Thymidine phosphorylase induces carcinoma cell oxidative stress and promotes secretion of angiogenic factors.

Thymidine phosphorylase (TP) (E.C. 2.4.2.4), also known as platelet-derived endothelial cell growth factor, is a potent angiogenic factor. The expression of TP correlates with poor prognosis in a range of tumor types. 2-Deoxy-D-ribose-1-phosphate, a product of thymidine catabolism by TP, is a strongly reducing sugar that generates oxygen radical species during the early stages of protein glycation. We show that thymidine induces oxidative stress in TP-overexpressing carcinoma cells, promoting secretion of the stress-induced angiogenic factors vascular endothelial growth factor and interleukin-8, and inducing matrix metalloproteinase-1. Our findings outline a putative mechanism for TP-induced angiogenesis and identify novel targets for intervention.