TRANSFORMATION OF ESTRONE AND ESTRADIOL IN HORMONE-DEPENDENT AND HORMONE-INDEPENDENT HUMAN BREAST-CANCER CELLS - EFFECTS OF THE ANTIESTROGEN ICI-164,384, DANAZOL, AND PROMEGESTONE (R-5020)

Using different hormone-dependent (MCF-7, T-47D) and hormone-independe nt (MDA-MB-231, Hs-578S, MDA-MB-436) human breast cancer cells, the in terconversion estrone (E(1)) reversible arrow estradiol (E(2)) was exp lored. The data show very clearly that in the hormone-dependent cells the tendency is to form E(2) after incubation with E(1), whereas after incubation with E(2) most of this estrogen cells, in contrast most of E(1) remains E(1), while E(2) is converted into E(1). The tendency of the reductive reversible arrow oxidative direction is supported by th e analysis of estrogens in the culture medium. To explore the possible action of different drugs on the 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity, it was observed that the potent antiestrogen ICI 164,384 inhibits the conversion of E(1) to E(2), while a lesser ef fect is observed with Danazol and only weak inhibition is obtained wit h the progestagen Promegestone (R-5020). It is concluded that the orie ntation of 17 beta-HSD activity for the interconversion E(1) reversibl e arrow E(2) in hormone-dependent and -independent cells is related to the hormonal status of the cells.