Previous studies demonstrated that the immunohistochemical expression of
thymidine phosphorylase (dThdPase) was related with distant
metastasis and
disease progression. In this study we investigated the production of dThdPase/
platelet-derived endothelial cell growth factor in
gastric cancer quantitatively. In a total of 75 tumour tissues and 60 normal gastric mucosa specimens, dThdPase
protein concentrations were determined by ELISA. The amount of dThdPase was significantly higher in the tumour tissue than in the normal tissue. Intratumoural dThdPase concentrations were significantly higher in Borrmann types I and II macroscopically, in poorly differentiated and solid type histologically, in the medullary type of the tumour stroma, and in the tumour-invading serosa. In the medullary type of the amount of tumour stroma,
protein levels of dThdPase were positively correlated with the vertical diameter of the tumour (r = 0.580, P = 0.019). By immunohistochemical study, dThdPase expression on tumour cells was observed in all seven specimens with high dThdPase
protein levels, but not in all 14 cases with low dThdPase
protein levels (P < 0.05). In summary, these data indicated that dThdPase is up-regulated in advanced solid types of
gastric cancer, suggesting that dThdPase production in
carcinoma cells might be induced by the microenvironment.