Effects of inhibition of miR-221 expression on proliferation and apoptosis of bladder cancer cells

Objective: To investigate the effects of inhibition of microRNA-221 (miR-221) expression on the proliferation and apoptosis of bladder cancer cells. Methods: Has-miR-221 inhibitor and has-miR-221 inhibitor negative control were synthesized, and then transfected into bladder cancer T24 and J82 cells. The transfection efficiency was observed under a fluorescence microscope 5 h after transfection. The expression levels of miR-221 in T24 and J82 cells were detected by real-time fluorescence quantitative PCR at 24, 48 and 72 h after transfection; the proliferation of T24 and J82 cells was also detected by MTT assay. The expression levels of p53 upregulated modulator of apoptosis (PUMA), Bax and Bcl-2 mRNAs and proteins in T24 and J82 cells 48 h after transfection were measured by RT-PCR and Western blotting, respectively; the apoptosis of T24 and J82 cells was determined by flow cytometry (FCM) and acridine orange (AO)-ethidium bromide (EB) staining. Results: The efficiencies of has-miR-221 inhibitor transfection into T24 and J82 cells were 80% and 90%, respectively. The expression levels of miR-221 in T24 and J82 cells after transfection with has-miR-221 inhibitor were lower than those in the negative control group and the blank control group (only adding liposome) (P < 0.05). The proliferative inhibition rates of T24 and J82 cells after transfection with has-miR-221 inhibitor were higher than those in the negative control group and the blank control group (P < 0.05), and this effect was in a time-dependent manner. The expression levels of PUMA and Bax mRNAs and proteins in T24 and J82 cells after transfection with has-miR-221 inhibitor were higher than those in the negative control group and the blank control group (P < 0.05), and the expression levels of Bcl-2 mRNA and protein were opposite (P < 0.05). The apoptosis rates of T24 and J82 cells after transfection with has-miR-221 inhibitor were higher than those in the negative control group and the blank control group (P < 0.05). Conclusion: Inhibition of miR-221 expression can suppress the proliferation of bladder cancer cells and induce apoptosis.