DNA错配修复基因甲基化在肝细胞癌发生发展中的作用  

Methylation of mismatch repair gene (MMR) in primary hepatocellular carcinoma

作　　者：张翠娟[1] 李晓明[1] 丘礼武[1] 孙建华[1] 周庚寅[2] 喻芳[2] 刘宗石[1] 

机构地区：[1]香港中文大学威尔斯亲王医院病理解剖及细胞学系,山东大学医学院病理学教研室250012 [2]山东大学医学院病理学教研室

出　　处：《中华病理学杂志》2004年第5期433-436,共4页Chinese Journal of Pathology

摘　　要：目的　探讨DNA错配修复基因 (MMR)hMLH1,hMSH2和hMSH3甲基化在肝细胞癌(HCC)发生发展中的作用。方法　采用甲基化特异性聚合酶链反应 (MSP)法对 38例新鲜HCC组织 ,相应非肿瘤肝组织 ,2例正常的捐肝组织及 6种肝癌细胞系的hMLH1,hMSH2和hMSH3基因启动子CpG岛甲基化进行检测 ;培养 6种肝癌细胞系 ,MSP法检测加入 5 aza 2′ deoxycytidine前后hMSH2基因在HCC中的甲基化状态改变 ;逆转录 聚合酶链反应 (RT PCR)方法检测加入 5 aza 2′ deoxycytidine前后hMSH2在肝癌细胞株中的mRNA表达改变。 结果　HCC标本中 13 2 % (5 / 38)发生了hMLH1启动子甲基化 ,6 8 4 % (2 6 / 38)发生了hMSH2启动子甲基化 ;相应的非肿瘤肝组织中hMLH1,hMSH2启动子甲基化阳性率分别为 2 6 % (1/ 38) ,5 5 3% (2 1/ 38) ;2例正常肝组织中未发现甲基化 ;6株肝癌细胞系中有 5株发生了hMSH2启动子甲基化 ,而未发现有MLH1启动子甲基化。所有标本中均未发现有hMSH3启动子甲基化。 5 aza 2′ deoxycytidine处理细胞株后 ,可部分或完全逆转hMSH2启动子甲基化 ,各细胞株的mRNA均有不同程度的表达增加。结论　hMSH3基因启动子CpG岛甲基化与HCC的发生发展关系不大。hMSH2基因甲基化与mRNA表达密切相关 ,是基因表达调节的一种重要方式。Objective To assess the role of methylated mismatch repair (MMR) genes (hMLH1, hMSH2 and hMSH3) in the carcinogenesis and progression of hepatocellular carcinoma (HCC). Methods Samples of 38 cases of HCC along with their corresponding noncancerous tissues, 2 samples of donated normal tissue and 6 cell lines were collected and subject to the methylation-specific PCR (MSP) to examine promoter methylation status of MLH1, MSH2 and MSH3. Six tumor cell lines were analyzed before and after 5-aza-2′-deoxycytidine treatment. In addition, alterations of mRNA expression of MMRs were investigated by quantitative reverse transcription-PCR. Results CpG island methylation of hMLH1 and hMSH2 was observed in 13.2% (5 of 38 samples) and 68.4% (26 of 38 samples) respectively in HCC, 2.6 % ( 1 of 38 samples) and 55.3 % ( 21 of 38) respectively in corresponding noncancerous tissues, but not in normal control tissues. Promoter methylation of the hMSH2 gene was present in 83.3% of cell lines tested (5/6), but none were observed for the hMLH1 gene. Promoter methylation of the hMSH3 gene was not identified in any tissue samples or cell lines. After 5-aza-2′-deoxycytidine treatment, hMSH2 methylation was induced or completely reversed, and its mRNA expression was increased in most cell lines. Conclusions Our results suggest that promoter hypermethylation of hMLH1 and hMSH2 genes is common in HCC. Particularly, there is a high frequency of methylation of hMSH2 in both cancer and noncancerous tissues, but not in normal control tissue. Therefore, hypermethylation of MMR genes, especially hMSH2, may be involved in the carcinogenesis of HCC and may serve as an early diagnostic marker for HCC. The close correlation between hMSH2 methylation and low expression of its mRNA suggests that hMSH2 methylation is an important pathway in the regulation of gene expression.

关 键 词：启动子甲基化 HCC HMSH2基因 HMLH1 DNA错配修复基因 肝癌细胞系 肿瘤 发现 标本 RNA 

分 类 号：R735.7[医药卫生—肿瘤]