Chronic rhinosinusitis (CRS) is characterized by chronic inflammation of the sinonasal mucosa with epithelial dedifferentiation toward the mesenchymal phenotype, known as the epithelial-mesenchymal transition (EMT). Asian sand dust (ASD) can induce nasal mucosal inflammation and cause the development of EMT. Korean red ginseng (KRG) and ginsenoside Rg3 have been used as traditional herbal medicines to treat various diseases. The aim of this study was to investigate their effect on ASD-induced EMT in nasal epithelial cells. Primary nasal epithelial cells were incubated with ASD with or without KRG or Rg3, and the production of transforming growth factor-β1 (TGF-β1) and interleukin (IL)-8 was measured. EMT markers were determined by RT-PCR, Western blot analysis, and confocal microscopy, and transcription factor expression by Western blot analysis. The effect on cell migration was evaluated using the wound scratch assay. Results showed ASD-induced TGF-β1 production, downregulation of E-cadherin, and upregulation of fibronectin in nasal epithelial cells. KRG and Rg3 suppressed TGF-β1 production (31.7% to 43.1%), upregulated the expression of E-cadherin (26.4% to 88.3% in mRNA), and downregulated that of fibronectin (14.2% to 46.2% in mRNA and 52.3% to 70.2% in protein). In addition, they suppressed the ASD-induced phosphorylation of ERK, p38, and mTOR, as well as inhibiting the ASD-induced migration of nasal epithelial cells (25.2% to 41.5%). The results of this study demonstrate that KRG and Rg3 inhibit ASD-induced EMT by suppressing the activation of ERK, p38, and mTOR signaling pathways in nasal epithelial cells.
Keywords: Asian sand dust; Korean red ginseng; epithelial–mesenchymal transition; ginsenoside Rg3; nasal epithelial cell.