The Function Of MiR-193b In HCC

Hepatocellular carcinoma (HCC) is one of the most common cancers, with nearly 600,000 deaths each year worldwide. Despite therapeutic advances, the 5-year survival rate of HCC patients still is low and HCC remains the second most common cause of cancer mortality in China. Thus, the identification of new possible targets for the development of non-conventional treatments is urgent and will necessarily take advantage of progresses in the comprehension of the molecular pathogenesis of HCC.MicroRNAs (miRNAs) are an extensive class of small noncoding RNA molecules that are processed from much longer primary transcripts (termed pri-miRNAs) and arise from hairpin loop structures after successive enzymatic maturation steps (by Drosha in the nucleus and Dicer in the cytoplasm). miRNAs can regulate gene expression both at the level of messenger RNA degradation and translation. By regulating the expression of target genes, miRNAs are involved in a variety of biological processes including cell cycle regulation, differentiation, development, metabolism, neuronal patterning, and aging.In recent years, many miRNAs have been shown to be aberrantly expressed in human hepatocellular carcinoma in comparison with matched non-neoplastic tissue.To identify the miRNAs associated with HCC, we analyzed the miRNAs expression profile in a pair of HCC tissue and adjacent normal liver tissue by microarray hybridization. A set of miRNAs, miR-193b,miR-101,miR-16,miR-148a,miR-422b,miR-451, including miR-193b, were revealed to be down-regulated in HCC tissue. In this study, we examined the expression level of miR-193b in human HCC specimens, screened its potential target genes, and analyzed its functions in hepatoma cells. Our data suggest that miR-193b may exert its tumour suppressor function via targeting different oncogenes.Here, we detected the expression levels of miR-193b in a set of 25 human hepatocellular carcinoma specimens by quantitative real-time polymerase chain reaction. The results revealed that miR-193b was significantly down-regulated in most of HCC tissues compared the matching non-tumoral liver tissues. Using quantitative real-time PCR, luciferase reporter assay and Western blot analysis, we found that two crucial oncogenes, including MCL1, and CCND1, were regulated by miR-193b directly.Conclusions:1,MCL1 and CCND1 are the target genes of miR-193b. miRNA target prediction software Targetscan shows that MCL1and CCND1 are candidate target genes of miR-193b. According to the results of dual luciferase reporter assay we demonstrated that miR-193b may interact with the 3'UTR of MCL1 and CCND1 directly. Moreover, the overexpression of miR-193b could inhibit the high expression of MCL1 or CCNDl protein in HepG2 cells.2,miR-193b could sensitizes hepatoma cells to chemotherapeutic drug-induced apoptosis by targeting MCL1. We tested the effect of MCL1 downregulation on chemotherapeutic drug-induced apoptosis of HCC cells by the apoptotic morphology. MiR-193b would sensitize HepG2 to chemotherapeutic drugs cytoxicity.3,miR-193b could induce cell cycle arrest by targeting CCND1. In vitro, we detected no G0/G1 accumulation phenotype in HepG2 cells transfected with miR-193b. And, we tested the capacity of colony formation on HCC cell line (SK-HEP-1). Notably, miR-193b-transfected cells displayed obviously fewer and smaller colonies. These results indicate a growth-inhibitory role of miR-193b on hepatoma cell line SK-HEP-1.4,In vivo, to further confirm the antitumour effects of miR-193b, NC RNA and miR-193b-transfected SK-HEP-1 cells were injected into six nude mice. Over-expression of miR-193b significantly inhibits tumorigenicity of SK-HEP-1 cells in nude mouse xenograft model.As a result, in this study we examined the expression level of miR-193b in human HCC specimens, screened its potential target genes, and analyzed its functions in hepatoma cells. Our data suggest that miR-193b may exert its tumour suppressor function via targeting different oncogenes.miR-193b may function as a tumour suppressor in the development of HCC by acting on multiple tumorigenic pathways.