ABSTRACT
Objective:To evaluate the effect of miR-133b on the apoptosis and radiosensitivity of colon cancer cell line (SW620 cells), and to explore its mechanism.Methods:SW620 cells were transfected with miR-con (miR-con group), miR-133b mimics (miR-133b group), si-con (si-con group) and si-HER-2(si-HER-2 group) by the liposome method, and then irradiated with 0, 2, 4, 6, 8 Gy. The miR-133b protein expression, HER-2 protein expression, apoptosis, cell survival fraction and cytofluoroactivity in each group were evaluated by qRT-PCR, Western blot, flow cytometry, colony formation assay and dual luciferase reporter gene assay, respectively.Results:Compared with the pre-irradiation group, the expression level of miR-133b was significantly down-regulated ( P<0.05), whereas that of HER-2 was significantly up-regulated in SW620 cells after irradiation ( P<0.05). Overexpression of miR-133b and knockdown of HER-2 remarkably reduced the survival fraction (both P<0.05), and significantly promoted the apoptosis of SW620 cells ( P<0.05). miR-133b could considerably inhibit the fluorescent activity of wild-type HER-2 cells ( P<0.05) and negatively regulate the expression of HER-2 protein. Conclusion:miR-133b can inhibit the survival of colon cancer cells, promote the apoptosis and enhance the sensitivity of radiotherapy probably via the mechanism of targeting HER-2.