Synergistic tumor promoter effects of estrone and progesterone in methylnitrosourea-induced rat mammary cancer.
Tumor promoter effects of steroid hormones were tested in ovariectomized rats treated with the tumor initiator, methylnitrosourea. Continuous treatment with low doses of estrone induced tumor in 55% of experimental animals while intact control animals had a 96-100% incidence. Although progesterone alone produced no tumors in ovariectomized, methylnitrosourea-treated animals, estrone and progesterone acted synergistically, inducing tumorigenesis in 88% of treated rats. These results point to an important interaction between estrogens and progestins in promoting mammary tumorigenesis.
Bigsby
Robert M
RM
Department of Obstetrics and Gynecology, Indiana University School of Medicine, 975 West Walnut Street (IB360), Indianapolis, IN 46202, USA. rbigsby@iupui.edu
D000477:Alkylating Agents / Q000633:toxicity*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004357:Drug Synergism; D004970:Estrone / Q000494:pharmacology*; D005260:Female; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000473:pathology; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000473:pathology*; D008770:Methylnitrosourea / Q000633:toxicity*; D009929:Organ Size / Q000187:drug effects; D010052:Ovariectomy; D010902:Pituitary Gland / Q000187:drug effects / Q000254:growth & development; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014599:Uterus / Q000187:drug effects / Q000254:growth & development
D000477:Alkylating Agents; D004970:Estrone; D011374:Progesterone; D008770:Methylnitrosourea