siRNA 对人脐静脉内皮细胞中人剪切修复基因表达和凋亡的影响

目的：向人脐静脉内皮细胞（HUVEC）中导入靶向人剪切修复基因D干扰序列（XPD-siRNA）,观察其对HUVEC的XPD基因表达和凋亡的影响。方法以XPD为靶基因,构建3个特异性siRNA重组质粒,经转染后观察其对HUVEC中XPD的沉默作用;并转染沉默效率最佳的siRNA,观察其对细胞凋亡的影响。结果Western blot和RT-PCR结果显示,与阴性对照组相比,3个重组质粒XPD-siRNA的转染均能降低HUVEC中XPD的表达（P＜0.01）,其中XPD-siRNA-2的沉默效率最高（P＜0.01）。流式细胞仪结果显示,与阴性对照组相比,XPD-siRNA-2组能降低HUVEC凋亡率（P＜0.01）。 Western blot结果显示,与阴性对照组相比,转染XPD-siRNA-2能下调Bax（P＜0.01）和上调Bcl-2（P＜0.01）的表达。结论 XPD-siRNA转染能有效沉默HUVEC中XPD基因的表达。所筛选沉默效率最佳的XPD-siRNA能抑制HUVEC凋亡,而Bax和Bcl-2可能参与了此过程。     

ERCC2/XPD单核苷酸多态与苯并芘体外诱导DNA加合物损伤的关联性研究

目的评价环境致癌因子苯并芘(B[a]P)所致DNA损伤修复与ERCC2/XPD单核苷酸多态(SNP)的关联。方法收集282例辽宁地区汉族健康人群外周血8ml,常规提取淋巴细胞及DNA,采用Taqman实时定量PCR检测ERCC2/XPDLys751Gln(rs13181),Asp312Asn(rs1799793)和Arg156Arg(rs238406)的基因型;体外培养淋巴细胞,应用B[a]P及S9活化系统,诱导BPDE-DNA加合物的形成;高效液相色谱法检测BPDE-DNA加合物含量;分析BPDE-DNA加合物水平与ERCC2/XPD SNP位点的关联。结果携带ERCC2/XPD Arg156Arg位点AA基因型个体BPDE-DNA加合物水平显著高于CC基因型携带者;50～70岁和≥70岁年龄组人群的加合物水平高于≤30岁年龄组(P<0.05);多元线性回归分析同样显示,ERCC2/XPD Arg156Arg位点SNP及年龄对BPDE-DNA加合物含量的影响有统计学意义(P<0.05)。结论 ERCC2/XPD Arg156Arg位点A等位基因可能与BPDE-DNA加合物的DNA修复能力降低相关联,可能会增加肿瘤易感风险。     

ERCC1、ERCC2的多态性对常见消化系统肿瘤的影响

机体DNA修复系统如核苷酸切除修复在维持基因组功能整体性、修复致癌因素所致的损伤及抗癌过程中有着重要作用。一些核酸修复基因,如切除修复交叉互补基因1(ERCC1)及人类着色性干皮病基因D(XPD/ERCC2)的水平下降,可能会成为某种或某几种肿瘤的易感因素;但如果此种基因的水平较高,修复损伤的能力提高,对化疗药物所致基因损伤的修复能力也就增强了,那么可能对化疗药物产生耐药现象。以上两种基因的单核苷酸多态与以DDP、5-FU为基础的化疗方案的疗效存在一定关系,而消化道肿瘤又多应用铂剂及5-FU治疗,故本文对ERCC1、XPD/ERCC2与几种常见消化道肿瘤的发生及其化疗疗效的关系予以综述。     

