Pterygium is an ultraviolet (UV) related disease. UV radiation can produce DNA damage, which is repaired by the DNA repair systems. Among the DNA repair systems, the base excision repair (BER) and nucleotide excision repair (NER) systems are the major ones involved in repairing UV-induced DNA damage; X-ray repair cross complementary 1 (XRCC1) and human 8-oxoguanine DNA glycosylase 1 (hOGG1) are two BER genes, and xeroderma pigmentosum group A (XPA) and xeroderma pigmentosum group D (XPD) are two NER genes. Polymorphisms of these genes are associated with the differences in their repair DNA damage capacity, and they modulate the susceptibility to cancer. Because the polymorphism of hOGG1 was reported to be associated with pterygium, it is logical to assume the correlation between XRCC1, XPA, and XPD polymorphisms and pterygium formation.
One hundred and twenty-seven pterygium patients and 103 volunteers without pterygium were enrolled in this study. Polymerase chain reaction based analysis was used to resolve the XRCC1 codon 107, 194, 280, and 399; XPA A23G; XPA codon 228; and XPD codon 751 polymorphisms.
There were significant differences in the frequency of genotypes and alleles of XRCC1 codon 194 and 399 polymorphisms between the groups. In codon 194, individuals who carried at least 1 Trp allele had a decreased risk of developing pterygium compared to those who carried the Arg/Arg wild-type genotype (odds ratio [OR]=0.58; 95% CI: 0.34–0.98). In codon 399, individuals who carried at least 1 Gln allele had a threefold increased risk of developing pterygium compared to those who carried the Arg/Arg wild-type genotype (OR=3.06; 95% CI: 1.78–5.26). There were no significant differences in the frequency of the genotypes and alleles of XRCC1 codon 107 and 280, XPA A23G, and XPD codon 751 polymorphisms between the groups. The XPA codon 228 polymorphism was not detected in any of the cases or controls.
The XRCC1 codon 194 polymorphism causes a decreased risk of developing pterygium, but the codon 399 polymorphism increases the risk. There is no correlation between pterygium and XRCC1 codon 107 and 280, XPA A23G, and XPD codon 751 polymorphisms.
Age related cataract is the leading cause of blindness in the world today. The association between DNA damage to the lens epithelium and the development of lens opacities has been reported in many studies. Polymorphisms of DNA repair enzymes may affect repair efficiency and thereby lead to the development of age related cataract.
In this study, we aimed to determine the frequency of polymorphisms in two DNA repair enzyme genes, xeroderma pigmentosum complementation group (XPD) codon 312 and X-ray complementing group1 (XRCC1) codon 399, in a sample of 208 cataract patients (69 with cortical, 69 with nuclear and 70 with posterior sub capsular) and 151 sex and age matched healthy controls. XPD genotype was determined by Amplification Refractory Mutation System (ARMS) while XRCC1 was genotyped using the PCR-RFLP method.
There was a significant difference between frequencies for XPD-312 Asn/Asn genotype in cataract patients (21.6%) and healthy controls (13.2%; p=0.03, OR=1.97, 95% CI=1.06–3.63). Considering the types of cataract, XPD-312 Asn/Asn genotype was found to be significantly different in patients with cortical (29%) type in comparison to controls (13.2%; p=0.03, OR=2.39, 95% CI=1.11–5.12). No statistically significant difference was found for the genotypic and allelic distributions of the polymorphism in XRCC1. The MDR interaction analysis revealed weak synergism between the markers XPD-Asp312Asn and XRCC1-Arg399Gln contributing to cataract. It also showed that the AA genotype of XPD-Asp312Asn polymorphism when present in combination with the GA genotype of XRCC1-Arg399Gln had a fivefold and with AA had a fourfold risk for developing cataract.
The present study suggests that a polymorphism in XPD codon 312 may be associated with the development of maturity onset cataract. This is the first report on the association of XPD Asp312Asn polymorphism with maturity onset cataract.
Oxidative DNA damage has been shown to have some role in the development of primary open angle glaucoma (POAG). In this study, we aimed to determine the frequency of polymorphisms in two DNA repair enzyme genes, Xeroderma pigmentosum complementation group D (XPD) codon 751 and X-ray cross-complementing group 1 (XRCC1) codon 399, in a sample of Turkish patients with POAG, and to evaluate their association with POAG development.
We used polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP), to analyze XRCC1-Arg399Gln and XPD -Lys751Gln polymorphisms in 144 patients with POAG and in 121 disease-free controls, who were of a similar age.
There was no significant difference in the genotype distribution between POAG patients and controls for each polymorphism (p>0.05). Allele frequencies were also not statistically different between the groups (p=0.46; OR: 0.77; 95% CI:0.42-1.43 for XRCC1 399Gln and p=0.88; OR: 0.92 95% CI: 0.50-1.67 for XPD 751Gln).
Polymorphisms in XPD codon 751 and XRCC1 codon 399 were not associated with risk of POAG in a sample of Turkish patients.
Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with risk of developing cancer. For colorectal cancer the importance of mutations in mismatch repair genes has been extensively documented. Less is known about other DNA repair pathways in colorectal carcinogenesis. In this study we have focused on the XRCC1, XRCC3 and XPD genes, involved in base excision repair, homologous recombinational repair and nucleotide excision repair, respectively.
We used a case-control study design (157 carcinomas, 983 adenomas and 399 controls) to test the association between five polymorphisms in these DNA repair genes (XRCC1 Arg194Trp, Arg280His, Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln), and risk of colorectal adenomas and carcinomas in a Norwegian cohort. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated by binary logistic regression model adjusting for age, gender, cigarette smoking and alcohol consumption.
