[Expression of cyclooxygenase-2 in human transitional cell bladder carcinomas].Ai Zheng. 2002 Nov; 21(11):1212-6.AZ
BACKGROUND & OBJECTIVES
Cyclooxygenase(COX) is a rate-limiting enzyme in prostaglandin synthesis. Recent study suggested that COX-2 was associated with carcinogenesis. This study was designed to investigate the role of COX in the development and progression of bladder cancer through examining the expression of COX-1 and COX-2 in human bladder cancer tissue, normal bladder mucosa, and cystitis tissue.
Reverse transcriptase-polymerase chain reaction(RT-PCR) and immunohistochemistry(Envision method) were applied to detect the mRNA and protein expression of COX-1 and COX-2 in bladder transitional cell carcinoma(BTCC), tissue adjacent to cancer, normal bladder mucosa, and chronic cystitis tissue. Furthermore, the relationship between COX expression level and cancer pathologic parameters was analyzed.
Using RT-PCR, all 15 frozen specimens from bladder cancer were shown to express COX-2 mRNA, while only 1 of 5 specimens from grossly normal mucosa adjacent to cancer expressed COX-2 mRNA, with significant difference. But COX-1 mRNA was expressed constitutionally in all of the fresh cancer tissue samples. The immunohistochemical result was analogous to RT-PCR result. COX-2 protein was mainly localized at cytoplasm of malignant cell (positive rate was 50%) but was not expressed in normal bladder mucosa (n = 4) and chronic cystitis tissues (n = 5). In contrast, COX-1 protein was mainly localized at smooth muscle cell of normal tissue and cystitis tissue(positive rate was 100%) but was not expressed in cancer tissue. In 40 paraffin embedded specimens of BTCC, the intensity of COX-2 expression was associated with tumor grade and stage. The level of COX-2 expression was higher in grade III tumor, than in grade I, II tumors, and was higher in invasive tumor (T2-T4) than in superficial tumor(Ta-T1).
The expression of COX-2 mRNA and protein was enhanced in human BTCC, and was associated with the malignant degree of the tumor, indicating that COX-2 may play a key role in the development and progression of BTCC.