[Molecular mechanisms of sex steroid-induced growth of cancer cells].

Recent studies have suggested that the growth of sex steroid-dependent cancer is mediated through sex steroid-induced growth factors in an autocrine manner. In order to prove the hypothesis, estrogen-responsive human breast cancer cell lines such as MCF-7 have been used by many investigations. However, these studies have been unable to prove the hypothesis, since estrogen-dependent growth system in serum-free medium could not be established. We established in 1987 an androgen-dependent growth system in a serum-free medium using androgen-dependent mouse mammary cancer cells (SC-3). By use of this androgen-dependent growth system in serum-free medium, we could demonstrate that androgen-dependent growth of SC-3 cells is mediated via an androgen-induced new growth factor in fibroblast growth factor (FGF) family (AIGF; 8th member of FGF family) in an autocrine mechanism.