XRCC1 polymorphism and lung cancer risk in relation to tobacco smoking

DNA repair plays a critical role in protecting the genome of the cell from carcinogens or ionising radiation. Reduced DNA-repair capacity can increase susceptibility to occupational-induced cancer. Three coding polymorphisms at codons 194, 280, and 399 in X-ray cross complementing group 1 (XRCC1) DNA-repair gene have been identified, and it is possible that these polymorphisms may affect DNA- repair capacity and thus modulate cancer susceptibility. In the current German study, we investigated the role of XRCC1-polymorphisms as a genetic modifier of risk for individuals with lung cancer as susceptible genotypes, especially in relation to tobacco smoking. Three polymorphisms; XRCC1 Arg194Trp, XRCC1 Arg280His and XRCC1 Arg399Gln, were determined by real-time PCR analysis in 446 lung cancer patients and 622 controls. The observed allele frequencies in the population were within the range described for Caucasians. Multivariate analyses of lung cancer patients who carried at least one mutant variant allele of XRCC1 Arg194Trp (OR=1.03; 95%-CI: 0.66-1.61), XRCC1 Arg280His (OR=0.95; 95%-CI: 0.57-1.60), or XRCC1 Arg399Gln (OR=0.99 CI: 0.73-1.34), did not show any elevated risks. When analysed by histology, no individual subtype of lung cancer was significantly associated with the polymorphisms. Lung cancer risk rose significantly with higher cumulative cigarette consumption. Stratified analysis between tobacco smoking and variant genotypes revealed increasing risks for heavy smokers (>60 pack-years), with the presence of at least one copy of the XRCC1 Arg194Trp variant allele (OR=79.29; 95%-CI: 8.53-737.04) and the XRCC1 Arg399Gln (OR=61.87; 95%-CI: 15.65-244.67). By analysing the interaction between tobacco smoking and the genotypes, combined smoking and having the susceptible genotypes did not show a joint effect. In this study, the XRCC1 Arg194Trp, XRCC1 Arg280His, and XRCC1 Arg399Gln-polymorphisms, had no relevant modifying effect on lung cancer risk and cumulative smoking dose.     

Influence of DNA repair gene polymorphisms on the yield of chromosomal aberrations

We evaluated the influence of several DNA repair gene polymorphisms on the frequency of chromosomal aberrations (CAs) analyzed in peripheral lymphocytes, using the fluorescence in situ hybridization technique. The CA data were obtained from an earlier study of 84 healthy nonsmokers (48 women and 36 men) carefully characterized for indoor radon exposure. The frequency of translocations showed a wide interindividual variability, which was only partly explained by age. To investigate the potential role of DNA repair polymorphisms in this variation, genotypes of DNA repair genes OGG1 (codon 326), XPD (codon 751), XRCC1 (X-ray repair cross-complementing group 1) (codons 194, 280, and 399), and XRCC3 (X-ray repair cross-complementing group 3) (codon 241) were determined from leukocyte DNA using polymerase chain reaction-based methods. Negative binomial regression models were applied to evaluate the effect of the polymorphisms and other factors (age, gender, radon exposure, and medical exposure) on the frequency of CAs. No interactions between genotypes and radon, medical exposure, or gender were found. Carriers of the XRCC1 codon 280His variant allele had a two-fold increase (frequency ratio [FR] = 2.01, 95% confidence interval [CI] = 1.01-3.98; P = 0.046) in unstable exchanges (dicentrics and ring chromosomes). In addition, the XRCC3 codon 241 homozygous variant genotype (Met/Met) was associated with an increase (FR = 1.70, 95% CI = 1.06-2.74; P = 0.028) in two-way translocations when age was taken into account in the analysis. Our data suggest that the XRCC1 280His and XRCC3 241Met alleles affect individual CA levels, most probably via influencing the DNA repair phenotype.     

