Expression Of MicroRNA Let-7c In Hepatocellular Carcinoma And Its Function,Target Research

Objective:To investigate the expression level of microRNA-let-7c (miR-let-7c) in hepatocellular carcinoma(HCC) tissues and cell lines, analysis the potential relationship between miR-let-7c expression and clinicopathologic parameters in HCC patients;Over-expression of miR-let-7c,to find the change of liver cancer cell proliferation,cell cycle and apoptosis; the targets of miR-let-7c to be predicted, analysis and preliminary validation,provide a basis for the targeting treatment of HCC.Methods:The expression level of miR-let-7c in hepatocellular carcinoma tissues and cell lines were quantified by using TaqMan MicroRNA Assays-based real-time RT-PCR. The correlations of clinicalpathologic parameters with the miR-let-7c expression level in cancerous tissues were analyzed by using independent-Samples T Test respectively. miR-let-7c Agomir was transfected into hepatocellular carcinoma cell to overexpression miR-let-7c. The effect of over-expression miR-let-7c on HepG2cell proliferation, apoptosis and cell cycle were evaluated by using CCK-8kit and flow cytometer respectively.The miR-let-7c targets were predicted by using algorithms miRBase,PicTar and TargetScan and verified by qRT-PCR, western Blot analysis and Luciferase assay.Therefore, miR-let-7c was considered as a similar to tumor suppressor genes molecular in the development of liver cancerResults:The expression level of miR-let-7c in HCC tissues was significantly decreased than the expression in paracancerous tissues (P<0.01). Compared to L-02cell, the expression level of miR-let-7c was significantly decreased in6HCC cell lines(P<0.01). The highly metastatic potential variant, MHCC97-H had a lower miR-let-7c expression than the low metastatic potential variant, MHCC97-L(P<0.01). The expression level of miR-let-7c was significantly correlated with the HCC differentiation grade (P<0.01).In vitro experiment, over-expression of miR-let-7c significantly inhibited the proliferation(P<0.01), promoted the apoptosis and cell cycle arrest of HepG2cell (P<0.01), compared to the negative control group cells, over expression of miR-let-7c,the target CDC25A mRNA level has no change,but the CDC25A protein level has significantly lower (P<0.01).Overexpression of miR-let-7c,the luciferase activity of pmiR-CDC25A-3’-UTR-wt has significantly suppressed (P<0.01),compared to pmiR-CDC25A-3’UTR-mut1andpmiR-CDC25A-3’-UTR-mut2.Conclusions:1. The expression level of miR-let-7c was significantly down-regulated in HCC tissues and cell lines, and its down-regulation was correlated with poor differentiation of hepatocellular carcinoma.2. Over expression of miR-let-7c could inhibit HepG2and SMCC-7721cell growth, promote the cell apoptosis and cell cycle arrest. 3. miR-let-7c inhibit liver cell proliferation by targeting CDC25A.