TRANSFORMING-GROWTH-FACTOR BETA-1 INCREASES THE EXPRESSIONS OF HIGH-MOLECULAR-WEIGHT TROPOMYOSIN ISOFORMS AND VINCULIN AND SUPPRESSES THE TRANSFORMED PHENOTYPES IN HUMAN LUNG-CARCINOMA CELLS

Exposure of the human lung carcinoma cell line, A549 cells, to transfo rming growth factor beta 1 (TGF beta 1) resulted in an alteration in t he morphology from epithelial-like to fibroblastic flat cells. Immunof luorescent study revealed that microfilament organization was partiall y restored in the TGF beta 1-treated cells. We also investigated the e ffects of TGF beta 1 on the transformed phenotypes including the ancho rage-independent growth and invasive ability of A549 cells and found t hat the phenotypes were strikingly suppressed in TGF beta 1-treated A5 49 cells. Accompanying these changes, the levels of the expression of high molecular weight tropomyosin (TM) isoforms, especially TM1 and TM 2, were significantly increased in the TGF beta 1-treated cells. The e xpression level of vinculin was also increased in these cells. These r esults suggest that the increased tropomyosin and vinculin syntheses m ay be involved in the suppression of the transformed phenotypes of A54 9 cells. (C) 1997 Elsevier Science Ireland Ltd.