中国人群XRCC1 Arg399Gln 基因多态性与结直肠癌易感性关系的Meta分析

摘 要：［目的］探讨X线修复交叉互补基因1（X-ray repair cross complementing group 1,XRCC1）Arg399Gln基因多态性与中国人群结直肠癌易感性的关系。［方法］在PubMed、MEDLINE、EMBASE、中国知网、维普、中国生物医学文献及万方数据库中检索建库至2016年4月10日之间发表的有关XRCC1 Arg399Gln基因多态性与中国人群结直肠癌易感性关系的相关文献。按照纳入和排除标准独立选择文献、提取资料,采用Stata 12.0软件进行Meta分析,计算合并比值比（OR）及其95%可信区间（95%CI）,并进行敏感性分析和发表偏倚的估计。［结果］ 共纳入11项研究,包括3502例患者和4828例对照者。Meta分析结果显示,在Gln/Gln vs Arg/Gln遗传模型中,XRCC1 Arg399Gln基因多态性与中国人群结直肠癌发生风险有显著相关性,与基因型Arg/Gln相比,基因型Gln/Gln增加了中国人群罹患结直肠癌的风险（OR=1.23,95%CI：1.04~1.46,P=0.016）。其余遗传模型中两者间无明显相关性。［结论］ 在Gln/Gln vs Arg/Gln遗传模型中,XRCC1 Arg399Gln基因多态性与中国人群结直肠癌易感性相关,基因型Gln/Gln增加中国人群罹患结直肠癌的风险。     

XRCC1 Arg399Gln基因多态性与中国人群肝细胞癌易感性的Meta分析

目的 探讨XRCC1 Arg399Gln基因多态性与肝细胞癌（HCC）易感性的关系。方法 计算机检索PubMed、中国生物医学文献（CBM）、中国知网、万方及维普等数据库,收集有关XRCC1 Arg399Gln基因多态性与HCC易感性关系的病例对照研究,提取纳入文献的相关数据进行Meta分析,以病例组与对照组XRCC1 Arg399Gln各种基因模型的比值比（OR）为效应指标,发表偏倚采用Eggers检验和Beggs检验。结果 共17篇文献符合纳入标准,累计病例数3301例,对照组4156例。XRCC1 Arg399Gln基因多态性与中国人群HCC易感性有明显关联性（G/G vs. A/A：OR=1.32,95％CI：1.13～1.54,P=0.000;A/G vs. A/A：OR=1.25,95％CI：1.10～1.41,P=0.000;A/G+G/G vs. A／A：OR=1.22,95％CI：1.09～1.36,P=0000;G／G vs. A／A+A／G：OR=1.20,95％CI：1.04～1.39,P=0.014）。根据健康对照组来源不同的亚组分析中,所有地区或者控制人口来源医院的研究结果均显示,XRCC1 Arg399Gln 基因多态性与HCC易感性有明显关联性,但控制人口非医院来源的研究结果显示XRCC1 Arg399Gln 基因多态性与HCC易感性无明显关联性;根据地区不同分组的亚组分析中,在广西地区,除隐性遗传模型外（G/G vs. A/A+A/G：OR=1.25,95％CI：0.95～1.65,P=0.115）,其余遗传模型结果显示XRCC1 Arg399Gln基因多态性与广西地区HCC易感性有明显相关性（G/G vs. A/A：OR=1.47,95％CI：1.10～1.95,P=0.009;A/G vs. A/A：OR=1.35,95％CI：1.17～1.56,P=0.000;A/G+G/G vs.A／A：OR=133,95％CI：1.16～1.52,P=0.000）。结论 XRCC1 Arg399Gln 基因多态性可能增加中国人群HCC的易感性,尤其在广西地区。     

