Downregulation of N6-methyladenosine binding YTHDF2 protein mediated by miR-493-3p suppresses prostate cancer by elevating N6-methyladenosine levels

Abstract

// Jiangfeng Li 1, * , Shuai Meng 2, * , Mingjie Xu 1, * , Song Wang 1 , Liujia He 1 , Xin Xu 1 , Xiao Wang 1 and Liping Xie 1 1 Department of Urology, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310000, Zhejiang Province, China 2 Department of Urology, Zhejiang Provincial People’s Hospital, Hangzhou, 310000, Zhejiang Province, China * These authors have contributed equally to this work Correspondence to: Liping Xie, email: xielp@zju.edu.cn Xiao Wang, email: zjuwangxiao@zju.edu.cn Keywords: m6A; YTHDF2; miR-493-3p; epigenetics; PCa Received: August 23, 2017     Accepted: October 28, 2017     Published: December 18, 2017 ABSTRACT Recent evidence suggests that m6A modifications regulate the progressions of several types of tumors. YTHDF2, an m6A reader, has been implicated in the regulation of hepatocellular carcinoma (HCC). miR-493-3p has been defined as tumor suppressor that inhibits the progressions of several types of cancers. However, the functions and mechanisms of YTHDF2 and the indirect m6A regulated role of miR-493-3p in prostate cancer (PCa) remains to be elusive. In this study, immuno-histochemical (IHC) staining and chromogenic in situ hybridization (CISH) were performed to find YTHDF2 was frequently upregulated but miR-493-3p was downregulated in both PCa tissues and cell lines (DU-145 and PC3) which was negatively correlated with each other. Knock down of YTHDF2 significantly elevated m6A levels, and inhibited the cell proliferation and migration of DU-145 and PC3 cell lines. The dual-luciferase reporter assay confirmed YTHDF2 as the direct target of miR-493-3p. In addition, forced expression of miR-493-3p consistently elevated the m6A levels and inhibited proliferation and migration with the knock down of YTHDF2. In contrast, overexpression of YTHDF2 and inhibition of miR-493-3p conversely reduced m6A levels. Additionally, the rescue experiments revealed that inhibition of miR-493-3p abrogated the suppression of proliferation and migration induced by si-YTHDF2. To conclude, YTHDF2 and miR-493-3p, as two crucial m6A regulators, are involved in the progression of PCa by indirectly modulating m6A levels. In view of these promising results, YTHDF2 and miR-493-3p may provide new insights into the carcinogenesis and new potential therapeutic targets for PCa.