Stimulatory effects of androgen and antiandrogen on the in vitro proliferation of human mammary carcinoma cells.

The proliferation of three mammary carcinoma cell lines was explored for the effectiveness of dihydrotestosterone (DHT) and the antiandrogenic substances cyproterone acetate (CPA) or hydroxyflutamide. The cell growth, determined in multiple experimental cultures of the estrogen-sensitive lines MCF-7 and EFM-19, was stimulated by 10(-9) M to 10(-6) M DHT, whereas estrogen-resistant MFM-21 cells were unresponsive to the hormonal factors applied. Growth-promoting effects of 10(-8) M to 10(-6) M CPA were detected in cultures of those cell lines which were sensitive to estrogen and androgen. Competition experiments with DHT and the antiandrogens suggested involvement of the androgen receptor in the stimulation of cell growth by CPA. Participation of the estrogen receptor was excluded by lack of competition between CPA and the enhancement of proliferation by estradiol-17 beta. At the receptor level the antiandrogens were able to compete with androgen binding. The results of the study demonstrate androgenic properties of CPA in regard to the growth of human mammary carcinoma cells.