The XRCC1 280His allele was associated with an increased risk of adenomas (OR 2.30, 95% CI 1.19–4.46). The XRCC1 399Gln allele was associated with a reduction of risk of high-risk adenomas (OR 0.62, 95% CI 0.41–0.96). Carriers of the variant XPD 751Gln allele had an increased risk of low-risk adenomas (OR 1.40, 95% CI 1.03–1.89), while no association was found with risk of carcinomas.
Our results suggest an increased risk for advanced colorectal neoplasia in individuals with the XRCC1 Arg280His polymorphism and a reduced risk associated with the XRCC1 Arg399Gln polymorphism. Interestingly, individuals with the XPD Lys751Gln polymorphism had an increased risk of low-risk adenomas. This may suggest a role in regression of adenomas.
Polymorphisms in DNA repair genes have been associated to repair DNA lesions, and might contribute to the individual susceptibility to develop different types of cancer. Nucleotide excision repair (NER), base excision repair (BER), and double-strand break repair (DSBR) are the main DNA repair pathways. We investigated the relationship between polymorphisms in two NER genes, XPC (poly (AT) insertion/deletion: PAT-/+) and XPD (Asp312Asn and Lys751Gln), the BER gene XRCC1 (Arg399Gln), and the DSBR gene XRCC3 (Thr241Met) and the risk of developing lung cancer.
A hospital-based case-control study was designed with 516 lung cancer patients and 533 control subjects, matched on ethnicity, age, and gender. Genotypes were determined by PCR-RFLP and the results were analysed using multivariate unconditional logistic regression, adjusting for age, gender and pack-years.
Borderline association was found for XPC and XPD NER genes polymorphisms, while no association was observed for polymorphisms in BER and DSBR genes. XPC PAT+/+ genotype was associated with no statistically significant increased risk among ever smokers (OR = 1.40; 95%CI = 0.94–2.08), squamous cell carcinoma (OR = 1.44; 95%CI = 0.85–2.44), and adenocarcinoma (OR = 1.72; 95%CI = 0.97–3.04). XPD variant genotypes (312Asn/Asn and 751Gln/Gln) presented a not statistically significant risk of developing lung cancer (OR = 1.52; 95%CI = 0.91–2.51; OR = 1.38; 95%CI = 0.85–2.25, respectively), especially among ever smokers (OR = 1.58; 95%CI = 0.96–2.60), heavy smokers (OR = 2.07; 95%CI = 0.74–5.75), and adenocarcinoma (OR = 1.88; 95%CI = 0.97–3.63). On the other hand, individuals homozygous for the XRCC1 399Gln allele presented no risk of developing lung cancer (OR = 0.87; 95%CI = 0.57–1.31) except for individuals carriers of 399Gln/Gln genotype and without family history of cancer (OR = 0.57; 95%CI = 0.33–0.98) and no association was found between XRCC3 Thr241Met polymorphism and lung cancer risk (OR = 0.92; 95%CI = 0.56–1.50), except for the 241Met/Met genotype and squamous cell carcinoma risk (OR = 0.47; 95%CI = 0.23–1.00).
In conclusion, we analysed the association between XPC, XPD, XRCC1, and XRCC3 polymorphisms and the individual susceptibility to develop lung cancer in the Spanish population, specifically with a highly tobacco exposed population. We attempt to contribute to the discovery of which biomarkers of DNA repair capacity are useful for screening this high-risk population for primary preventing and early detection of lung cancer.
We have recently suggested that polymorphisms in metabolism and repair pathways may play a role in modulating the effects of exposure to the carcinogen vinyl chloride in the production of biomarkers of its mutagenic damage. The aim of the present study was to extend these observations by examining gene–environment interactions between several common polymorphisms in the DNA repair genes XRCC1 and ERCC2/XPD and vinyl chloride exposure on the production of vinyl chloride-induced biomarkers of mutation. A cohort of 546 French vinyl chloride workers were genotyped for the XRCC1 codon 194 (Arg>Trp; rs1799782), 280 (Arg>His; rs25489) and 399 (Arg>Gln; rs25487) polymorphisms and the ERCC2/XPD codon 312 (Asp>Asn; rs1799793) and 751 (Lys>Gln; rs13181) polymorphisms. The results demonstrated a statistically significant allele dosage effect of the XRCC1 399 variant on the production of the vinyl chloride-induced mutant p53 biomarker, even after controlling for confounders including cumulative vinyl chloride exposure (p = 0.03), with a potentially supramultiplicative gene–environment interaction. In addition, the results demonstrate statistically significant allele dosage effects of the ERCC2/XPD 312 and 751 variants on the production of the vinyl chloride-induced mutant ras-p21 biomarker, even after controlling for confounders including cumulative vinyl chloride exposure (p < 0.0001 and p = 0.0006, respectively), with a potentially supramultiplicative gene–environment interaction for the codon 751 allele. Finally, the results suggest potential supramultiplicative gene–gene interactions between CYP2E1 (c2 allele; rs3813867) and ERCC2/XPD polymorphisms that are consistent with the proposed carcinogenic pathway for vinyl chloride, which requires metabolic activation by CYP2E1 to reactive intermediates that form DNA adducts that, if not removed by DNA repair mechanisms, result in oncogenic mutations.