Influence of DNA repair gene polymorphisms on the initial repair of MMS-induced DNA damage in human lymphocytes as measured by the alkaline comet assay

We have applied the alkaline comet assay to study the functional impact of gene polymorphisms in base excision repair (APEX1 Asp148Glu, XRCC1 Arg194Trp, XRCC1 Arg399Gln) and homologous recombination repair (XRCC3 Thr241Met, NBS1 Glu185Gln), two pathways that play crucial roles in the repair of DNA damage induced by methylmethane sulphonate (MMS). We also examined the effect of polymorphisms in mismatch repair (MLH1 -93 A/G) and nucleotide excision repair (XPD Lys751Gln) as putative negative controls based on the limited roles of these pathways in MMS-induced repair. Phytohemagglutinin-stimulated peripheral lymphocytes from 52 healthy individuals were treated with MMS and allowed to repair for 0, 15, 40, or 120 min after a 6-min washing step. DNA damage was measured as a pseudo-percentage score (comparable to % tail DNA) converted from a total visual score calculated from the distribution of cells with different degrees of damage (normal, mild, moderate and severe). The repair was faster at the beginning of the observation period than towards the end, and was not complete after 2 hr. Presence of the APEX1 148Asp, XRCC3 241Met or NBS1 185Gln alleles were significantly associated with a high pseudo-percentage score (above median) at early time points, with the APEX1 effect being most prolonged (up to 40 min after washing, odds ratio 5.6, 95% confidence interval 2.0-15.5). No significant effects were seen with the XRCC1 Arg194Trp, XRCC1 Arg399Gln, MLH1 -93A/G and XPD Lys751Gln polymorphisms. Our results provide evidence for the functional nature of the variant alleles studied in the APEX1, XRCC3, and NBS1 genes.     

BER修复基因多态性与肺癌易感性的研究进展

碱基切除修复(base excision repair,BER)通路是DNA损伤修复的关键通路,通路中的8-羟基鸟嘌呤DNA糖苷酶基因(human 8-oxoguanine glycosylase,hOGG1),人类X线交叉互补修复基因(X-ray repair cross-complementing group 1,XRCC1),MutY homolog(MUTYH)基因的单核苷酸多态性影响BER通路中重要的酶和蛋白质的功能,导致修复障碍,最终引起癌症发生.DNA损伤修复基因单核苷酸多态性和肺癌易感性的研究结果尚存在争议,本文对近年来BER通路基因hOGG1Ser326Cys,XRCC1 Arg194Trp,XRCC1 Arg280His,XRCC1 Arg399Gln,XRCC1-77T>C和MUTYHHis324Gln多态性与肺癌易感性的关系的研究进行汇总,并探讨了多项研究对BER基因多态性与不同肺癌亚型的关系以及与吸烟之间关系.基因多态性与肺癌易感性关系受多因素影响,其相关性尚待进一步探索.     

BER修复基因多态性与肺癌易感性的研究进展

碱基切除修复(base excision repair,BER)通路是DNA损伤修复的关键通路,通路中的8-羟基鸟嘌呤DNA糖苷酶基因(human 8-oxoguanine glycosylase,hOGG1),人类X线交叉互补修复基因(X-ray repair cross-complementing group 1,XRCC1),MutY homolog(MUTYH)基因的单核苷酸多态性影响BER通路中重要的酶和蛋白质的功能,导致修复障碍,最终引起癌症发生.DNA损伤修复基因单核苷酸多态性和肺癌易感性的研究结果尚存在争议,本文对近年来BER通路基因hOGG1Ser326Cys,XRCC1 Arg194Trp,XRCC1 Arg280His,XRCC1 Arg399Gln,XRCC1-77T>C和MUTYHHis324Gln多态性与肺癌易感性的关系的研究进行汇总,并探讨了多项研究对BER基因多态性与不同肺癌亚型的关系以及与吸烟之间关系.基因多态性与肺癌易感性关系受多因素影响,其相关性尚待进一步探索.     

BER修复基因多态性与肺癌易感性的研究进展

碱基切除修复(base excision repair,BER)通路是DNA损伤修复的关键通路,通路中的8-羟基鸟嘌呤DNA糖苷酶基因(human 8-oxoguanine glycosylase,hOGG1),人类X线交叉互补修复基因(X-ray repair cross-complementing group 1,XRCC1),MutY homolog(MUTYH)基因的单核苷酸多态性影响BER通路中重要的酶和蛋白质的功能,导致修复障碍,最终引起癌症发生.DNA损伤修复基因单核苷酸多态性和肺癌易感性的研究结果尚存在争议,本文对近年来BER通路基因hOGG1Ser326Cys,XRCC1 Arg194Trp,XRCC1 Arg280His,XRCC1 Arg399Gln,XRCC1-77T>C和MUTYHHis324Gln多态性与肺癌易感性的关系的研究进行汇总,并探讨了多项研究对BER基因多态性与不同肺癌亚型的关系以及与吸烟之间关系.基因多态性与肺癌易感性关系受多因素影响,其相关性尚待进一步探索.     

