Abstract P2-03-04: Down-regulation of Bcl2-related ovarian killer (BOK) by miR-296-5p protects breast cancer cells from paclitaxel-induced apoptosis

Abstract

Abstract Accumulating evidence shows that miRNAs play a role in drug resistance. Despite these observations, little is known about the identities of the miRNAs involved in drug resistance and their downstream targets. In the present study, we identified miR-296-5p for which a tumor suppressive role has been previously described, as a miRNA that is involved in paclitaxel drug resistance in triple negative breast cancer (TNBC) cells. Enforced expression of miR-296-5p suppressed cell growth, migration, and invasion in MDA-MB-231 breast cancer cells. Using a microarray approach, we identified BCL2-related Ovarian Killer (BOK), a pro-apoptotic gene as a target of miR-296-5p. BOK levels were validated BOK levels in miR-296-5p transfected MDA-MB-231 and MDA-MB-468 cells using real-time PCR and Western blot. Our results demonstrated that over-expression of miR-296-5p down-regulated BOK expression in TNBC cells. Transfection of miR-296-5p significantly suppressed luciferase reporters containing wild-type BOK-3'-UTR constructs. In contrast, mutant BOK-3'-UTR constructs were unaffected by ectopic miR-296-5p. Furthermore, BOK expression was induced in the presence of paclitaxel, but ectopic miR-296-5p significantly suppressed BOK induction by paclitaxel treatment compared to the control cells. These data provide new insights on the role of miRNAs in drug resistance and suggests that therapeutic strategies against miR-296-5p may be warranted. Citation Format: Onyeagucha BC, Rajamanickam S, Subbarayalu P, Bansal B, Bansal H, Chang Y-F, Timilsina S, Abdelfaltah N, Eedunuri VK, Rao MK. Down-regulation of Bcl2-related ovarian killer (BOK) by miR-296-5p protects breast cancer cells from paclitaxel-induced apoptosis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-03-04.