The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, Xi'an 710032, PR China.
Department of Neurosurgery, Xijing Institute of Clinical Neuroscience, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, PR China.
Biochem Biophys Res Commun. 2014 Jan 17;443(3):1078-84. doi: 10.1016/j.bbrc.2013.12.095. Epub 2013 Dec 25.
Growing evidence has demonstrated that the aberrant expression of miRNA is a hallmark of malignancies, indicating the important roles of miRNA in the development and progression of cancer. MiR-7 is considered as a tumor suppressor miRNA in multiple types of cancer. However, the role of miR-7 in human hepatocellular carcinoma (HCC) and its underlying mechanism remain elusive. In this study, we found that overexpression of miR-7 arrested cell cycle at G1 to S transition in HCC. By combinational use of bioinformatic prediction, reporter assay, quantitative real-time PCR (qRT-PCR) and Western blot, we confirmed that CCNE1, an important mediator in G1/S transition is one of new direct target genes of miR-7. Further studies revealed that silencing of CCNE1 recapitulated the effects of miR-7 overexpression, whereas enforced expression of CCNE1 reversed the suppressive effects of miR-7 in cell cycle regulation. Finally, analysis of qRT-PCR showed a reciprocal relationship between miR-7 and CCNE1 in clinical cancer tissues and multiple types of tumor cell lines. These findings indicate that miR-7 exerts tumor-suppressive effects in hepatocarcinogenesis through the suppression of oncogene CCNE1 expression and suggest a therapeutic application of miR-7 in HCC.
越来越多的证据表明,miRNA 的异常表达是恶性肿瘤的一个标志,这表明 miRNA 在癌症的发生和发展中起着重要作用。miR-7 被认为是多种类型癌症中的肿瘤抑制 miRNA。然而,miR-7 在人肝细胞癌(HCC)中的作用及其潜在机制仍不清楚。在这项研究中,我们发现 miR-7 的过表达使 HCC 细胞周期停滞在 G1 到 S 期转换。通过生物信息学预测、报告基因检测、定量实时 PCR(qRT-PCR)和 Western blot 的组合使用,我们证实 CCNE1,G1/S 转换中的一个重要介质,是 miR-7 的一个新的直接靶基因。进一步的研究表明,CCNE1 的沉默再现了 miR-7 过表达的效果,而 CCNE1 的强制表达逆转了 miR-7 在细胞周期调控中的抑制作用。最后,qRT-PCR 分析显示 miR-7 和 CCNE1 在临床癌症组织和多种肿瘤细胞系中存在相互关系。这些发现表明,miR-7 通过抑制癌基因 CCNE1 的表达在肝癌发生中发挥肿瘤抑制作用,并提示 miR-7 在 HCC 中的治疗应用。