Abstract 466: Role of miR-15b-3p in mitoquinone induced autophagy of breast cancer cells

Abstract

Abstract Mitoquinone, a redox-active mitochondrially targeted ubiquinone, activates autophagy more potently in breast cancer cells (MDA-MB-231) than in normal breast cells (MCF-12A). Mitoquinone induces the production of reactive oxygen species (ROS) and a concomitant activation of the Nrf2-dependent antioxidant response. MicroRNA are endogenous small double stranded RNA that bind to the 3’ UTR of several target mRNAs and function through translational repression or mRNA degradation. The goal of this study was to evaluate microRNA as a link between oxidative stress and autophagy signaling. We performed RNA sequencing analysis of the microRNAs modulated by mitoquinone treatment of MDA-MB-231 cells. miRNAs were identified using Illumina RNA sequencing. DEseq analysis revealed 97 miRNAs that were differentially expressed at an α < 0.05. Within this set, 15 miRNAs were down-regulated by stimulation with mitoquinone making them attractive as potential autophagy inhibitors. We characterized the role of a miR-15b-3p by transfecting the cells with miR-mimic and anti-miR before inducing an autophagy response. Western blot analysis showed a reduction in the expression of the autophagy marker LC3, the autophagosome chaperon p62 and the transcription factor Nrf2 in presence of the miR-15b-3p mimic. Conversely, miR-15b-3p mimic pre-treatment increased the expression of the cell cycle inhibitor p27 both at the basal level and after mitoquinone stimulation for 48 hrs. The administration of the anti-miR-15b-3p did not change the expression level of these proteins suggesting that miR-15b-3p may work with other miRs toward regulating autophagy. Combining the action of miR-15b-3p mimic with redox active chemotherapeutic drugs could represent a novel strategy for breast cancer therapy by reducing survival signaling through autophagy. Citation Format: Francesca Mascia, Kaytee Pokrzywinski, Ashutosh Rao. Role of miR-15b-3p in mitoquinone induced autophagy of breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 466. doi:10.1158/1538-7445.AM2017-466