BINDING OF ESTRADIOL TO WHOLE PROSTATIC DU-145 CELLS IN THE PRESENCE AND ABSENCE OF TAMOXIFEN AND ACETYLSALICYLIC-ACID

Conflicting results have been obtained with regard to the estradiol re ceptor (ER) capacity of human prostatic tissue. Human prostatic DU-145 cells have been found to be ER-negative with immunohistochemical assa ys. The object of this investigation was to determine if whole DU-145 cells, which had been grown in monolayer culture, have ER and, if so, to confirm the finding with antiestrogens. After cells had been lysed, a B-max of 44.7 +/- 4.0 fmol/mg (K-d = 0.6 +/- 0.6 nM) was obtained. Subcellular localization studies showed that the estrogen receptor lev el in the cytoplasmic fraction was approximately 10 times higher than in the nuclear fraction. Competitive binding studies showed that tamox ifen, DES, and acetylsalicylic acid decreased estradiol binding. The d issociation constants and relative affinities for tamoxifen, DES, and acetylsalicylic acid were 0.2 nM (281.7%), 0.2 nM (224.0%), and 0.8 nM (78.43%), respectively. However, 5 alpha-dihydrotestosterone and meta bolites of acetylsalicylic acid had no effect in competitive binding s tudies. These results may contribute to a better understanding of pros tatic carcinogenesis, which may in turn lead to more effective treatme nt. (C) 1995 Wiley-Liss, Inc.