XRCC1 Arg399Gln位点多态性和结直肠癌易感性关系的Meta分析

[目的]探讨X射线交叉互补修复基因1（X-ray repair cross-complementing group1,XRCC1）的399位点（Arg399Gln）多态性与结直肠癌（CRC）易感性的关系。[方法]检索中国生物医学数据库（CBM）、PubMed、Springer等数据库,获取有关XRCC1Arg399Gln多态性同结直肠癌易感性关系的病例对照研究并进行Meta分析,以病例组及对照组XRCC1Arg399Gln等位基因分布的比值比（OR）为效应指标,应用Meta分析软件Review Manager（version5.0.10）对各研究原始数据进行统计处理及异质性检验,计算合并OR值及其95%可信区间（95%CI）。[结果]纳入11项病例对照研究,共2287例结直肠癌患者和3485例对照,Meta分析结果显示,Gln/Gln vs.Arg/Arg OR=1.12,95%CI为0.76～1.65,Z=0.58,POR=0.56;Gln/Gln＋Arg/Gln vs.Arg/Arg OR=1.11,95%CI为0.85～1.44,Z=0.78,POR=0.43;Gln/Glnvs.Arg/Arg＋Arg/Gln OR=1.07,95%CI为0.79～1.46,Z=0.43,POR=0.67;Arg/Gln vs.Arg/Arg OR=1.14,95%CI为0.88～1.48,Z=1.02,POR=0.31。[结论]XRCC1Arg399Gln多态性与结直肠癌易感性之间无显著相关性。     

XRCC1基因Arg399Gln多态性与中国人群神经胶质瘤易感性Meta分析

目的:探讨XRCC1基因Arg399Gln (G/A)多态性与中国人群神经胶质瘤易感性的关系.方法:计算机检索Pubmed、EMBASE、中国知网、万方期刊、维普等中英文数据库,检索2014年10月之前公开发表的相关文献,对符合标准的文献采用NOS量表评价文献质量,应用RevMan5.1软件进行Meta分析.结果:共纳入9篇与XRCC1基因Arg399Gln多态性与神经胶质瘤易感性相关的病例对照研究,包括7 131例患者,其中病例组3 428例,对照组3 703例,NOS评分≥6分为高质量文献,仅2项研究质量评分＜6.Meta分析结果显示携带A等位基因可增加中国人群神经胶质瘤的患病风险(OR=1.20,95％CI:1.04～1.38,P=0.01).结论:中国人群中XRCC1基因Arg399Gln (G/A)多态性与神经胶质瘤的易感性存在相关性.     

CYP1B1 基因 Leu432Val 位点多态性与头颈癌易感性的 Meta 分析

目的：运用Meta分析方法研究CYPlBl基因Leu432Val位点多态性与头颈癌易感性的发生风险。方法：检索CNKI和PubMed数据库中有关CYPlBl基因Leu432Val位点多态性与头颈癌易感性关联研究的文献。对符合纳入标准的文献进行资料提取后，以OR值和95％可信区间为效应指标，应用STATA11．0软件进行Meta分析，并对发表偏倚进行检测。结果：纳入5个对照研究，共计1580例头颈癌患者和2076例正常对照人群。Meta分析结果显示，总人群中，CYPlBl基因Leu432Val位点多态性与头颈癌易感性之间有显著关联（ValVS．Leu：OR=1．13，95％CI=1．03—1．25，P=0．014；Val／ValV8．Leu／Leu：OR=1．30。95％CI=1．06—1．60，P=0．013；Val／ValVS．Leu／Leu＋Leu／Val：OR=1．23，95％CI：1．05—1．46，P=0．013）。在针对种族的亚组分析中，发现CYPlBl基因Leu432Val位点多态性可能会增加欧洲人群发生头颈癌的风险。结论：CYPlBl基因Leu432Val位点多态性可能是增加欧洲人群发生头颈癌易感性的危险因素。     

NBS1基因657de15突变与乳腺癌易感性Meta分析

目的：综合分析NBS1基因中657de15突变与乳腺癌易感性的相关性。方法：检索PubMed、EMBAsE和Co—chrane Library等外文数据库,CNKI和万方等中文数据库,检索起止时间为1990—01—2013—11,收集关于NBS1基因657de15突变与乳腺癌易感性的独立病例对照研究,使用Meta分析的方法对各研究数据合并0R值及95％可信区间,进行统计学分析及异质性检验,并检测敏感性及发表偏倚。结果：共纳入8篇文献,包括7534例病例和14034例对照,Meta分析结果显示,NBS1基因657de15突变人群乳腺癌发病风险明显增高,0R=2．63,95％CI：1．76～3．93。种族亚组分析结果显示,NBS1基因中657de15突变与德国人无统计学关联,0R=2．46,95％CI：0．28～17．86,与俄罗斯及白俄罗斯（OR=5．22,95％CI：1．54～17．63）和波兰人（OR=2．29,95％CI：1．47～3．55）乳腺癌易感性相关。结论：NBS1基因657de15突变与乳腺癌易感性相关,657de15突变人群是乳腺癌的高危人群。     

