title: Silencing of pi-class glutathione S-transferase in MDA PCa 2a and MDA PCa 2b cells.
abstract: BACKGROUND
  Loss of expression of the glutathione S-transferase-pi (GSTP1) is the most common genetic alteration described in human prostate cancer, occurring in virtually all tumors regardless of grade or stage. Of the available human prostate cancer cell lines, only LNCaP mirrors this phenotype. We investigated whether the prostate cancer cell lines MDA PCa 2a and MDA PCa 2b share this phenotype.
  
  
  METHODS
  GSTP1 protein and mRNA levels were assessed in the MDA PCa 2a and MDA PCa 2b cell lines by Western and Northern blot. DNA methylation was evaluated by Southern blot analysis of genomic DNA digested with the methylation-sensitive restriction enzymes BssHII, NotI, and SacII. Re-expression of GSTP1 was determined by RT-PCR following treatment with 5-azacytidine, a DNA methyltransferase inhibitor, and/or the histone deacetylase inhibitor trichostatin A (TSA).
  
  
  RESULTS
  Like all human prostatic carcinomas in vivo, both the MDA PCa 2a and 2b cell lines lack protein and mRNA expression of GSTP1. This lack of expression is associated with methylation in the GSTP1 gene promoter. Treatment with the methyltransferase inhibitor 5-azacytidine resulted in re-expression of GSTP1. By itself, TSA did not result in re-expression of GSTP1, nor did it augment expression induced by 5-azacytidine.
  
  
  CONCLUSIONS
  MDA PCa 2a and 2b appear to be useful models of human prostatic carcinoma in that they lack expression of GSTP1 due to gene silencing via promoter methylation. Inhibition of histone acetylation does not appear to affect GSTP1 expression.
authors: Department of Urology, Stanford University Medical Center, Pasteur Drive, Stanford, California 94305-5118, USA.
authors: Genevieve M
authors: GM
authors: Vidanes
authors: Vince
authors: V
authors: Paton
authors: Eric
authors: E
authors: Wallen
authors: Donna M
authors: DM
authors: Peehl
authors: Nora
authors: N
authors: Navone
authors: James D
authors: JD
authors: Brooks
mesh_terms: D019175:DNA Methylation; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000096:biosynthesis* / Q000235:genetics*; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics*; D008297:Male; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000473:pathology; D014407:Tumor Cells, Cultured / Q000502:physiology*
chemical_list: D017931:DNA Primers; D004273:DNA, Neoplasm; D007527:Isoenzymes; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase