Respiratory carcinoma cell lines - MUC genes and glycoconjugates

Lung carcinoma cell lines are being used in many laboratories to study vari ous airway epithelial functions, including mucin gene expression. To identi fy model systems for investigating regulation of MUC5/5AC gene expression a nd secretion of MUC5/5AC mucins in airway epithelial cells, we evaluated th e expression of several mucin genes in six carcinoma cell lines of respirat ory tract origin. RNA was extracted from A549, Calu-3, NCI H292. Calu-6, RP MI 2650, and A-427 cells; MUC1, MUC2, MUC4, MUC5/5AC, and MUC5B messenger R NA (mRNA) expression was determined. By Northern analyses, all cell lines e xpressed MUC1 mRNA, whereas MUC2 mRNA was not detectable in any of the cell lines. RPMI 2650 cell lines expressed only MUC1 mRNA. NCI-H292 cells expre ssed MUC4 and low levels of MUC5/5AC mRNA. Calu-3 and A549 cells expressed MUC5/5AC mRNA, A549 cells also expressed MUC5B mRNA. Glycoconjugates secret ed by lung carcinoma cells were also examined. By wheat germ lectin analysi s, Calu-3, H292, and A549 cells secreted high molecular weight glycoprotein s having N-acetylglucosamine and/or sialic acid moieties, Western blot anal yses with an anti-MUC5:TR-3A antibody demonstrated that Calu-3 and A549 cel ls secreted MUC5/5AC mucins. All six carcinoma cell lines secreted large, r adiolabeled, sulfated macromolecules; the majority were proteoglycans that were digested by hyaluronidase. However, Calu-3 cells also secreted sulfate d high molecular-weight glycoproteins that were immunoprecipitated by anti- MUC5:TR-3A antibody. These studies demonstrated that Calu-3 and A549 cell L ines expressed high and moderate amounts of MUC5/5AC mRNA and MUC5/5AC muci ns, whereas H292 cells expressed lesser amounts. These cell lines should pr ove useful for studies of MUC5/5AC gene expression and MUC5/5AC biosynthesi s, trafficking, and secretions in airway epithelial cells.