MUC5B Production Is Unaffected by Akt Inhibition in Human Lung Epithelial NCI-H292 Cells

In the human airway, the gelforming mucin subtypes MUC5B and MUC5AC play important roles in biophylaxis. However, the regulation of MUC5B production is less clear than that of MUC5AC. Therefore, the regulation of MUC5B production by cell attachment and Akt was investigated in human lung epithelial NCI-H292 cells. We found that low cell attachment to culture plates induced the upregulated production of both MUC5B and MUC5AC. Cell attachment induces the activation of Akt, a serine/threonine kinase. Cell treatment with Akt inhibitor I decreased Akt phosphorylation and activation. However, MUC5B production was unaffected by Akt inhibition, whereas MUC5AC production was upregulated. MUC5B production was also unaffected by Akt inhibition in cells cultured on type IV collagen or fibronectin. These results suggest that the production of both MUC5B and MUC5AC is regulated by cell attachment. However, the regulation of MUC5B is unaffected by Akt inhibition, in contrast to that of MUC5AC.