Upregulation of microRNA-122 by farnesoid X receptor suppresses the growth of hepatocellular carcinoma cells.
Upregulation of microRNA-122 by farnesoid X receptor suppresses the growth of hepatocellular carcinoma cells.
复制标题
法尼醇X受体上调microRNA-122抑制肝细胞癌细胞的生长
DOI：
10.1186/s12943-015-0427-9
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发表时间：
2015-08-25
期刊：
影响因子：
37.3
通讯作者：
He F
中科院分区：
文献类型：
--
作者：
He J;Zhao K;Zheng L;Xu Z;Gong W;Chen S;Shen X;Huang G;Gao M;Zeng Y;Zhang Y;He F
研究背景microRNA-122（miR-122）是肝脏中含量最高、特异性最强的miRNA。它通过调控靶基因在肝细胞癌（HCC）中发挥重要的抑癌作用，但其自身调控的细节在很大程度上尚不清楚。法尼酯X受体（Farnesoid X receptor，FXR）是一种具有多种功能的转录因子，在抗肝癌发生中起重要作用，但FXR的抗肝癌作用是否与miR-122的调控有关尚不清楚。采用qRT-PCR检测miR-122靶基因在mRNA水平的表达，Western blotting检测其蛋白产物的表达。荧光素酶报告基因检测FXR对miR-122启动子转录活性的影响。采用电泳迁移率变动分析（EMSA）和染色质免疫沉淀（ChIP）方法鉴定miR-122启动子区的FXR结合位点。CCK-8法检测细胞增殖情况。FXR对肝癌裸鼠移植瘤生长和miR-122表达的影响进行了监测。HCC细胞中FXR的激活上调miR-122的表达，进而下调miR-122靶基因的表达，包括胰岛素样生长因子-1受体和细胞周期蛋白G1。FXR直接与miR-122启动子区域的DR 2元件（-338至-325）结合，并增强启动子的转录活性。结论miR-122是FXR的一个新靶基因，FXR上调miR-122可抑制肝癌细胞的生长，提示FXR可能是调控miR-122表达的关键转录调控因子。FXR/miR-122通路可能成为HCC治疗的新靶点。
BackgroundmicroRNA-122 (miR-122) is the most abundant and specific miRNA in the liver. It acts as an important tumor suppressor in hepatocellular carcinoma (HCC) through regulating its target genes, but details of its own regulation are largely unknown. Farnesoid X receptor (FXR), a transcription factor with multiple functions, plays an important role in protecting against liver carcinogenesis, but it is unclear whether the anti-HCC effect of FXR is involved in the regulation of miR-122.MethodsThe levels of miR-122 and FXR in HCC tissues and cell lines were examined by quantitative real-time PCR (qRT-PCR). qRT-PCR was also used to detect the expression of miR-122 target genes at mRNA level, while Western blotting was used to analyze that of their protein products. The effect of FXR on the transcriptional activity ofmiR-122promoter was evaluated by a luciferase reporter assay. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay were performed to identify the FXR binding site withinmiR-122promoter region. The cell proliferation was analyzed by a CCK-8 assay. The influence of FXR on tumor growth and miR-122 expressionin vivowas monitored using HCC xenografts in nude mice.ResultsThe expression of FXR was positively correlated with that of miR-122 in HCC tissues and cell lines. Activation of FXR in HCC cells upregulated miR-122 expression and in turn downregulated the expression of miR-122 target genes including insulin-like growth factor-1 receptor and cyclin G1. FXR bound directly to the DR2 element (−338 to −325) inmiR-122promoter region, and enhanced the promoter’s transcriptional activity. Functional experiments showed that the FXR-mediated upregulation of miR-122 suppressed the proliferation of HCC cellsin vitroand the growth of HCC xenograftsin vivo.ConclusionsmiR-122is a novel target gene of FXR, and the upregulation of miR-122 by FXR represses the growth of HCC cells, suggesting that FXR may serve as a key transcriptional regulator for manipulating miR-122 expression, and the FXR/miR-122 pathway may therefore be a novel target for the treatment of HCC.