Role of miR-16-5p in the proliferation and metastasis of hepatocellular carcinoma.

OBJECTIVE: The aim of this study was to investigate the role of miR-16-5p in hepatocellular carcinoma (HCC), and to explore the possible underlying mechanism. PATIENTS AND METHODS: 100 pairs of cancerous and para-cancerous tissues surgically removed in our hospital were collected. Real Time quantitative-Polymerase Chain Reaction (qRT-PCR) was used to detect the expression level of miR-16-5p in tissues. Bioinformatics and Dual-Luciferase reporter gene assay were used to screen and verify the potential target genes of miR-16-5p, respectively. Human HCC SMMC-7721 cells were used for functional experiments. Cell proliferation was detected by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. Cell invasion and migration were evaluated by transwell and scratch wound-healing assay, respectively. The protein expression levels of epithelial-mesenchymal transition (EMT) associated markers were measured by Western blot (WB) assay. RESULTS: QRT-PCR showed that miR-16-5p expression in HCC tissues was significantly lower than that of adjacent normal liver tissues. At the cellular level, miR-16-5p was lowly expressed in HCC cells (SMMC-7721). Bioinformatics web sites (including Targetscan, PicTar, miRanda) predicted that insulin-like growth factor 1 receptor (IGF1R) was a potential target gene of miR-16-5p. Meanwhile, IGF1R was selected for further investigation due to its metastatic function. The results showed that no significant difference was found in the mRNA expression level of IGF1R in HCC tissues. However, the protein level of IGF1R was significantly up-regulated, which was negatively correlated with miR-16-5p. Combined with Dual-Luciferase reporter gene assay, it was confirmed that miR-16-5p could regulate the expression of IGF1R in a targeted manner. Furthermore, down-regulation of IGF1R significantly reduced the inhibitory effect of miR-16-5p on the proliferation and metastasis of SMMC-7721 cells. CONCLUSIONS: We showed that miR-16-5p suppressed invasion and migration of HCC cells, mechanically by directly targeting and inhibiting IGF1R protein expression. The newly identified miR-16-5p/IGF1R axis might provide new insights into the pathogenesis of HCC and novel potential therapeutic targets for the treatment of HCC.