| Abstract: | Estrogen and progesterone receptor (ER, PgR) were quantitated by Scatchard analysis in cytosolic and nuclear extracts of R3327H prostatic carcinomas from rats injected with 100 micrograms diethylstilbestrol or with vehicle for 1-3 weeks. Total tissue ER concentrations were less than 80 fm/mg DNA in control tumors and were not significantly higher in treated tumors: however, in the latter, a significantly higher proportion (73 +/- 16%) was associated with the nuclear fraction than in the control tumors (less than 33%). Mean PgR concentrations were more than seven-fold higher in treated than in control tumors, and approximately 25% of the total was associated with the nuclear fraction in both treated and control tumors, under the assay conditions used. There was a strong linear correlation between nuclear ER and PgR concentrations. These data indicate that although ER concentration in these tumors was low compared with that in female target organs, it was functional in its ability to associate with the nuclear fraction and induce synthesis of an estrogen-induced protein (PgR) in proportionate amounts. |
