Background & objective: Recently, Angiopoietin-1 (Ang-1) and Angiopoietin-2 (Ang-2) have been identified as potential angiogenic factors. The local balance between them and other angiogenic factors determines the growth, stableness, or regression of blood vessels. This study was to investigate the correlations of Ang-1 and Ang-2 expression to clinicopathologic features, microvessel density (MVD), and vessel maturation index (VMI) of oral squamous cell cacinoma (OSCC), and evaluate the significance of Ang-1 and Ang-2 coexpression in tumor angiogenesis and vessel maturation.
Methods: The expression of Ang-1 and Ang-2 in 41 specimens of OSCC, 30 specimens of adjacent noncancerous oral tissues, and 10 specimens of normal oral mucosa was detected by immunohistochemistry. MVD and VMI were assessed with double-labeling immunohistochemical staining against CD34 and alpha-smooth muscle actin (alpha-SMA).
Results: The positive rate of Ang-1 was significantly lower in OSCC than in adjacent noncancerous oral tssues and normal oral mucosa (41.46% vs. 90.00% and 90.0%, P < 0.05); the positive rate of Ang-2 was significantly higher in OSCC than in adjacent noncancerous oral tssues and normal oral mucosa (51.22% vs. 26.67% and 0, P < 0.05). The differences in Ang-1 and Ang-2 expression between adjacent noncancerous oral tssues and normal oral mucosa were not significant (P > 0.05). The positive rate of Ang-1 was significantly higher in highly differentiated tumor than in moderately differentiated tumor (56.00% vs. 18.75%, P < 0.05); the positive rate of Ang-2 was significantly higher in tumor with lymph node metastasis than in tumor without lymph node metastasis (84.62% vs. 35.71%, P < 0.01). Ang-1 and Ang-2 expression were closely correlated with angiogenesis and vessel maturation of tumor (P < 0.05). Ang-1 and Ang-2 had antagonistic effect on the regulation of tumor vessel maturation.
Conclusion: The down-regulation of Ang-1 and up-regulation of Ang-2 are closely related to tumor angiogenesis and vessel maturation.