miR-200b ameliorates myofibroblast transdifferentiation in precancerous oral submucous fibrosis through targeting ZEB2

Oral submucous fibrosis (OSF) is a progressive scarring disease. MicroRNA-200b (miR-200b) has been reported as a tumour suppressor, but its role in the precancerous OSF remains unknown. In this study, we investigated the impact of miR-200b on myofibroblastic differentiation activity. Arecoline is a major areca nut alkaloid and has been employed to induce the elevated myofibroblast activity in human buccal mucosal fibroblasts (BMFs). Treatment of arecoline in BMFs dose-dependently reduced gene expression of miR-200b, which corresponded with the decreased expression of miR-200b in fBMFs. The arecoline-induced myofibroblast activities were abolished by overexpression of miR-200b in BMFs, and the same results were observed in fBMFs. In addition, alpha-SMA was inhibited by an increase in miR-200b. We further demonstrated that miR-200b-mediated decrease in ZEB2 led to down-regulation of alpha-SMA, vimentin. Loss of miR-200b resulted in enhanced collagen contraction and migration capabilities, and knockdown of ZEB2 reversed these phenomena. Lastly, we showed the expression of miR-200b was significantly less and ZEB2 was markedly higher in OSF tissues. These results suggested that down-regulation of miR-200b may contribute to the pathogenesis of areca quid-associated OSF through the regulation of ZEB2 and myofibroblast hallmarks.