Fibroblast activating protein promotes the proliferation, migration, and activation of fibroblasts in oral submucous fibrosis

Abstract Objectives Fibroblast activating protein (FAP) is associated with various organ fibrosis. However, the expression and molecular function of FAP in oral submucous fibrosis (OSF) is still unclear. Materials and Methods The high‐performance liquid chromatography was used to detect the presence of alkaloids in areca nut extract (ANE). Real‐time qPCR, Western blot, and Immunohistochemistry assay were used to analyze the expression of FAP mRNA or protein in OSF and normal oral tissue. A chi‐squared test analyzed the relationship between FAP protein expression and clinicopathological data of OSF patients. CCK‐8, Wound‐healing, and Transwell migration assay were employed to assess the effect of the proliferation and migration ability of hOMF cells with FAP overexpression or knockdown. The expression level of a‐SMA, FSP1, and P13K–Akt signaling pathways‐related protein in hOMF cells transfected with FAP overexpression or knockdown plasmid was verified by western blot assay. Results The four specific areca alkaloids (Arecoline, Guvacine, Arecaidine, and Guvacoline) were successfully detected in the ANE. The viability of hOMF cells was significantly improved in the 50 μg/mL ANE group and was inhibited in the 5 and 50 mg/mL ANE groups. The expression of FAP was upregulated in OSF tissues, and hOMF cells treated with 50 μg/mL ANE and was related to pathology grade, clinical stage, and history of chewing betel nut. Additionally, FAP may promote the proliferation, migration, and activation of hOMF cells through the P13K–Akt signaling pathway. Conclusions This study found that ANE had a bidirectional effect on the viability of hOMF cells, and the FAP gene was a potential therapeutic target in OSF.