Abstract: Objective To explore the effects of the Smoothened (Smo) inhibitor PF-5274857 on cigarette smoke (CS)-induced epithelial-mesenchymal transition (EMT) and apply a new idea fororal squamous cell carcinoma (OSCC) treatment. Methods Beas-2b cells were used to investigate the CS-induced EMT. Both pretreat and post-treat were performed in the study. In pretreat group, after being pretreated with 3 μmol/L PF-5274857 for 2 h, cells were cultured with CS for 8 d; In post-treat group, cells were treated by 3 μmol/L PF-5274857 for 4 d after CS cultrue. Western blot and immunofluorescence were applied to examine the EMT markers E-cadherin, vimentin, and smooth muscle actin α (α-SMA) in Beas-2b epithelial cells. The transwell culture system was used in migration assays. Results Pretreat Beas-2b cells with PF-5274857 for 2 h can prevent the CS-induced EMT for epithelial and mesenchymal markers, as well as migration capacity. Up regulated E-cadherin and down regulated vimentin and α-SMA were observed by Western blot. Furthermore Beas-2b cells induced by CS that underwent EMT showed increased E-cadherin and decreased vimentin and α-SMA after treatment with PF-5274857 for 4 d. Importantly, the elevated migration capacity level was also decreased. Conclusion The Smo inhibitor PF-5274857 has both preventive effect and therapeutic potential against CS-induced EMT.