Gene–environment interaction; polymorphisms; mutations; biomarkers; cancer
A major barrier to understanding the role of polymorphic DNA repair genes for environmental cancer is that the functions of variant genotypes are largely unknown. Using our cytogenetic challenge assays, we conducted an investigation to address the deficiency. Using X-rays or ultraviolet (UV) light, we irradiated blood lymphocytes from 80 nonsmoking donors to challenge the cells to repair the induced DNA damage, and we analyzed expression of chromosome aberrations (CA) specific to the inducing agents. We have genotyped polymorphic DNA repair genes preferentially involved with base excision repair (BER) and nucleotide excision repair (NER) activities (XRCC1, XRCC3, APE1, XPD) corresponding to the repair of X-ray- and UV light-induced DNA damage, respectively. We expected that defects in specific DNA repair pathways due to polymorphisms would cause corresponding increases of specific CA. From our data, XRCC1 399Gln and XRCC3 241Met were associated with significant increases in chromosome deletions compared with the corresponding homozygous wild types (18.27 1.1 vs 14.79 1.2 and 18.22 0.99 vs 14.20 1.39, respectively); XPD 312Asn and XPD 751Gln were associated with significant increases in chromatid breaks compared with wild types (16.09 1.36 vs 11.41 0.98 and 16.87 1.27 vs 10.54 0.87, respectively), p < 0.05. The data indicate that XRCC1 399Gln and XRCC3 241Met are significantly defective in BER, and the XPD 312Asn and XPD 751Gln are significantly defective in NER. In addition, the variant genotypes interact significantly, with limited overlap of the two different repair pathways.
Although the pathogenesis of Hodgkin disease (HD) remains unknown, the results of epidemiologic studies suggest that heritable factors are important in terms of susceptibility. Polymorphisms in DNA repair genes may contribute to individual susceptibility for development of different cancers. However, to the authors’ knowledge, few studies to date have investigated the role of such polymorphisms as risk factors for development of HD.
The authors evaluated the relation between polymorphisms in 3 nucleotide excision repair pathway genes (XPD [Lys751Gln], XPC [Lys939Gln], and XPG [Asp1104His]), the base excision repair XRCC1 (Arg399Gln), and double-strand break repair XRCC3 (Thr241Met) in a population of 200 HD cases and 220 matched controls. Variants were investigated independently and in combination; odd ratios (OR) were calculated.
A positive association was found for XRCC1 gene polymorphism Arg399Gln (OR, 1.77; 95% confidence interval [95% CI], 1.16−2.71) and risk of HD. The combined analysis demonstrated that XRCC1/XRCC3 and XRCC1/XPC polymorphisms were associated with a significant increase in HD risk. XRCC1 Arg/Arg and XRCC3 Thr/Met genotypes combined were associated with an OR of 2.38 (95% CI, 1.24−4.55). The XRCC1 Arg/Gln and XRCC3 Thr/Thr, Thr/Met, and Met/Met genotypes had ORs of 1.88 (95% CI, 1.02−4.10), 1.97 (95% CI, 1.05−3.73), and 4.13 (95% CI, 1.50−11.33), respectively. XRCC1 Gln/Gln and XRCC3 Thr/Thr variant led to a significant increase in risk, with ORs of 3.00 (95% CI, 1.15−7.80). Similarly, XRCC1 Arg/Gln together with XPC Lys/Lys was found to significantly increase the risk of HD (OR, 2.14; 95% CI, 1.09−4.23).
These data suggest that genetic polymorphisms in DNA repair genes may modify the risk of HD, especially when interactions between the pathways are considered.
DNA repair; Hodgkin disease; susceptibility; genetic polymorphisms
Recent studies relating to the association between DNA repair-gene polymorphisms and colorectal cancer risk would, to the best of our knowledge, appear to be very limited. This study was designed to examine the polymorphisms associated with three DNA repair genes, namely: XRCC1 Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln, and investigate their role as susceptibility markers for colorectal cancer.
We conducted a case-control study including 727 cases of cancer and 736 hospital-based age- and sex-matched healthy controls to examine the role of genetic polymorphisms of three DNA-repair genes (XRCC1, XRCC3 and XPD) in the context of colorectal cancer risk for the Taiwanese population. Genomic DNA isolated from 10 ml whole blood was used to genotype XRCC1 Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln by means of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis.
The risk for colorectal cancer did not appear to differ significantly amongst individuals featuring the XRCC1 399Arg/Arg genotype (OR = 1.18; 95% CI, 0.96–1.45), the XRCC3 241Thr/Thr genotype (OR = 1.25; 95% CI, 0.88–1.79) or the XPD 751Gln allele (OR = 1.20; 95% CI, 0.90–1.61), although individuals featuring a greater number of risk genotypes (genotype with OR greater than 1) did experience a higher risk for colorectal cancer when compared to those who didn't feature any risk genotypes (Trend test P = 0.03). Compared with those individuals who didn't express any putative risk genotypes, individuals featuring all of the putative risk genotypes did experience a significantly greater cancer risk (OR = 2.43, 95% CI = 1.21–4.90), particularly for individuals suffering tumors located in the rectum (OR = 3.18, 95% CI = 1.29–7.82) and diagnosed prior to the age of 60 years (OR = 4.90, 95% CI = 1.72–14.0).
Our results suggest that DNA-repair pathways may simultaneously modulate the risk of colorectal cancer for the Taiwanese population, and, particularly for rectal cancer and younger patients.
