Expression of angiopoietin-2 gene and its receptor Tie2 in hepatocellular carcinoma.

Abstract

To explore the relationship of angiogenesis-related angiopoietin-2 gene and its receptor Tie2 with angiogenesis and the biology of hepatocellular carcinoma (HCC), angiopoietin-2 gene, Tie2 and CD34 protein expression in 22 resected HCC, 8 cirrhotic and 8 control liver specimens were investigated by in situ hybridization and immunohistochemistry respectively, and the level of angiopoietin-2 and Tie2 expression in HCC were compared in terms of tumor biological parameters. It was found that CD34 was not expressed in control liver, expressed scarcely in cirrhotic liver (17.8 +/- 13.5/HP), but intensively expressed in HCC (86.3 +/- 34.8/HP, P < 0.01). Tie2 receptor was not expressed in controls, expressed at low level in cirrhotic liver (11.3 +/- 8.7/HP), while strongly positive in the microvascular endothelia of HCC (52.4 +/- 16.7/HP, P < 0.01). The level of Tie2 receptor expression in HCC was closely related with tumor diameter, angiogenesis and portal invasion. Angiopoietin-2 gene was not expressed in control liver, expressed mildly in cirrhotic liver (11.2 +/- 9.7/HP), but extensively in tumor zone (36.4 +/- 17.5/HP), the level of angiopoietin-2 expression was closely related with angiogenesis, portal invasion and histological grading of HCC. It is concluded that angiogenesis is increased in HCC; angiopoietin-2/Tie2 expression in human hepatic carcinoma is closely related with angiogenesis, which are probably involved in the HCC angiogenesis regulation, promoting the development and metastasis of human hepatic cancer.