Comparison of the R‐3327H rat prostatic adenocarcinoma to human benign prostatic hyperplasia and metastatic carcinoma of the prostate with regard to steroid hormone receptors

Quantitative analyses of cytosolic steroid hormone receptors were performed on nine tumors from the transplantable rat prostatic adenocarcinoma R-3327H. Androgen receptors and estrogen receptors were found in eight of nine and five of six tumors, respectively. None of the tumors analyzed contained detectable progestin or glucocorticoid receptors (four and seven tumors, respectively). The apparent equilibrium dissociation constants for the androgen and estrogen receptors were 0.7-4.3 nM and 0.6-1.8 nM, respectively. The apparent equilibrium B(max) values (maximum number of binding sites) were 1,500-25,000 fmoles/gm tissue for the androgen receptor and 640 to 5,800 fmoles/gm tissue for the estrogen receptor. A comparison between the receptor contents of the R-3327H rat tumor and human benign prostatic hyperplasia and metastatic carcinoma of the prostate showed that the rat tumor was different from the human tissues in several respects. Hence, the search for an optimal animal model for prostatic carcinoma in man must be continued.