野生型XPD转染对胆管癌QBC939细胞生物学行为的影响

目的:探讨野生型XPD基因对人胆管癌QBC939细胞的生物学影响. 方法:用碱裂解法提取空载质粒pEGFP-N2和重组质粒pEGFP-N2-XPD,提取出的质粒以KPNⅠ、BGIⅡ和SPHⅠ酶切鉴定.实验分4组,重组质粒pEGFP-N2-XPD组、空载质粒pEGFP-N2组、脂质体组,并用具有相同遗传背景和代数的QBC939细胞作为空白对照.用脂质体转染法瞬时转染四组细胞.荧光显微镜下观察转染后绿色荧光蛋白报告基因表达情况.提取各组细胞总RNA,合成cDNA,用聚合酶链反应(PCR)检测4组细胞中XPD、p53、cyclin D1、c-myc表达情况.并用四甲基偶氮唑盐(MTT)和流式细胞仪检测细胞增殖及其细胞周期的变化. 结果:pEGFP-N2-XPD细胞与pEGFP-N2、脂质体组和空白对照组相比,XPD mRNA表达量明显增加(0.778±0.018 vs 0.561±0.039,0.544±0.035,0.542±0.034,均P<0.01).pEGFP-N2-XPD细胞中p53 mRNA相对表达量与pEGFP-N2、脂质体组和空白对照组比较具有统计学意义(0.421±0.019 vs 0.256±0.014,0.267±0.015,0.274±0.018,均P<0.01).pEGFP-N2-XPD细胞与其他组相比,cyclin D1 mRNA相对表达量明显降低(0.339±0.041 vs 0.560±0.039,0.558±0.050,0.560±0.041,均P<0.01).pEGFP-N2-XPD细胞与其他组相比,c-myc mRNA相对表达量明显降低(0.355±0.045 vs 0.570±0.075,0.560±0.041,0.537±0.050,均P<0.01).流式细胞仪检测pEGFP-N2-XPD组细胞周期G1期为81.65%,S期为11.83%,其他组G1期分别为65.54%、56.61%、63.26%;S期分别为24.10%、29.52%、27.28%,结果具有统计学意义(P<0.05).MTT检测示pEGFP-N2-XPD细胞生长率为0.249±0.02,与其他组相比,细胞增殖力明显减弱(P<0.01). 结论:野生型XPD基因可以抑制胆管癌细胞的生长,XPD基因可抑制c-myc、cyclin D1基因的表达,增加p53基因表达.     

Prognostic importance of DNA repair gene polymorphisms of <Emphasis Type="Italic">XRCC1</Emphasis> Arg399Gln and <Emphasis Type="Italic">XPD</Emphasis> Lys751Gln in lung cancer patients from India

Purpose Inter individual variation in lung cancer susceptibility may be modulated in part through genetic polymorphisms in the DNA repair genes, especially the genes involved in the Base Excision Repair (BER) and nucleotide excision repair (NER) pathway. Two of the genetic polymorphisms, XRCC1Arg399Gln and XPD Lys751Gln have been extensively studied in the association with lung cancer risk, although published studies have been inconclusive. Methods In order to verify the role of the common variant alleles in the XPD gene, we have genotyped 211 lung cancer patients and 211 healthy controls using PCR-RFLP assays in a hospital based, case-control study in an Indian population. Logistic regression models were fit to examine the relationship between the log odds of lung cancer and each covariate. Overall Survival in relation to various genotypes and clinicopathological factors were analyzed using Kaplan Meier estimates and hazard ratios were calculated using Cox Regression analysis. Results The carriers of XRCC1 399 AA genotypes were at higher risk of lung cancer (OR = 2.1, 95% CI:1.224–3.669, P = 0.007) than carriers of GG genotype. Subjects carrying 751 AC genotype were at an increased risk of carcinoma of the lung (OR = 1.8; 95% CI:1.233–2.807, P = 0.003) than subjects with AA genotypes. Compared to the XRCC1 399 GG/ XPD 751 AA reference genotype, the combined variants, XRCC1 399 GG/ XPD 751 AC+CC (OR = 1.9, 95% CI: 1.037–3.481), P = 0.03), XRCC1 399 GA+AA/ XPD 751 AA (OR = 1.7, 95% CI: 1.020–2.833, P = 0.04), XRCC1 399 GA+AA/XPD 751 AC+CC (OR = 2.7, 95% CI: 1.582–4.864, P = 0.01), had significantly higher odds ratios. Increasing numbers of either XPD or XRCC1 variant alleles were associated with shorter overall survival, the risk being significant for the XRCC1 gene polymorphism (P = 0.01 by log-rank test). The hazard of dying was significant for the XRCC1 399 AA genotype (HR = 3.04, 95%CI: 1.393–6.670, P = 0.005). Higher tumour stage also came out as significant predictors of patient death. Conclusions These findings suggest that genetic polymorphisms in the DNA repair genes may modulate overall lung cancer susceptibility and that pathological stage and XRCC1 Arg399Gln independently predicted overall survival among Indian lung cancer patients.     

