Stroma is not a major target in DMBA-mediated tumorigenesis of mouse mammary preneoplasia.

Carcinogenesis in the mammary gland is thought to involve carcinogen-induced initiation in mammary epithelial cells. Recent experiments have demonstrated that the mammary stroma can be a target of carcinogenic agents, which results in the stroma positively affecting carcinogenesis. To determine whether the stroma or epithelium is the primary target in chemically induced mouse mammary tumorigenesis, we used transplantation of untreated or 7,12-dimethylbenzanthracene (DMBA)-treated immortalized preneoplastic mammary cells into untreated or DMBA-treated stroma. The results demonstrate that the chemical-carcinogen treated stroma did not enhance mammary tumorigenesis in this model and that carcinogen treatment of the mammary epithelium was essential for tumorigenesis.