Differences in steroid 5α-reductase iso-enzymes expression between normal and pathological human prostate tissue

We studied the expression level and cell-specific expression patterns of 5 alpha-reductase (5 alpha-R) types 1 and 2 iso-enzymes in human hyperplastic and malignant prostate tissue by semi-quantitative RT-PCR and in situ hybridisation analyses. In situ hybridisation established that 5 alpha-R1 mRNA is preferentially expressed by epithelial cells and little expressed by stromal cells whereas 5 alpha-R2 mRNA is expressed by both epithelium and stroma. Semi-quantitative RT-PCR has been performed on total RNA from different zones of normal prostate, BPH tissues and liver. We found that 5 alpha-R1 and 5 alpha-R2 mRNAs expression was near the same in all zones of normal prostate. In BPH tissue, 5 alpha-R1 and 5 alpha-R2 mRNAs expression was slightly but significantly increased, when it was compared to the levels recorded for normal prostate. In cancer samples, 5 alpha-R1 mRNA expression was higher than in normal and hyperplastic prostate but the level of 5 alpha-R2 mRNA was not statistically different from that observed in the different zones of normal prostate. In liver, 5 alpha-R2 mRNA level was similar to that measured in BPH but 5 alpha-R1 mRNA expression was ten times higher. The increase observed in 5 alpha-R isoenzymes expression in BPH tissue could play an important role in the pathogenesis and/or maintenance of the disease. (C) 1999 Elsevier Science Ltd. All rights reserved.