Testosterone-induced DNA synthesis in cultured rat ventral prostate: effects of estracyt and its derivatives.

Testosterone-induced DNA synthesis in cultured rat ventral prostate was used to compare the direct effects of Estracyt and Emcyt with that of their metabolite, estramustine, and their carrier-hormone, oestradiol-17 beta on prostatic growth. In serum-supplemented medium (5-20% FCS), all the compounds were equally effective in suppressing testosterone stimulated DNA synthesis which was reduced by between 40-50%, whereas in serum-free medium the estramustine compounds were consistently less effective than oestradiol-17 beta. In the presence of 4 X 10(-9) M testosterone in serum-free medium, stimulated DNA synthesis was reduced by 15-30% following incubation with 4 X 10(-7) M of Estracyt, Emcyt and estramustine and by 60% with 4 X 10(-7) M oestradiol-17 beta. Thus, none of the estramustine compounds appear to offer any selective advantage over that of oestradiol-17 beta in suppressing prostatic DNA synthesis at the target tissue level.