Background:
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.
Methods:
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.
Results:
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.
Conclusions:
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.