Crude ethanolic extracts of Zingiber cassumunar ROXB. inhibit PMA-induced MUC2 and MUC5AC expression via ERK inhibition in human airway epithelial cells.

BACKGROUND Over expression of mucin often leads to serious airway pathologies. The rhizome of Zingiber cassumunar Roxb. ("Phlai" in Thai) has been used as an anti-asthmatic drug in Thai traditional medicine. However, the effect of this plant on mucin production has not been reported. OBJECTIVE The aim of the present study was to investigate whether crude ethanolic extracts of Zingiber cassumunar (CEZE) suppress phorbol12-myristate 13-acetate (PMA)-induced mucin production and gene expression in human airway epithelial cells and if so, to examine whether the suppression of mucin gene expression is mediated via the mitogen-activated protein kinase (MAPK) signal transduction pathways. METHODS Confluent NCI-H292 cells were pretreated with CEZE for 2 hours and then stimulated with 100 or 200 nmol/l PMA for 8 h. The levels of MUC2 and MUC5AC mRNA were determined by RT-PCR and real-time PCR. Levels of total mucin; MUC2 and MUC5AC inculture supernatants were measured using ELLA and ELISA assays, respectively. Extracellular signal-regulated kinase (ERK), JNK, p38 MAPK protein levels were analyzed by Western blotting. RESULTS CEZE (5-100?g/ml) significantly inhibited total mucin production, including MUC2 and MUC5AC mRNA and proteins induced by PMA in NCI-H292 cells. The extracts obviously inhibited the phosphorylation of ERK, but not JNK and p38 in PMA-stimulated NCI-H292 cells. Our results suggest that Z. cassumunar-mediated suppression of PMA-induced MUC2 and MUC5AC mRNA operates via ERK inhibition. CONCLUSION Z. cassumunar suppresses PMA-induced MUC2 and MUC5AC gene expression in human airway epithelial cells via inhibition of ERK MAPK-dependent pathway.