CHARACTERIZATION OF 5-ALPHA-REDUCTASE GENE-EXPRESSION IN STROMA AND EPITHELIUM OF HUMAN PROSTATE

The expression of 5 alpha-reductase type 1 and type 2 isoenzymes in hy perplastic human prostate tissue and several human prostate cell lines was investigated by Northern blot analyses, reverse transcription-pol ymerase chain reaction (RT-PCR), and enzyme activity. Separation of st roma and epithelium was confirmed histologically and only preparations with no apparent contamination were employed in the subsequent studie s. Poly(A)(+) RNA was isolated from stromal and epithelial fractions a nd analysed by Northern blot and RT-PCR. Inhibition of epithelial and stromal 5 alpha-reductase activities by 17 beta-N,N-diethylcarbamoyl-4 -methyl-4-aza-5 alpha-androstan-3-one (4MA) was assessed using a range of concentrations between 10(-13) and 10(-5) M. Results from Northern blot analyses and RT-PCR showed that the prostate stroma expressed 5 alpha-reductase type 1 and type 2 isoenzymes, whereas the prostate epi thelium only expressed 5 alpha-reductase type 1. This was consistent w ith biphasic inhibition of 5 alpha-reductase activity by 4MA in stroma and monophasic inhibition in epithelium. Cultured epithelial cells de rived from human prostate only expressed 5 alpha-reductase type 1 and had V-max and K-m values that approximated the lower end of the range reported for surgically removed prostate epithelium. The foregoing dat a explains the disparate activities of 5 alpha-reductase, previously r eported, in stroma and epithelium. The differential localization of th ese isoenzymes in the prostate suggests that future therapy of androge n-sensitive disease may be more successful through the use of selectiv e inhibitors of the different 5 alpha-reductase isoenzymes. Copyright (C) 1996 Elsevier Science Ltd.