ESTRONE FORMATION FROM DEHYDROEPIANDROSTERONE IN CULTURED HUMAN BREAST ADIPOSE STROMAL CELLS

The metabolism of dehydroepiandrosterone (DHA) and androstenedione (A- dione) was studied in cultured human adipose stromal cells obtained fr om breast tissue of six premenopausal patients undergoing reduction ma mmoplasty. Cells were maintained in culture in the presence of 10% fet al bovine serum. Studies were carried out during the proliferative and confluent phases of culture with radiolabelled substrates (2 mu Ci, 1 0 nM). During the early phases of replication 7 alpha-hydroxydehydroep iandrosterone (7 alpha-OHDHA) was formed from DHA. As the cells reache d confluence, the major metabolite of DHA in cells from all patients w as A-dione indicating the presence of 3 beta-hydroxysteroid dehydrogen ase/isomerase (3 beta-HSD). The conversion of DHA to A-dione was varia ble among patients when cells were confluent with 30-80% of substrate being metabolized to this product. Adipose stromal cells synthesized e strone (E(1)) from DHA once A-dione formation was established. Under b asal conditions E(1) was obtained in cells from three of the six patie nts examined with up to 36% substrate converted to this product. Dexam ethasone (Dex 10(-7) M) stimulated E(1) formation in cells from all su bjects with up to 50% of substrate being converted. Parallel studies c omparing the conversion of DHA with A-dione to E(1) revealed that as t he cells became confluent, E(1) formation from both substrates was sim ilar. The pattern of steroid metabolism was also examined in primary c ulture and in subculture. Passage 1 cells continued to form A-dione as a major metabolite of DHA, and did not revert to the pattern of metab olism found in primary cells during the early stages of replication, w hen 7 alpha-hydroxylation predominated. Human adipose stromal cells ac tively metabolize DHA, producing 7 alpha-OHDHA, A-dione and E(1) as pr incipal metabolites. Changes in the circulating levels of DHA may dire ctly influence the formation of E(1) in peripheral tissues. This sourc e of E(1) will be modulated by factors controlling 3 beta-HSD and arom atase activities.