THE INFLUENCE OF PYRIMIDINE NUCLEOSIDE PHOSPHORYLASE-ACTIVITY ON METASTASIS OF BREAST-CANCER

The activity of pyrimidine nucleoside phosphorylase (PyNPase) was anal yzed in thirty-six cases of resected breast cancer and 9 cases of rese cted benign breast tumor. PyNPase is an enzyme which converts 5'-DFUR to 5-FU in tumor tissue and has been reported to be identical to the p latelet-derived endothelial cell growth factor (PD-ECGF) that has angi ogenic activity. PyNPase activity was significantly elevated in cancer and metastatic lymph nodes compared to normal lesions of the same bre ast. PyNPase activity was higher in T2 and T3 breast cancer than of T1 breast cancer. Furthermore, cases of high PyNPase activity (>200 mu g FU/mg protein/h) were significantly more likely to develop distant me tastasis (p<0.01) than those of low PyNPase activity. These results su ggest an important role of PyNPase activity in the progression of brea st cancer.