title: Suppressive effect of estrogen on hepatocellular tumorigenesis induced in mice by 3'-methyl-4-dimethylaminoazobenzene.
abstract: Treatment of female C57BL/6 x DS-F1 mice with 3'-methyl-4- dimethylaminoazobenzene (3'-Me-DAB) neonatally resulted in the development of hepatocellular adenomatous nodules. Ovariectomy at 1 month of age greatly hastened the time of appearance of these nodules and significantly increased their incidence. The incidence of adenomatous nodules in females ovariectomized at 1 month of age was about 70% at 12 months of age, and was decreased to 4% by implantation of a pellet containing estradiol-17 beta (E2 pellet) at 1 month of age (at the time of ovariectomy). The incidence of adenomatous nodules at 12 months of age was not decreased significantly when the implanted E2 pellet was removed at 4 or 6 months of age, but was decreased significantly when it was removed at 8 or 10 months of age. Implantation of E2 pellets into ovariectomized females at 4 and 6 months of age decreased the incidence of adenomatous nodules as effectively as their implantation at 1 month of age. The implantation of E2 pellets into ovariectomized females at 8 or 10 months of age resulted in significantly lower incidences of adenomatous nodules at 12 months of age, than that in females ovariectomized at 1 month of age. The present results suggest that the ovarian hormone, estrogen suppresses the development of hepatocellular tumors induced by 3'-Me-DAB, exerting its effect from about 6 months of age.
authors.affiliation: Department of Gastrointestinal Oncology, Center for Adult Diseases, Osaka, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Yamamoto
authors.forename: H
authors.initials: H
authors.lastname: Iishi
authors.forename: M
authors.initials: M
authors.lastname: Tatsuta
authors.forename: M
authors.initials: M
authors.lastname: Tsuji
authors.forename: N
authors.initials: N
authors.lastname: Terada
mesh_terms: D018248:Adenoma, Liver Cell / Q000139:chemically induced*; D000818:Animals; D004343:Drug Implants; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D008113:Liver Neoplasms / Q000139:chemically induced*; D008749:Methyldimethylaminoazobenzene / Q000037:antagonists & inhibitors*; D051379:Mice; D008810:Mice, Inbred C57BL; D010052:Ovariectomy; D010053:Ovary / Q000502:physiology*
chemical_list: D004343:Drug Implants; D004958:Estradiol; D008749:Methyldimethylaminoazobenzene