Hepatocellular carcinoma (HCC) is a serious public health issue, the incidence of which is considered to be closely related to tobacco smoking, alcohol consumption, hepatitis B virus (HBV) infection and family history. The DNA repair system is an important protective mechanism against the development of malignant cells induced by internal and external environmental factors. The aim of this study was to investigate the association of polymorphisms of XRCC1-194, XRCC1-280 and XPD-312 DNA repair genes and the risk of development of HCC in Han Chinese patients. A case-control design was used including 252 HCC inpatients and 250 healthy controls recruited and matched by age, gender, tobacco smoking, alcohol consumption, HBV infection and family history. XPD Asp312Asn, XRCC1 Arg194Trp and XRCC1 Arg280His genes were examined using a sequencing assay method. Distributions of the genotype frequency and odds ratio (OR) between the two groups were analyzed. The results demonstrated that there was no significant difference in the frequencies of XPD Asp312Asn, XRCC1 Arg194Trp and XRCC1 Arg280His in the HCC cases and the control group. In the stratified analysis of different allele genotypes, the frequency of the XRCC1-194 site genotype was not significantly different between the case and control group. The presence of the XRCC1 280His genotype was associated with a significantly increased risk of HCC under conditions of HBV infection and family history [OR (95% CI): 1.68 (1.08–2.60), 4.20 (1.34–13.20), respectively]. Similarly, the XPD 312Asn significantly increased the risk of HCC under conditions of alcohol consumption, tobacco smoking, HBV infection and family history [OR (95% CI): 1.67 (1.10–2.60), 1.87 (1.18–2.96), 1.96 (1.24–3.10), 3.40 (1.32–8.76), respectively]. In conclusion, tobacco smoking and alcohol consumption are high risk factors of HCC for the XPD 312Asn genotype; HBV infection and family history increase the risk of HCC for the genotypes XRCC1 280His and XPD 312Asn.
hepatocellular carcinoma; genotype; polymorphisms; susceptibility
Our retrospective cohort study investigated the effect of tumor site and stage on the associations between the allelic variants of glutathione S-transferase (GST) and DNA-repair genes and overall survival (OS) in CRC patients treated with 5-fluorouracil (5-FU)-based adjuvant chemotherapy.
Material and Methods
We genotyped GSTM1, GSTT1, GSTP1 Ile105Val, XRCC1 Arg399Gln, XRCC3 Thr241Met, and XPD Lys751Gln in 491 CRC patients between 1995 and 2001. A Cox proportional-hazards model was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the relationships between the allelic variants and OS. Survival analyses were performed for each allelic variant by using the log-rank test and Kaplan-Meier analysis.
The CRC patients with the XPD Gln allelic variants had poorer survival than patients with the Lys/Lys genotype (HR = 1.38, 95% CI = 1.02–1.87), and rectal cancer patients had the poorest survival among them (HR = 1.87, 95% CI = 1.18–2.95). A significantly shorter OS was observed among stage II/III colon cancer patients with the XRCC1 Gln allelic variants (HR = 1.69, 95% CI = 1.06–2.71), compared to those with XRCC1 Arg/Arg genotype. In the combined analysis of the XRCC1 and XPD genes patients with stage II/III tumors, the poorest OS occurred in colon cancer patients with the XRCC1 Gln and XPD Gln allelic variants (HR = 2.60, 95% CI = 1.19–5.71) and rectal cancer patients with the XRCC1 Arg/Arg and XPD Gln allelic variants (HR = 2.77, 95% CI = 1.25–6.17).
The XPD and XRCC1 allelic variants may be prognostic markers for CRC patients receiving 5-FU based chemotherapy. The contributions of the XPD and XRCC1 allelic variants to OS are tumor site- and/or stage-dependent.
The gene XRCC1 (X-ray repair cross-complementing group 1) encodes a protein involved in DNA base excision repair. Two non-synonymous polymorphisms in XRCC1 (Arg194Trp and Arg399Gln) have been shown to alter DNA repair capacity in some studies in vitro. However, results of previous association studies of these two XRCC1 variants and breast cancer have been inconsistent. We examined the association between polymorphisms in XRCC1 and breast cancer in the American Cancer Society Cancer Prevention Study II (CPS-II) Nutrition Cohort, a large prospective study of cancer incidence in the USA.
Among the 21,965 women who were cancer-free in 1992 and gave blood between 1998 and 2001, 502 postmenopausal breast cancer cases were diagnosed between 1992 and 2001; 502 controls were matched to cases on age, race/ethnicity, and date of blood collection. Genotyping on DNA extracted from buffy coat was performed with Taqman. Conditional logistic regression was used to examine the association between each polymorphism and breast cancer risk controlling for breast cancer risk factors. We also examined whether factors associated with DNA damage, such as smoking and antioxidant intake, modified the association between XRCC1 polymorphisms and breast cancer.
We observed a significant inverse association between Trp194 carriers (Trp/Trp and Trp/Arg) compared with Trp194 non-carriers in relation to breast cancer (Arg/Arg) (odds ratio (OR) 0.62, 95% confidence interval (CI) 0.40 to 0.95). The inverse association between breast cancer and Trp194 carriers compared with non-carriers was slightly stronger among smokers (OR 0.47, 95% CI 0.24 to 0.94) than never smokers (OR 0.78, 95% CI 0.43 to 1.40). An increased risk associated with the Arg399Gln polymorphism (Gln/Gln versus Arg/Arg) was observed only among women who reported ever smoking cigarettes (OR 2.76, 95% CI 1.36 to 5.63), and not in women who were lifelong non-smokers (OR 0.64, 95% CI 0.33 to 1.26). No other factor examined modified the association between XRCC1 polymorphisms and breast cancer risk.
