MiR-489 modulates cisplatin resistance in human ovarian cancer cells by targeting Akt3.

MicroRNAs are a conserved class of small noncoding RNA molecules that harbour the capacity to regulate protein-coding gene expression at the post-transcriptional level. In the current study, we show that miR-489 is downregulated in cisplatin (CDDP)-resistant ovarian cancer cells, SKOV3/CDDP and OVCAR3/CDDP cells. MiR-489 overexpression results in an inhibition of SKOV3 and OVCAR3 cell survival and cell growth after CDDP treatment and an induction of cell apoptosis. Inhibition of miR-489 yields the opposite results. In addition, miR-489 overexpression increases the sensitivity of SKOV3/CDDP and OVCAR3/CDDP cells to CDDP and inhibits their colony number. Akt3 is validated as a direct target of miR-489 in SKOV3, OVCAR3, SKOV3/CDDP and OVCAR3/CDDP cells. In addition, miR-489 suppresses Akt3 protein expression by binding sites on its 3'UTR. Knockdown of Akt3 results in a similar effect as that because of miR-489 overexpression; importantly, Akt3 silencing rescues the functions induced by miR-489. Furthermore, we also use the Akt3 inhibitor, MK-2206 2HCl, to determine the role of Akt3 in CDDP resistance. Our study showed that MK-2206 2HCl increased the sensitivity of SKOV3/CDDP and OVCAR3/CDDP cells to CDDP. Taken together, our results indicate that miR-489 inhibited CDDP resistance and cell growth, and promotes apoptosis by suppressing Akt3 expression. Furthermore, the identification of a novel miR-489-based pathway in CDDP-resistant ovarian cancer will facilitate the development of therapeutic strategies.