Inhibition of miR-497 Attenuates Oral Submucous Fibrosis by Inhibiting Myofibroblast Transdifferentiation in Buccal Mucosal Fibroblasts.

PURPOSE: Oral submucous fibrosis (OSF) is a common chronic condition with poor prognosis, and existing therapies for OSF are limited in effectiveness. This study was designed to explore the role of miR-497 in arecoline (AR)-induced OSF. MATERIALS AND METHODS: After miR-497 was silenced or overexpressed in buccal mucosa fibroblasts (BMFs), different concentrations of AR (5-200 mug/ml) were applied to incubate BMFs, and 50 mug/ml of AR was chosen for subsequent experiments. Thereafter, collagen gel contraction assay was used to detect the contractile capacity of BMFs. Transwell assay and wound healing assay were applied to detect migration and invasiveness of the cells. In addition, immunofluorescence staining, qRT-PCR and western blot were conducted to measure the expression of miR-497, collagen I and alpha-SMA, as well as the phosphorylation of Smad2 and Smad3. RESULTS: After successful inhibition or overexpression of miR-497 in AR-induced BMFs, the results showed that miR- 497 inhibition suppressed the contractility, migration and invasiveness of AR-induced BMFs, whereas overexpression of miR-497 produced the opposite. In addition, miR-497 inhibition down-regulated the expression level of collagen I and alpha-SMA in AR-exposed BMFs. Furthermore, TGF-beta1 expression, Smad2 and Smad3 phosphorylation were also repressed in AR-induced BMFs after miR-497 inhibition. Correspondingly, overexpression of miR-497 reversed the expression of the aforementioned proteins. CONCLUSION: miR-497 inhibition may attenuate OSF by inhibiting myofibroblast transdifferentiation in BMFs via the TGF-beta1/Smads signaling pathway, indicating that miR-497 might represent an underlying target for treating OSF.