Dataset Information

5?-Reductase Isozymes in the Prostate.

ABSTRACT: 5?-reductases convert testosterone to dihydrotestosterone (DHT). There are two 5?-reductase isozymes, type 1 and type 2 in humans and animals. Mutations in type 2 isozyme with decreased enzymatic activity cause male pseudohermaphroditism. The affected 46XY individuals have high normal or elevated plasma testosterone levels with low normal or decreased DHT levels, resulting in an elevated testosterone/DHT ratios. They are born with ambiguous external genitalia and normal Wolffian differentiation. Their prostate is small and rudimentary, and plasma levels of prostate specific antigen (PSA) are low or undetectable in adulthood. Prostate cancer and benign prostate hyperplasia (BPH) have never been reported in these patients. Similar defects in prostate development are observed in animals with either 5?-reductase-2 or 5?-reductase-2 plus 5?-reductase-1 gene knockout, and in animals treated with specific 5?-reductase inhibitor. 5?-reductase isozymes are expressed in multiple tissues, and the predominant isozyme in human prostate is 5?-reductase-2. The expression of 5?-reductase-2 gene in prostate cells is regulated by various factors. A high dietary fat intake, a risk factor of prostate cancer, induces prostate 5?-reductase-2 gene expression and subsequently stimulates prostate growth, which is blocked by genistein, a phytoestrogen. Inhibition of 5?-reductase activity by medication is used in the treatment of BPH and male-pattern baldness, while its use in prostate cancer prevention is still controversial although it can decrease the incidence of prostate cancer. The analyses of 5?-reductases in humans and animals highlight the differences between testosterone and DHT, and the significance of DHT in male sexual differentiation and prostate physiology and pathophysiology.

SUBMITTER: Zhu YS

PROVIDER: S-EPMC2386416 | biostudies-literature | 2005

REPOSITORIES: biostudies-literature

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5α-Reductase Isozymes in the Prostate.

Zhu Yuan-Shan YS Sun Guang-Huan GH

Journal of medical sciences (Taipei, Taiwan) 20050101 1

5α-reductases convert testosterone to dihydrotestosterone (DHT). There are two 5α-reductase isozymes, type 1 and type 2 in humans and animals. Mutations in type 2 isozyme with decreased enzymatic activity cause male pseudohermaphroditism. The affected 46XY individuals have high normal or elevated plasma testosterone levels with low normal or decreased DHT levels, resulting in an elevated testosterone/DHT ratios. They are born with ambiguous external genitalia and normal Wolffian differentiation. ...[more]

