Liliane Patrícia Gonçalves Tenório ^1,2,3,4,5* Felipe Xavier ^2,3,4,5 Mônica Silveira Wagner ⁶ Kayo Moreira Bagri ⁷ Romulo G A Galvani ^2,3,4,5 Claudia Mermelstein ⁷ Adriana Bonomo ^2,3,4,5* Wilson Savino ^2,3,4,5* Emiliano Barreto ^1,3*

• ¹ Cell Biology Laboratory, Federal University of Alagoas, 57072-900, Maceió, Brazil
• ² Laboratory on Thymus Research, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Rio de Janeiro, Brazil
• ³ National Institute of Science and Technology on Neuroimmunomodulation, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Rio de Janeiro, Brazil
• ⁴ Rio de Janeiro Network on Neuroinflammation, Oswaldo Cruz Institute, Oswaldo Cruz Foundation,, 21040-360, Rio de Janeiro, Brazil
• ⁵ INOVA-IOC Network on Neuroimmunomodulation, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, 21040-360, Rio de Janeiro. Brazil, Brazil
• ⁶ Cell Structure and Dynamics Laboratory, National Cancer Institute-INCA, 20231-050, Rio de Janeiro, Brazil
• ⁷ Muscle Differentiation Laboratory, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, 21941-901, Rio de Janeiro, Brazil

The epithelial-mesenchymal transition (EMT) is a biological process in which epithelial cells change into mesenchymal cells with fibroblast-like characteristics. EMT plays a crucial role in the progression of fibrosis. Classical inducers associated with the maintenance of EMT, such as TGF-β1, have become targets of several anti-EMT therapeutic strategies. Natural products from the pentacyclic triterpene class have emerged as promising elements in inhibiting EMT. Uvaol is a pentacyclic triterpene found in olive trees (Olea europaea L.) known for its anti-inflammatory, antioxidant, and antiproliferative properties. Yet, its effect on the TGF-β1-induced EMT in alveolar epithelial cells is unknown. The present study aimed to investigate the impact of uvaol upon TGF-β1-induced EMT in a cultured A549 human alveolar epithelial cell line, a classic in vitro model for studies of EMT. Changes in cell shape were measured using phase-contrast and confocal microscopy, whereas protein expression levels were measured using immunofluorescence, flow cytometry, and western blotting. We also performed wound scratch experiments to explore its effects on cell migration. Uvaol had no significant cytotoxic effects on A549 cells. By contrast, the changes in the cell morphology consistent with TGF-β1-induced EMT were largely suppressed by treatment with uvaol. In addition, increased contents of mesenchymal markers, namely vimentin, N-cadherin, and fibronectin in TGF-β1-induced A549 cells, were downregulated by uvaol treatment. Furthermore, the TGF-β1-induced migration of A549 cells was significantly suppressed by uvaol. Mechanistically, uvaol prevented the nuclear translocation of β-catenin and reduced the TGF-β1-induced levels of ZEB1 in A549 cells. These results provide compelling evidence that uvaol inhibits EMT by regulating proteins related to the mesenchymal profile in human alveolar epithelial cells, likely by modulating β-catenin and ZEB1 levels.