Messenger Ribonucleic Acid Levels of Steroid 5α-Reductase 2 in Human Prostate Predict the Enzyme Activity1

Testosterone is converted to dihydrotestosterone by 5α-reductase2 in the prostate. Dihydrotestosterone controls cell division, and interindividual differences in prostatic 5α-reductase 2 expression and activity may be a determinant of the risk of developing prostate cancer. However, little is known about interindividual differences in intraprostatic hormonal activity in vivo. To determine whether 5α-reductase-specific messenger RNA (mRNA) is predictive of 5α-reductase activity in prostatic tissue, we analyzed 30 prostatic tissue specimens from 15 Caucasian patients, 47–82 yr old. The mRNA was measured by RT-PCR. Five specimens consisted of cancer, whereas the remaining 25 were derived from benign prostate hyperplasia (BPH). We found a strong association between enzyme activity at pH 5.5 and the 5α-reductase 2-specific mRNA expression when expressed on the basis of β-actin [Spearman’s rank-correlation coefficient (rs) = 0.81; 95% confidence interval, 0.64–0.91; P < 0.0001]. The expression of 5α-reductase 2...