Single nucleotide polymorphisms in base-excision repair genes hOGG1, APE1 and XRCC1 do not alter risk of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with a poorly understood etiology. There is considerable evidence that oxidative stress occurs in AD and increased DNA damage has been found in brain tissues and leukocytes of AD patients. Base excision repair (BER) is the major pathway responsible for removing oxidative DNA damage. Polymorphisms in DNA-repair genes have been associated with the increased risk of several age-related disorders including various types of cancer and could also be related to the etiology of AD. We conducted a case-control study including 91 patients with AD and age- and sex-matched 93 control subjects to examine the role of single nucleotide polymorphisms of BER genes, hOGG1 (Ser326Cys), APE1 (Asp148Glu) and XRCC1 (Arg280His and Arg399Gln) as a risk factor for AD. The frequencies of the hOGG1-Ser326Cys, APE1-Asp148Glu and XRCC1-Arg280His and XRCC1-Arg399Gln variant alleles in our control group were 0.23, 0.31, 0.10 and 0.33, respectively. No significant association was observed between the variant alleles of hOGG1-Ser326Cys (OR=1.32, 95% CI=0.83-2.11), APE1-Asp148Glu (OR=1.08, 95% CI=0.70-1.68), XRCC1-Arg280His (OR=0.53, 95% CI=0.24-1.14) and XRCC1-Arg399Gln (OR=1.05, 95% CI=0.68-1.63) and AD. Our results suggest that the polymorphic variants of these BER genes are not independent risk factors for AD.     

DNA repair gene XRCC1 and XPD polymorphisms and the risk of idiopathic azoospermia in a Chinese population

Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity and further influence the risk of developing cancer. However, little information is available on these polymorphisms in infertility. To investigate whether polymorphisms in DNA repair genes, X-ray repair cross-complementing group 1 (XRCC1) and xeroderma pigmentosum group D (XPD), alone or in combination, are associated with the risk of developing idiopathic azoospermia, the genotype and allele frequencies of three observed polymorphisms (XRCC1 Arg194Trp and Arg399Gln, and XPD Lys751Gln) were examined by polymerase chain reaction-restriction fragment length polymorphism based on a Chinese population consisting of 171 idiopathic azoospermia patients and 247 normal-spermatogenesis fertile controls. Associations between the polymorphisms and the idiopathic azoospermia risk were estimated by logistic regression, and the Statistical analysis system was used to test the gene-gene joint effects. All observed polymorphisms were in agreement with Hardy-Weinberg equilibrium. The XPD 751Gln allele seemed to be a risk allele for azoospermia, with a frequency of 11.40% in the cases and 5.67% in the controls (p=0.004). Compared with the Lys/Lys genotype, the XPD 751 Lys/ increased 5.100- or 3.064-fold, respectively, when combined with the XRCC1 194 Arg/Arg or 399 Arg/Arg genotype. In conclusion, our study provided the first evidence that the XPD and XRCC1 polymorphisms contributed to the risk of developing idiopathic azoospermia in a selected Chinese population.     

Association between XRCC1 and XRCC3 gene polymorphisms and risk of thyroid cancer

We conducted a case-control study to examine the role of genetic polymorphisms in XRCC1 at codons 194 (Arg>Trp), 280 (Arg>His) and 399 (Arg>Gln) and XRCC3 at codon 241 (Thr>Met) in the risk of TC. This study included 276 consecutive primary TC patients and 552 control subjects. The genotypes of XRCC1 at codons 194 (Arg>Trp), 280 (Arg>His) and 399 (Arg>Gln) and XRCC3 at codon 241 (Thr>Met) were analyzed by PCR-RFLP. TT and CT+TT genotypes of XRCC1 194 (Arg>Trp) were significantly associated with increased risk of TC, and CC and TC+CC genotypes of XRCC3 241 (Thr>Met) revealed a significant associated with the TC risk. We only found that XRCC1 194 (Arg>Trp) and XRCC3 241 (Thr>Met) polymorphisms had interaction with smoking and drinking habits. In conclusion, the current study suggests that XRCC1 194 (Arg>Trp) and XRCC3 241 (Thr>Met) polymorphisms may be associated with TC risk in a Chinese population, especially in smokers and drinkers.     

