Expression of antioxidant enzymes (catalase, superoxide dismutase, and glutathione peroxidase) in human bladder cancer

Purpose: Intrinsic antioxidant enzymes (AOE) are essential for protection against potential cellular damage by reactive oxygen species (ROS), which affect many biological processes including carcinogenesis. The aim of the present study was to characterize the expression of antioxidant enzymes in human bladder cancer tissue and to evaluate the relationship with histopathological characteristics. Materials and methods: Immunohistochemical staining for catalase, superoxide dismutase (SOD), and glutathione peroxidase (GPx) was performed on formalin-fixed, paraffin-embedded tissues obtained from 75 bladder cancersand 30 normal bladders. The degree of AOE expression was compared with cancer invasiveness or the cell grade. Results: The expression of catalase and SOD were significantly lower in cancer tissue than in normal bladder tissue (44% vs 73.3%, p=0.012; 49.3% vs 80%, p=0.007, respectively) but GPx expression was not significantly different (45.3% vs 63.3%, p=0.146). Catalase and SOD expression were significantly lower in invasive transitional cell carcinomas than in superficial transitional cell carcinomas (32.4% vs 53.7%, p=0.034; 32.4% vs 63.4%, p=0.014, respectively), but again GPx expression was not significantly different (38.2% vs 51.2%, p=0.26). Moreover, no significant difference was observed between the expression of all three enzymes and the cancer cell grade. Conclusions: Down-regulation of the antioxidant enzyme system, as indicated by the expression of catalase and SOD, appears to be related with carcinogenesis and progression in bladder cancer.