Upregulation of AQP3 and AQP5 induced by dexamethasone and ambroxol in A549 cells.

Aquaporins (AQPs) are membrane channel proteins that play roles in the regulation of water permeability in many tissues. AQP1 and AQP5 expressed in lung provide the principal route for osmotically driven water transport. In the airways, AQP3 and AQP4 facilitate water transport. Dexamethasone and ambroxol are often used to treat patients with pulmonary diseases accompanied by airway hypersecretion. The role of AQPs in these effective treatments has not been addressed. In this study, we analyzed the expression of AQPs in a human airway epithelial cell line (A549 cells) and showed that AQP3 and 5, but not AQP1 and 4, were expressed in A549 cells. Both dexamethasone and ambroxol stimulated the expression of AQP3 and 5 at the mRNA and protein levels. The data suggest potential roles of AQP3 and 5 in the regulation of airway hypersecretion, perhaps ultimately providing a target for treating such diseases.