Characterization of a receptor-negative, hormone-nonresponsive clone derived from a T47D human breast cancer cell line kept under estrogen-free conditions.

ABSTRACT

We have established an estrogen receptor- and progesterone receptor-negative, hormone-nonresponsive breast cancer cell line from a receptor-positive, hormone-responsive line grown under estrogen-free conditions. T47D breast cancer cells were cultured under estrogenized conditions (in phenol red-containing medium supplemented with whole fetal bovine serum) and cloned to produce line T47DA18. The parental T47D line was also estrogen deprived (in phenol red-free medium supplemented with dextran-coated charcoal-treated fetal bovine serum) for more than 1 year and subsequently clone T47DC4 was established. T47DA18 was estrogen receptor and progesterone receptor positive as determined by both ligand binding assay analysis and enzyme immunoassay analysis. T47DC4 cells were estrogen receptor and progesterone receptor negative and mRNA for these receptors was not detected. Incubation of hormone-responsive T47DA18 cells with 17 beta-estradiol caused a 3-fold increase in cell growth over 8 days when compared to control. This stimulation of growth was completely inhibited by the anti-estrogens 4-hydroxytamoxifen (0.1 microM) and ICI 164,384 (1.0 microM). Receptor-negative T47DC4 cells were refractory to the effects of both 17 beta-estradiol and the antiestrogens. T47DA18 cells grown under both estrogen-containing and estrogen-free conditions expressed low levels of transforming growth factor (TGF)-alpha and epidermal growth factor receptor mRNA. In the presence of estrogen, high levels of TGF-beta 1 mRNA were detected in T47DA18 cells. These levels decreased when T47DA18 cells were grown in estrogen-free media. Conversely, TGF-beta 2 mRNA was not detected in T47DA18 cells cultured under estrogenic conditions; however, message was detected after the cells were cultured under estrogen-free conditions. T47DC4 cells expressed low levels of TGF-alpha, epidermal growth factor receptor, TGF-beta 1, and TGF-beta 2 mRNA. These studies characterize a novel hormone-nonresponsive cell line which has been established from a hormone-responsive cell line grown under estrogen-free and drug-free conditions. Further analysis of these lines should provide valuable information concerning the development of antiestrogen-resistant breast cancer.