MiR-181a upregulation is associated with epithelial-to-mesenchymal transition (EMT) and multidrug resistance (MDR) of ovarian cancer cells.

OBJECTIVE Elevated miR-181a is associated with the transition of ovarian tissues from normal into a cancerous state. However, its regulative effect on multidrug resistance (MDR) of ovarian cancer is not quite clear. Therefore, this study aimed to investigate its regulative effects on epithelial-to-mesenchymal transition (EMT) and MDR in ovarian cancer. MATERIALS AND METHODS The expression profile of miR-181a in normal and ovarian cancer tissues was firstly quantified using qRT-PCR analysis. Then, human ovarian cancer cell line SKOV3 were transfected for miR-181a overexpression and the paclitaxel-resistant variant SKOV3/PTX cells were transfected for miR-181a knockdown. The effect of miR-181a overexpression/knockdown on EMT and PTX sensitivity were studied. RESULTS MiR-181a level in chemoresistant (CR) cancer tissues were significantly higher than in chemosensitive (CS) cancer tissues and in normal tissue. SKOV3/PTX cells had significantly higher expression of miR-181a and N-cadherin than SKOV3 cells. SKOV3 cells had decreased E-cadherin expression and increased N-cadherin expression after enforced miR-181a expression, while SKOV3/PTX cells had increased E-cadherin expression and decreased N-cadherin expression after miR-181a knockdown. SKOV3 cells had increased P-gp expression after enforced miR-181a expression. Following MTT assay and flow cytometry analysis both confirmed that miR-181a overexpression decreased the PTX sensitivity of SKOV3 cells and while miR-181a inhibition increased the sensitivity of SKOV3/PTX cells. CONCLUSIONS MiR-181a is an important oncomiR significantly increased in chemoresistant ovarian cancer. Its upregulation is associated with increased level of EMT and decreased cell apoptosis induced by PTX treatment.