Human T47D-ERß breast cancer cells with tetracycline-dependent ERß expression reflect ERα/ERß ratios in rat and human breast tissue.

T47D-ERß breast cancer cells with tetracycline-dependent ERß expression and constant ERα expression can be used to investigate effects of varying ERα/ERß ratios on estrogen-induced cellular responses. This study defines conditions at which ERα/ERß ratios in T47D-ERß cells best mimic ERα/ERß ratios in breast and other estrogen-sensitive tissues in vivo in rat as well as in human. Protein and mRNA levels of ERα and ERß were analyzed in T47D-ERß cells exposed to a range of tetracycline concentrations and compared to ERα and ERß levels found in breast, prostate, and uterus from rat and human origin. The ERα/ERß ratio in T47D-ERß cells exposed to >150ng/ml tetracycline is comparable to the ratio found in rat mammary gland and in human breast tissue. The ERα/ERß ratio of other estrogen-sensitive rat and human tissues can also be mimicked in T47D-ERß cells. The ERα/ERß ratio found in MCF-7 and native T47D breast cancer cell lines did not reflect ratios in analyzed rat and human tissues, which further supports the use of T47D-ERß cells as model for estrogen-responsive tissues. Using 17ß-estradiol and the T47D-ERß cells under the conditions defined to mimic various tissues it could be demonstrated how these different tissues vary in their proliferative response.