Assay of nuclear androgen receptor in human prostate

Nuclei were recovered from normal and hyperplastic human prostates and from well differentiated carcinoma using triton N-101 and discontinuous sucrose density gradient centrifugation. The nuclei were sonicated and dissolved in 2-([2-hydroxy-1,1-bis(hydroxymethyl)ehtyl]amino)ethane sulfonic acid buffer, pH 7.0, containing 0.6 M. sodium chloride. After incubation of the nuclear extract in the presence of 2 to 20 nM. 3H-dihydrotestosterone at 4C for 18 hours, an androgen receptor was isolated by Sephadex G-25/G-200 dual-column chromatography. The receptor demonstrated greater specificity for testosterone and dihydrotestosterone than for cortisol, progesterone and 17beta-estradiol. It was characterized by a sedimentation coefficient of 3 S and a Kd of 4.5 x 10(-9) M. The mean concentration of the nuclear androgen receptor, in terms of molecules per nucleus, was normal prostate-1,000, hyperplastic prostate-1,400 and well differentiated carcinoma-1,900. With this assay the problems associated with the measurement of a cytoplasmic androgen receptor can be avoided.