Molecular analysis of rat mammary carcinogenesis: an approach from carcinogenesis research to cancer prevention

A rat strain carrying the human c-Ha- ras proto-oncogene is highly susceptible to chemically induced mammary carcinogenesis. All the transgenic rats develop preneoplastic mammary lesions within 20 days of an injection of N -methyl- N -nitrosourea, and mammary carcinomas appear within 8 weeks of treatment with a variety of chemical carcinogens. In this review, we summarize molecular aspects of mammary carcinogenesis in transgenic rats and the potential application of this model for studies of breast cancer prevention.