androstane-3-17-dione--(5alpha)-isomer and Prostatic-Hyperplasia

The presence and possible role of androgen-metabolizing enzymes in androgen-independent prostate carcinoma (CaP) are still unclear. The aim of the present study was: 1) to evaluate the pattern of androgen metabolism (relative production of 5alpha-reduced vs. 17-keto androgens); and 2) to analyze whether one or both the two known 5alpha-reductase isoforms (5alpha-R1 and 5alpha-R2) and the aromatase (Aro) are expressed and active in this pathology.. Two different cell lines (DU145 and PC3) were used as a model of androgen-independent human CaP. In these cells, the expression of the two 5alpha-Rs and of Aro were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot, using specific sets of oligoprimers and of [(32)P]-labeled oligoprobes; the enzymatic activities of 5alpha-R and of Aro were evaluated by radioenzymatic methods. The pH optimum for the activity of the two 5alpha-Rs was assessed in cell homogenates at different pH (from 3.5-8), using substrate concentrations similar either to 5alpha-R1 or to 5alpha-R2 Kms.. The two CaP cell lines DU145 and PC3, although unresponsive to androgens, possess the enzymatic machinery involved in the metabolism of this class of hormonal steroids: 5alpha-Rs, which allow their transformation into 5alpha-reduced steroids (5alpha-dihydrotestosterone, DHT, and 5alpha-androstandione, 5alpha-A), and 17beta-hydroxysteroid-oxidoreductase (17beta-HSD), which interconverts testosterone (T) and androstenedione (ADIONE); however, the two cell lines show differences in the rate of formation of these metabolites. Furthermore, two cell lines expressed the type 1 isoform of 5alpha-R, but only DU145 cells also possess 5alpha-R2. Aro is expressed and active in DU145 as well as in PC3 cells.. The present findings suggest that T might still be indirectly active in androgen-unresponsive CaP through its local conversion into estrogens by the action of Aro; the biological role played by the two 5alpha-Rs in androgen-independent CaP deserves further investigation.

Topics: 3-Oxo-5-alpha-Steroid 4-Dehydrogenase; Anastrozole; Androgens; Androstenedione; Aromatase; Aromatase Inhibitors; Blotting, Southern; Dihydrotestosterone; Enzyme Inhibitors; Etiocholanolone; Humans; Hydrogen-Ion Concentration; Isoenzymes; Male; Microsomes; Nitriles; Prostatic Hyperplasia; Prostatic Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Testosterone; Triazoles; Tumor Cells, Cultured

It has been well established that hyperplastic human prostatic tissue is characterized by a 3- to 4-fold elevation in the content of dihydrotestosterone (DHT) compared to that in normal prostatic tissue. However, the exact mechanism responsible for DHT accumulation has not been established. One hypothesis for the abnormal elevation of DHT content in hyperplastic prostatic tissue is that changes occur in the tissue itself which shift the overall balance of androgen metabolism favoring the increased accumulation of DHT. To test this hypothesis, the metabolic activities that produce and remove DHT were determined in a series of normal as well hyperplastic human prostates. The results of these studies demonstrated that in each of the eight separate hyperplastic prostatic tissues assayed, there was a significant increase in 5 alpha-reductase activity producing DHT concomitant with significant decreases in the 3 alpha- and 3 beta-hydroxysteroid oxidoreductase reductase and 17 beta-hydroxysteroid oxidoreductase oxidase activities removing DHT. These specific alterations result in a major shift in the overall balance of androgen metabolism which favors an increase in the net formation of DHT in hyperplastic prostatic tissue. Such a shift in androgen metabolism is, therefore, at least one mechanism for the well documented increase in DHT content found in hyperplastic human prostatic tissue.

Topics: 17-Hydroxysteroid Dehydrogenases; 3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); 3-Hydroxysteroid Dehydrogenases; 3-Oxo-5-alpha-Steroid 4-Dehydrogenase; Adult; Aged; Androstane-3,17-diol; Dihydrotestosterone; Etiocholanolone; Humans; Male; Middle Aged; Prostate; Prostatic Hyperplasia; Testosterone