109 INDUCTION OF DIFFERENTIATION OF A549 HUMAN ALVEOLAR TUMOR CELLS BY BASEMENT MEMBRANE

Abstract

A 549 tumor cells may be of type II cell origin, but do not synthesize surfactant under normal conditions. We cultured this cell line either on tissue culture-treated plastic or on top of an extracellular matrix, obtained from the Englebreth-Holm-Swarm (EHS) tumor. We found that cells cultured on EHS matrix synthesized surfactant protein A (SP-A) as shown by Western blot and by slot blot hybridization with an SP-A cDNA probe (n=5). Compared to cells cultured on plastic, cells cultured on EHS for 3-5 days also contained a higher percentage of 16:0-16:0 phosphatidylcholine (10 vs. 2 %, n=2) and incorporated more 3H-glycerol into this lipid species (10 vs. 2.8 %, n=2). On EHS matrix, the cells became cuboidal, and formed alveoli-like spherical structures surrounding a closed lumen. Also, cell division rate was reduced on basement membrane-type matrix. These results suggest that culture on basement membrane induces expression of type II pneumocyte-specific properties in human A549 cells. This culture model may allow a better understanding of the mechanisms by which cell-extracellular matrix interactions modulate specific gene expression. Supported by DFG Ste 459/1-1.