title: Immunohistochemical expression of pi-class glutathione S-transferase is down-regulated in adenocarcinoma of the prostate.
abstract: BACKGROUND
  Glutathione S-transferase is often up-regulated in neoplastic tissues. A single previous study found a loss of expression associated with carcinogenesis of the prostate.
  
  
  METHODS
  To extend these results, the authors performed immunohistochemical staining for the pi-class of glutathione S-transferase (GSTpi) on 74 archival sequential prostate specimens. The antibody used was derived from rabbits immunized against purified human GSTpi. Paraffin blocks containing both benign tissue and adenocarcinoma were studied.
  
  
  RESULTS
  Heterogeneous expression of GSTpi in benign acini was found in 96% of cases, but GSTpi was not expressed in 95% of invasive adenocarcinomas of the prostate, nor was it expressed in any of the foci of high grade prostatic intraepithelial neoplasia. Basal cells of benign acini showed strong, diffuse staining for GSTpi, whereas the secretory luminal epithelium expressed GSTpi weakly and focally.
  
  
  CONCLUSIONS
  This study confirms the down-regulation of GSTpi in adenocarcinoma of the prostate and shows that the loss of GSTpi expression is a phenotype associated with malignant transformation.
authors.affiliation: Laboratory of Pathology, National Cancer Institute, Bethesda, Maryland 20892, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Moskaluk
authors.forename: P H
authors.initials: PH
authors.lastname: Duray
authors.forename: K H
authors.initials: KH
authors.lastname: Cowan
authors.forename: M
authors.initials: M
authors.lastname: Linehan
authors.forename: M J
authors.initials: MJ
authors.lastname: Merino
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology*; D000818:Animals; D000906:Antibodies; D015536:Down-Regulation; D005982:Glutathione Transferase / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009363:Neoplasm Proteins / Q000276:immunology / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000201:enzymology*; D011817:Rabbits
chemical_list: D000906:Antibodies; D009363:Neoplasm Proteins; D005982:Glutathione Transferase