XRCC1 polymorphisms and risk of papillary thyroid carcinoma in a Korean sample

Polymorphisms of DNA repair genes, X-ray repair cross-complementing group 1 (XRCC1) might contribute to individual susceptibility to different types of cancers. We analyzed the relationship between XRCC1 polymorphisms and the risk of papillary thyroid carcinoma in a Korean sample. A hospital-based case-control study was performed in 111 papillary thyroid carcinoma patients and 100 normal control subjects. XRCC1 Arg194Trp and Arg399Gln single nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The XRCC1 Arg194Trp Arg/Trp genotype was significantly associated with a decreased risk of papillary thyroid carcinoma compared to that of Arg/Arg genotype (odds ratio [95% confidence intervals]; 0.550 [0.308-0.983]). There was no significant association between XRCC1 Arg399Gln genotypes and risk of papillary thyroid carcinoma. Based on these results, the XRCC1 Arg194Trp Arg/Trp genotype could be used as a useful molecular biomarker to predict genetic susceptibility for papillary thyroid carcinoma in Koreans.     

Detection of XRCC1 gene polymorphisms in Egyptian patients with acute myeloid leukemia

XRCC1 is a polymorphic gene belonging to one of the major deoxyribonucleic acid (DNA) repair pathways. XRCC1 is involved in base excision repair (BER) and the repair of single-strand breaks. Several variants of XRCC1 have been described, including one affecting codon 399 in exon 10 that results in an arginine (Arg) to glutamine (Gln) substitution and one affecting codon 194 in exon 6 that results in an Arg to tryptophan (Trp) substitution. The aim of this study was to determine the presence of these polymorphisms in the Egyptian population and to define their role in modulating susceptibility to development of acute myeloblastic leukemia (AML) using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique in 40 de novo AML patients and 20 controls. The risk of development of AML was found to be significantly increased when variant XRCC1-399 (Arg/Gln) is present (P value 0.025). Moreover, the risk of AML development was found to be significantly increased when variant XRCC1-194 (Arg/Trp) is present (P value 0.002), whereas the risk of AML development is even higher when both variants XRCC1-Arg-399 Gln and Arg-194 Trp alleles are present (odds ratio [OR] 6.15 and 4.00 and 95% CI 1.88–20.05 and 1.13–14.08, respectively), presumably because an increase in DNA damage significantly increases the risk of development of AML, and the phenotypes, as a result, interact to increase this risk. These results strongly suggest that BER pathway, notably XRCC1, is important in the pathogenesis of de novo AML.     

A meta-analysis on XRCC1 R399Q and R194W polymorphisms, smoking and bladder cancer risk

To elucidate the role of X-ray repair cross-complementing group 1 (XRCC1) R399Q and R194W genotypes in bladder cancer risk, all available studies were considered in the present meta-analysis, with 4152 patients and 5372 controls for R399Q and 3215 patients and 4313 controls for R194W. Studies were identified in PubMed up to June 2008. Overall, the 399Q allele showed no significant effect on bladder cancer compared to 399R allele in all subjects. Insignificant association between R399Q and bladder cancer was observed under other genetic contrasts in worldwide population, Caucasians and never-smokers. Among ever-smokers, protective effects of 399QQ genotype were observed under recessive model [P = 0.004, fixed-effects (FEs) model odds ratio (OR) = 0.65; 95% confidence interval (CI) (0.49, 0.86), I(2) = 0% P(heterogeneity) = 0.57] and homozygote contrast (P = 0.01, FE OR = 0.66; 95% CI (0.49, 0.90), I(2) = 0%, P(heterogeneity) = 0.76). No apparent effect of 194W allele compared to 194R on bladder cancer risk was found in all subjects and Caucasians. It indicated that XRCC1 R399Q and R194W might not be risk factors to bladder cancer, but the 399QQ genotype decreased susceptibility of bladder cancer under recessive model and homozygote contrast among ever-smokers. Further studies based on larger, stratified population were required to explore the role of XRCC1 polymorphisms in bladder cancer risk.     

