(MicroRNA 200c-3p regulates autophagy via upregulation of endoplasmic reticulum stress in PC-3 cells)

BACKGROUND: Autophagy is a response to cellular and environmental conditions and facilitates cell survival. Here, we investigated the role of ectopic expression of microRNA (miRNA) 200c-3p in autophagy. METHODS: miRNA mimics were used to overexpress miRNAs. Quantitative real-time polymerase chain reaction (RT-qPCR) was performed to analyze miRNA expression. RT-qPCR and western blotting were performed to determine the expression levels of inositol requiring protein-1 (IRE1α), activating transcription factor-6 (ATF6), C/EBP homologous protein (CHOP), and light chain-3 (LC3). RESULTS: Western blotting and RT-qPCR analysis revealed that ectopic expression of miR-200c-3p increased the expression of IRE1α, ATF6, and CHOP in PC-3 prostate cancer cells. Furthermore, the level of miR-200c-3p was enhanced by treatment with the endoplasmic reticulum (ER) stress inducer thapsigargin. In addition, ectopic expression of miR-200c-3p led to an increase in LC3-II expression, and formed puncta of green fluorescent protein-fused LC3-II in PC-3 cells. Interestingly, starvation stress induced by Hank’s balanced salt solution buffer increased the level of miR-200c-3p and conversely miR-200c-3p inhibitor blocked the increased expression of LC3-II induced by starvation in PC-3 cells. In addition, silencing of IRE1α by transfection of short interfering RNA attenuated the expression of LC3-II induced by upregulation of miR-200c-3p in PC-3 cells. CONCLUSIONS: Overall, our findings suggest that miR-200c-3p regulates autophagy via upregulation of ER stress signaling.