PRESENCE OF 5-ALPHA-REDUCTASE ISOZYMES AND AROMATASE IN HUMAN PROSTATE-CANCER CELLS AND IN BENIGN PROSTATE HYPERPLASTIC TISSUE

BACKGROUND. Prostate trophism depends on DHT formed from T by the enzy me 5 alpha-R. Two 5 alpha-R isoforms with different biochemical charac teristics have been cloned. Also estrogens might contribute to the pro state growth; however, their intraglandular formation by the enzyme ar omatase is still debated. The aim of the present study was to verify w hether (a) only one or both isoforms of the 5 alpha-Rs are expressed i n the prostate cancer cell line LNCaP and in BPH, or (b) the aromatase is present in these samples. METHODS. The profile of the pH optimum o f the 5 alpha-Rs was evaluated ''in vitro'' in LNCaP cells by the prod uction of labeled 5 alpha-reduced metabolites either from [C-14]-T or [C-14]-D4 at pH 3.5-8. The gene expression of the two 5 alpha-Rs and o f the aromatase in LNCaP cells and in BPH specimens was analyzed by RT -PCR combined to Southern blot analysis, using specific sets of oligon ucleotides. The tissue localization of 5 alpha-R1 was analyzed by immu nohistochemistry using an anti-5 alpha-R1 polyclonal antibody. RESULTS . (a) In LNCaP cells, the formation of 5 alpha-reduced metabolites fro m the respective precursors increases progressively as a function of p H, being the highest at neutral pH values; (b) the 5 alpha-R1 isoform is expressed in both LNCaP cells and in BPH, while the 5 alpha-R2 mRNA is present only in BPH, but not in LNCaP cells; and (c) no aromatase transcripts were observed either in BPH or in LNCaP cells. CONCLUSIONS . A careful examination of the possible differential expression of T-a ctivating enzymes, particularly in prostate cancer, would be of help t o choose the appropriate treatment. (C) 1998 Wiley-Liss, Inc.