NBS1基因SNPs与中国汉族人群原发性肝癌的遗传易感性

Association of Single Nucleotide Polymorphisms of NBS1 Gene With Genetic Susceptibility to Primary Liver Cancer in a Chinese Han Population

为分析DNA损伤修复相关基因NBS1单核苷酸多态性(SNPs)与原发性肝癌遗传易感性的关系,并对高分辨率单链构象多态性(SSCP)检测技术在SNPs分型中的适用性进行评估,本研究对来自中国汉族人群的327例原发性肝癌以及295例阴性对照中NBS1基因常见SNPs的稀有等位基因频率进行检测和分析.此外,对NBS1基因6个常见SNPs分别选择部分样本同时进行直接序列测定,以比较2种方法的检测效果.119例原发性肝癌以及95例肝硬化/慢性肝炎组织标本的SSCP分析结果表明,6个常见NBS1基因SNPs位点(102G>A,320+208G/A,553G>C,1197T>C,2016A>G和2071-30A>T)中,SNP1197T>C的稀有等位基因频率为68.1%,显著高于肝硬化/慢性肝炎对照的57.9%(P=0.0298).对该SNP位点另外采用208份肝细胞癌和200份健康人群血液标本进一步分析,肝细胞癌SNP 1197T>C的稀有等位基因频率为66.8%,显著高于健康人群对照的58.8%(P=0.0170).其他5个SNPs的稀有等位基因频率在原发性肝癌与肝硬化/慢性肝炎之间均无显著性差异.高分辨率SSCP分析法与直接序列测定法对所选样本的SNPs基因分型结果完全一致,而且直接测序法对PCR扩增产物质量的要求相对高分辨率SSCP分析更高.研究表明,中国汉族人群NBS1基因SNP 1197T>C可能与原发性肝癌的发生相关,高分辨率SSCP技术准确度与直接测序法相当,且操作更加简便易行,非常适用于大量样本多个已知SNPs的基因分型.

As DNA repair associated gene, NBS1 plays a key role in the repair of DNA double strand breaks and the maintenance of genomic stability. It has been shown in recent studies some common NBS1 variants maybe associated with genetic susceptibility of tumors. In the present study, rare allele frequency of single nucleotide polymorphisms （SNPs） of NBS1 gene in primary liver cancer were detected by the method of high resolution Single Strand Conformation Polymorphism （SSCP） analysis, with the aims to analyze the correlation between NBS1 SNPs and primary liver cancer, and evaluate the applicability of the high resolution SSCP technique in the genotyping of SNPs. The rare allele frequency of NBS1 SNPs were detected in 327 cases of primary liver cancer and 295 negative controls from Han people of China by the method of high resolution SSCP analysis. The correlation was analyzed between NBS1 SNPs and primary liver cancer. Genotyping of six common NBS1 SNPs in part samples was carried out by both SSCP analysis and direct sequencing simultaneously to compare the difference between them and evaluate the accuracy and applicability of SSCP analysis in genotyping of SNPs. The results from the tissue samples showed, among six NBS1 SNPs （102G〉A, 320＋208G/A, 553G〉C, 1197T〉C, 2016A〉G and 2071-30A〉T）, the rare allele frequency of NBS1 SNP 1197T〉C was significantly higher in the 119 cases of primary liver cancer （68.1%） than that in the 95 controls of cirrhosis/chronic hepatitis B （57.9%） （P=0.0298）. Similar results was obtained by detection with blood samples of 208 cases of hepatocellular carcinoma （66.8%） and 200 cases of health controls（58.8%）（P=0.0170）. There was no any significant difference of the rare allele frequency of the other five NBS1 SNPs. The same result was observed for genotyping of NBS1 SNPs either by the high resolution SSCP analysis or by the direct sequencing. However, higher quality of PCR products is requested for the direct sequencing compared with SSCP analysis. These results suggest that the NBS1 SNP 1197T〉C may be associated with the risk of primary liver cancer in the Chinese Han population. High resolution SSCP analysis, with the same accuracy as direct sequencing in the genotyping ofNBS1 SNPs and easier to handle, is suitable for the genotyping of multiple known SNPs in large scale cohort study.