Mitogenic and dedifferentiating effect of the K-fgf/hst oncogene on rat thyroid PC clone 3 epithelial cells.

Transfection of rat thyroid differentiated epithelial cells, PC clone 3, with the K-fgf/hst oncogene results in alleviation of thyrotropin dependency for growth and suppression of the differentiated phenotype without the acquisition of the fully transformed phenotype. An autocrine mechanism is responsible for these effects, since the proliferation of PC clone 3 cells, induced by K-FGF-conditioned medium, is blocked by anti-K-FGF-specific antibodies. Moreover, addition of K-FGF-conditioned medium inhibits the thyroid differentiated functions. Also, such other members of the fibroblast growth factor family as basic and acidic fibroblast growth factor are able to induce thyroid cell growth and to block expression of the differentiated functions.