Metabolism of 7,12-dimethylbenz[a]anthracene by mouse mammary cells in serum-free organ culture medium.

The murine mammary gland is a prime target organ for 7,12-dimethylbenz[a]anthracene, (DMBA)-induced carcinogenesis. We analyzed the metabolism of 3H-DMBA in a cell-free microsomal activation system derived from mouse mammary microsomes and in a whole mammary organs in culture. The in vitro microsomal activation system failed to show the more polar diol derivative of DMBA after HPLC. The metabolites obtained directly from the 3H-DMBA-treated whole mammary organs, however, revealed the presence of both the diol as well as the phenolic derivatives of DMBA. Analysis of the glands and the culture medium further showed that nearly 95% of the radioactivity added to the culture medium was associated with the adipose tissue and complete solubilization of the fat pad released substantial amounts of DMBA and its metabolites. It appears that a large portion of DMBA and its metabolites remain entrapped in the adipose tissue surrounding the parenchyma. Formic acid digestion of the gland releases the DMBA and the metabolites allowing their ethylacetate extraction, and HPLC characterization.