Letters

209Urology Journal    Vol 5    No 3    Summer 2008

Re: Overexpression of BMI1, a Polycomb Group  
Repressor Protein, in Bladder Tumors: a Preliminary 
Report

Urol J. 2008;5:209-10. 
www.uj.unrc.ir

Sir,
The polycomb group of transcriptional repressors 
is associated with tumor progression and 
metastasis in varying types of malignancies. In 
Volume 5 Number 2 of the Urology Journal, 
Shafaroudi and colleagues reported that increased 
urinary BMI1, but not BMI2, is associated with 
bladder cancer staging.(1) The question of whether 
patients with bladder cancer harbor genetically 
different features is an important issue, but the 
clinical relevance may be limited until such time 
as genetic profiling and individualized molecular 
treatment enter clinical settings. The 5-year 
survival after curative surgery for bladder cancer 
remains 50% to 60%, despite recent refinement 
of various therapeutic strategies, including 
surgery, radiotherapy, and chemotherapy.(2,3) 
Therefore, better identification of targeting genes 
associated with progression of bladder cancer 
is now mandatory to improve patient survival 
with this type of refractory cancer. In recent 
years, several new specific biomarkers have been 
identified for predicting prognosis of patients 
with bladder cancer. For example, expression 
of E-cadherin, beta-catenin, plakoglobin, and 
vimentin are associated with the clinicopathologic 
variables of grade and stage.(4) Overexpression of 
HER-2/neu is associated with tumor progression 
and poor prognosis.(5) In the present study, 
BMI1 was mainly stained in the nuclei of tumor 
cells, whereas no normal cell showed BMI1 
staining. (1) Overexpression of BMI1 was roughly 
associated with advanced pathological stage 
and higher tumor grade of bladder cancer.(1) 
Although the major limitation of this study is a 
weakness in the number of patients, the finding 

that BMI expression intensity correlates with 
cancer stage, suggests BMI1 may be a potential 
molecular target in patients with bladder cancer. 
Statistical evaluations will reveal whether BMI1 
overexpression is associated with an increased 
probability of bladder cancer-specific survival and 
recurrence-free survival. We hope that this article 
leads to additional studies.

Teruo Inamoto
Haruhito Azuma
Yoji Katsuoka

Department of Urology, Osaka Medical 
College, Osaka, Japan

E-mail: tinamoto@poh.osaka-med.ac.jp

REFERENCES
1. Malekzadeh Shafaroudi A, Mowla SJ, Ziaee SAM, 

Bahrami AR, Atlasi Y, Malakootian M. Overexpression 
of BMI1, a polycomb group repressor protein, 
in bladder tumors: a preliminary report. Urol J. 
2008;5:99-105.

2. Cookson MS. The surgical management of muscle 
invasive bladder cancer: a contemporary review. 
Semin Radiat Oncol. 2005;15:10-8.

3. Stein JP, Lieskovsky G, Cote R, et al. Radical 
cystectomy in the treatment of invasive bladder 
cancer: long-term results in 1,054 patients. J Clin 
Oncol. 2001;19:666-75.

4. Baumgart E, Cohen MS, Silva Neto B, et al. 
Identification and prognostic significance of an 
epithelial-mesenchymal transition expression 
profile in human bladder tumors. Clin Cancer Res. 
2007;13:1685-94.

5. Yamada Y, Naruse K, Nakamura K, et al. Potential for 
molecular targeted therapy of HER-2/neu for invasive 
bladder cancer: examination of gene amplification 
by fluorescence in situ hybridization. Oncol Rep. 
2007;18:1183-7.