ATP-induced mucin release from cultured airway goblet cell involves, in part, activation of phospholipase A2

Daidzein regulates secretion, production and gene expression of mucin from airway epithelial cells stimulated by proinflammatory factor and growth factor

In this study, we investigated whether daidzein significantly affects secretion, production and gene expression of mucin from cultured airway epithelial cells. Confluent primary rat tracheal surface epithelial (RTSE) cells were pretreated with adenosine triphosphate (ATP) for 5 min and then chased for 30 min in the presence of daidzein to assess the effect on mucin secretion using ELISA. At the same time, confluent NCI-H292 cells were pretreated with daidzein for 30 min and then stimulated with EGF and PMA for 24 h, respectively. The MUC5AC mucin gene expression and mucin protein production were measured by RT-PCR and ELISA. The results were as follows: (1) daidzein significantly decreased ATP-induced mucin secretion from cultured RTSE cells; (2) daidzein inhibited the production of MUC5AC mucin protein induced by EGF or PMA from NCI-H292 cells; (3) daidzein also inhibited the expression of MUC5AC mucin gene induced by EGF or PMA from NCI-H292 cells. This result suggests that daidzein can regulate secretion, production and gene expression of mucin, by directly acting on airway epithelial cells.

Carbenoxolone and triterpenoids inhibited mucin secretion from airway epithelial cells

This study investigated whether carbenoxolone, oleanolic acid and ursolic acid affect ATP-induced mucin secretion from cultured airway epithelial cells. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled using (3)H-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on (3)H-mucin secretion. The possible cytotoxicity of each agent was investigated with a lactate dehydrogenase assay. The results were as follows: (1) carbenoxolone, oleanolic acid and ursolic acid significantly inhibited the secretion of airway mucin induced by ATP; (2) none of the compounds showed significant cytotoxicity at any concentration. This result suggests that carbenoxolone, oleanolic acid and ursolic acid can regulate 'mucin secretion induced by ATP'--phenomenon simulating mucus overproduction from inflamed airway epithelial cells--y directly acting on airway mucin-secreting cells.