Synergistic tumor promoter effects of estrone and progesterone in methylnitrosourea-induced rat mammary cancer

Cancer Lett. 2002 May 28;179(2):113-9. doi: 10.1016/s0304-3835(02)00032-0.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alkylating Agents / toxicity*
  • Animals
  • Body Weight / drug effects
  • Drug Synergism
  • Estrone / pharmacology*
  • Female
  • Mammary Glands, Animal / drug effects
  • Mammary Glands, Animal / pathology
  • Mammary Neoplasms, Experimental / chemically induced
  • Mammary Neoplasms, Experimental / pathology*
  • Methylnitrosourea / toxicity*
  • Organ Size / drug effects
  • Ovariectomy
  • Pituitary Gland / drug effects
  • Pituitary Gland / growth & development
  • Progesterone / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Time Factors
  • Uterus / drug effects
  • Uterus / growth & development

Substances

  • Alkylating Agents
  • Estrone
  • Progesterone
  • Methylnitrosourea