Properties and functions of TP/PD-ECGF — enzyme and angiogenic factor in norm and in neoplastic pathology

Abstract

Thymidine phosphorylase is a protein which may has a dual action: it is a rate-limiting enzyme in thymidine metabolism and it is similar to the platelet – derived endothelial cell growth factor (PD/ECGF). The enzyme catalyzes the reversible reaction of phosphorolytic cleavage of thymidine to thymine and deoxyribose-1-phosphate. It has been found that TP has higher activity in tumor tissues. Also it is involved in a proliferative process in a wide variety of chronic inflammatory diseases. Increased expression of PD/ECGF in many tumors is associated with aggressive disease and/or poor prognosis. Its known that high TP activity is related to malignant angiogenesis and invasion.
 On the other hand, TP inhibits a hypoxia induced apoptotic pathway and enhances expression of various inflammatory cytokines and interferons. This apparent role of enzyme in tumor progression has prompted investigation a large number of TP inhibitors for applicability in chemotherapy backbone regimens. The enzymatic activity of PD/ECGF is being able to generate 5-fluorouracile from capecitabine and other precursors. Thus TP is identified as a prime target for developing novel anticancer therapies. The serum TP level in cancer patients provides useful prognostic information regarding both responses to chemotherapy and length of survival and should be used in planning appropriate therapy. TP could be suggested that control of individual enzyme activity in blood serum may be used as informative tool for monitoring of patients and treatment optimization.