THYMIDINE PHOSPHORYLASE-ACTIVITY IN HUMAN BLADDER-CANCER - DIFFERENCEBETWEEN SUPERFICIAL AND INVASIVE CANCER

The activity of thymidine phosphorylase (TdR-Pase), which is identical to platelet-derived endothelial cell growth factor (a potent angiogen ic factor), was analysed in primary human bladder cancer tissues, TdR- Pase activity in tissues was determined from the conversion rate of 5' -deoxy-5-fluorouridine to 5-fluorouracil, The mean activity in 37 blad der cancers and in 8 samples of normal bladder epithelial tissue was 1 08.5 and 19.2 mu g 5-fluorouracil/mg protein/h, respectively, showing a statistically significant difference, Among the cancer tissues, diff erences in activity were seen according to the stage and grade of tumo rs, Low-grade (grade 1) tumors had significantly lower activities than high-grade tumors, and high-grade invasive tumors showed significantl y higher activities than low-grade superficial tumors, These results d emonstrate that a high TdR-Pase activity in bladder cancer is associat ed with the tumor characteristics of invasion and malignant potential, Our conclusions support the hypothesis that angiogenesis that is medi ated by this molecule may be involved in the development of invasive h uman bladder cancer, as suggested by T. O'Brien et al, (Cancer Res., 5 5: 510-513, 1995), and also suggest that TdR-Pase is a potential thera peutic target in human bladder cancer.