Our results support the hypothesis that genetic variation in XRCC1, particularly in Arg194Trp, may influence postmenopausal breast cancer risk. In our study, genetic variation in XRCC1 Arg399Gln was associated with breast cancer risk only among women with a history of smoking cigarettes.
Variations in genes involved in DNA repair systems have been proposed as risk factors for the development of preeclampsia (PE). We conducted a case-control study to investigate the association of Human apurinic/apyrimidinic (AP) endonuclease (APEX1) Asp148Glu (rs1130409), Xeroderma Pigmentosum group D (XPD) Lys751Gln (rs13181), X-ray repair cross-complementing group 1 (XRCC) Arg399Gln (rs25487) and X-ray repair cross-complementing group 3 (XRCC3) Thr241Met (rs861539) polymorphisms with PE in a Mexican population. Samples of 202 cases and 350 controls were genotyped using RTPCR. Association analyses based on a χ2 test and binary logistic regression were performed to determine the odds ratio (OR) and a 95% confidence interval (95% CI) for each polymorphism. The allelic frequencies of APEX1 Asp148Glu polymorphism showed statistical significant differences between preeclamptic and normal women (p = 0.036). Although neither of the polymorphisms proved to be a risk factor for the disease, the APEX1 Asp148Glu polymorphism showed a tendency of association (OR: 1.74, 95% CI = 0.96–3.14) and a significant trend (p for trend = 0.048). A subgroup analyses revealed differences in the allelic frequencies of APEX1 Asp148Glu polymorphism between women with mild preeclampsia and severe preeclampsia (p = 0.035). In conclusion, our results reveal no association between XPD Lys751Gln, XRCC Arg399Gln and XRCC3 Thr241Met polymorphisms and the risk of PE in a Mexican mestizo population; however, the results in the APEX1 Asp148Glu polymorphism suggest the need for future studies using a larger sample size.
preeclampsia; polymorphisms; APEX1; XPD; XRCC1; XRCC3
Recent data in esophageal cancer suggests the variant allele of a single-nucleotide polymorphism (SNP) in XRCC1 may be associated with resistance to radiochemotherapy. However, this SNP has not been assessed in a histologically homogeneous clinical trial cohort that has been treated with a uniform approach. In addition, whether germline DNA may serve as a surrogate for tumor genotype at this locus is unknown in this disease. Our objective was to assess this SNP in relation to the pathologic complete response (pCR) rate in subjects with esophageal adenocarcinoma who received cisplatin-based preoperative radiochemotherapy in a multicenter clinical trial (Eastern Cooperative Oncology Group 1201). As a secondary aim, we investigated the rate of allelic imbalance between germline and tumor DNA.
Eighty-one eligible treatment-naïve subjects with newly diagnosed resectable esophageal adenocarcinoma received radiotherapy (45 Gy) concurrent with cisplatin-based chemotherapy, with planned subsequent surgical resection. The primary endpoint was pCR, defined as complete absence of tumor in the surgical specimen after radiochemotherapy. Using germline DNA from 60 subjects, we examined the base-excision repair SNP, XRCC1 Arg399Gln, and 4 other SNPs in nucleotide excision (XPD Lys751Gln and Asp312Asn, ERCC1 3' flank) and double-stranded break (XRCC2 5' flank) repair pathways, and correlated genotype with pCR rate. Paired tumor tissue was used to estimate the frequency of allelic imbalance at the XRCC1 SNP.
The variant allele of the XRCC1 SNP (399Gln) was detected in 52% of subjects. Only 6% of subjects with the variant allele experienced a pCR, compared to 28% of subjects without the variant allele (odds ratio 5.37 for failing to achieve pCR, p = 0.062). Allelic imbalance at this locus was found in only 10% of informative subjects, suggesting that germline genotype may reflect tumor genotype at this locus. No significant association with pCR was noted for other SNPs.
Assessed for the first time in a prospective, interventional trial cohort of esophageal adenocarcinoma, XRCC1 399Gln was associated with resistance to radiochemotherapy. Further investigation of this genetic variation is warranted in larger cohorts. In addition, these data indicate that germline genotype may serve as a surrogate for tumor genotype at this locus.
DNA repair enzymes repair DNA damaged by platinum agents and ionising radiation. Single nucleotide polymorphisms (SNPs) in DNA repair genes modulate the repair capacity and might affect response and prognosis following platinum-based chemoradiotherapy (CRT). We investigated associations between the functional SNPs in DNA repair genes and response and survival in muscle-invasive bladder cancer patients treated with CRT to determine the predictive value of the SNPs in patient selection for bladder conservation therapy. The study group comprised 78 patients who underwent CRT for transitional cell carcinoma of the bladder. Single nucleotide polymorphisms in xeroderma pigmentosum complementation groups C (Lys939Gln, A/C), D (XPD; Lys751Gln, A/C), and G (Asp1104His, G/C), and X-ray repair cross-complementing groups 1 (XRCC1; Arg399Gln, G/A) and 3 (Thr241Met, T/C) genes were genotyped. Combined genotypes with at least one variant allele in XPD or XRCC1 were significantly associated with improved cancer-specific survival compared with remaining groups (P=0.009). In multivariate analysis, only the combined XPD and XRCC1 genotypes were independently associated with cancer-specific survival (P=0.04). The association was stronger in stage T3/T4 patients (P=0.0008). These results suggest that combined XPD and XRCC1 genotypes might be prognostic factors in muscle-invasive bladder cancer patients treated with CRT.
single nucleotide polymorphism; DNA repair gene; muscle-invasive bladder cancer; chemoradiotherapy; survival
Occupational chromium exposure may induce DNA damage and lead to lung cancer and other work-related diseases. DNA repair gene polymorphisms, which may alter the efficiency of DNA repair, thus may contribute to genetic susceptibility of DNA damage. The aim of this study was to test the hypothesis that the genetic variations of 9 major DNA repair genes could modulate the hexavalent chromium (Cr (VI))-induced DNA damage.