DNA修复基因XRCC1的399位点多态性同肺癌易感性关系的Meta分析

目的综合评价DNA修复基因XRCC1(X-raycross-complementinggroup1)的399位点多态性同肺癌易感性的关系。方法检索中国生物医学数据库和Medline,获得有关XRCC1基因399位点多态性同肺癌易感性关系的研究结果,并进行Meta分析。所有文献均采用病例对照研究,以非条件Logistic回归校正年龄、性别和吸烟状况等混杂因素后的OR值为效应指标,对文献进行评价筛选、异质性检验。利用Meta分析软件RevMan4·2对各研究原始结果进行统计处理,并计算合并OR值及其95%可信区间。结果本次Meta分析共纳入15项研究,累计病例6818例,对照7610例。Arg/Gln和Gln/Gln等位基因同Arg/Arg比较,OR值分别为0·99(95%CI0·91~1·06)和1·04(95%CI0·92~1·17),Z值分别为-0·37和0·67,对应的P值分别为0·71和0·50。结论尚无足够证据证明DNA修复基因XRCC1的399位点多态性同肺癌易感性有关。     

X射线损伤修复交叉互补基因1多态性与非吸烟女性肺癌易感性的关系

目的探讨X射线损伤修复交叉互补基因1（XRCCl）单核苷酸多态性与非吸烟女性肺癌易感性的关系。方法采用以医院患者为基础的病例一对照研究方法,非吸烟女性肺癌患者50例,非癌对照50例。以聚合酶链反应一限制性片段长度多态性（PCR—RFLP）方法检测XRCC1基因Arg399Gln多态性,计算各基因型的比值比（OR）,并探讨烹饪油烟暴露史与多态基因型交互作用对肺癌患癌风险的影响。结果肺癌组与对照组XRCC1 Arg399Gln多态基因型分布差异无统计学意义（P〉0．05）,而腺癌组基因型分布与对照组差异有统计学意义（P〈0．05）。相对于399Arg／Arg基因型,携带至少1个Gin等位基因的个体患肺腺癌的调整OR值为2．19（95％CI为0．73～6．61）,而XRCC1 399Gin／Gin基因型携带者的调整OR值为14．12（95％CI为2、14～92．95）。携带至少1个399Gln等位基因的烹饪油烟暴露者患肺腺癌的风险明显升高,调整OR值为6．29（95％c,为1．99～19、85）。结论XRCC1基因Arg399Gln多态可能是非吸烟女性肺腺癌的遗传易感因素,399Gln等位基因与烹饪油烟交互作用,可提高非吸烟女性肺腺癌的发病风险。     

MDM2启动子309位点多态性与乳腺癌易感性关系的Meta分析

[目的]综合评价MDM2（routine double minute2）基因启动子309位点多态性与乳腺癌易感性的关系。[方法]检索中国医学文献数据库和PubMed中MDM2基因SNP309与乳腺癌易感性关系的病例对照研究,并用Meta分析的方法合并SNP309与乳腺癌易感性OR值。然后进行其中有家族史的乳腺癌亚组分析,敏感性分析和文献的发表偏倚检验。[结果]Meta分析共纳入10篇文献,乳腺癌家族史组有3篇;累计病例7535例,对照8272例,G等位基因相对于T等位基因0R值为1．01（95％CI：0．96～1．06）。乳腺癌家族史组G等位基因相对于T等位基因OR值为1．06（95％CI：0．94～1．19）。[结论]MDM2基因309T〉G多态与乳腺癌易感性无统计学意义。     

