Activation of related transforming genes in mouse and human mammary carcinomas.

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Abstract
High MW DNA of 5 tumors induced by mouse mammary tumor virus (MMTV), 2 mouse mammary tumors induced by a chemical carcinogen and 1 human mammary tumor cell line (MCF-7) were assayed for the presence of transmissible activated transforming genes by transfection of NIH 3T3 mouse cells. DNA of all 5 MMTV-induced tumors, 1 chemical carcinogen-induced tumor and the human tumor cell line induced transformation with high efficiencies (.apprxeq. 0.2 transformant/.mu.g DNA). NIH cells transformed by DNA of MMTV-induced tumors did not contain exogenous MMTV DNA sequences, indicating that MMTV-induced mammary carcinomas contained activated cellular transforming genes that were not linked to viral DNA. The transforming activities of DNA of all 5 MMTV-induced tumors, the chemical carcinogen-induced mouse tumor and the human tumor cell line were inactivated by digestion with the restriction endonucleases PvuII and SacI, but not by BamHI, EcoRI, HindIII, KpnI or XhoI. The same or closely related transforming genes were activated in 6 different mouse mammary carcinomas, induced by either MMTV or a chemical carcinogen, and in a human mammary carcinoma cell line.