Role and mechanism of microRNA-15b in the regulation of epithelial-mesenchymal transition of peritoneal mesothelial cells

Objective To explore the role and mechanism of microRNA-15b in the regulation of epithelial-mesenchymal transition (EMT) of human peritoneal mesothelial cells (HPMCs). Methods PCR assay was used to determine the expression of microRNA-15b in the HMrSV5 induced by 138 mmol/L high glucose for 24 h. MicroRNA-15b mimic or inhibitor was transfected into human peritoneal mesothelial cells (HMrSV5) to over-express or down-regulate microRNA-15b. The cells were then incubated with 138 mmol/L high glucose for 24 h, and the expressions of E-cadherin(E-Cad), Vimentin (VIM), Fibronectin(FN) and Smad7 were detected by real-time PCR and Western blotting respectively. Results microRNA-15b in the HMrSV5 cells was over-expressed and down-regulated. Increased level of microRNA-15b was obtained in HMrSV5 cells treated with high glucose. In vitro, high glucose led to the up-regulation of vimentin as well as fibronectin and the down-regulation of E-cadherin in HMrSV5 cells (all P<0.05), which indicated EMT and fibrosis. Suppression of microRNA-15b by transfection with microRNA-15b inhibitor partially reversed the EMT and fibrosis changes (P<0.05), while over-expression of microRNA-15b by transfection with microRNA-15b mimic obviously enhanced the EMT and fibrosis changes (P<0.05). Conclusions MicroRNA-15b mediates high glucose induced EMT in human peritoneal mesothelial cells by the inhibition of Smad7 possibly. MicroRNA-15b maybe a new target for the prevention and treatment of peritoneal fibrosis during peritoneal dialysis (PD). Key words: Peritoneal dialysis; Cell transdifferentiation; Fibrosis; Peritoneum; MicroRNAs