RNA-seq reveals microRNA-302b as a suppressor of prostate cancer epithelial-mesenchymal transition by targeting RELA/NF-κB.

To identify novel biomarker(s) in prostate cancer and demonstrate the mechanistic involvements in this disease, RNA-seq was employed to reveal the differentially expressed genes in the blood samples from prostate cancer patients. Relative expression of miR-302b-3p was evaluated using real-time PCR. The potential regulation of RELA by miR-302b-3p was assessed by luciferase reporter assay. Protein levels of NF-κB, Vimentin, N-cadherin and E-cadherin, were quantified using western blotting. Transwell chamber was employed to measure cell migratory and invasive capacity, while cell attachment/detachment assay was performed to evaluated epithelial-mesenchymal transition (EMT)-related behavior. Xenograft tumor model was adopted to determine the anti-tumor activity of miR-302b-3p in vivo. We demonstrated miR-302b-3p was down-regulated in prostate cancer both in vivo and in vitro. We predicted and identified RELA as directly targeted by miR-302b-3p. Ectopic miR-302b-3p expression in PC-3 cells significantly suppressed cell migration, invasion, attachment, detachment capacity, which was accompanied with a decrease in the expression of N-cadherin and Vimentin, and an increase of E-cadherin expression. MiR-302b-3p-proficiency greatly delayed xenograft tumor growth and associated with favorable overall survival. Co-introduction of RELA completely abolished anti-tumor effects of miR-302b-3p, which indicated a potential genetic interaction between RELA/NF-κB and miR-302b-3p. We characterized the aberrant down-regulation of miR-302b-3p in prostate cancer and unraveled a possible involvement of miR-302b-3p/RELA signaling axis in this scenario.