Influence of genetic polymorphisms on biomarkers of exposure and genotoxic effects in styrene-exposed workers

A study on 44 workers exposed to styrene and 44 matched referents was performed in order to examine the influence of genetic polymorphisms in biotransformation and DNA repair enzymes on the levels of N-terminal hemoglobin adducts and genotoxicity biomarkers. Urinary mandelic acid concentration averaged 201.57 mg/g creatinine +/-148.32 in exposed workers, corresponding to a calculated average airborne styrene exposure of 9.5 ppm +/-9.6. Individuals with a high level of N-terminal valine adducts had higher levels of DNA damage, as evaluated by the Comet assay (r = 0.29, P = 0.008). Frequencies of micronucleated mononucleated lymphocytes (MNMC) (0.71 +/- 0.88 vs 0.11 +/- 0.20, P<0.0001), micronucleated binucleated lymphocytes (MNBC) (3.93 +/- 2.75 vs 2.65 +/- 1.94, p = 0.02) and micronucleated nasal epithelial cells (0.52 +/- 0.49 vs 0.23 +/- 0.31, p = 0.04) differed significantly between the exposed and referent groups. In the whole group of 88 individuals, higher frequencies of MNMC were found in individuals possessing the XRCC3 Met(241) allele and those individuals with the XRCC1 Gln( (399) ) allele showed higher frequencies of MNMC and MNCB. In vitro DNA repair capacity, as measured by residual DNA strand breaks in peripheral blood leukocytes after a styrene oxide challenge, was also influenced by styrene exposure, with an apparent induction of early repair mechanisms associated with the intensity of recent exposure and a reduction of late (24 h) repair capacity that was associated with the duration of employment. After 1 h of repair, lower levels of residual DNA damage were found in individuals possessing GSTT1 (P = 0.043). After 24 h of repair, lower residual DNA damage was found in individuals homozygous for XRCC1 Arg(194) (P = 0.013). Multivariate regression analysis indicated that the duration of exposure, smoking habits and polymorphisms of XRCC1 at codon 399 were important variables affecting the genotoxic responses. Our data suggest that DNA damage is formed in workers exposed to low concentrations of styrene, and that genotypes of metabolising and DNA-repair genes are important for the assessment of individual genotoxic risk to styrene. The in vitro DNA repair phenotype assay might be a valuable method to estimate the susceptibility of workers.     

Polymorphisms in the thymidylate synthase promoter and the DNA repair genes XRCC1 and XPD in a Brazilian population

Polymorphisms in genes responsible for maintaining genomic integrity are potential modifiers of disease risk. Since considerable interindividual and interethnic variation in DNA repair capacity has been associated with polymorphic alleles, we evaluated the frequency of the 2R/3R variants in the TS promoter, Arg194Trp and Arg399Gln in the XRCC1 gene, and Asp312Asn and Lys751Gln in the XPD gene in 364 healthy individuals from a Brazilian population separated by ethnicity (European ancestry and African ancestry). The genotypes were determined by PCR (TS) or by PCR-RFLP (XRCC1 and XPD). The frequency of the TS 3R allele was 0.56 for whites and 0.51 for nonwhites. In the case of the XRCC1 MspI polymorphism, the allele frequencies were 0.09 for 194Trp in both nonwhites and whites and 0.27 and 0.28 for 399Gln in nonwhites and whites, respectively. For the XPD 312Asn allele, we found a frequency of 0.25 in white individuals, which was significantly different (P = 0.025) from that seen in nonwhites (0.15). Similarly, the 751Gln polymorphic allele of the XPD gene was significantly more frequent (P < 0.002) in whites (0.30) than in nonwhites (0.20). The genotype frequencies were within Hardy-Weinberg equilibrium. We concluded that the genotype and allele frequencies of XPD gene polymorphism differed between white and nonwhite Brazilians, and that the frequencies of the XPD 312Asn and XRCC1 399Gln alleles in this Brazilian population showed ethnic variability when compared with those observed in other populations.     

hOGG1(326), XRCC1(399) and XRCC3(241) polymorphisms influence micronucleus frequencies in human lymphocytes in vivo

