Establishment of pharmacological doses of estrogen-dependent mammary tumors with estrogen and progesterone receptors.

A new mammary carcinoma (TF15) which was derived from ovary-dependent mammary carcinoma (TF4) and which was dependent on pharmacological doses of estrogen was established. TF15 grew well in ovariectomized rats given injections of 1mg 17 beta-estradiol but not in intact or ovariectomized rats with injections of 0,1, 10 or 100 micrograms 17 beta-estradiol. TF15 was found to be a secretory carcinoma and contained estrogen and progesterone receptors. In general, pharmacological doses of estrogen inhibit the growth of mammary carcinomas with estrogen receptors (ER) and progesterone receptors (PgR) in humans and animals whether they are ovary-dependent or not (1-10). Recently, we obtained mammary carcinomas which are dependent on pharmacological doses of estrogen by subcutaneous implantation of explants from ovary-dependent mammary carcinomas (TF4) in female rats after ovariectomy and injections of low doses of estrogen. In the present paper, the biological, biochemical and morphological characteristics of these carcinomas are reported.