[Smad3 signaling pathway promotes silica-induced epithelial-mesenchymal transition]

Objective: To investigate the role of the Smad3 signaling pathway in the process of silica-induced epithelial-mesenchymal transition (EMT) . Methods: In September 2022, lung epithelial cells (BEAS-2B) were exposed to different concentrations of silica suspension (0, 50, 100, and 150 μg/ml) for 6 and 12 hours. Additionally, SIS3, a specific inhibitor of phosphorylated Smad3 (p-Smad3) , was utilized to establish the p-Smad3 inhibition model. The cells were divided into four groups: blank control gruop, silica group, SIS3 intervention group, and SIS3 +silica group. Cell morphology was observed using an inverted fluorescence microscope, while cell viability was assessed using a Cell Counting Kit-8 (CCK-8) . The mRNA and protein expression levels of E-cadherin (E-Cad) , N-cadherin (N-Cad) , Vimentin, Smad3, and p-Smad3 were analyzed by Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting, respectively. Differences between two groups were compared using Student's t-test, and multiple group comparisons were analyzed using a one-way analysis of variance with the Student-Newman-Keuls test. Results: Compared with the blank control group, the morphology of BEAS-2B cells shifted from epithelial to mesenchymal cell-like following silica exposure, and the cell viability of BEAS-2B cells declined after exposure to 150 μg/ml silica for 6 and 12 hours. Furthermore, silica exposure led to significant reductions in mRNA and protein expression levels of the epithelial cellular marker (E-Cad) in BEAS-2B cells, accompanied by increased expressions of interstitial cellular markers (N-Cad and Vimentin) . Importantly, the level of p-Smad3/Smad3 expression levels was also elevated in silica-treated cells (P<0.05) . Compared to the blank control group, the level of p-Smad3/Smad3 expression levels was significantty reduced. Moreover, compared to the silica group, the protein expression levels of N-Cad and Vimentin in the cell of the SIS3+silica group were significantly reduced, while the E-Cad expression was increased (P<0.05) . Conclusion: Silica exposure can prmote the epithelial mesenchymaol transformotion process by activating smod3 signa ling pathuay, and in hibiting smad3 signa ling pathuay can effctively alleviate the occurrence of epithelial mesenchymal transformation process.