Pax-5 protein expression in bladder cancer: a preliminary study that shows no correlation to grade, stage or clinical outcome.
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.
Denzinger
Stefan
S
Department of Urology, University of Regensburg, Regensburg, Germany.
Burger
Maximilian
M
Hammerschmied
Christine G
CG
Wieland
Wolf F
WF
Hartmann
Arndt
A
Obermann
Ellen C
EC
Stoehr
Robert
R
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*
D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human