Polymorphisms at XPD and XRCC1 DNA repair loci and increased risk of oral leukoplakia and cancer among NAT2 slow acetylators

Polymorphisms at N-acetyl transferase 2 locus (NAT2) lead to slow, intermediate and rapid acetylation properties of the enzyme. Improper acetylation of heterocyclic and aromatic amines, present in tobacco, might cause DNA adduct formation. Generally, DNA repair enzymes remove these adduct to escape malignancy. But, tobacco users carrying susceptible NAT2 and DNA repair loci might be at risk of oral leukoplakia and cancer. In this study, 389 controls, 224 leukoplakia and 310 cancer patients were genotyped at 5 polymorphic sites on NAT2 and 3 polymorphic sites on each of XRCC1 and XPD loci by PCR-RFLP method to determine the risk of the diseases. None of the SNPs on these loci independently could modify the risk of the diseases in overall population but variant genotype (Gln/Gln) at codon 399 on XRCC1 and major genotype (Lys/Lys) at codon 751 on XPD were associated with increased risk of leukoplakia and cancer among slow acetylators, respectively (OR = 4.2, 95% CI = 1.2-15.0; OR = 1.6, 95% CI = 1.1-2.3, respectively). Variant genotype (Asn/Asn) at codon 312 on XPD was also associated with increased risk of cancer among rapid and intermediate acetylators (OR = 1.9, 95% CI = 1.2-2.9). Variant C-G-A haplotype at XRCC1 was associated with increased risk of leukoplakia (OR = 1.7, 95% CI = 1.2-2.4) but leukoplakia and cancer in mixed tobacco users (OR = 3.1, 95% CI = 1.4-7.1, OR = 2.4, 95% CI = 1.1-5.4, respectively) among slow acetylators. Although none of the 3 loci could modulate the risk of the diseases independently but 2 loci in combination, working in 2 different biochemical pathways, could do so in these patient populations.     

在晚期非小细胞肺癌中XRCC1和XPD基因多态性的联合和铂类化疗的关系

目的探讨DNA修复基因XRCC1和XPD两种基因多态性的联合与接受铂类治疗的非小细胞肺癌（NSCLC）患者临床疗效及生存时间的关系。方法对接受铂类治疗的108例ⅢB期和Ⅳ期NSCLC患者,利用聚合酶链反应（PCR）结合限制性片段长度多态性（RFLP）来检测XRCC1第399位点和XPD第751位点基因多态性,通过电话随访等方式获得患者的生存状态,以STATA软件分析比较基因多态性与铂类化疗疗效及生存时间的关系。结果在所有接受含铂药物治疗的患者中,化疗总有效率为21.6%。携带XRCC1 Arg/Gln基因型和XPD Lys/Gln基因型的患者有更高有效率（33.33%）,但此类患者与其他各种基因型患者相比,化疗有效率的差异无统计学意义（P〉0.05）。Cox比例风险模型显示,携带XRCC1 Arg/Gln基因型和XPD Lys/Gln基因型的患者中位生存时间（MST）最长35.5个月,但与其他基因型患者相比,MST差异无统计学意义（P〉0.05）。结论同时携带XRCC1 Arg/Gln和XPD Lys/Gln基因型的NSCLC患者,使用含铂方案化疗可能有更高的有效率和更长的生存期。但此结果仍需扩大样本进一步验证。     