The median (P25-P75) of Olive tail moment was 0.93 (0.58–1.79) for individuals carrying GG genotype of XRCC1 Arg399Gln (G/A), 0.73 (0.46–1.35) for GA heterozygote and 0.50 (0.43–0.93) for AA genotype. Significant difference was found among the subjects with three different genotypes (P = 0.048) after adjusting the confounding factors. The median of Olive tail moment of the subjects carrying A allele (the genotypes of AA and GA) was 0.66 (0.44–1.31), which was significantly lower than that of subjects with GG genotype (P = 0.043). The A allele conferred a significantly reduced risk of DNA damage with the OR of 0.39 (95% CI: 0.15–0.99, P = 0.048). No significant association was found between the XRCC1Arg194Trp, ERCC1 C8092A, ERCC5 His1104Asp, ERCC6 Gly399Asp, GSTP1 Ile105Val, OGG1 Ser326Cys, XPC Lys939Gln, XPD Lys751Gln and DNA damage.
The polymorphism of Arg399Gln in XRCC1 was associated with the Cr (VI)- induced DNA damage. XRCC1 Arg399Gln may serve as a genetic biomarker of susceptibility for Cr (VI)- induced DNA damage.
DNA damage; Genetic susceptibility; XRCC1; Occupational chromium exposure
DNA repair gene X-ray repair cross complementing group 1 (XRCC1) plays an important role in the maintenance of the genomic integrity and protection of cells from DNA damage. Sequence variation in XRCC1 gene may alter head and neck cancer (HNC) susceptibility. However, these results are inconclusive. To derive a more precise estimation of the relationship between XRCC1 polymorphism and HNC risk, we undertook a meta-analysis involving 16,344 subjects.
A search of the literature by PubMed, Embase, Web of Science and China National Knowledge Infrastructure was performed to identify studies based on the predetermined inclusion criteria. The odds ratio (OR) with 95% confidence interval (CI) was combined using a random-effects model or a fixed-effects model.
Twenty-nine studies consisting of 6,719 cases and 9,627 controls were identified and analyzed. Overall, no evidence of significant association was observed between XRCC1 Arg194Trp, XRCC1 Arg280His, XRCC1 Arg399Gln genotypes and the risk of HNC in any genetic models. Subgroup analyses according to ethnicity, tumor site, publication year, genotyping method also detected no significant association in any subgroup, except that oral cancer was associated with Arg194Trp variant in recessive model. Furthermore, no significant effect of these polymorphisms interacted with smoking on HNC risk was detected but Arg194Trp homozygous variant.
In conclusion, this meta-analysis suggests that the XRCC1 Arg194Trp, Arg280His and Arg399Gln polymorphism may not involve in HNC susceptibility. Further studies about gene-gene and gene-environment interactions in different populations are required.
Functional variation in DNA repair capacity through single nucleotide polymorphisms (SNPs) of key repair genes is associated with a higher risk of developing various types of cancer. Studies have focused on the nucleotide excision repair (NER) and base excision repair (BER) pathways. We investigated whether variant alleles in seven SNPs within these pathways increased the risk of esophageal adenocarcinoma.
DNA was extracted from prospectively collected blood specimens. The samples were genotyped for SNPs in NER genes (XPD Lys751Gln, XPD Asp312Asn, ERCC1 8092C/A, and ERCC1 118C/T), and BER genes (XRCC1 Arg399Gln, APE1 Asp148Glu, and hOGG1 Ser326Cys). The presence of variant alleles was correlated with risk of esophageal adenocarcinoma both individually and jointly.
Variant alleles in NER SNPs XPD Lys751Gln (AOR = 1.50, 95% CI 1.1–2.0), ERCC1 8092 C/A (AOR = 1.44, 95% CI 1.1–1.9), and ERCC1 118C/T (AOR = 1.42, 95% CI 1.0–1.9) were individually associated with esophageal adenocarcinoma risk. An increasing number of variant alleles in NER SNPs showed a significant trend with esophageal adenocarcinoma risk (p = 0.007).
The presence of variant alleles in NER genes increases risk of esophageal adenocarcinoma. There is evidence of an additive role for SNPs along a common DNA repair pathway. Future larger studies of esophageal adenocarcinoma etiology should evaluate entire biological pathways.
DNA repair; Esophageal cancer; Adenocarcinoma; Polymorphism; Nucleotide excision pathway
Nucleotide excision repair (NER) and base excision repair (BER) are the primary mechanisms for repair of bulky adducts caused by chemical agents, such as PAHs. It is expected that polymorphisms in NER or BER genes may modulate individual susceptibility to PAHs exposure. Here, we evaluate the effects of PAHs exposure and polymorphisms in NER and BER pathway, alone or combined, on polycyclic aromatic hydrocarbon-DNA (PAH–DNA) adducts in human sperm.
Sperm PAH-DNA adducts were measured by immunofluorescent assay using flow cytometry in a sample of 465 infertile adults. Polymorphisms of XPA, XPD, ERCC1, XPF, and XRCC1 were determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniques. The PAHs exposure was detected as urinary 1-hydroxypyrene (1-OHP) levels. In multivariate models adjusted for potential confounders, we observed that XRCC1 5′pUTR -T/C, Arg194Trp, Arg399Gln polymorphisms were associated with increased sperm adduct levels. Furthermore, the stratified analysis indicated that adverse effects of XRCC1 Arg194Trp, Arg399Gln polymorphisms on PAH-DNA adducts were detected only in the high PAHs exposure group.
