Chemical carcinogen activation in the rat mammary gland: intra-organ cell specificity.

Cells from 50-55 day old virgin Sprague-Dawley female rat mammary gland were divided into parenchymal (epithelial) and stromal enriched populations. The ability of these cells to activate carcinogens was quantitated employing a mediated mutagenesis assay. In addition, the populations' ability to produce water soluble metabolites from these carcinogens was estimated. We report that the potent mammary carcinogen 7,12-dimethylbenz[a]anthracene was activated by both mammary parenchymal and stromal cells, while the non-mammary carcinogen aflatoxin B1 was not activated by either cell type. However, the weak mammary carcinogen benzo[a]pyrene was activated by the stromal cells and not by the parenchymal cells from which mammary carcinomas arise. The data suggest that the intra-organ relationship between cell types that activate a carcinogen, and cell types that undergo neoplastic transformation, may in part help explain the organ specific potency of a carcinogen.