Growth stimulation of human breast epithelial cells by basic fibroblast growth factor in serum-free medium

Growth-stimulating activities of basic and acidic fibroblast growth factors (FGFs) toward human breast epithelial cells were examined and compared with the mitogenic activity of bovine pituitary extract (BPE) by the use of a serum-free medium which contained epidermal growth factor, insulin, transferrin, hydrocortisone, ethanolamine, phosphoethanolamine, prolactin and prostaglandin. Addition of 1 ng/ml of basic FGF (bFGF) to the serum-free medium significantly enhanced the growth potential of epithelial cells derived from human breast carcinoma, and the number of cells grown for 7 days with bFGF was more than 1 1/2 times higher than that in the serum-free medium containing BPE instead of prolactin and prostaglandin. Growth responsiveness toward bFGF of epithelial cells derived from histologically non-malignant breast tissues was lower than that of carcinoma-derived cells, and the growth-stimulating activity of bFGF was lower than that of BPE, which could significantly enhance the growth potential of the cells. Contrary to bFGF, acidic FGF at 1 ng/ml had no significant effect on the growth potential of breast epithelial cells which had grown out from either carcinoma or non-malignant tissues. The present results suggest that bFGF is a putative growth-stimulating factor for human breast epithelial cells, especially for carcinoma-derived cells, and can substitute at least in part for BPE in serum-free monolayer culture of the cells.