Altered Expression of p33(ING1) in Human Bladder Cancer / 대한비뇨기과학회지

ABSTRACT

PURPOSE: p33(ING1) seems to be a candidate of novel growth inhibitor as a tumor suppressor gene and plays a critical role in regulation of cell cycle progression and susceptibility to apoptosis. In this study, we investigated p33(ING1) expression pattern in human bladder cancer and normal tissue. MATERIALS AND METHODS: RNA was extracted from 42 bladder cancer specimens and 24 normal bladder mucosa. Expression of p33(ING1) was examined by quantitative RT- PCR in which the ratio to GAPDH, an internal control, was used as a standardized expression value of the p33(ING1). Alterations of p33(ING1) expression between cancer and normal mucosa were compared and interrelationship with stage and grade was analyzed. To detect the mutations in the p33(ING1), PCR-SSCP analysis was also performed. RESULTS: Out of 42 bladder cancer (25 superficial and 17 invasive), 9 were grade I, 23 were grade II, and 10 were grade III. p33(ING1) expression in bladder cancer significantly decreased compared to that in normal bladder mucosa. The ratio of p33(ING1)/ GAPDH was 0.45 +/- 0.13 in bladder cancer, whereas for normal bladder mucosa this ratio was 0.66 +/- 0.17 (p <0.001). However, expression of p33(ING1) was neither correlated with tumor stage nor grade (p=0.489 and p=0.375, respectively). Changes in electrophoretic mobility of PCR-SSCP products were not detected in any of bladder cancers. CONCLUSIONS: These data suggest that decreased expression of p33(ING1) may contribute to the development of bladder cancer in part, even though the gene is mostly preserved. However, considering a discrepancy between the rate of mutation and the decreased expression, further study is warranted to determine the mechanism.