A pooled analysis of five biomonitoring studies was performed to assess the influence of hOGG1(326), XRCC1(399) and XRCC3(241) gene polymorphisms on micronuclei (MN) frequency in human peripheral blood lymphocytes, as measured by the ex vivo/in vitro cytokinesis-block micronucleus (CBMN) assay. Each study addressed a type of occupational exposure potentially able to induce DNA strand breakage (styrene, ionising radiation, cobalt/hard metal, welding fumes and inorganic arsenite compounds), and therefore MN, as a result of base excision repair and double-strand break repair deficiencies. The effect of genotype, age, exposure to genotoxic agents and smoking habit on MN induction was determined using Poisson regression analysis in 171 occupationally exposed male workers and in 132 non-exposed male referents. The analysis of genotype-genotype, genotype-smoking and genotype-exposure interactions by linear combinations of parameters showed significantly higher MN frequencies in the following subsets: (i) occupationally exposed workers carrying either the Thr/Thr or the Thr/Met XRCC3(241) genotypes compared to their referent counterparts (P < 0.001) and (ii) carriers of the Met/Met XRCC3(241) genotype compared to Thr/Thr XRCC3(241) carriers, as far as they are non-exposed and bear the variant (Ser/Cys or Cys/Cys) hOGG1(326) genotype (P < 0.01). Significantly lower MN frequencies were observed in carriers of the variant hOGG1(326) genotype compared to Ser/Ser hOGG1(326) carriers in the subgroup of non-smokers with Thr/Thr XRCC3(241) genotype (P < 0.01). Stratified analysis by occupational exposure showed a significant MN increase with smoking in occupationally exposed carriers of the Arg/Gln XRCC1(399)genotype (P < 0.001). In contrast, a significant MN decrease with smoking was observed in referents carrying the Ser/Ser hOGG1(326) genotype (P < 0.01). These findings provide evidence that the combination of different DNA repair genes and their interaction with environmental genotoxic agents may modulate MN induction. Understanding the complexity of the relationships between exposure, DNA repair and MN frequencies require larger scale studies and complementary biomarkers.     

Interaction between Polymorphisms of DNA Repair Genes Significantly Modulated Bladder Cancer Risk

DNA repair is a primary defense mechanism against damage caused by exogenous and endogenous sources. We examined the associations between bladder cancer and 7 polymorphisms from 5 genes involved in the maintenance of genetic stability (MMR: MLH1-93G>A; BER: XRCC1--77T>C and Arg399Gln; NER:XPC Lys939Gln and PAT +/-; DSBR:ATM G5557A and XRCC7 G6721T) in 302 incident bladder cancer cases and 311 hospital controls. Genotyping was done using a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) technique. The homozygous variant of XRCC7 G6721T (Odds Ratio [OR]: 2.36; 95% Confidence Interval [CI]: 1.13-4.92) was associated with increased bladder cancer risk. In an analysis of combined genotypes, the combination of XRCC1Arg399Gln (Gln allele) with XRCC1-77 T/T led to an increase in risk (OR: 1.61; 95% CI: 1.10-2.36). Moreover, when the XPCLys939Gln (Gln allele) (nucleotide excision repair [NER]) was present together with XRCC7 (T allele) (double strand break repair [DSBR]), the bladder cancer risk dramatically increased (OR: 4.42; 95% CI: 1.23-15.87). Our results suggest that there are multigenic variations in the DNA repair pathway involved in bladder cancer susceptibility, despite the existence of ethnic group differences.     

XRCC1、hOGG1基因多态性与喉癌遗传易感性的关系

目的 探讨X线修复交叉互补组1基因(X-ray repair cross complementing group 1,XRCC1)、8-羟基鸟嘌呤修复酶基因(human 8-oxoguanine glycosylase I,hOGG1)多态性与喉癌遗传易感性的关系.方法 采用病例-对照设计,应用聚合酶链反应-限制性片段长度多态性分析法检测了72例经病理确诊的喉癌患者和随机抽样的72例无肿瘤、无遗传病对照者XRCC1-Arg399Gln、hOGG1-Ser326Cys多态性.结果 病例组XRCC1第399位密码子杂合型(Arg/Gln)及突变型(Gln/Gln)和hOGG1第326位密码子杂合型(Ser/Cys)及突变型(Cys/Cys)分布频率均高于对照组(P＜0.05),与携带XRCC1-399野生型(Arg/Arg)、hOGG1-326野生型(Ser/Ser)个体相比,携带该基因型的个体喉癌的发病风险分别升高了3.37和2.54倍.交互作用分析显示,吸烟组与不吸烟组相比,携带XRCC1、hOGG1各基因型的个体的喉癌发病风险差异未发现存在统计学意义(xH12=0.15,xH22=0.28,P＞0.05).结论 XRCC1-399位点Arg→Gln和hOGG1-326位点Ser→Cys的氨基酸替换可能导致喉癌的发病风险增加,XRCC1-Arg399Gln、hOGG1-Ser326Cys多态性可能与喉癌的遗传易感性有关.     

