The role of thymidine phosphorylase and thrombospondin-1 in angiogenesis and progression of intrahepatic cholangiocarcinoma

Thymidine phosphorylase (TP), an important regulator of angiogenesis, is correlated with progression, metastasis, and prognosis in various types of tumor. In contrast, both positive and negative effects of thrombospondin-1 (TSP-1) on angiogenesis have been reported. In the present study, we examined the expression of TP and TSP-1 in carcinoma cells in 67 primary intrahepatic cholangiocarcinomas (ICCs) immunohistochemically and its correlation with angiogenesis, clinicopathological features, and prognosis. Twenty-six (38.8%) cases were classified as exhibiting positive TP expression. TP expression showed a significant correlation with vascular invasion, lymphatic permeation, perineural invasion, and lymph node metastasis. Thirty-four (50.7%) cases were classified as exhibiting positive TSP-1 expression. TSP-1 expression was significantly correlated with only lymphatic permeation. The microvessel count in positive TP expression cases was significantly higher than that in negative cases. In contrast, the microvessel count in negative TSP-1 expression cases was significantly higher than that in positive cases. Survival in patients who were positive for both TP and TSP-1 expression was significantly poor. Our results suggest that the increased TP expression and decreased TSP-1 expression contribute to angiogenesis, but that the role of angiogenesis in ICC is not closely related to tumor aggressiveness. The TP and TSP-1 expression in ICC may enhance tumor aggressiveness.