DNA修复基因XPD单核苷酸多态性和环境因素的交互作用与肝细胞癌的关联研究

目的 探讨XPD基因751、312位点单核苷酸多态性和环境因素的交互作用与肝细胞癌的关系.方法 采用以医院为基础的病例对照研究方法,运用TaqMan MGB荧光定昔实时PCR分析方法对病例组300例肝细胞癌患者和对照组312例非肿瘤患者进行XPD基因751和312位点的基因型分析.以非条件logistic回归模型分析比较各基因型在两组中分布频率的差异,以及基因多态性和环境因素的交互作用.结果 XPD基因751位点3种基因型AA、AC、CC在病例组和对照组中的分布差异无统计学意义(P>0.05),与携带XPD751野生纯合子AA基因型者比较,携带XPD751AC或CC基因型者患肝细胞癌风险无显著增加(P>0.05).XPD基因312位点3种基因型GG、GA、AA在病例组和对照组中的分布差异有统计学意义(P<0.01).与携带XPD312野生纯合子GG基因型者比较,携带XPD312 AA基因型个体罹患HCC的风险是携带XPD312 GG基因型的2.67倍(OR=2.67,95%CI:0.431～16.537),但差异无统计学意义;携带至少一个XPD312A等位基因的个体罹患肝细胞癌的风险是GG基因型的2.62倍(95%CI:1.626～4.222),且差异有统计学意义.交互作用分析结果表明XPD基因751位点多态性与吸烟、XPD基因312位点多态性与吸烟、XPD基因312位点多态性与HBsAg阳性之间在肝细胞癌发生中存在交瓦作用,交互作用的OR值分别为4.291、5.341、7.348.结论 DNA修复基因XPD312A等位基因可能是广西南部地区人群肝细胞癌的危险等位基因,XPD基因多态性与吸烟、HBsAg阳性之间在肝细胞癌发生中存在交互作用,能增加罹患肝细胞癌的风险.     

北京地区汉族人群DNA修复基因XPD单核苷酸多态性与肺癌及食管癌风险的研究

目的：研究核苷酸切除修复基因XPD单核苷酸多态性与北京地区汉族人群肺癌及食管癌风险的关系。方法：采用以医院患者为基础的病例－对照研究方法，包括正常对照383人，肺癌患者351例，食管癌患者325例。以聚合酶链反应－限制性片段长度多态性方法分析了XPD基因Asp312 Asn和Lys751Gln多态性，比较不同基因型与肺癌及食管癌风险的关系，并探讨吸烟与基因多态交互作用对患癌风险的影响。结果：与携带312 Asp/Asp基因型者比较，携带至少1个312Asn等位基因者（即Asp/Asn和Asn/Asn基因型）罹患肺鳞癌的风险增加1．8倍（95％CI1．10－2．93），而与肺腺癌无关（校正的比值比为1．07，95％CI0．55－2．08）。分层分析显示，风险型等位基因312Asn和751Gln与吸烟有明显的交互作用。吸烟剂量≥29包／年且携带312Asn或751Gln者罹患肺鳞癌的风险最高，校正的比值比分别为12．44（95％CI4．97－31．17）和10．74（95％CI4．51－25．57）。XPD基因Asp312Asn和Lys751Gln多态与食管鳞癌风险无关。结论：XPD基因Asp312Asn和Lys751Gln多态是地区汉族人群肺鳞癌遗传易感因素，而与肺腺癌以及食管鳞癌风险无关，可能反映了不同组织学类型肺癌以及肺癌和食管癌之间的病因学差异。