These findings provided the first evidence that polymorphisms of XRCC1 may modify sperm PAH-DNA adduct levels and may be useful biomarkers to identify individuals susceptible to DNA damage resulting from PAHs exposure.
The genetic polymorphisms of X-ray repair cross complementing group 1 (XRCC1), X-ray repair cross complementing group 3 (XRCC3), and xeroderma pigmentosum complementation group D (XPD) repair genes may lead to genetic instability and leukemogenesis. The purpose of the study was to evaluate the association between XRCC1 Arg399Gln, Arg280His and Arg194Trp, XRCC3 Thr241Met, and XPD Lys751Gln polymorphisms and the risk of developing CML in Romanian patients. A total of 156 patients diagnosed with CML and 180 healthy controls were included in this study. We found no association between CML and XRCC1 or XRCC3 variant genotypes in any of the investigated cases. A significant difference was observed in the variant genotype frequencies of the XPD Lys751Gln polymorphism between the patients with CML and control group (for variant homozygous genotypes, OR = 2.37; 95% CI = 1.20–4.67; P value = 0.016 and for combined heterozygous and variant homozygous genotypes, OR = 1.72; 95% CI = 1.10–2.69; P value = 0.019). This was also observed when analyzing the variant 751Gln allele (OR = 1.54; 95% CI = 1.13–2.11; P value = 0.008). Our results suggest that the XPD Lys751Gln variant genotype increases the risk of CML.
A number of common non-synonymous single nucleotide polymorphisms (SNPs) in DNA repair genes have been reported to modify bladder cancer risk. These include: APE1-Asn148Gln, XRCC1-Arg399Gln and XRCC1-Arg194Trp in the BER pathway, XPD-Gln751Lys in the NER pathway and XRCC3-Thr241Met in the DSB repair pathway.
To examine the independent and interacting effects of these SNPs in a large study group, we analyzed these genotypes in 1,029 cases and 1,281 controls enrolled in two case-control studies of incident bladder cancer, one conducted in New Hampshire, USA and the other in Turin, Italy.
The odds ratio among current smokers with the variant XRCC3-241 (TT) genotype was 1.7 (95% CI 1.0–2.7) compared to wild-type. We evaluated gene-environment and gene-gene interactions using four analytic approaches: logistic regression, Multifactor Dimensionality Reduction (MDR), hierarchical interaction graphs, classification and regression trees (CART), and logic regression analyses. All five methods supported a gene-gene interaction between XRCC1-399/XRCC3-241 (p = 0.001) (adjusted OR for XRCC1-399 GG, XRCC3-241 TT vs. wild-type 2.0 (95% CI 1.4–3.0)). Three methods predicted an interaction between XRCC1-399/XPD-751 (p = 0.008) (adjusted OR for XRCC1-399 GA or AA, XRCC3-241 AA vs. wild-type 1.4 (95% CI 1.1–2.0)).
These results support the hypothesis that common polymorphisms in DNA repair genes modify bladder cancer risk and highlight the value of using multiple complementary analytic approaches to identify multi-factor interactions.
DNA repair; Bladder cancer; Polymorphism; Interaction
Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with risk of hepatocellular carcinoma (HCC) related to the exposure of aflatoxin B1 (AFB1). In this study, we have focused on the polymorphisms of xeroderma pigmentosum complementation group D (XPD) codon 312 and 751 (namely Asp312Asn and Lys751Gln), involved in nucleotide excision repair.
We conducted a case-control study including 618 HCC cases and 712 controls to evaluate the associations between these two polymorphisms and HCC risk for Guangxi population by means of TaqMan-PCR and PCR-RFLP analysis.
We found that individuals featuring the XPD genotypes with codon 751 Gln alleles (namely XPD-LG or XPD-GG) were related to an elevated risk of HCC compared to those with the homozygote of XPD codon 751 Lys alleles [namely XPD-LL, adjusted odds ratios (ORs) were 1.75 and 2.47; 95% confidence interval (CIs) were 1.30-2.37 and 1.62-3.76, respectively]. A gender-specific role was evident that showed an higher risk for women (adjusted OR was 8.58 for XPD-GG) than for men (adjusted OR = 2.90 for XPD-GG). Interestingly, the interactive effects of this polymorphism and AFB1-exposure information showed the codon 751 Gln alleles increase the risk of HCC for individuals facing longer exposure years (Pinteraction = 0.011, OR = 0.85). For example, long-exposure-years (> 48 years) individuals who carried XDP-GG had an adjusted OR of 470.25, whereas long-exposure-years people with XDP-LL were at lower risk (adjusted OR = 149.12). However, we did not find that XPD codon 312 polymorphism was significantly associated with HCC risk.
These findings suggest that XPD Lys751Gln polymorphism is an important modulator of AFB1 related-HCC development in Guangxi population.
