Expression of cyclooxygenase-2 in human transitional cell carcinoma of theurinary bladder

Recent studies suggest that expression of cyclooxygenase-2 (Cox-2) is eleva ted in transitional cell carcinoma (TCC) of the urinary bladder and that in hibition of Cox-2 activity suppresses bladder cancer in experimental animal models. We have investigated the expression of Cox-2 protein in human TCCs (n = 85), in in situ carcinomas (Tis) of the urinary bladder (n = 17), and in nonneoplastic urinary bladder samples (n = 16) using immunohistochemist ry. Cox-2 immunoreactivity was detected in 66% (67 of 102) of the carcinoma s, whereas only 25% (4 of 16) of the nonneoplastic samples were positive (P < 0.005), Cox-2 immunoreactivity localized to neoplastic cells in the carc inoma samples. The rate of positivity was the same in invasive (T1-3; 70%, n = 40) and in noninvasive (Tis and Ta; 65%, n = 62) carcinomas, but non in vasive tumors had a higher frequency (32%) of homogenous pattern of stainin g (>90% of the tumor cells positive) than the invasive carcinomas (10%) (P < 0.05). However, several invasive TCCs exhibited the strongest intensity o f Cox-2 staining in the invading cells, whereas other parts of the tumor we re virtually negative. Finally, strong Cox-2 positivity was also found in n onneoplastic ulcerations (2 of 2) and in inflammatory pseudotumors (2 of 2) , in which the immunoreactivity localized to the nonepithelial cells, Taken together, our data suggest that Cox-2 is highly expressed in noninvasive b ladder carcinomas, whereas the highest expression of invasive tumors associ ated with the invading cells, and that Cox-2 may also have a pathophysiolog ical role in nonneoplastic conditions of the urinary bladder, such as ulcer ations and inflammatory pseudotumors.