肝细胞癌中ZHX2基因启动子甲基化增强AFP的表达

The methylation of ZHX2 gene promoter enhances AFP gene expression in hepatocellular carcinoma

目的探讨肝细胞癌中锌指和同源框2(ZHX2)基因启动子甲基化表达与血清AFP水平的关系,分析AFP基因的表达调控机制。方法以0.5、1.0及5.0μmol/L甲基化抑制剂5-氮杂脱氧胞苷(5-Aza-Dc)培养人肝癌细胞株HepG2,采用RT-PCR及Western blot法检测用药前后ZHX2及AFP基因的mRNA和蛋白表达差异。运用甲基化特异性PCR检测肝细胞癌组织38例中ZHX2基因启动子表达情况,分析其与血清AFP水平的关系。结果 HepG2可见少量ZHX2 mRNA扩增,未检测到ZHX2蛋白表达,而AFP却高表达;应用终浓度为1.0μmol/L和5.0μmol/L的5-Aza-Dc处理肝癌细胞6 d,ZHX2表达明显增加,而AFP却表达下调。血清AFP高于25 ng/mL肝细胞癌组织中ZHX2启动子甲基化51.6%,明显高于血清AFP小于25 ng/mL组(P<0.05)。结论 ZHX2基因启动子甲基化与AFP基因的表达有关。

Objective To investigate the relationship between Zinc-fingers and homeoboxes 2 （ZHX2） promoter methyl- ation and alpha-fetoprotein （AFP） gene expression, and analyze the mechanism of AFP gene expression. Methods HepG2 cell line was cultured with 0.5, l. 0 or 5.0 tjmoVL of 5-aza-deoxycytidine （5-Aza-Dc）. RT-PCR and Western blotting were used to detect the expressions of ZHX2 and AFP in HepG2 cell line. Methylation-specific PCR was used to detect ZHX2 pro- moter methylation in 38 hepatocellular carcinoma tissues. Results The HepG2 cell line showed a low level of ZHX2 mRNA, negative expression of ZHX2 protein, but high expression of AFP at both mRNA and protein levels. After the HepG2 cells were treated with l. 0 or 5.0 lamoVL 5-Aza-Dc for 6 d, the expression of ZHX2 mRNA and protein increased and the expres- sion of AFP mRNA and protein decreased. Among 38 hepatocellular carcinoma tissues, ZHX2 promoter methylation was found in 16 hepatocellular carcinoma tissues with AFP 〉 25 ng/mL in serum. No methylation of ZHX2 promoter was found in 8 hepatocellular carcinoma tissues with AFP 〈25 ng/mL. Conclusion ZHX.？, promoter methylation is closely related with AFP expression.