[Expression and significance of steroid 5alpha-reductase isoenzymes in benign hyperplastic prostate tissues]

To study the expression levels and cell-specific expression patterns of steroid 5alpha-reductase type 1 and type 2 isoenzymes in human benign prostatic hyperplasia (BPH) tissues.

Immunohistochemistry and RT-PCR were used to investigate qualitatively and semi-quantitatively the expression of 5alpha-reductases type 1 and type 2 in 15 specimens of normal prostate tissues from dead kidney donor or patients undergoing cystectomy and 25 BPH tissues obtained from suprapubie enucleation.

Both steroid 5alpha-reductase type 1 mRNA and protein and 5alpha-reductase type 2 mRNA and protein were present in the normal and BPH tissues, especially in the glandular epithelial cells and mainly in the cytoplasm. In the BPH group the expression of type 2 reductase in the periurethral tissues was significant higher than that in the subcapsular tissues (1.50 +/- 0.42 vs. 1.07 +/- 0.35, P < 0.01), however, there was no significant difference in the expression of type 1 reductase between these 2 zones (P > 0.05). The expression level of 5alpha-reductase type 2 mRNA in BPH tissues was significantly higher than that in the normal specimens (e.g. in periurethral zone 1.50 +/- 0.42 vs. 0.98 +/- 0.32, P < 0.01), but there was no statistically significant difference in the expression of 5alpha-reductase type 1 mRNA between these 2 groups (e.g. in periurethral zone 0.62 +/- 0.31 vs 0.51 +/- 0.24, P > 0.05). In BPH tissues, the expression of type 2 mRNA was significantly higher in the larger prostate tissues (>or= 40 g) than in the smaller ones (e.g. in periurethral zone 1.58 +/- 0.47 vs. 1.14 +/- 0.46, P < 0.05), however, there was no significant difference in the expression of 5alpha-reductase type 1 mRNA between the BPH tissues with different volumes.

Type 2 5alpha-reductase plays an important role in the pathogenesis and maintenance of BPH. The role of type 1 expression in the pathogenesis of BPH needs further research.