In-vitro growth promotion of human mammary carcinoma cells by steroidal hormones, tamoxifen and prolactin

ABSTRACT-Individually different growth responses of 10 cell lines newly derived from metastasizing mammary carcinomas were determined by cell counts in experimental incubations with the steroid hormones 17,B-estradiol, progesterone, testosterone, hydrocortisone (cortisol), the antiestrogenic compound tam-oxifen, or prolactin. Of 7 cell lines derived from ductal carcinomas, 5 were stimulated by prolactin. The growth of 4 of 7 cell lines established from the tumors of postmenopausal or ovariectomized patients was enhanced by doses of testosterone, which are in the range of the physiologic serum level. The proliferation of 5 cell lines was promoted by hydrocortisone in the physiologic concen-tration of 100 nM, supporting the notion that concentrations of testosterone or hydrocortisone normally present in body fluids may facilitate the in vivo growth of breast cancer. The in vitro growth of cells derived from tumors after relapse under treatmen