Differences in steroid 5 alpha-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 hybr idisation analyses. In situ hybridisation established that 5 alpha-R1 mRNA is preferentially expressed by epithelial cells and little expressed by str omal cells whereas 5 alpha-R2 mRNA is expressed by both epithelium and stro ma. 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 pr ostate. In BPH tissue, 5 alpha-R1 and 5 alpha-R2 mRNAs expression was sligh tly but significantly increased, when it was compared to the levels recorde d for normal prostate. In cancer samples, 5 alpha-R1 mRNA expression was hi gher than in normal and hyperplastic prostate but the level of 5 alpha-R2 m RNA was not statistically different from that observed in the different zon es 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 in crease 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.