中国人群COMT Val158Met基因多态性与乳腺癌易感性Meta分析

目的：系统评价中国人群儿荼酚氧位甲基转移酶（catechol-O-methyltransferase,COMT）Vall58Met基因多态性与乳腺癌易感性的关系。方法：在PubMed、MEDLINE、webofScience、Embase、中国期刊全文数据库（CJFD）及万方数据库中检索1999-10-01-2012-01-01发表的所有有关中国人群COMTVall58Met基因多态性与乳腺癌易感性关系的相关文献,并按STREGA原则对文献进行筛选、评价。纳入文献均为病例对照研究,对照群体基因型分布均符合H-W遗传平衡定律。应用Stata 12．0软件进行Meta分析,计算合并0R值及95％CI,并进行敏感性分析和发表偏倚的估计。结果：按照入选标准,有11项病例对照研究纳入,包括乳腺癌患者3184例,健康对照4065例。Meta分析结果显示,与基因型Val／Val（GG）、Val／Met（GA）比较,基因型Met／Met（AA）均增加中国人群罹患乳腺癌的风险[OR=1．55,95％CI：1.03～2．33,P=0．035;OR-1．63,95％CI：1．10～2．42,P=0．015];在隐性效应模型（Met／Met／vs Val／Val＋Val／Met）中,基因型Met／Met（AA）增加中国人群罹患乳腺癌的风险,0R-1．59,95％CI：1．07～2．36,P=0．021。与等位基因Val（G）比较,等位基因Met（A）不增加中国人群罹患乳腺癌的风险,OR=1．12,95％CI：0．96～1．32,P=0．157。结论：COMTVall58Met基因多态性与中国人群乳腺癌易感性相关,基因型Met／Met（AA）增加中国人群罹患乳腺癌的风险。     

Oral presentation

Radiotherapy is an important weapon in the treatment of breast cancer, but normal tissue injury after radiotherapy can be a threat for patients. Genetic markers conferring the ability to identify hyper-sensitive patients at risk of normal tissue injury in advance would considerably improve therapy. Association studies on genetic variation and occurrence of normal tissue injury can help us identify such markers, but previous studies on the association between XRCC1 R399Q polymorphism and risk of normal tissue injury after radiotherapy in breast cancer patients report conflicting findings. We performed a meta-analysis to comprehensively evaluate the association between XRCC1 R399Q polymorphism and risk of normal tissue injury after radiotherapy in breast cancer patients. The pooled odds ratios (ORs) with their 95 % confidence interval (95 % CIs) were calculated to assess the strength of the association. Fourteen case–control studies with a total of 2,448 breast cancer cases were finally included into the meta-analysis. Overall, XRCC1 R399Q polymorphism was significantly associated with increased risk of normal tissue injury after radiotherapy under all three models (for QQ versus RR: fixed-effects OR?=?1.06, 95 % CI 1.00–1.13, P?=?0.050; for RQ versus RR: fixed-effects OR?=?1.05, 95 % CI 1.00–1.10, P?=?0.047; for QQ/RQ versus RR: fixed-effects OR?=?1.26, 95 % CI 1.01–1.58, P?=?0.041). The meta-analysis suggests that XRCC1 R399Q polymorphism was significantly associated with increased risk of normal tissue injury after radiotherapy in breast cancer patients, and XRCC1 R399Q polymorphism is a genetic marker of normal tissue injury after radiotherapy in breast cancer patients.     

Selected base excision repair gene polymorphisms and susceptibility to biliary tract cancer and biliary stones: a population-based case-control study in China

Base excision repair (BER) corrects DNA damage caused by oxidative stress and chronic inflammation, putative risk factors for cancer. To understand the relationship between genetic variation in BER genes and risk of biliary tract cancer and biliary stones, we examined non-synonymous polymorphisms in three key BER genes-x-ray repair cross-complementing group 1 (XRCC1) (R194W, rs1799782; R280H, rs25489 and R399Q, rs25487), apurinic/apyrimidinic endonuclease (APEX1) (D148E, rs3136820) and 8-oxoguanine DNA glycosylase (OGG1) (S326C, rs1052133), in a population-based study of 411 biliary tract cancer cases (237 gallbladder, 127 bile duct and 47 ampulla of Vater), 891 biliary (gallbladder or bile duct) stone cases and 786 population controls conducted in Shanghai, China. Compared with subjects carrying the XRCC1 194RR genotype, those with the WW genotype had a 1.9-fold risk of bile duct cancer [odds ratio (OR) = 1.9, 95% confidence interval (CI) = 1.1-3.5, P(trend) = 0.03], and compared with subjects carrying the XRCC1 280RR genotype, those with the XRCC1 280H allele had a 50% reduced risk of bile duct cancer (OR = 0.5, 95% CI = 0.3-0.9, P(trend) = 0.05). The effect of the R280H polymorphism persisted (P(trend) = 0.03), when all three XRCC1 polymorphisms were jointly considered in the model, a finding supported by the haplotype results (covariate-adjusted global permutation P = 0.03). We also found an inverse association between the APEX1 148E allele and gallbladder stones (P(trend) = 0.03), but no association for the OGG1 polymorphism. This study suggests that genetic variants in XRCC1 and APEX1 may alter susceptibility to biliary tract cancer and stones. Further studies are required to confirm the reported associations.     

