Effects of microRNA-15b on proliferation of colorectal cancer cells and the preliminary mechanism

Abstract

Objective To investigate the effect of the inhibition of microRNA (miR)-15b on proliferation of human colorectal carcinoma (CRC) cells and the preliminary mechanism. Methods Caco2, HCT116 and SW620 cells were examined for miR-15b and metastasis suppressor 1 (MTSS1) mRNA expression using reverse transcription-polymerase chain reaction (RT-PCR). We constructed the recombinant plasmids pMIR-Report-MTSS1 and pMIR-Report-MTSS1 mut. The targeting effect of miR-15b on MTSS1 gene was verified by the dual-luciferase reporter assay system. Then we transfected miR-15b inhibitor and miR-15b mimics into HCT116 cells by Lipofectamine 2000, and detected the cell proliferation, cell cycles, expression of MTSS1 mRNA and its protein by methyl thiazol tetrazolium (MTT), flow cytometric (FCM), RT-PCR and Western blotting, respectively. Results Caco2, HCT116 and SW620 cells showed significantly upregulated and downregulated expression of miR-15b and MTSS1 mRNA respectively. miR-15b could inhibit MTSS1 expression as a target. miR-15b could promote HCT116 cell proliferation, inhibition of miR-15b could inhibit cell proliferation of HCT116. Meanwhile, the MTSS1 mRNA and its protein could be upregulated by miR-15b inhibitor (P=0.004, 0.001). Conclusion MiR-15b could promote colorectal cancer cell proliferation by downregulating MTSS1 expression. Inhibition of miR-15b could inhibit CRC cell proliferation by up-regulating expression of MTSS1. MiR-15b can be used as a new pharmacological target gene for CRC therapy in further study. Key words: MicroRNA-15b; Metastasis suppressor 1; Colorectal carcinoma; Cell proliferation; Cell cycles