MicroRNA-132 reverses cisplatin resistance and metastasis in ovarian cancer by the targeted regulation on Bmi-1

OBJECTIVE: To explore the role of micro ribonucleic acid-132 (miR-132) in cisplatin (DDP) resistance and metastasis of ovarian cancer and its related mechanisms. MATERIALS AND METHODS: Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting were applied to detect the expression levels of miR-132 and B lymphoma Mo-MLV insertion region 1 homolog (Bmi-1) in maternal SKOV3 cells and cisplatin-resistant SKOV3/DDP cells. SKOV3/DDP cells were transfected with miR-132 mimic and miR-132 mimic negative control (NC). QRT-PCR and Western blotting were used to detect the expression changes in Bmi-1, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was adopted to detect the sensitivity of cells to DDP after transfection with miR-132 mimic. The effect of transfection on the apoptosis was detected via flow cytometry, and that on cell invasion and migration abilities were examined using wound healing assay and transwell assay. Bmi-1 wild-type (wt) and mutant-type (mut) luciferase reporter plasmids were co-transfected with miRNA-132 mimic or miRNA-132 NC, and luciferase activity was analyzed by dual-luciferase reporter system. RESULTS: QRT-PCR and Western blotting results manifested that the miR-132 expression level in SKOV3/DDP cells was significantly lower than that in SKOV3 cells, while the expression level of Bmi-1 in SKOV3/DDP cells was significantly higher than that in SKOV3 cells. The over-expression of miR-132 could reduce the expression level of Bmi-1 in SKOV3/DDP cells, increase the sensitivity of SKOV3/DDP cells to DDP, and inhibit cell invasion and metastasis. Data detected by the luciferase activity revealed that miR-132 could bind to the three prime untranslated region (3'-UTR) of the Bmi-1 gene and negatively regulate the protein expression. CONCLUSIONS: MiR-132 may regulate ovarian cancer's sensitivity to DDP and inhibit its invasion and metastasis by targeted regulation on Bmi-1.