启动子区甲基化对肝细胞癌锌指蛋白331表达的调控

Zinc-finger protein 331 expression is regulated by promoter region hypermethylation in hepatocellular carcinoma

目的:探讨启动子区甲基化对肝细胞癌中锌指蛋白331(zinc-finger protein331,ZNF331)表达的调控及意义.方法:采用甲基化特异性PCR(methylation specific PCR,MSP)检测ZNF331在肝癌细胞系和50例原发性肝细胞癌组织中的甲基化状况,并采用半定量RT-PCR分析5-杂氮-2'-脱氧胞苷(5-Aza-2'-deoxycytidine,5-Aza)处理前后肝癌细胞系中ZNF331的表达情况.结果:ZNF331在肝癌细胞系HBXF344、PLC/PRF/5、HepG2、BEL-7402中低表达,SNU449中表达正常.5-Aza处理后HBXF344、HepG2、BEL-7402及PLC/PRF/5中ZNF331恢复表达.50例原发性肝细胞癌标本中,ZNF331启动子区的甲基化率为80%(40/50),而10例正常肝脏组织中ZNF331均无甲基化.ZNF331启动子区的甲基化与肝细胞癌患者的性别、年龄、肿瘤直径大小、血清甲胎蛋白值、肝炎病毒感染、分化水平及TNM分期均无关联(P>0.05).结论:ZNF331启动子区高甲基化是肝癌的频发事件,ZNF331基因表达受启动子区甲基化调控.

AIM： To analyze the methylation status and the expression regulation of zinc-finger protein 331 （ZNF331） in hepatocellular carcinoma. METHODS： Five human hepatic cancer cell lines and 50 specimens of human primary hepatic cancer were employed to detect ZNF331 promoter region methylation by methylation specific PCR （MSP）. Semi-quantitative RT-PCR was used to examine the expression of ZNF331. RESULTS： Partial methylation was found in HBXF344, PLC/PRF/5, HepG2 and BEL-7402 celllines. Methylation was not detected in SNU449 cell line. Weak expression of ZNF331 was found in HBXF344, PLC/PRF/5, HepG2 and BEL-7402 cell lines. ZNF331 was moderately expressed in SNU449 cell line. Increased expression of ZNF331 was found in HBXF344, HepG2, BEL-7402, and PLC/PRF/5 cell lines after 5-Aza treatment. No significant change was examined in ZNF331 expression in SNU449 cell line before and after 5-Aza treatment. ZNF331 was methylated in 80% （40/50） of primary human hepatic cancer specimens, but methylation was not detectable in normal liver tissue specimens （0/10）. No correlation was found between promoter region methylation and gender, age, AFP level, hepatitis virus infection, tumor size or tumor stage.CONCLUSION： ZNF331 expression is silenced by promoter region hypermethylation in human hepatocellular carcinoma. ZNF331 is frequently methylated in human primary hepatic cancer.