MS-920: DNA repair gene polymorphisms, diet and colorectal cancer risk in Taiwan

This hospital-based case-control study examined whether polymorphic DNA repair genes: XRCC1 Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln, play a role in the susceptibility to colorectal cancer. We genotyped these polymorphisms for 727 newly diagnosed colorectal adenocarcinoma cases and 736 age and sex matched healthy controls in Taiwan. Although the colorectal cancer risk was not significantly associated with these genes, the risk was significantly elevated in younger subjects (< or =60 years) with the XRCC1 399Arg/Arg genotype compared to those with XRCC1 399Gln allele (OR=1.46, 95% CI=1.06-2.99, P=0.02). The stratified analysis showed that XRCC3 interacted with meat consumption (P for interaction=0.02), but was limited to the low meat consumption (OR=2.34, 95% CI=1.28-4.29). Our results suggest that the XRCC1 Arg399Gln polymorphism may contribute to the risk of early-onset colorectal cancer and the XRCC3 Thr241Met polymorphism may modify the risk for meat-associated colorectal cancer.     

Polymorphisms XRCC1-R399Q and XRCC3-T241M and the risk of breast cancer at the Ontario site of the Breast Cancer Family Registry.

This study investigates the role of two nonsynonymous single nucleotide polymorphisms in DNA repair genes, X-ray repair cross-complementing group 1 (XRCC1)-R399Q and X-ray repair cross-complementing group 3 (XRCC3)-T241M, in breast cancer. Incident cases of invasive breast cancer in Caucasian women [n = 402, mean age = 45.7 (SD = 6.2) years] and female Caucasian controls [n = 402, mean age = 45.2 (6.5) years] frequency matched on 5-year age intervals were identified from the Ontario Familial Breast Cancer Registry. No evidence for a main effect of the XRCC1-R399Q genotype on breast cancer risk was observed. Estimates of risk for a family history (FH) of breast cancer compared with no FH differed by XRCC1-R399Q genotype (P value for interaction = 0.001). Homozygote XRCC1-399 R/R individuals and FH+ were at a 2.92-fold [95% confidence interval (95% CI) = 1.47-5.79] increased risk of disease compared with FH- individuals; the estimate of risk increased for R/Q heterozygotes with FH+ [odds ratio (OR) = 3.85, 95% CI = 1.94-7.65] but not for Q/Q homozygotes with FH+ (OR = 0.54, 95% CI = 0.20-1.47) compared with homozygous R/R and FH- individuals. A marginal positive association for XRCC3-241 M/M compared with T/T genotype was found (OR = 1.44, 95% CI = 0.94-2.19), but the heterozygous T/M was not associated with an increase in risk (OR = 0.96, 95% CI = 0.71-1.32). There was also some evidence for a combined effect of body mass index and XRCC3-T241M on estimates of risk. Our results suggest that these polymorphisms may influence breast cancer risk by modifying the effect of risk factors such as FH. There is a need for further study into the role of these polymorphisms as effect modifiers.     

