Extracellular High mobility group box 1-induced epithelial mesenchymal transition through β-catenin pathway in human airway epithelial cells

Abstract

Abstract High mobility group box 1 (HMGB1) protein belongs to late inflammatory phase cytokine which shows a crucial role in the pathology of chronic pulmonary inflammatory diseases. Epithelial–mesenchymal transition (EMT) is implicated in airway remodeling and lung dysfunction in chronic inflammatory airway diseases. At present, the effects and mechanisms of HMGB1 in EMT of human airway epithelial cells is still unclear. In this study, we found that HMGB1 treatment modulated EMT-related gene expression in human primary airway epithelial cells by RNA sequencing assay. HMGB1 induced downregulation of E-cadherin and ZO-1, and upregulation of vimentin mRNA transcription and protein translation in a dose-dependent manner. To dissect the mechanisms of HMGB1-induced EMT in human airway epithelial cells, we used western blotting, RNA interference and chemical inhibitors to investigate. Treatment with PI3K inhibitor (LY294006) and β-catenin shRNA reversed HMGB1-induced EMT. HMGB1 caused AKT phosphorylation, resulting in GSK3β inactivation, cytoplasmic accumulation, and nuclear translocation of β-catenin to induce EMT in human airway epithelial cells. Additionally, HMGB1 upregulated expression of receptor for advanced glycation products (RAGE), but not that of Toll-like receptor (TLR) 2 or TLR4, and RAGE shRNA attenuated HMGB1-induced EMT in human airway epithelial cells. In conclusion, we found that extracellular HMGB1 induced EMT through RAGE and β-catenin signaling pathway which might deteriorate bronchial epithelium which enhance disease severity and steroid resistance of airway.