Pharmacogenetic studies in DNA repair pathway have consistently demonstrated correlations between the XRCC1 Arg399Gln, XPD Lys751Gln and XPD Asp312Gln genotypes, previously associated with suboptimal DNA repair, and differential cancer treatment outcomes. We evaluated these polymorphisms and XPD haplotypes in adult de novo (n=214) and secondary (n=79) acute myeloid leukemia (AML) patients treated with cytarabine and anthracycline chemotherapy. Genotyping was performed by MALDI-TOF mass spectrometry. Logistic and proportional hazards regression models were used to evaluate relationships. Differential responses were observed in secondary, but not de novo, AML. Among secondary AML patients, the odds of achieving complete remission (CR) were higher for the XPD 312Asn/Asn (OR= 11.23; 95% CI, 2.23–56.63) and XPD 751Gln/Gln (OR= 7.07; 95% CI, 1.42–35.18) genotypes. The XPD diplotypes were coded as the combination of two of the following haplotypes: haplotype A=(Lys)751A/(Asp) 312G; B=(Gln)751C/(Asn)312A; C=(Lys)751A/(Asn)312A; and D=(Gln)751C/(Asp)312G. The BB diplotype was associated with CR attainment [OR=18.31; 95% CI: 2.08–283.57] and longer survival [HR=0.31; 95% CI: 0.14–0.73] compared to the referent AA diplotype. The XPD 751 CC, 312GA, 312AA genotypes and the XPD DC diplotype were also associated with longer overall survival (OS). Thus, XPD codon 312 and 751 variant genotypes and haplotypes containing at least one variant allele may predict better treatment responses. If validated, these findings could support stratification of chemotherapy in secondary AML.
Acute Myeloid Leukemia (AML); secondary AML; pharmacogenetics/pharmacogenomics; DNA repair gene polymorphisms
Pharmacogenetic studies in DNA repair pathway have consistently demonstrated correlations between the XRCC1 Arg399Gln, XPD Lys751Gln and XPD Asp312Gln genotypes, previously associated with suboptimal DNA repair, and differential cancer treatment outcomes. We evaluated these polymorphisms and XPD haplotypes in adult de novo (n=214) and secondary (n=79) acute myeloid leukemia (AML) patients treated with cytarabine and anthracycline chemotherapy. Genotyping was performed by MALDI-TOF mass spectrometry. Logistic and proportional hazards regression models were used to evaluate relationships. Differential responses were observed in secondary, but not de novo, AML. Among secondary AML patients, the odds of achieving complete remission (CR) were higher for the XPD 312Asn/Asn (OR= 11.23; 95% CI, 2.23-56.63) and XPD 751Gln/Gln (OR= 7.07; 95% CI, 1.42-35.18) genotypes. The XPD diplotypes were coded as the combination of two of the following haplotypes: haplotype A=(Lys)751A/(Asp) 312G; B=(Gln)751C/(Asn)312A; C=(Lys)751A/(Asn)312A; and D=(Gln)751C/(Asp)312G. The BB diplotype was associated with CR attainment [OR=18.31; 95% CI: 2.08-283.57] and longer survival [HR=0.31; 95% CI: 0.14-0.73] compared to the referent AA diplotype. The XPD 751 CC, 312GA, 312AA genotypes and the XPD DC diplotype were also associated with longer overall survival (OS).Thus, XPD codon 312 and 751 variant genotypes and haplotypes containing at least one variant allele may predict better treatment responses. If validated, these findings could support stratification of chemotherapy in secondary AML.
Acute Myeloid Leukemia (AML); secondary AML; pharmacogenetics/pharmacogenomics; DNA repair gene polymorphisms
Subtle functional deficiencies in highly conserved DNA repair or growth regulatory processes resulting from polymorphic variation may increase genetic susceptibility to breast cancer. Polymorphisms in DNA repair genes can impact protein function leading to genomic instability facilitated by growth stimulation and increased cancer risk. Thus, 19 single nucleotide polymorphisms (SNPs) in eight genes involved in base excision repair (XRCC1, APEX, POLD1), BRCA1 protein interaction (BRIP1, ZNF350, BRCA2), and growth regulation (TGFß1, IGFBP3) were evaluated.
Genomic DNA samples were used in Taqman 5'-nuclease assays for most SNPs. Breast cancer risk to ages 50 and 70 were estimated using the kin-cohort method in which genotypes of relatives are inferred based on the known genotype of the index subject and Mendelian inheritance patterns. Family cancer history data was collected from a series of genotyped breast cancer cases (N = 748) identified within a cohort of female US radiologic technologists. Among 2,430 female first-degree relatives of cases, 190 breast cancers were reported.
Genotypes associated with increased risk were: XRCC1 R194W (WW and RW vs. RR, cumulative risk up to age 70, risk ratio (RR) = 2.3; 95% CI 1.3–3.8); XRCC1 R399Q (QQ vs. RR, cumulative risk up to age 70, RR = 1.9; 1.1–3.9); and BRIP1 (or BACH1) P919S (SS vs. PP, cumulative risk up to age 50, RR = 6.9; 1.6–29.3). The risk for those heterozygous for BRCA2 N372H and APEX D148E were significantly lower than risks for homozygotes of either allele, and these were the only two results that remained significant after adjusting for multiple comparisons. No associations with breast cancer were observed for: APEX Q51H; XRCC1 R280H; IGFPB3 -202A>C; TGFß1 L10P, P25R, and T263I; BRCA2 N289H and T1915M; BRIP1 -64A>C; and ZNF350 (or ZBRK1) 1845C>T, L66P, R501S, and S472P.
Some variants in genes within the base-excision repair pathway (XRCC1) and BRCA1 interacting proteins (BRIP1) may play a role as low penetrance breast cancer risk alleles. Previous association studies of breast cancer and BRCA2 N372H and functional observations for APEX D148E ran counter to our findings of decreased risks. Due to the many comparisons, cautious interpretation and replication of these relationships are warranted.
Breast cancer; kin-cohort; genetic variation; epidemiology; methods; risk factors