The human breast cancer cell line MDA-MB231 produces an aromatase stimulating activity

Extraovarian estrogen production is localized mainly in stromal vascular cells from adipose tissue, which contain the aromatase activity necessary for the conversion of androgens to estrogens. Induction of aromatase activity in these cells by glucocorticoids occurs only in the presence of a serum factor, the properties and origin of which are unknown (serum-derived aromatase stimulating activity, serum-ASA). Cells of the breast cancer line MDA-MB231 produce a factor resembling serum-ASA, as it is able to completely replace serum during the induction of aromatase by glucocorticoids. MDA-MB231-derived ASA is destroyed by proteolytic digestion and is purified about 100-fold by ultrafiltration of MDA-MB231 conditioned media and anion exchange chromatography.