Long-term cultivation of a human breast cancer cell line, MCF-7, in a chemically defined medium. Effect of estradiol

The human breast cancer cell line, MCF-7, has been adapted to long-term growth in chemically defined medium without loss of estrogen and progesterone receptors or tumorigenicity in athymic mice. An estrogen reversible inhibition of cell proliferation is exerted by newborn calf serum (NCS) 10%, athymic mouse serum (AMS) 2% or tamoxifen 0.1 to 1.0 microM. The mamma-related hormones, hydrocortisone, progesterone, prolactin, and insulin could not mimic this growth inhibitory effect, and estradiol alone or combined with these hormones did not stimulate cell proliferation in chemically defined medium.