乙型肝炎病毒 X 蛋白通过调控 DNA 甲基化抑制肝癌细胞中钙腔蛋白-1 的表达。
Hepatitis B virus X protein suppresses caveolin-1 expression in hepatocellular carcinoma by regulating DNA methylation.
机构信息
Institute of Hepatobiliary Surgery, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.
出版信息
BMC Cancer. 2012 Aug 15;12:353. doi: 10.1186/1471-2407-12-353.
BACKGROUND
To understand the molecular mechanisms of caveolin-1 downregulation by hepatitis B virus X protein (HBx).
METHODS
The DNA methylation status of the caveolin-1 promoter was examined by nested methylation-specific PCR of 33 hepatitis B virus (HBV)-infected hepatocellular carcinoma (HCC) samples. The SMMC-7721 hepatoma cell line was transfected with a recombinant HBx adenoviral vector, and the effects of HBx protein on caveolin-1 expression and promoter methylation were examined and confirmed by sequencing. A reporter gene containing the caveolin-1 promoter region was constructed, and the effects of HBx on the transcriptional activity of the promoter were also studied.
RESULTS
Methylation of the caveolin-1 promoter was detected in 84.8% (28/33) of HBV-infected HCC samples. Expression of caveolin-1 was significantly downregulated (P = 0.022), and multiple CpG sites in the promoter region of caveolin-1 were methylated in SMMC-7721 cells after HBx transfection. Transfected HBx significantly suppressed caveolin-1 promoter activity (P = 0.001).
CONCLUSIONS
HBx protein induces methylation of the caveolin-1 promoter region and suppresses its expression.
背景
为了了解乙型肝炎病毒 X 蛋白（HBx）下调小窝蛋白-1 的分子机制。
方法
通过嵌套甲基化特异性 PCR 检测 33 例乙型肝炎病毒（HBV）感染的肝癌（HCC）样本中小窝蛋白-1 启动子的 DNA 甲基化状态。用重组 HBx 腺病毒载体转染 SMMC-7721 肝癌细胞系，通过测序验证 HBx 蛋白对小窝蛋白-1 表达和启动子甲基化的影响。构建含有小窝蛋白-1 启动子区的报告基因，研究 HBx 对启动子转录活性的影响。
结果
在 84.8%（28/33）的 HBV 感染的 HCC 样本中检测到小窝蛋白-1 启动子的甲基化。HBx 转染后 SMMC-7721 细胞中小窝蛋白-1 的表达明显下调（P=0.022），小窝蛋白-1 启动子区域的多个 CpG 位点发生甲基化。转染的 HBx 显著抑制小窝蛋白-1 启动子活性（P=0.001）。
结论
HBx 蛋白诱导小窝蛋白-1 启动子区域甲基化，抑制其表达。
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