ANDROGEN RECEPTOR IN THE PROSTATE

STUDIES ON FACTORS AFFECTING THE RELIABILITY OF THE ASSAY

Abstract

Our aim was to optimize the conditions of an exchange assay, based on the recently reported for rat and human prostate and to measure androgen receptor (AR) in the cytoplasm and nucleus of cells from those tissues.
The major technical problems in the detection of AR had been the paucity of AR in prostate tissue and its lability even at low temperatures as well as the development of a molybdate buffer that suppressed proteolytic enzyme activity and was beneficial on stabilizing AR and on yielding the enhancement of the number of binding sites. An additional, rather practical problem was obtaining sufficient tissue for biochemical assay. Single saturating dose method provided useful and reliable information on needle biopsy specimen for the microassay of AR. Use of hydroxylapatite was also efficient, especially if the cytosolic protein content was lower than 1mg/ml.
Measurement of nuclear AR was more instructive than simple concentration of receptor in the cytosol, because most of the AR found in human prostate would be concentrated in the nuclear compartment.
Optimization of an exchange assay for the measurement of specific binding appears to be the most promising approaches to date for the response to endocrine manipulation.