Oestradiol, vasoactive intestinal peptide and fibroblast growth factor in the growth of human pituitary tumour cells in vitro

The growth of two human prolactin-secreting cell lines developed in our laboratory has been investigated in response to a number of factors. Oestrogen stimulated the synthesis of DNA and protein and increased prolactin secretion. Dexamethasone had the opposite effect to oestrogen. In the presence of serum, epidermal growth factor (EGF) inhibited cell growth at concentrations of 5 ng/ml. Known secretagogues of prolactin (vasoactive intestinal peptide (VIP), TRH, bombesin and neurotensin) were investigated for their action on cell growth but only VIP had a stimulatory effect. Two preparations of fibroblast growth factor (FGF) were studied. One form, derived from bovine pituitary glands, stimulated human pituitary cell growth. In contrast, another FGF, of the basic type (rFGF), was inhibitory to cell growth, increasing the time for cell doubling from 30 to 72 h. This inhibitory effect of rFGF was modified but not abolished by serum, oestradiol, platelet-derived growth factor or EGF. We conclude that bovine pituitary contains at least two fibroblast growth factors, both of which stimulate fibroblast cell growth, but one stimulates and the other inhibits human pituitary tumour cell growth.