An association of polymorphism of DNA repair genes XRCC1 and XRCC3 with colorectal cancer

Variability in DNA repair genes may contribute to human cancer risk. We performed a case-control study (51 cases and 100 controls) to test the association between two polymorphisms: Arg399Gln in the XRCC1 gene and Thr241Met in the XRCC3 gene and colorectal cancer risk. Genotypes were determined in tumour tissue and distant mucosa samples by PCR RFLP with the NciI restriction enzyme for XRCC1 and NcoI for XRCC3. Cancer occurrence was strongly associated with the XRCC3 Met/Met polymorphic variant (OR = 9.45; (95% CI 8.77-11.65)), whereas Thr/Thr and Thr/Met variants were associated with significant reduction in colorectal cancer risk (OR = 0.16; 95% CI 0-0.26 and OR = 0.26; 95% CI 0.25-0.27, respectively). Weak association was found between the XRCC1 Arg/Arg and Gln/Gln variants and the risk of colorectal cancer (OR = 1.28; 95% CI 1.00-1.84 and OR = 1.13; 95% CI 0.85-2.34, respectively). Gene-gene interaction between the XRCC1 Arg/Arg and XRCC3 Met/Met homozygous variants slightly increased the risk (OR = 10.50; 95% CI 5.67-14.79). Both polymorphisms were not associated with colorectal cancer progression.     

Genetic polymorphisms in base-excision repair pathway genes and risk of breast cancer.

Impaired base-excision repair (BER) function can give rise to the accumulation of DNA damage and initiation of cancer. We evaluated whether genetic variation in six BER pathway genes (XRCC1, ADPRT, APEX1, OGG1, LIG3, and MUTYH) is associated with breast cancer risk in two large population-based case-control studies in the United States (3,368 cases and 2,880 controls) and Poland (1,995 cases and 2,296 controls). A detailed evaluation was first done in a subset of 1,898 cases and 1,514 controls with mouthwash DNA samples in the U.S. study. Significant findings were followed up in the remainder of the U.S. study population that provided cytobrush DNA samples and in the Polish study. Using data from U.S. study participants with mouthwash DNA, we found no significant overall association between breast cancer risk and XRCC1 R280H and R194W, ADPRT V726W, APEX1 D148E, OGG1 S326C, LIG3 R780H, or MUTYH 5' untranslated region. These data suggested a decreased risk for XRCC1Q399R homozygous variants compared with homozygous wild-type in premenopausal women, but these findings were not confirmed when data from cytobrush DNA samples were added [combined odds ratio (OR), 0.8; 95% confidence interval (95% CI), 0.6-1.1] or in the Polish study (OR, 1.0; 95% CI, 0.7-1.5). Meta-analyses based on our data and published data from studies of two single nucleotide polymorphisms in XRCC1 showed no evidence of an overall association between breast cancer risk and homozygous variants versus wild-type for Q399R (OR, 1.1; 95% CI, 1.0-1.2) or R194W (OR, 1.0; 95% CI, 0.7-1.8), although there was a suggestion for an association in Asian populations for Q399R (OR, 1.6; 95% CI, 1.1-2.4; P = 0.02). In conclusion, our results do not support that the polymorphisms evaluated in six BER pathway genes play a major role in breast carcinogenesis, particularly in Caucasian populations.     

Polymorphisms of XRCC1 gene, alcohol consumption and colorectal cancer

To evaluate contribution of polymorphisms of the XRCC1 gene to the risk of colorectal cancer, we conducted a case-control study of 209 colorectal cancer cases and 209 age- and gender-matched controls in the Korean population. We tested the hypothesis by constructing allele combinations with known SNP. Allelic variants of the XRCC1 gene at codons 194, 280 and 399 were analyzed in lymphocyte DNA by PCR-RFLP. We observed an increased risk of colorectal cancer associated with the 399Gln allele. The odds ratio (OR) was 1.61 (95% confidence interval [CI] 1.09-2.39) for the 399Gln allele. When combined allele-specific OR were calculated after estimating frequencies, 3 common allele combinations were found to be associated with an increased risk of colorectal cancer. The OR for the 194Trp-280Arg-399Arg was 1.48 (95% CI = 1.06-2.07) using 194Arg-280Arg-399Arg as the reference. The OR for the 194Arg-280His-399Arg and the 194Arg-280Arg-399Gln were 1.78 (95% CI = 1.09-2.89) and 1.78 (95% CI = 1.23-2.59), respectively. Analysis after controlling for smoking, exercise and dietary habits indicated that alcohol consumption (> or =80 g/week) is a significant risk factor of colorectal cancer (OR = 2.60, 95% CI = 1.46-4.62). An increased risk for colorectal cancer was identified in alcohol drinkers with the risky allele combinations. Our results suggest that polymorphisms in the XRCC1 genes may contribute to colorectal cancer susceptibility, and some evidence was obtained of a genetic modification for the relationship between alcohol intake and colorectal cancer.     

