Objective: Tumor angiogenesis is an essential step for tumor growth, progression and metastasis. Vascular endothelial growth factor (VEGF) is a mitogen specific for vascular endothelial cells, and plays a key role in tumor angiogenesis. The purpose of the present study was to investigate the expression of VEGF mRNA and VEGF protein in choroidal melanoma and to correlate these factors and the microvessel density (MVD) with the clinicopathologic prognostic features.
Methods: In a total of 65 cases of choroidal melanoma from the Pathology Laboratory of Tongren Hospital, the expression of VEGF mRNA was assessed by in situ hybridization (ISH); the expression of VEGF protein and factor VIII-related antigen (FVIII-RAg) was assessed using immunohistochemical methods. MVD was evaluated by immunohistochemical staining of FVIII-RAg for vascular endothelial cells.
Results: VEGF mRNA expression was present in 56/65 cases (86%), while VEGF immunoreactivity was present in 55/65 cases (85%). Positive expression of VEGF and VEGF mRNA was correlated with the tumor size (P = 0.025) and local invasion of tumor to scleral emissaria (P = 0.034), but it's relation to the histologic type, the tumor location and the largest tumor diameter (LTD) was not statistically significant. MVD was significantly higher in the VEGF-positive melanoma than in the VEGF-negative melanoma (one way analysis of variance, P = 0.000). There was no significant correlation between MVD and tumor location, as well as the tumor height and the patient's age; however, significant correlation was found between MVD and LTD, as well as with the tumor size, cell type and the invasion of tumor to the scleral emissaria (t test, P = 0.012, 0.008, 0.001 and 0.000, respectively).
Conclusions: Most choroidal melanomas express VEGF mRNA and VEGF protein, and this expression is correlated with MVD. This suggests that angiogenesis is significantly correlated with clinicopathologic prognostic factors of choroidal melanoma, such as LTD, tumor size, cell type and tumor invasion. MVD and the expression of VEGF may be useful prognostic indicators for the biological behavior and the outcome of choroidal melanoma.