Production of acidic and basic fibroblast growth factor by the hormone-independent breast cancer cell line MDA-MB-231.

Normal, as well as the majority of malignant, mammary epithelial cells will proliferate upon stimulation by FGFs. However estrogen-independent MDA-MB-231 cells (which are able to grow in vitro in serum-free medium) are not significantly stimulated by exogenous FGFs even though they possess high and low affinity receptors for these growth factors. Biological assays, measuring CCL39 fibroblast proliferation or PC12 pheochromocytoma cell neurite outgrowth, demonstrated the presence of FGF activity in MDA-MB-231 cell extracts and also in the culture medium conditioned by these cells. This biological activity decreased in the presence of neutralizing anti-FGF antibodies. Using immunohistochemical methods FGF1 and FGF2 immunoreactivity was detected in MDA-MB-231 cells. After purification by heparin-Sepharose chromatography and Western blot analysis, M(r) 18000 molecules showed the same physicochemical characteristics as FGFI and FGF2. These results demonstrate the production and release of FGF related molecules by MDA-MB-231 cells and suggest an autocrine stimulation of these cells.