Androgen Receptors in Prostatic Cancer
There are good grounds for the premise that measurement of androgen receptor proteins in carcinoma of the prostate may be of value in the prediction of responsiveness to hormone manipulation. Although a receptor protein which binds dihydrotestosterone has been identified and characterised in the human prostate by sucrose density gradient centrifugation and column chromatography, routine quantitative measurements in human prostatic tissues have been beset by a number of problems in methodology. In the first place, the high level of sex hormone binding protein (SHBG) and of endogenous androgens in prostatic tissues interfere with the receptor assay and the earlier dextran charcoal technique (Mobbe et al, 1975) has proved to be unreliable. In the dextran charcoal method cytosol is labelled with either 3H testosterone or dihydrotestosterone. The free and loosely bound steroids are then separated from tightly bound steroids by the addition of dextran coated charcoal. However, due to the high affinity of androgens to SHBG it proved impossible to separate SHBG from androgen receptors using this technique. This method was replaced by the “Agar gel electrophoresis technique” (Wagner, 1972), which can separate SHBG from androgen receptors by agar gel electrophoresis, but in turn has the disadvantage that only (free) receptors are measured.
KeywordsCortisol Testosterone Fractionation Progesterone Androgen
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