Increased resistance to transforming growth factor beta accompanies neoplastic progression of rat tracheal epithelial cells

Transforming growth factor beta (TGF/3) is an inhibitor of normal epithelial cell growth. To investigate the role of TGF/3 in respiratory epithelial cell neoplasia, normal, preneoplastic, tumorigenk and tumor-derived rat tracheal epithelial (RTE) cells were plated in serum-free medium and grown in the presence of 0-300 pg TGFfr/ml. TGF/3, markedly inhibited the formation of colonies by primary RTE cells and some pre-neoplastic RTE cells. However, tumor-derived RTE cells were relatively resistant to TGF^-induced growth inhibition. Resistance to TGF/Srinduced growth inhibition, therefore, accompanies neoplastic progression of RTE cells