Department of Hepatobiliary Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
Cell Signal. 2013 May;25(5):1037-43. doi: 10.1016/j.cellsig.2013.01.019. Epub 2013 Jan 30.
Hepatitis B virus x (HBx) protein is involved in the initiation and progression of HBV-related hepatocellular carcinoma (HCC) by regulating host protein-coding genes. However, the role of HBx in the epigenetic repression of miRNAs, which play important roles in gene regulation during hepatocarcinogenesis, remains largely unknown. In this study, the expression of miR-132 in HCC cells, HBV-related HCC tissues, and serum were determined using real-time PCR. The level of DNA methylation on the promoter of miR-132 was examined using methylation-specific PCR (MSP). MiR-132 was functionally characterized in HCC cells with transiently altered miR-132 expression. HBx-induced DNA hypermethylation of the promoter of miR-132 was found to be more prevalent in HBx-expressing HepG2 cells than in control cells. Consistently, MiR-132 expression was also more frequently down-regulated in HBV-related HCC tissues than in adjacent noncancerous hepatic tissues and had a significant inverse correlation with HBx expression in HBV-related HCCs. Serum miR-132 levels were found to be significantly correlated with levels in tumor tissue. Finally, proliferation and colony formation of HCC cells were found to be suppressed by miR-132-mediated inhibition of the Akt-signaling pathway in miR132 transfected cells. Our study has demonstrated the epigenetic repression of miR-132 expression through DNA methylation induced by HBx. This work provides novel mechanistic insights into HBV-mediated hepatocarcinogenesis and suggests that miR-132 may be a promising biochemical marker and may have therapeutic applications in HBV-related HCC.
乙型肝炎病毒 x(HBx)蛋白通过调节宿主蛋白编码基因参与乙型肝炎病毒相关肝细胞癌(HCC)的发生和发展。然而,HBx 在 miRNA 的表观遗传抑制中的作用,miRNA 在肝癌发生过程中对基因调控起着重要作用,在很大程度上仍然未知。在这项研究中,使用实时 PCR 测定 HCC 细胞、HBV 相关 HCC 组织和血清中的 miR-132 表达。使用甲基化特异性 PCR(MSP)检查 miR-132 启动子上的 DNA 甲基化水平。使用瞬时改变 miR-132 表达的 HCC 细胞对 miR-132 进行功能表征。发现 HBx 表达的 HepG2 细胞中 miR-132 启动子的 DNA 超甲基化比对照细胞更为普遍。一致地,在 HBV 相关 HCC 组织中 miR-132 的表达也比相邻的非癌性肝组织更为频繁地下调,并且在 HBV 相关 HCC 中与 HBx 表达呈显著负相关。血清 miR-132 水平与肿瘤组织中的水平呈显著相关。最后,发现 miR-132 转染细胞中 Akt 信号通路的抑制可抑制 HCC 细胞的增殖和集落形成。我们的研究表明,HBx 通过 DNA 甲基化抑制了 miR-132 的表达。这项工作为 HBV 介导的肝癌发生提供了新的机制见解,并表明 miR-132 可能是一种有前途的生化标志物,并可能在 HBV 相关 HCC 中具有治疗应用。
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