title: Pax-5 protein expression in bladder cancer: a preliminary study that shows no correlation to grade, stage or clinical outcome.
abstract: OBJECTIVE
  Pax (paired box) genes comprise a gene family crucial for cell differentiation that encodes a set of transcription factors. Recently, Pax-5 mRNA expression was suggested as a prognostic marker in bladder cancer (BC). However, a functional role of Pax-5 in BC is questionable because the protein expression was not determined in these studies. Therefore, we evaluated Pax-5 protein expression in an unselected, consecutive series of BC.
  
  
  METHODS
  We immunohistochemically investigated Pax-5 protein expression in 100 archival bladder tumours and 22 normal urothelial samples using tissue microarray (TMA) technology and a monoclonal antibody against Pax-5. Staining intensity and percentage of positively stained cells were determined and correlated to histopathological characteristics of the tumours and clinical follow-up data.
  
  
  RESULTS
  All 22 samples of histopathologically normal urothelium were negative for Pax-5 protein expression. Overall, 70 of 100 tumours gave interpretable results. Only seven of 70 (10%) cases showed a positive nuclear Pax-5 staining but without significant correlation to clinicopathological characteristics. Interestingly, we could observe Pax-5 positive lymphocytes located within the tumour or closely adjacent in the underlying stroma in 24 of 70 (34%) cases in our series.
  
  
  CONCLUSIONS
  Pax-5 protein expression is infrequent in BC. Absence of correlation to clinicopathological characteristics suggests a minor functional role of Pax-5 in BC. Pax-5 positive lymphocytes within reactive infiltrates adjacent to the tumour warrant further studies evaluating biological, immunological and clinical relevance.
authors.affiliation: Department of Urology, University of Regensburg, Regensburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Denzinger
authors.forename: Maximilian
authors.initials: M
authors.lastname: Burger
authors.forename: Christine G
authors.initials: CG
authors.lastname: Hammerschmied
authors.forename: Wolf F
authors.initials: WF
authors.lastname: Wieland
authors.forename: Arndt
authors.initials: A
authors.lastname: Hartmann
authors.forename: Ellen C
authors.initials: EC
authors.lastname: Obermann
authors.forename: Robert
authors.initials: R
authors.lastname: Stoehr
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016246:Lymphocytes, Tumor-Infiltrating / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D051757:PAX5 Transcription Factor / Q000096:biosynthesis*; D046888:Tissue Array Analysis; D001749:Urinary Bladder Neoplasms / Q000276:immunology / Q000378:metabolism* / Q000473:pathology*
chemical_list: D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human