Mechanism of the enhancing effects of miR-93 on resistance of breast cancer MCF-7 cells to adriamycin

This study aimed to investigate the effects of miR-93 on resistance of breast cancer MCF-7 cells to adriamycin, and to explore the possible mechanism. Expression of miR-93 in breast cancer cell lines MCF-7 and MCF-7/ADM was detected by reverse transcription-quantitative PCR (RT-qPCR). miR-93 mimics and inhibitors were transfected into MCF-7/ADM and MCF-7 cells, and MTT assay was used to detect the resistance of cells to adriamycin after transfection. Western blot analysis was used to detect the expression of anti-apoptotic protein Bcl-2 and multidrug resistance gene MDR1 related P-gp protein in MCF-7/ADM and MCF-7 cells before and after the transfection of miR-93 mimics. Expression level of miR-93 in MCF-7/ADM cells was decreased, and was 40% of that in MCF-7 cells (0.39±0.04, p<0.05). Before transfection, IC(50) value of MCF-7 cells to adriamycin (11.02±0.95) was lower than that of MCF-7/ADM cells (21.29±1.83, p<0.05). IC(50) value of MCF-7/ADR cells at 72 h after transfection with miR-93 mimics (13.55±0.86) was lower than that of the negative control group (24.67±1.51, p<0.05). IC(50) value of MCF-7 cells 72 h after transfection with miR-93 inhibitor (19.88±1.28) was higher than that of negative control group (11.02±0.95, p<0.05). Expression levels of Bcl-2 and P-gp proteins in MCF-7/ADM cells were 1.63±0.24 and 1.76±0.22 times that of MCF-7 cells, respectively (p<0.05). At 72 h after transfection of miR-93 mimics, expression levels of Bcl-2 and P-gp proteins in MCF-7/ADM cells were 0.27±0.06 and 0.39±0.05, respectively, compared with the negative control group (p<0.05). At 72 h after transfection with miR-93 inhibitor, expression levels of Bcl-2 and P-gp protein in MCF-7 cells were 1.48±0.10 and 1.56±0.11 times of the negative control group, respectively (p<0.05). miR-93 can increase the apoptosis of MCF-7/ADM cells and their resistance to adriamycin by inhibiting the expression of Bcl-2 and P-gp proteins.