MicroRNA-133b inhibits colorectal cancer cell proliferation through targeting matrix metalloproteinase-9

Abstract

Objective To investigate the molecular mechanism by which microRNA (miRNA, miR)-133b inhibits colorectal cancer cell proliferation through targeting matrix metalloproteinase-9 (MMP-9). Methods To examine the expression level of MMP-9 in clinic tissue specimens using real-time fluorescent quantitative polymerase chain reaction (FQ-PCR); to achieve MMP-9 knockdown or overexpression using RNA interference or recombinant overexpressing plasmid, and then monitor the cell proliferation of colorectal cancer cell, HCT116, in response to MMP-9 knockdown or overexpression using methyl thiazol tetrazolium (MTT) and colony formation assays; to predict the upstream candidate miRNA which might regulate MMP-9 expression and to validate the prediction using FQ-PCR and luciferase reporter gene assays; to achieve miR-133b and MMP-9 overexpression in HCT116 cells, and then monitor the cell proliferation of colorectal cancer cells. Results The expression of MMP-9 significantly increased in colorectal tissues, compared with the paired adjacent normal tissues (3.17±0.79 vs. 1.00±0.25, P 0.05). After overexpression of miR-133b, the cell proliferation ability was significantly lower than control group by MTT (1.34±0.04 vs. 1.54±0.06, P<0.01) and cloning efficiency (8.67±3.06 vs. 17.67±2.52, P<0.05), respectively. Furthermore, we con-overexpression of miR-133b and MMP-9, the cell proliferation ability was higher than miR-133b overexpression group by MTT (1.66±0.05 vs. 1.34±0.04, P<0.01) and cloning efficiency (22.00±4.00 vs. 8.67±3.05, P<0.05). Conclusion MiR-133b could inhibit colorectal cancer cell proliferation through direct targeting and downregulating MMP-9. Key words: Colorectal cancer; MicroRNA-133b; Matrix metalloproteinase-9; Cell proliferation