肝细胞癌ASC基因启动子区甲基化及其mRNA表达研究

目的：探讨肝细胞肝癌 （HCC） ASC基因启动子区甲基化与mRNA表达及其临床病理特征的关系。方法： 运用甲基化特异性聚合酶链反应 （MSP） 和实时荧光定量PCR技术， 检测58例肝细胞癌及其相应癌旁组织、 15例肝硬化肝组织、 5例慢性病毒性肝炎肝组织和5例正常肝组织中ASC基因启动子区甲基化状态及其mRNA的表达水平。结果： 58例肝细胞癌组织中有40例（69.0%） 发生ASC基因启动子区甲基化， 其相应癌旁组织中有27例 （46.6%） 发生该基因启动子区甲基化， 而在肝硬化、 肝炎和正常肝组织中均未检测到该基因启动子区甲基化。ASC基因在肝细胞癌组织中甲基化频率高于其相应癌旁组织 （P=0.015）。ASC基因启动子区甲基化与肿瘤直径 （P=0.001）、 生长方式 （P=0.003） 以及国际抗癌联盟第6版TNM （TNM6） 分期 （P=0.001） 有关。以ASC基因在正常肝组织中的表达量为参照， 58例肝细胞癌组织中有33例出现ASC基因mRNA低表达或表达缺失， 其相应癌旁组织中有14例出现低表达或表达缺失， 而在肝硬化及肝炎肝组织中ASC基因mRNA均呈正常表达。与癌旁组织相比， 肝细胞癌组织中ASC基因mRNA表达明显下调 （P<0.05）。在发生ASC基因启动子区甲基化的40例肝细胞癌组织中有26例出现mRNA低表达。结论： ASC基因启动子区甲基化是肝细胞癌中的频发事件， 可能在肝细胞癌的进展中起重要作用。

Promoter Methylation and mRNA Expression of ASC Gene in Hepatocellular Carcinoma

PromoterMethylation and mRNA Expression of ASC Gene in Hepatocellular CarcinomaYu BAI1, Zhi DU2, Yingtang GAO2, Bin YANG2, Zhengyan ZHU2, Yayue LI2, YijunWANG2, Tong LIU2Correspondence to: Zhi DU, E-mail: zhi-du@163.com1Department of Hepatobiliary Disease, The Third Central Hospital of Tianjin Medical University, Tianjin 300170, China2The Third Central Hospital of Tianjin Medical University, Key Laboratory of Artificial Cell, Tianjin 300070, ChinaThis study was supported by a grant from the Key Program of Tianjin Science Committee (No. 05YFSZSF02500) and the Key Projectof Science and Technology of Tianjin (08JCYBJCO8300)Abstract Objective: To investigate the promoter methylation and mRNA expression of ASC gene and its clinicopathologicalsignificance in hepatocellular carcinoma ( HCC ). Methods: Methylation specific PCR was employed to detect the methylation statusof ASC gene promoter in 58 HCC and their matched adjacent noncancerous tissue samples, 15 liver cirrhosis, 5 chronic viral hepatitisand 5 normal liver samples. Real-time fluorescent quantitation PCR was performed to examine the expression of ASC mRNA. Results:Aberrant methylation of the ASC gene was detected in 40 of 58 ( 69.0% ) HCC tissues, and 27 of 58 ( 46.6% ) corresponding noncan-cerous tissues. There was no methylation found in liver cirrhosis, chronic viral hepatitis and normal liver samples. The frequency ofmethylation of ASC gene promoter was higher in HCC than in adjacent noncancerous tissue ( P = 0.015 ). ASC gene methylation wassignificantly associated with tumor size ( P = 0.001 ) , growth pattern ( P = 0.003 ) and TNM staging (UICC 6th edition) ( P = 0.001 ).Compared with those in normal liver tissue, mRNA levels were downregulated in 33 cancerous and 14 noncancerous tissue samples.ASC mRNA level was significantly lower in HCC tissue than in adjacent noncancerous tissue ( P < 0.05 ). In 40 HCC tissue sampleswith ASC methylation, 26 showed low level of mRNA expression. Conclusion: The hypermethylation of ASC gene promoter is fre-quent and may play an important role in the development of HCC.Keywords Hepatocellular carcinoma; ASC gene; Methylation; Real-time fluorescent PCR