194 Blochimica et Biophysica Acta, 970 (1988) 194-204 Elsevier BBA 12272 Differential effects of glucocorticoid on expression of surfactant proteins in a human lung adenocarcinoma cell line Michael A. O'Reilly, Adi F. Gazdar *, Randal E. Morxi~ ** and Jeffrey A. Whitsett Univc .ff of Cincinnati Collegeof Medicine, Department of Pediatrics, Division of Neonatology, Cincinnati, OH (U.S.A.) (Received20 October 1987) (Revisedmanuscript rc.ceived 15 March 1988) Key words: Pulmonary~urfactant; Corticosteroid;(3erieexpression;(Human lung) Synthesis of pulmonary surfactant.assodated 81ycoprotelns of Mr 28~0-36~0 (SPA) and M r 42000-46000 (proSP-B) has been identified in a continuous cell llne derived from a human lung adenocardnoma. SP.A was dete~4ed by immunoblot analysis, ELISA assay and by I~Slmethlonlne labelling of the cells. SPA was secreted into tile media as an endoglycosldase F sensitive glycoprotein which co-migrated with the isoforms of SPA identified in human lavage fluid by 2D-IEF-SDS-PAGE. Hybridiza- tion of cellular RNA with SP-A-spedfic eDNA identified an ulmndant 2.2 kb mRNA spedes, identical to that observed in human lung. SPA RNA ana protein content were markedly inhibited by dexamethasone in a dose-dependent fashion. Under identical culture conditions, synthesis of a distinct sm~aetent protein, SP-B, was markedly stimulated by the 81ueoeorlicoid. The SP-B preeorsor was secreted into the media as heterogenous Mr 42000-46000 protein, pl 4.6-5.1, and was sensitive to endoglyeosidase F. Synthesis d proSP.B was enhanced by the glucocorticoid in a dose-dependent fashion and was associated wifl, h~reay..~ql SP-B mRNA of 2.0 kb detected by Northern blot analysis. The tell line secreted proSP.B as M, 42000-46000 glycosylated protein and did not process the precursor to the M, 7000-8000 sudamat peptlde. In summary, a human adenocarcinoum cell line has been identilied which synthesizes and secretes two surfactant-associated proteins, SPA and proSP-B. Glucocorticoid enhanced SP-B but inhibited SPA expression in this cell line. The identification of a continuous cell line secreting smfactant proteins may be useful in the study of synthesis and secretion of these important proteins and for production of the proteills for clinical uses. InU'oduction Pulmonary surfactant is a lipoprotein complex which is synthesized and secreted into alveofi of the lung by Type II epithelial cells. Phospholipids comprise the major component of surfactant; however, several surfactant proteins have been recently identified which confer important bio- * Present address: National Cancer Institute, Bethesda, MD, U.S.A. * * Present address: Department of Anatomyand Cell Biology at the University of Cincinnati Co!!ege of Medicine, Cincinnati, OH, U.S.A. Abbreviations: SP-A, surfactant-associated protein (Mr 280G0-36000); SP-B, surfactant proteolipid (M 7500) with amino terminus phenylalanine (SPL(Phe)); 2D-1EF-SDS- PAGE, two-dimensional isoelectric focusing ~,~h,.~ dodecyl sulfate polyacrylamide gel electrophoresis;NEPHGE, nonequi- librium pH gradient electrophoresis. Correspondence: J.A. Whltsett, University of Cincinnati, Col- lege of Medicine, Department of Pediatrics, Division of Neonatology, 231 Bethesda Avenue, Cincinnati, OH 45267- 0541, U.S.A. 01674889/88/$03.50 © 1988 ElsevierSciencePublishers B.V. (BiomedicalDivision)