title: Steroid 5-alpha reductase type 2 activity in biopsies from malignant and normal prostatic tissues.
abstract: BACKGROUND
  The conversion of testosterone (T) to the more potent metabolite dihydrotestosterone (DHT) by prostate-specific steroid 5 alpha-reductase isoenzymes is a key mechanism in the action of androgens in the prostate and it is important in the promotion and progression of prostate diseases. We described an adaptation of a sensitive method for evaluation of the 5 alpha-reductase type 2 (5 alpha-R2) activity using a small quantity of protein.
  
  
  METHODS
  We used 29 human prostate transrectal ultrasound-guided core biopsies obtained from patients (median age 70, range 55-86 y) undergoing this procedure for diagnostic purposes. 4-[(14)C]testosterone and NADPH were incubated with biopsy homogenate. Reaction products were extracted, separated by thin layer chromatography and revealed by autoradiography. Areas correspondent to T and DHT were scraped into vials and their radioactivity determined.
  
  
  RESULTS
  The 5 alpha-R2 activity was expressed as ln (natural logarithm). The assay was validated according to the protein concentration and incubation time linearities. The 5 alpha-R2 activity showed a significant difference between normal and neoplastic tissues with significance level set at P<0.05, mainly in the left prostate lobe. This was independent from the PSA levels.
  
  
  CONCLUSIONS
  Determination of 5 alpha-R2 activity, using the conditions reported herein, could be utilized as an efficient biochemical parameter of prostate neoplastic processes.
authors.affiliation: Urology Service, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos 2350, Porto Alegre, RS, Brazil. ooliveira@hcpa.ufrgs.br
authors.forename: Osmar Luiz Magalhães
authors.initials: OL
authors.lastname: Oliveira
authors.forename: Walter José
authors.initials: WJ
authors.lastname: Koff
authors.forename: Francine
authors.initials: F
authors.lastname: Muraro
authors.forename: Emanuel Burck
authors.initials: EB
authors.lastname: Santos
authors.forename: Daniel Freitas
authors.initials: DF
authors.lastname: Gomes Soares
authors.forename: Vera Maria Treis
authors.initials: VM
authors.lastname: Trindade
mesh_terms: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000378:metabolism*; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D013196:Dihydrotestosterone / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000201:enzymology*; D011470:Prostatic Hyperplasia / Q000201:enzymology*; D011471:Prostatic Neoplasms / Q000201:enzymology*; D013739:Testosterone / Q000378:metabolism*
chemical_list: D013196:Dihydrotestosterone; D013739:Testosterone; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase