title: The carcinogenicity of 15,16-dihydro-11-methyl-cyclopenta[a]phenanthren-17-one.
abstract: Direct comparison of skin-tumour induction by 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one (I) and by benzo[a]pyrene on mouse skin, both by repeated application or by initiation with a single dose followed by promotion with croton oil, demonstrated that these two carcinogens have similar potency. After repeated application of (I) the mean latent period for skin-tumour induction was linearly related to the logarithm of the dose over a 10-fold dose range. Under these conditions, application of the aryl-hydrocarbon-hydroxylase inhibitor 7,8-benzoflavone together with (I) inhibited tumour induction by about 40%. By contrast, in the 2-stage experiment, little effect on tumour incidence or latent period was observed when this inhibitor was applied with the single initiating dose of (I). Co-administration of the epoxide-hydratase inhibitor 1,1,1-trichloropropene oxide caused enhancement by shortening the latent period. After s.c. injection of (I) into mice, a similar number of tumours was induced on skin remote from the site of injection by promotion with corton oil begun either one week or 6 months after initiation. Gastric instillation of (I) into female rats induced mammary adenocarcinomas.
mesh_terms: D000818:Animals; D001580:Benzopyrenes / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D005260:Female; D006067:Gonanes / Q000633:toxicity*; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced; D051379:Mice; D051381:Rats; D012878:Skin Neoplasms / Q000139:chemically induced*
chemical_list: D001580:Benzopyrenes; D006067:Gonanes; C005765:15,16-dihydro-11-methylcyclopenta(a)phenanthren-17-one