PMID: 18483578

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Project description:Importance5α-Reductase inhibitors (5-ARIs), commonly used to treat benign prostatic hyperplasia, reduce serum prostate-specific antigen (PSA) concentrations by 50%. The association of 5-ARIs with detection of prostate cancer in a PSA-screened population remains unclear.ObjectiveTo test the hypothesis that prediagnostic 5-ARI use is associated with a delayed diagnosis, more advanced disease at diagnosis, and higher risk of prostate cancer-specific mortality and all-cause mortality than use of other or no PSA-decreasing drugs.Design, setting, and participantsThis population-based cohort study linked the Veterans Affairs Informatics and Computing Infrastructure with the National Death Index to obtain patient records for 80 875 men with American Joint Committee on Cancer stage I-IV prostate cancer diagnosed from January 1, 2001, to December 31, 2015. Patients were followed up until death or December 31, 2017. Data analysis was performed from March 2018 to May 2018.ExposuresPrediagnostic 5-ARI use.Main outcomes and measuresThe primary outcome was prostate cancer-specific mortality (PCSM). Secondary outcomes included time from first elevated PSA (defined as PSA≥4 ng/mL) to diagnostic prostate biopsy, cancer grade and stage at time of diagnosis, and all-cause mortality (ACM). Prostate-specific antigen levels for 5-ARI users were adjusted by doubling the value, consistent with previous clinical trials.ResultsMedian (interquartile range [IQR]) age at diagnosis was 66 (61-72) years; median [IQR] follow-up was 5.90 (3.50-8.80) years. Median time from first adjusted elevated PSA to diagnosis was significantly greater for 5-ARI users than 5-ARI nonusers (3.60 [95% CI, 1.79-6.09] years vs 1.40 [95% CI, 0.38-3.27] years; P < .001) among patients with known prostate biopsy date. Median adjusted PSA at time of biopsy was significantly higher for 5-ARI users than 5-ARI non-users (13.5 ng/mL vs 6.4 ng/mL; P < .001). Patients treated with 5-ARI were more likely to have Gleason grade 8 or higher (25.2% vs 17.0%; P < .001), clinical stage T3 or higher (4.7% vs 2.9%; P < .001), node-positive (3.0% vs 1.7%; P < .001), and metastatic (6.7% vs 2.9%; P < .001) disease than 5-ARI nonusers. In a multivariable regression, patients who took 5-ARI had higher prostate cancer-specific (subdistribution hazard ratio [SHR], 1.39; 95% CI, 1.27-1.52; P < .001) and all-cause (HR, 1.10; 95% CI, 1.05-1.15; P < .001) mortality.Conclusions and relevanceResults of this study demonstrate that prediagnostic use of 5-ARIs was associated with delayed diagnosis and worse cancer-specific outcomes in men with prostate cancer. These data highlight a continued need to raise awareness of 5-ARI-induced PSA suppression, establish clear guidelines for early prostate cancer detection, and motivate systems-based practices to facilitate optimal care for men who use 5-ARIs.

Project description:ImportanceThere have been concerns raised by patients and regulatory agencies regarding serious psychiatric adverse effects associated with 5α-reductase inhibitors.ObjectiveTo determine if there is an increased risk of suicide, self-harm, or depression among older men starting a 5α-reductase inhibitor for prostatic enlargement.Design, setting, and participantsA population-based, retrospective, matched cohort study using linked administrative data for 93 197 men ages 66 years or older (median [IQR] age, 75 [70-80] years) in Ontario, Canada, who initiated a new prescription for a 5α-reductase inhibitor during the study period (2003 through 2013). Participants were matched (using a propensity score that included 44 of our 96 covariates that included medical comorbidities, medication usage, and health care system utilization) to an equal number of men not prescribed a 5α-reductase inhibitor.ExposuresDuration of finasteride or dutasteride usage.Main outcomes and measuresSuicide. Secondary outcomes were self-harm and depression.ResultsMen who used 5α-reductase inhibitors were not at a significantly increased risk of suicide (HR, 0.88; 95% CI, 0.53-1.45). Risk of self-harm was significantly increased during the initial 18 months after 5α-reductase inhibitor initiation (HR, 1.88; 95% CI, 1.34-2.64), but not thereafter. Incident depression risk was elevated during the initial 18 months after 5α-reductase inhibitor initiation (HR, 1.94; 95% CI, 1.73-2.16), and continued to be elevated, but to a lesser degree, for the remainder of the follow-up period (HR, 1.22; 95% CI, 1.08-1.37). The absolute increases in the event rates for these 2 outcomes were 17 per 100 000 patient-years and 237 per 100 000 patient-years, respectively. The type of 5α-reductase inhibitor (finasteride or dutasteride) did not significantly modify the observed associations with suicide, self-harm, and depression.Conclusions and relevanceIn a large cohort of men ages 66 years or older, we did not demonstrate an increased risk of suicide associated with 5α-reductase inhibitor use. However, the risk of self-harm and depression were increased compared with unexposed men. This is in keeping with postmarketing experience and patient concerns, and discontinuation of the medication in these circ umstances may be appropriate.

Dataset Information

5?-Reductase Isozymes in the Prostate.

Publications

5α-Reductase Isozymes in the Prostate.

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