HBV X蛋白对抑癌基因p16的表达和启动子甲基化的影响  

Effects of HBV X protein on expression and promoter methylation of p16 tumor suppressor gene

作　　者：康艳红[1] 李威[1] 占伟丽[1] 尚佳[1] 杨林[2] 

机构地区：[1]河南省人民医院感染科,郑州450000 [2]中山大学附属第三医院感染科,广州510630

出　　处：《临床肝胆病杂志》2016年第3期484-487,共4页Journal of Clinical Hepatology

基　　金：国家自然科学基金(81071409)

摘　　要：目的探讨HBV X蛋白(HBx)对抑癌基因p16的表达、p16启动子甲基化的影响,从表观遗传学的角度探讨HBx参与HBV相关性HCC发生发展的相关机制。方法以人肝母细胞瘤细胞Hep G2、表达绿色荧光蛋白(GFP)的Hep G2/GFP、稳定表达HBx蛋白的Hep G2/GFP-HBx细胞为实验系统;采用Western Blot法检测Hep G2、Hep G2/GFP、Hep G2/GFP-HBx细胞中p16蛋白的表达水平。以DNA甲基转移酶(DNMT)抑制剂5-氮杂-2'脱氧胞苷(5-Aza-2'-DC)处理Hep G2/GFP-HBx细胞,采用甲基化特异性PCR(MSP)法检测Hep G2、Hep G2/GFP细胞及药物处理和未处理的Hep G2/GFP-HBx细胞中抑癌基因p16启动子区域的甲基化情况。计量资料多组间比较采用单因素方差分析。结果 Western Blot分析示Hep G2/GFP-HBx细胞中p16蛋白相对灰度值(23.68±3.93)显著低于Hep G2(91.23±6.87)、Hep G2/GFP(94.55±8.40)细胞,差异均有统计学意义(P值分别为0.0007、0.0014),Hep G2/GFP与Hep G2细胞中p16蛋白相对灰度值差异无统计学意义(P>0.05);MSP法检测示Hep G2/GFP-HBx细胞中存在p16基因启动子区域部分Cp G位点甲基化,Hep G2、Hep G2/GFP细胞中未检出其甲基化,DNMT抑制剂5-Aza-2'-DC处理的Hep G2/GFP-HBx细胞却能恢复p16基因启动子区域的未甲基化状态。结论在肝癌细胞系中,HBx通过诱导抑癌基因p16启动子甲基化而下调其表达,DNMT抑制剂5-Aza-2'-DC能恢复p16基因启动子区域的未甲基化状态,这种可逆性修饰可为HBV相关性HCC的治疗、预防提供新思路。Objective To explore the effects of hepatitis B virus X protein（ HBx） on the expression and promoter methylation of the p16 tumor suppressor gene,and to investigate the epigenetic role of HBx in the development and progression of hepatitis B virus（ HBV）- associated hepatocellular carcinomas（ HCC）. Methods Experiments were performed in the human hepatoblastoma cell line Hep G2,Hep G2 cells expressing green fluorescent protein（ Hep G2 / GFP）,and Hep G2 cells stably expressing GFP- HBx fusion protein（ Hep G2 / GFP- HBx）.Western blot was used to determine the expression levels of the p16 protein in Hep G2 cells,Hep G2 / GFP cells,and Hep G2 / GFP- HBx cells. Hep G2 / GFP- HBx cells were treated with a universal inhibitor of DNA methyltransferase（ DNMT）,5- aza- 2’- deoxycytidine（ 5-aza- 2’- d C）. Methylation- specific polymerase chain reaction（ MSP） was used to determine the promoter methylation of the p16 tumor suppressor gene in Hep G2 cells,Hep G2 / GFP cells,and Hep G2 / GFP- HBx cells treated with or without 5- aza- 2’- d C. Multiple- group comparison was made by analysis of variance. Results According to the results of Western blot,Hep G2 / GFP- HBx cells had a significantly lower expression level of the p16 protein than Hep G2 cells and Hep G2 / GFP cells（ P = 0. 0007; P = 0. 0014）; there was no significant difference in the expression level of the p16 protein between Hep G2 / GFP and Hep G2 cells（ P 〉 0. 05）. The MSP assay revealed partial Cp G methylation in the p16 promoter region in Hep G2 / GFP- HBx cells. No promoter methylation was detected in Hep G2 cells or Hep G2 / GFP cells. Non- methylation in the p16 promoter region was restored in Hep G2 / GFP- HBx cells treated with 5- aza- 2’- d C. Conclusion In the hepatoblastoma cell line,HBx down- regulates the expression of the p16 tumor suppressor gene by inducing methylation in its promoter region. The DNMT inhibitor,5- aza- 2’- d C,restores non- methylation in the p16 promoter region. The reversible modi

关 键 词：细胞系 肿瘤 基因 p16 DNA甲基化 

分 类 号：R735.7[医药卫生—肿瘤]