口腔黏膜下纖維化症(oral submucous fibrosis) 為一種口腔癌發生之癌前病變(precancerous condition)，流行病學指出口腔黏膜下纖維化症主要與檳榔嚼食習慣相關，檳榔中的主要成分檳榔素(arecoline)對於口腔黏膜下纖維化症所造成的病理病灶已經被確立，然而口腔黏膜纖維化症之分子致病機轉至今仍尚未清楚有待進一步研究探討。微小RNA (microRNAs)是一類長度約19-24個核?酸之非編碼RNA，可利用鹼基配對的方式與標靶mRNA的3’UTR (untranslation region)結合而抑制mRNA的轉譯，許多證據亦顯示微小RNA在組織纖維化中扮演重要角色，但微小RNA於口腔黏膜下纖維化症之角色仍未知。本計畫成果發現臨床口腔黏膜纖維化組織中miR-200b表現量較正常頰黏膜組織低且初代培養之口腔黏膜纖維化細胞之miR-200b表現量較正常頰黏膜纖維母細胞初代培養低。正常頰黏膜纖維母細胞在處理不同檳榔鹼處理下會降低miR-200b的表現。過度表現miR-200b可反轉檳榔鹼在正常頰黏膜纖維母細胞誘發之膠體收縮能力及細胞移動性，同樣地，過度表現miR-200b可抑制口腔黏膜纖維化初代培養細胞膠體收縮能力及細胞移動性。在口腔黏膜纖維化初代培養細胞中miR-200b可直接標靶上皮間質轉化轉錄因子ZEB1及ZEB2。
Oral submucous fibrosis (OSF) is a chronic progressive scarring disease which has been considered as pre-cancerous condition of oral mucosa. OSF is highly associated with areca quid chewing habit. Arecoline is the major alkaloid in areca quid which has been suggested to be involved in the pathogenesis of OSF. But, the pathologic mechanism(s) of OSF needs to be further clarified. In the past decade, the biological function and biogenesis of microRNAs (miRNAs) became popular topics for biomedical researches. Analyses of these miRNAs in mechanistic studies are crucial to better understanding fibotic disease and with an aim to eventually identify novel therapeutic targets. The purpose of this study is to investigate the roles of miRNAs in the pathogenesis of OSF. Clinically, miR-200b expression was higher expression in areca quid chewing-associated OSF tissues than that of normal oral mucosa tissues. Compared with normal buccal mucosal fibroblasts cells (BMFs), primary cultivated OSF cells (OSFs) displayed the decreased miR-200b expression. We observed that the treatment of arecoline dose-dependently decreased miR-200b expression in BMFs. The myofibroblast activity including collagen gel contraction and migration capability was also induced by arecoline, while overexpression miR-200b reversed these phenomena. Overexpression miR-200b led to the suppression myofibroblastic differentiation activity primary cultivated OSFs. We identified ZEB1 and ZEB2 as direct targets of miR-200b in OSFs.
