BACKGROUND: Benign prostatic hyperplasia (BPH) development requires testicular androgens and aging. The principle prostatic androgen is dihydrotestosterone (DHT). Testosterone is converted to DHT by the enzyme 5 alpha-reductase. Two distinct 5 alpha-reductase enzymes, types 1 and 2, have been identified. While some studies have suggested that type 2 isoenzyme predominates in the prostate, studies on the prostatic localization of the two isoenzymes are controversial. The purpose of this study was to determine the quantitative expressions of 5 alpha-reductase types 1 and 2 in BPH tissues. METHODS: We examined the localizations of types 1 and 2 isoenzymes in BPH tissues using immunohistochemical staining and a real-time quantitative RT-PCR assay using the TaqMan system. We measured the enzyme activities of types 1 and 2 at pH values of 7.5 and 5.0, respectively. RESULTS: Our immunohistochemical study showed that type 1 isoenzyme was expressed predominantly in epithelial cells, whereas type 2 isoenzyme was expressed in both stromal and epithelial cells. The real-time RT-PCR assay demonstrated that the copy numbers of type 1 isoenzyme mRNA were significantly higher than those of type 2 isoenzyme mRNA. There were significant associations between enzyme activity at pH 7.5 and type 1 isoenzyme mRNA expression, and between the activity at pH 5.0 and type 2 mRNA expressions. CONCLUSIONS: We demonstrated that 5 alpha-reductase type 1 had a specific enzyme activity in the prostate, which supports the hypothesis that the type 1 isoenzyme may play a significant role in maintaining prostate enlargement along with the type 2 isoenzyme. Copyright 2003 Wiley-Liss, Inc.
BACKGROUND:Benign prostatic hyperplasia (BPH) development requires testicular androgens and aging. The principle prostatic androgen is dihydrotestosterone (DHT). Testosterone is converted to DHT by the enzyme 5 alpha-reductase. Two distinct 5 alpha-reductase enzymes, types 1 and 2, have been identified. While some studies have suggested that type 2 isoenzyme predominates in the prostate, studies on the prostatic localization of the two isoenzymes are controversial. The purpose of this study was to determine the quantitative expressions of 5 alpha-reductase types 1 and 2 in BPH tissues. METHODS: We examined the localizations of types 1 and 2 isoenzymes in BPH tissues using immunohistochemical staining and a real-time quantitative RT-PCR assay using the TaqMan system. We measured the enzyme activities of types 1 and 2 at pH values of 7.5 and 5.0, respectively. RESULTS: Our immunohistochemical study showed that type 1 isoenzyme was expressed predominantly in epithelial cells, whereas type 2 isoenzyme was expressed in both stromal and epithelial cells. The real-time RT-PCR assay demonstrated that the copy numbers of type 1 isoenzyme mRNA were significantly higher than those of type 2 isoenzyme mRNA. There were significant associations between enzyme activity at pH 7.5 and type 1 isoenzyme mRNA expression, and between the activity at pH 5.0 and type 2 mRNA expressions. CONCLUSIONS: We demonstrated that 5 alpha-reductase type 1 had a specific enzyme activity in the prostate, which supports the hypothesis that the type 1 isoenzyme may play a significant role in maintaining prostate enlargement along with the type 2 isoenzyme. Copyright 2003 Wiley-Liss, Inc.