Specific Expression of Endoglin (CD105) in Endothelial Cells of Intratumoral Blood and Lymphatic Vessels in Pancreatic Cancer

Objectives: Endoglin, a component of the transforming growth factor beta receptor expressed in embryonic vascular endothelial cells, is expressed in vascular endothelial cells in several types of cancer tissues and is involved in tumor angiogenesis. The aim of this study was to analyze the expression pattern of endoglin in pancreatic cancer and assess the involvement of this molecule in cancer progression. Methods: Pancreatic cancer and adjacent normal tissues obtained from 36 patients were subjected to immunostaining with anti-endoglin antibody, and the microvessel density (MVD) was assessed based on the number of endoglin-positive vessels. Results: Endoglin was expressed in endothelial cells of small capillary-like vessels in pancreatic cancer tissues from all 36 patients, and lymphatic endothelial cells in the tumors also expressed endoglin. In contrast, endothelial cells of vascular and lymphatic vessels in normal pancreatic tissue did not express endoglin. Patients with a higher MVD of endoglin-positive vessels had shorter disease-free and overall survival. Conclusions: Endoglin is specifically expressed in endothelial cells of small vascular and lymphatic vessels in cancer tissues. The MVD of endoglin-positive vessels may also be a useful prognostic marker in pancreatic cancer patients.