Objective: To investigate the expression of angiopoietin (Ang)-1 and Ang-2 in colorectal tumors and its relations to microvessel density (MVD) in tumor tissue.
Methods: Ang-1, Ang-2 and factor VIII-related antigen were stained immunohistochemically in 91 cases of primary colorectal adenocarcinoma, 20 cases of colorectal adenoma and 24 cases of normal colorectal mucosal tissue, and MVD was also assayed in above tissue specimens.
Result: (1) A significantly higher Ang-1 (7.07+/-2.00) was observed in normal tissue compared with 1.75 +/-1.98 in the adenoma and 1.40 +/- 1.22 in the adenocarcinoma (P<0.01). (2) Ang-2 protein positive rate in adenocarcinoma was significantly higher than that in normal tissue and adenoma (P<0.01). The expression of Ang-2 in adenocarcinoma was closely associated with poor differentiation and vessel invasion. (3) There were significant correlations between Ang-1 and Ang-2 (r=-0.338, P<0.01), Ang-1 and MVD (r=-0.388, P<0.01), Ang-2 and MVD (r=0.594, P<0.01) in the 135 cases.
Conclusion: The overexpression of Ang-2 may play an important role in angiogenesis of colorectal adenocarcinoma. It can be regarded as an index for malignancy and prognosis in colorectal adenocarcinoma.