Role of Cyclooxygenase-2 Enzyme in Human Transitional Cell Carcinoma of the Urinary Bladder

Cyclooxygenase (COX) is considered a key enzyme in the synthesis of prostaglandins from arachidonic acid. The enzyme is believed to be involved in the inflammation, proliferation and differentiation of cells. The generated form of COX, COX-2, is increased in colonic carcinoma. To evaluate the importance of COX-2 in tumor development in the urinary bladder, the expression of COX-2 in transitional cell carcinoma of the bladder was examined to determine the usage of selective COX-2 inhibitor treatment targeting COX-2. Sixty patients with pathologically diagnosed invasive transitional cell carcinoma of the urinary bladder (pT2-pT4) were evaluated. Immunohistochemical staining was used to evaluate COX-2 expression and cases with staining of 10% of tumor cells were defined as positive. The results indicated that in 5 patients, 0 % of the primary tumors stained for COX-2, while 1-5 % was stained in 20 patients, 6-10% in 7 patients and 10% in 28 patients (28/60, 46.7%). In terms of grade, 4 patients with grade 2 (4/6, 66.6%) and 24 patients with grade 3 (24/54, 46.7%) were COX-2 positive. When categorized by stage, 16 patients with PT2 (16/33, 48.5%), 9 patients with pT3 (9/20, 45%) and 3 patients with pT4 (3/7, 42.9%) were positive. Lymph node metastasis was observed in 15 patients; 4 of them, with pN2, were COX-2-positive.Those with COX-2-positive metastatic lymph nodes had grade 3 primary tumors, which were also COX-2positive. In addition, COX-2-negative metastatic lymph node patients also had negative primary tumors. The results of this study suggested that 46.7% of patients with invasive bladder cancer may show benefit from treatment with selective COX-2inhibitors targeting COX-2 and that treatment efficiency can be expected in patients with lymph node metastasis when their primary tumors are COX-2-positive.