EFFECT OF SERUM-ALBUMIN ON ESTROGEN METABOLISM IN HUMAN CANCER CELL-LINES

The observation that charcoal-treated fetal bovine serum (ctFBS) was a ble to modify one of main pathways of estrogens in cancer cells in cul ture, prompted us to initiate the present study. The active component of serum was isolated using native preparative polyacrylamide gel elec trophoresis (PAGE). Under analysis with SDS-PAGE, a M(w) of 68 kDa and mobility of authentic bovine serum albumin (BSA) was observed. The ad dition of BSA to the serum free culture medium of HEC 1A human endomet rial cancer cell line, resulted in an alteration of estradiol (E(2)) m etabolism similar to that observed in the presence of ctFBS. BSA in fa ct: much enhanced 16 alpha-hydroxylation and significantly reduced 2-h ydroxylation of E(2) in HEC 1A cells. Comparable results were obtained with different endometrial (Ishikawa) and mammary (MCF-7) tumor cell lines having a different metabolic conversion rate of E(2). Several al bumin preparations from either bovine or human serum had the same effe ct; besides, BSA activity was unaffected by treatment with dextran-cha rcoal or heat. In the light of the present results, the inclusion of s erum albumin (SA) in the formulation of media for studies evaluating s teroid metabolism in cultured cells should be carefully considered.