Effects of various growth factors on growth of a cloned human esophageal squamous cancer cell line in a protein-free medium.

In order to investigate molecular mechanisms of the growth of human esophageal cancer in relation to growth factors, we have recently established a protein-free culture system [Ham's F-12: Eagle's minimum essential medium (1:1, v/v)] of TE-3-OS cells (a cloned cell line from human esophageal squamous cancer, TE-3). In the present study, we first examined effects of exogenous growth factors on the growth of TE-3-OS cells. The growth of TE-3-OS cells in the protein-free medium was significantly stimulated by insulin and insulin-like growth factor (IGF)-I or IGF-II, and less effectively stimulated by epidermal growth factor (EGF) or transforming growth factor (TGF)-alpha; platelet-derived growth factor, TFG-beta, acidic fibroblast growth factor (FGF) or basic FGF had no effects. TE-3-OS cells contained specific IGF-I binding sites (110,000 sites/cell), with a Kd value of 800 pM. Moreover, the growth induced by IGF-I, IGF-II or insulin was markedly and similarly (70-80%) inhibited by anti-IGF-I receptor antibody IgG. These data suggest that IGF-I, IGF-II and insulin, as well as EGF and TGF-alpha, are important mitogens for human esophageal cancer cells and that effects of IGFs and insulin are mediated predominantly via IGF-I receptors.