Initiation, promotion and complete carcinogenesis by N-methyl- N′-nitro- N-nitrosoguanidine or ethylnitrosourea in the Sencar mouse skin tumorigenesis model

Abstract

Five doses of either N-methyl- N′-nitro- N-nitrosoguanidine (MNNG) or ethylnitrosourea (ENU) were tested as complete carcinogens, tumor initiators and tumor promoters in the SENCAR skin tumorigenesis model. As tumor initiators, MNNG-induced papillomas at all doses tested, while ENU was active from 10–40 μmol. As complete carcinogens, MNNG from doses of 0.5–5.0 μmol and ENU from doses of 10 μmol–40 μmol were potent inducers of both papillomas and carcinomas indicating that these agents are active as both tumor initiators and tumor promoters.