Inhibition of TNF-alpha-Induced MUC5AC Mucin Gene Expression and Production by Wogonin Through the Inactivation of NF-kappa B Signaling in Airway Epithelial Cells

In this study, we investigated whether wogonin significantly affects MUC5AC mucin gene expression and production in human airway epithelial cells. Confluent NCI-H292 cells were pretreated with wogonin for 30min and then stimulated with tumor necrosis factor- (TNF-) for 24h or the indicated periods. The MUC5AC mucin gene expression and mucin protein production were measured by RT-PCR and ELISA, respectively. We found that incubation of NCI-H292 cells with wogonin significantly inhibited mucin production and down-regulated MUC5AC gene expression induced by TNF- in a dose-dependent fashion. To elucidate the action mechanism of wogonin, effect of wogonin on TNF--induced NF-B signaling pathway was investigated by western blot analysis. Wogonin inhibited NF-B activation induced by TNF-. Inhibition of IKK by wogonin led to the suppression of IB phosphorylation and degradation, p65 nuclear translocation and NF-B-regulated gene expression. This, in turn, led to the down-regulation of MUC5AC protein production in NCI-H292 cells. Wogonin also inhibited the gene products involved in cell survival (Bcl-2) and proliferation (cyclooxygenase-2). These results suggest that wogonin inhibits the NF-B signaling pathway, which may explain its role in the inhibition of MUC5AC mucin gene expression and production. Copyright (c) 2013 John Wiley & Sons, Ltd.