Abstract 1104: MicroRNA miR-31 regulates oral squamous cell carcinoma cell migration by targeting critical enzyme of peroxisomal lipid metabolism

Abstract

Abstract MicroRNAs (miRNAs) are small endogenous non-coding RNAs that play important roles in a variety of cellular processes, such as growth, differentiation and metabolic homeostasis. Dysregulation of microRNA has been linked to the development of various types of human diseases, including cancer. Our previous study has identified that miR-31 is significantly up-regulated in oral squamous cell carcinoma (OSCC) tissues. Further gain- and loss-of-function analyses revealed that miR-31 promotes OSCC by enhancing the migration and invasiveness of OSCC cells but not cell proliferation. However, the exact role of miR-31 in OSCC neoplastic development, especially metastasis, has not been explored. Computational microRNA target prediction and pathway analysis showed an enrichment of putative targets in lipid metabolism pathway. In this study, we aimed to investigate the role of miR-31 in the regulation of lipid metabolism and to establish the relationship between lipid metabolism and tumor pathogenesis in OSCC cells. First, we demonstrated that ACOX1, the rate-limiting enzyme in peroxisomal β-oxidation, is the direct target of miR-31. We further analyzed publicly available mRNA and miRNA deep sequencing datasets and found that the expression levels of miR-31 inversely correlate with those of ACOX1. Furthermore, we discovered that depletion of miR-31 significantly decreased the intensity of cellular lipid droplets (LDs), and knockdown of ACOX1 conversely showed an increase of LD formation. These data suggested that miR-31 may regulate lipid metabolism by targeting ACOX1. In cultured OSCC cells, the migration capability and invasiveness were significantly increased after knockdown of ACOX1. We further confirmed that ACOX1 depletion enhances ERK1/2 expression and phosphorylation and increases the expression levels of MMP9 in OSCC cells. Collectively, our findings suggest that the elevated expression of miR-31 in OSCC cells directly contributes to the down-regulated expression of ACOX1, subsequently leading to accumulation of lipid metabolites and elevated OSCC migration and invasion through ERK pathway. Citation Format: Yi-Shiuan Lai, Hsuan Liu, Ting-Wen Chen, Shu-Jen Chen, Hua-Chien Chen, Bertrand Chin-Ming Tan. MicroRNA miR-31 regulates oral squamous cell carcinoma cell migration by targeting critical enzyme of peroxisomal lipid metabolism. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1104.