Presence of 5α-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 enzyme 5alpha-R. Two 5alpha-R isoforms with different biochemical characteristics have been cloned. Also estrogens might contribute to the prostate growth; however, their intraglandular formation by the enzyme aromatase is still debated. The aim of the present study was to verify whether (a) only one or both isoforms of the 5alpha-Rs are expressed in 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 of the 5alpha-Rs was evaluated "in vitro" in LNCaP cells by the production of labeled 5alpha-reduced metabolites either from [14C]-T or [14C]-D4 at pH 3.5-8. The gene expression of the two 5alpha-Rs and of the aromatase in LNCaP cells and in BPH specimens was analyzed by RT-PCR combined to Southern blot analysis, using specific sets of oligonucleotides. The tissue localization of 5alpha-R1 was analyzed by immunohistochemistry using an anti-5alpha-R1 polyclonal antibody. RESULTS: (a) In LNCaP cells, the formation of 5alpha-reduced metabolites from the respective precursors increases progressively as a function of pH, being the highest at neutral pH values; (b) the 5alpha-R1 isoform is expressed in both LNCaP cells and in BPH, while the 5alpha-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-activating enzymes, particularly in prostate cancer, would be of help to choose the appropriate treatment.