EXPRESSION OF TRANSFORMING GROWTH-FACTOR-BETA (TGF-BETA) RECEPTORS AND EXPRESSION OF TGF-BETA-1, TGF-BETA-2 AND TGF-BETA-3 IN HUMAN SMALL-CELL LUNG-CANCER CELL-LINES

A panel of 21 small cell lung cancer cell (SCLC) lines were examined for the presence of Transforming growth factor beta receptors (TGFbeta-r) and the expression of TGFbeta mRNAs. By the radioreceptor assay we found high affinity receptors to be expressed in six cell lines. scatchard analysis of the binding data demonstrated that the cells bound between 4.5 and 27.5 fmol mg-1 protein with a K(D) ranging from 16 to 40 pM. TGFbeta1 binding to the receptors was confirmed by cross-linking TGFbeta1 to the TGFbeta-r. Three classes of TGFbeta-r were demonstrated, type I and type II receptors with M(r) = 65,000 and 90,000 and the betaglycan (type III) with M(r) = 280,000. Northern blotting showed expression of TGFbeta1 mRNA in ten, TGFbeta2 mRNA in two and TGFbeta3 mRNA in seven cell lines. Our results provide, for the first time, evidence that a large proportion of a broad panel of SCLC cell lines express TGFbeta-receptors and also produce TGFbeta mRNAs.