6715

SRD5A1

steroid-5-alpha-reductase, alpha polypeptide 1 (3-oxo-5 alpha-steroid delta 4-dehydrogenase alpha 1);SRD5A1;steroid-5-alpha-reductase, alpha polypeptide 1 (3-oxo-5 alpha-steroid delta 4-dehydrogenase alpha 1)

3-oxo-5 alpha-steroid delta 4-dehydrogenase alpha 1|3-oxo-5-alpha-steroid 4-dehydrogenase 1|5-alpha reductase|SR type 1|steroid 5-alpha-reductase 1|steroid 5-alpha-reductase type I

5p15

protein-coding

PURPOSE: Considerable evidence has accumulated demonstrating that the 5alpha-reduction of testosterone to dihydrotestosterone occurs more efficiently in the normal and benign hyperplastic prostate than in prostate cancer tissues. Efforts have also been channeled into investigating the distribution of 5alpha-reductase isoenzymes in primary prostate tissues and in "in vitro" cell models of the human prostate. However, no one has, thus far, examined the expression of these isoenzymes in prostate cancer metastasis, although such studies might shed some light on the mechanism(s) responsible for the loss of hormone sensitivity in those tumors. The present report addresses this issue in the hope that this might help to identify the steps leading to the development of prostate cancer metastasis. EXPERIMENTAL DESIGN: In the present study we used in situ mRNA hybridization of sections from archival paraffin-embedded material to investigate the expression of 5alpha-reductase type I (5alphaR-I) and type II (5alphaR-II) mRNAs in prostate cancer bony (n = 9) and lymph node (n = 13) metastasis, and compared the mRNA distributions with those observed in sections from primary prostate tumors (n = 12). In parallel, sections were investigated for androgen receptor (AR) mRNA expression, and immunostained for AR and prostate-specific antigen. RESULTS: Neither 5alphaR-I nor 5alphaR-II mRNA expression was detected in any of the prostate metastatic lesions, although the same metastatic sites expressed AR mRNA, and stained for cytoplasmic prostate-specific antigen and nuclear AR. In contrast, primary prostate tumors displayed intense staining for 5alphaR-I and 5alphaR-II. CONCLUSION: These findings suggest that the loss of 5alpha-reductase mRNA expression in bone and lymph node metastasis may be associated, in part, with the progression of these tumors to androgen insensitivity.

BACKGROUND: In the prostate, conversion of testosterone to dihydrotestosterone (DHT), by the enzymes 5alpha-reductase types 1 and 2 (5alphaR1, 5alphaR2) is required for normal growth and probably also for development of prostate cancer (PCa). Finasteride, a 5alphaR2 inhibitor, was shown to reduce the prevalence of PCa in the Prostate cancer Prevention Trial. However, inhibition of both 5alphaR isoenzymes causes a greater decrease in serum DHT. The aim of this study was to assess differential expression of these enzymes at various stages of PCa development. METHODS: Immunostaining for 5alphaR1 and 5alphaR2, using specific, well-validated antibodies, was evaluated in 26 benign prostatic hyperplasia (BPH) (16 for 5alphaR2), 53 primary PCa (21 for 5alphaR2), 18 prostatic intraepithelial neoplasia (PIN), 12 primary PCa treated with neoadjuvant androgen ablation, 15 locally recurrent PCa specimens, and 18 PCa metastases. RESULTS: The mean area of moderate plus high intensity staining for 5alphaR1 increased from 4.8 +/- 2.8% of total epithelial area in BPH, to 18.9 +/- 5.7% in PIN, 17.0 +/- 3.2% in primary cancer, 38.0 +/- 7.3% in recurrent cancer, and 55.8 +/- 8.5% in PCa metastases. The mean staining area for 5alphaR2 decreased from 58.8 +/- 7.2% in BPH, to 21.1 +/- 5.5% in PIN and 34.8 +/- 6.7% in primary PCa. Staining for 5alphaR2 was increased in recurrent cancer and PCa metastases compared to primary PCa, at 58.7 +/- 5.2% and 69.2 +/- 8.7%, respectively. CONCLUSIONS: 5alphaR1 immunostaining is increased and 5alphaR2 immunostaining is decreased during development of PCa. In addition, there is increased expression of both 5alphaR isozymes in recurrent and metastatic cancers, suggesting that both isozymes may be important in the development and progression of PCa.