a meta-analysis based on 26 studies from 24 publications which included analyses of Asp312Asn (7121 cases, 8962 controls) and Lys751Gln (8396 cases, 10510 controls) polymorphisms. Overall, significantly elevated lung cancer risk was associated with ERCC2 312Asn allele(homozygous model: OR=1.20[1.05-1.36], P=0.006; recessive model: OR=1.20[1.06-1.35], P=0.004) and 751Gln allele(homozygous model: OR=1.31[1.17-1.46], P<0.00001; heterozygous model: OR=1.11[1.04-1.19], P=0.003; recessive model: OR=1.23[1.11-1.37], P<0.0001; dominant model: OR=1.15[1.08-1.23], P<0.0001). In ethnic subgroup analyses, significantly increased risk was associated with ERCC2 312Asn allele for both Caucasians and Asians, and 751Gln allele for both Caucasians and Latino-Americans. When stratified by smoking status, significantly elevated risk of both polymorphisms for never-smokers was detected (dominant model, OR=1.46[1.09-1.95] and 1.57[1.19-2.08], P=0.01 and 0.002, respectively). In conclusion, this meta-analysis suggests that the two ERCC2 polymorphisms may contribute to lung cancer susceptibility serving as low-penetrance risk factors. Extremely large-scale evidence would be necessary to confirm the effects on ethnically specific populations and gene-environment interactions.

Polymorphisms in tobacco metabolism and DNA repair genes modulate oral precancer and cancer risk

The highest rates of oral squamous cell carcinomas are observed in south Asia, particularly in India, where complex forms of tobacco and alcohol exposures exist. Genetic polymorphisms contribute significantly to observed differences in cancer susceptibility. We examined the association of 13 variants in eight genes (rs4646903, rs2031920, rs3813867, GSTM1 null, GSTT1 null, rs1695, rs1138272, rs1799782, rs25487, rs1799791, rs1799793, rs13181 and rs1052133) involved in various stages of tobacco and alcohol metabolism and the risk of leukoplakia and oral cancer (OC) in a case-control study involving 219 oral leukoplakia, 665 OC and 802 age, sex and habit-matched controls. GSTT1 null and rs1695 were inversely associated with oral leukoplakia while GSTM1 null, GSTT1 null, rs2031920, rs3813867 (CYP2E1), and rs13181 were associated with OC. We report that genetic variants associated with premalignant and malignant conditions of the oral cavity differ. The associations appeared to be consistent among smokeless tobacco users, a characteristic risk factor in these parts.

Genome-based prediction of breast cancer risk in the general population: a modeling study based on meta-analyses of genetic associations

BACKGROUND

Genome-wide association studies identified novel breast cancer susceptibility variants that could be used to predict breast cancer in asymptomatic women. This review and modeling study aimed to investigate the current and potential predictive performance of genetic risk models.

METHODS

Genotypes and disease status were simulated for a population of 10,000 women. Genetic risk models were constructed from polymorphisms from meta-analysis including, in separate scenarios, all polymorphisms or statistically significant polymorphisms only. We additionally investigated the magnitude of the odds ratios (OR) for 1 to 100 hypothetical polymorphisms that would be needed to achieve similar discriminative accuracy as available prediction models [modeled range of area under the receiver operating characteristic curve (AUC) 0.70-0.80].

RESULTS

Of the 96 polymorphisms that had been investigated in meta-analyses, 41 showed significant associations. AUC was 0.68 for the genetic risk model based on all 96 polymorphisms and 0.67 for the 41 significant polymorphisms. Addition of 50 additional variants, each with risk allele frequencies of 0.30, requires per-allele ORs of 1.2 to increase this AUC to 0.70, 1.3 to increase AUC to 0.75, and 1.5 to increase AUC to 0.80. To achieve AUC of 0.80, even 100 additional variants would need per-allele ORs of 1.3 to 1.7, depending on risk allele frequencies.

CONCLUSION

The predictive ability of genetic risk models in breast cancer has the potential to become comparable to that of current breast cancer risk models.

IMPACT

Risk prediction based on low susceptibility variants becomes a realistic tool in prevention of nonfamilial breast cancer.