No association between XRCC1 and XRCC3 gene polymorphisms and breast cancer risk: Iowa Women's Health Study

BACKGROUND: Genetic variation in DNA repair may contribute to differences in the susceptibility of several cancers. We evaluated two polymorphisms in the base excision repair pathway (BER) (XRCC1; Arg194Trp and Arg399Gln) and one polymorphism in the double strand DNA repair pathway (XRCC3; Thr241Met) for their association with breast cancer risk. METHODS: The association was analyzed in a nested case control study of 460 breast cancer cases and 324 cancer-free controls within the Iowa Women's Health Cohort. DNA was obtained from blood samples or paraffin embedded tissues (PET) and all samples were genotyped by one of three genotyping platforms-PCR-RFLP, PCR-INVADER, or Sequenom. RESULTS: None of the three polymorphisms studied were significantly associated with breast cancer risk (XRCC1: Arg194Trp (OR=1.21, 95% CI: 0.78-1.88); Arg399Gln (OR=1.20, 95% CI: 0.80-1.79); XRCC3: Thr241Met (OR=1.04, 95% CI: 0.76-1.41). CONCLUSIONS: These results suggest that independently these polymorphisms of XRCC1 and XRCC3 genes do not contribute significantly to the genetic susceptibility of breast cancer.     

Association of XRCC1 Arg399Gln Polymorphism with Colorectal Cancer Risk: A HuGE Meta Analysis of 35 Studies

Background: Non-synonymous polymorphisms in XRCC1 hase been shown to reduce effectiveness of DNArepair and be associated with risk of certain cancers. In this study we aimed to clarify any association betweenXRCC1 Arg399Gln and colorectal cancer (CRC) risk by performing a meta-analysis of published case-controlstudies. Materials and Methods: PubMed and Google Scholar were searched to explore the association betweenXRCC1 and CRC. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to estimate theassociation strength. Publication bias was assessed by Egger’s and Begg’s tests. Results: Up to January 2015, 35case control studies involving 9,114 CRC cases and 13,948 controls were included in the present meta-analysis.The results showed that the Arg399Gln polymorphism only under an allele genetic model was associated withCRC risk (A vs. G: OR 0.128, 95% CI 0.119-0.138, p<0.001). Also, this meta-analysis suggested that the XRCC1Arg399Gln polymorphism might associated with susceptibility to CRC in Asians (A vs G: OR 0.124, 95% CI0.112-0.138, p<0.001) and Caucasian (A vs G: OR 0.132, 95% CI 0.119-0.146, p<0.001) only under an allele geneticmodel. Conclusions: This meta-analysis confirms the association between XRCC1 Arg399Gln polymorphismand CRC risk and suggests that the heterogeneity is not strongly modified by ethnicity and deviation from theHardy-Weinberg equilibrium.     

Genetic polymorphism of XRCC1 and lung cancer risk among African-Americans and Caucasians.

Reduced DNA repair capacity may influence susceptibility to lung cancer. XRCC1 plays an important role in base excision repair and in rejoining DNA strand breaks. In the XRCC1 gene, two common polymorphisms induce amino acid changes in codon 194 and codon 399 and correlate with levels of genotoxic damage. We examined the relation between these two polymorphisms and susceptibility to lung cancer among 334 incident cases and 704 population controls of African-American and Caucasian ethnicity in Los Angeles County, California. African-American and Caucasian subjects smoking 20+ cigarettes/day and carrying at least one copy of the codon 194 variant allele were at somewhat decreased risk of lung cancer (African-Americans OR=0.2, 95% CI 0.1-0.9; Caucasians OR=0.5, 95% CI 0.2-1.1). Similarly, for the codon 399 polymorphism, there was some evidence of a decreased risk for the homozygous variant genotype among heavier smokers (African-Americans OR=0.3, 95% CI 0.0-2.9; Caucasians OR=0.4, 95% CI 0.2-1.0). These results suggest that genetic variation in XRCC1 might contribute to lung cancer and may interact with the amount smoked.