Assoication of XRCC1 gene polymorphisms with risk of non-small cell lung cancer

DNA repair genes is a key factor for cancer susceptibility, and we conducted a case-control study to investigate the association of XRCC1 codons 194 (Arg to Trp), 280 (Arg to His) and 399 (Arg to Gln) with risk of NSCLC. 210 NSCLC patients and 210 health control subjects were randomly selected from Huaihe Hospital between January 2012 and June 2014. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was taken to assess the genotyping of XRCC1 Arg194Trp, Arg280His and Arg399Gln. By multivariate logistic regression analysis, we found individuals carrying with Trp/Trp and Arg/Trp + Trp/Trp genotypes were associated with a significantly increased risk of NSCLC compared with Arg/Arg genotype, and the OR (95% CI) were 3.15 (1.32-8.09) and 1.52 (1.02-2.28), respectively. The potential association of Arg/Trp+ Trp/Trp genotype of XRCC1 Arg194Trp with the risk of NSCLC is more evidence in smokers, and the OR (95% CI) was 1.78 (1.01-3.24). In conclusion, we found that XRCC1 Arg194Trp polymorphism may be associated with NSCLC risk, especially in smokers.     

DNA repair gene ERCC2 polymorphisms and risk of squamous cell carcinoma of the head and neck

Introduction

Genetic aberrations of DNA repair enzymes are known to be common events and to be associated with different cancer entities. Aim of the following study was to analyze the genetic association of single nucleotide polymorphisms (SNP) of the DNA repair genes with the risk of squamous cell carcinoma of the head and neck (HNSCC).

Materials and methods

Genetic variants ERCC2 Lys751Gln (rs13181), ERCC2 Asp312Asn (rs1799793), XRCC1 Arg194Trp (rs1799782); XRCC1 Gln399Arg (rs25487), XRCC1 Arg280His (rs25489) and XRCC3 Thr241Met (rs861539) were analyzed in a primary study group comprising 169 patients with histologically confirmed HNSCC and 463 healthy control subjects. Polymorphisms associated with HNSCC were furthermore analyzed in an independent replication study including 125 HNSCC.

Results

Only the ERCC2 751 Gln/Gln genotype was associated with HNSCC in the primary study (p = 0.033) and in the replication study (p = 0.023), resulting in an overall odds ratio of 0.54 (95% confidence interval 0.35–0.92; p = 0.006).

Conclusion

Carriers of the homozygous ERCC2 751 Gln/Gln genotype may be at lower risk for HNSCC.     

Influence of common XPD and XRCC1 variant alleles on p53 mutations in lung tumors

The DNA repair proteins XPD and XRCC1 are involved in the nucleotide and base excision repair of DNA lesions induced by many tobacco and environmental carcinogens. Common variant alleles at the XPD (312Asn, 751Gln) and XRCC1 (399Gln) loci have been identified and associated with increased risk for lung cancer. We therefore investigated a possible effect of these variant alleles on the frequency and spectrum of p53 mutations in the tumors of 97 Swedish lung cancer patients (56 never-smokers and 41 age-, gender-, and hospital-matched ever-smokers). The p53 gene was mutated in 4 never-smokers (7%) and 11 ever-smokers (27%). Smoking-related transversion-type mutations predominated over transitions among smokers (8:3), but not among never-smokers (1:3). None of the variant alleles altered the overall frequency of p53 mutation. Transversions, however, were marginally increased among patients with at least one XPD variant allele compared with patients who were wild-type homozygotes (73% vs. 25% for the Asp312Asn polymorphism, P = 0.095; 78% vs. 33% for Lys751Gln, P = 0.085). Five of six women or six of seven smokers who carried at least one XPD 751Gln allele had p53 transversion. The XRCC1 variant allele did not show any effect on the p53 mutation. We conclude that the XPD variant alleles may be associated with an increased frequency of smoking-related p53 mutations in lung tumors, presumably due to reduced DNA repair proficiency.