title: Dose-dependent effect of 17 beta-estradiol determined by growth curves and flow cytometric DNA analysis of a human breast carcinoma (T61) grown in nude mice.
abstract: An estrogen and progesterone receptor-positive human breast carcinoma (T61) grown in nude mice was exposed to 1.0, 0.1, 0.01, and 0.001 mg 17 beta-estradiol. These doses resulted in serum peak concentrations (day 1) of estradiol ranging from 3.5 X 10(-8) to 6.9 X 10(-10) M. The effect of the treatment was evaluated using growth curves and flow cytometric DNA analysis. The treatment induced a dose-dependent growth delay and dose-dependent changes in the cell cycle distribution. The cell cycle changes comprised a decrease in the G1 phase, an accumulation of cells in the S phase, and an increasing fraction of polyploid cells. The results suggest that estradiol induces a dose-dependent cell killing effect in the T61 human breast carcinoma. The correlation between the treatment-induced growth delay and the effect on the cell cycle distribution indicates that the changes in the cell cycle are a reflection of the estradiol-induced cell destruction. Since no tumor growth stimulation could be observed even at very low serum estradiol concentrations, the T61 human breast carcinoma may represent a new aspect in the study of human breast cancer.
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects*; D004247:DNA / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000097:blood / Q000494:pharmacology*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D008875:Middle Aged
chemical_list: D004958:Estradiol; D004247:DNA