Polycyclic hydrocarbon activation and metabolism in epithelial cell aggregates prepared from human mammary tissue

The metabolism of benz(a)anthracene (BA), 7,12-dimethylbenz(a)anthracene (DMBA) and benzo(a)pyrene (BP) by human mammary epithelial cell aggregates in culture has been investigated using non-neoplastic tissues obtained from eight patients undergoing reduction mammoplasty. All three hydrocarbons were metabolized to water-soluble and organic solvent-soluble products and the latter included both K-region and non-K-region dihydrodiols. The major dihydrodiols detected as metabolites of the parent hydrocarbons were the 8,9-dihydrodiols of BA and DMBA and the 9,10-dihydrodiol of BP. The 1,2-dihydrodiols of BA and DMBA and the 11,12-dihydrodiol of BP were not detected. The hydrocarbons also became bound to the proteins and DNA of the epithelial cells but there were wide differences in the extents of binding occurring with the different hydrocarbons and in the extents of metabolism and binding occurring with tissue preparations from different patients. Some of the hydrocarbon-deoxyribonucleoside adducts formed from DMBA and BP appeared to have arisen through reactions of "bay-region" diol-epoxides with DNA, but only very low levels of reaction with DNA were detected in tissue preparations treated with BA.