Expression parameters of the polycomb group proteins BMI1, SUZ12, RING1 and CBX7 in urothelial carcinoma of the bladder and their prognostic relevance.
BACKGROUND
The polycomb group (PCG) proteins are epigenetic transcriptional repressors involved in the control of cellular proliferation and oncogenesis. This study aimed at examining whether mRNA tumor levels of the PCG family members BMI1, SUZ12, RING1, and CBX7 relate to histopathological parameters in urothelial carcinomas of the bladder and whether they may provide prognostic information following tumor resection.


METHODS
The relative gene expression of BMI1, SUZ12, RING1, and CBX7 was analyzed by real-time RT-PCR in tumor tissue obtained from 93 patients with urothelial carcinoma of the bladder undergoing surgical treatment. Expression data was correlated with pathological variables and outcome.


RESULTS
PCG family members BMI1, SUZ12, RING1, and CBX7 are commonly expressed in urothelial carcinomas of the bladder. The relative CBX7 mRNA expression levels gradually decreased from superficial (pTa) to invasive (pT1) and finally to muscle-invasive (> or =pT2) tumors (p = 0.008). Furthermore, CBX7 expression was statistically significantly correlated with tumor grade (p = 0.04). No correlation of mRNA levels with histopathological tumor features or tumor recurrence was observed for the other PCG components investigated.


CONCLUSIONS
Expression levels of CBX7 inversely correlate with the progression of tumor stage and grade in urothelial carcinomas of the bladder, suggesting that downregulation of CBX7 indicates aggressive urothelial carcinoma phenotype.
Hinz
S
S
Department of Urology, Charité - Universitätsmedizin Berlin, Berlin, Germany. stefan.hinz@charite.de
Kempkensteffen
C
C
Christoph
F
F
Krause
H
H
Schrader
M
M
Schostak
M
M
Miller
K
K
Weikert
S
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002352:Carrier Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008875:Middle Aged; D019042:Muscle Neoplasms / Q000235:genetics* / Q000473:pathology; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins; D009367:Neoplasm Staging; D009687:Nuclear Proteins / Q000235:genetics*; D063150:Polycomb Repressive Complex 1; D063151:Polycomb Repressive Complex 2; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015996:Survival Rate; D014157:Transcription Factors; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000473:pathology
C069077:BMI1 protein, human; C503627:CBX7 protein, human; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; C430461:SUZ12 protein, human; D014157:Transcription Factors; D063151:Polycomb Repressive Complex 2; D063150:Polycomb Repressive Complex 1; C080355:RING1 protein, human