The let-7 family of microRNAs inhibits Bcl-xL expression and potentiates sorafenib-induced apoptosis in human hepatocellular carcinoma
The let-7 family of microRNAs inhibits Bcl-xL expression and potentiates sorafenib-induced apoptosis in human hepatocellular carcinoma
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DOI：
10.1016/j.jhep.2009.12.024
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发表时间：
2010-05-01
影响因子：
25.7
通讯作者：
Hayashi, Norio
中科院分区：
文献类型：
--
作者：
Shimizu, Satoshi;Takehara, Tetsuo;Hayashi, Norio
背景和目标：Bcl-2家族的抗凋亡成员Bcl-xL在人肝细胞癌中过表达，赋予肿瘤细胞存活优势。其失调的机制尚未阐明。在本研究中，我们探讨了参与的microRNA作为内源性序列特异性抑制基因expressions.Methods的参与：在Huh 7肝癌细胞和原代人肝细胞microRNA的表达谱进行了比较，通过微阵列分析。通过Western blot和报告基因分析检测let-7对Bcl-xL表达的影响。通过蛋白质印迹和逆转录-PCR.Results：微阵列分析，随后通过计算机靶点预测，确定let-7 microRNA在Huh 7肝癌细胞中与原代人肝细胞相比下调，以及在bcl-xl mRNA中具有推定的靶位点。过表达let-7 c或let-7 g可明显降低Huh 7和HepG 2细胞系中Bcl-xL的表达。报告基因分析揭示了涉及let-7 c或let-7 g和bcl-xl mRNA的3 '非翻译区的直接转录后调节。低表达let-7 c的肝癌组织中Bcl-xL蛋白的表达高于高表达let-7 c的肝癌组织，提示let-7 microRNA的低表达有助于Bcl-xL蛋白的过度表达。结论：let-7 microRNA负调控Bcl-2蛋白Mcl-1的表达，并与靶向Mcl-1的抗癌药物协同诱导肝癌细胞凋亡。(C)2010年欧洲肝脏研究协会。Elsevier B. V.出版，保留所有权利。
Background & Aims: Bcl-xL, an anti-apoptotic member of the Bcl-2 family, is over-expressed in human hepatocellular carcinoma, conferring a survival advantage to tumour cells. The mechanisms underlying its dysregulation have not been clarified. In the present study, we explored the involvement of microRNAs that act as endogenous sequence-specific suppressors of gene expression.Methods: The expression profiles of microRNAs in Huh7 hepatoma cells and primary human hepatocytes were compared by microarray analysis. The effect of let-7 on Bcl-xL expression was examined by Western blot and a reporter assay. The involvement of let-7 microRNAs in human tissues was analysed by western blot and reverse transcription-PCR.Results: Microarray analysis, followed by in silico target prediction, identified let-7 microRNAs as being downregulated in Huh7 hepatoma cells in comparison with primary human hepatocytes, as well as possessing a putative target site in the bcl-xl mRNA. Over-expression of let-7c or let-7g led to a clear decrease of Bcl-xL expression in Huh7 and HepG2 cell lines. Reporter assays revealed direct post-transcriptional regulation involving let-7c or let-7g and the 3'-untranslated region of bcl-xl mRNA. Human hepatocellular carcinoma tissues with low expression of let-7c displayed higher expression of Bcl-xL protein than those with high expression of let-7c, suggesting that low let-7 microRNA expression contributes to Bcl-xL over-expression. Finally, expression of let-7c enhanced apoptosis of hepatoma cells upon exposure to sorafenib, which downregulates expression of another anti-apoptotic Bcl-2 protein, Mcl-1.Conclusions: let-7 microRNAs negatively regulate Bcl-xL expression in human hepatocellular carcinomas and induce apoptosis in cooperation with an anti-cancer drug targeting Mcl-1. (C) 2010 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.