CALU-3 - A HUMAN AIRWAY EPITHELIAL-CELL LINE THAT SHOWS CAMP-DEPENDENT CL- SECRETION

Of 12 cell lines derived from human lung cancers, only Calu-3 cells showed high transepithelial resistance (R(te)) and increases in short-circuit current (I-sc) in response to mediators. Calu-3 cells formed polarized monolayers with tight junctions and R(te) of similar to 100 Omega.cm(2). Baseline I-sc was similar to 35 mu A/cm(2) and was increased by similar to 75 mu A/cm(2) on elevation of intracellular adenosine 3',5'-cyclic monophosphate (cAMP) by isoproterenol. Flux studies showed that the increase in I-sc was due to Cl- secretion. Forskolin and permeant analogues of cAMP also increased I-sc. Consistent with the presence of cAMP-dependent Cl- secretion, immunoprecipitation demonstrated the presence of the cystic fibrosis transmembrane conductance regulator (CFTR). Bradykinin, methacholine, trypsin, and histamine all transiently (15-30 s) elevated I-sc, probably by increasing intracellular Ca concentration. Experiments in which the basolateral membrane was permeabilized with nystatin indicated that CFTR was substantially activated under baseline conditions and that Ca-activated Cl- channels were absent from the apical membrane. We anticipate that Calu-3 cells will prove useful in the study of Cl- secretion and other functions of human airway epithelial cells.