Autocrine and paracrine roles of VEGF/VEGFR-2 and VEGF-C/VEGFR-3 signaling in angiosarcomas of the scalp and face☆

Angiosarcoma of the skin is an extremely rare malignant tumor of vascular origin that usually arises in the scalp and face of elderly persons. To clarify its characteristic features and cell cycle kinetics, we quantitatively evaluated the expression of cell cycle–related molecules and vascular endothelial growth factors using immunohistochemical staining, for comparison with 2 benign vascular tumors of the skin, the capillary hemangioma and the cavernous hemangioma. Cell proliferation, determined with reference to the Ki-67 labeling index, was highest in angiosarcomas and lowest in cavernous hemangiomas (angiosarcomas versus capillary hemangioma, P = .014; capillary hemangioma versus cavernous hemangiomas, P = 1.4 × 10−4). Similar differences were also found in cyclin A, cyclin E, and p21Waf1 expression. Expressions of cyclin D1 and p16INK4A were also significantly higher in angiosarcoma than in cavernous hemangioma. Expressions of these 5 proteins showed significant positive correlations with Ki-67 labeling indices (Spearman ρ = 0.91-0.43). Expression levels of vascular endothelial growth factor and its receptor, VEGFR-2, were highest in angiosarcomas. VEGF-C expression in angiosarcomas was significantly higher than in cavernous hemangiomas, and its receptor VEGFR-3 expression was highest in angiosarcomas. Furthermore, significant positive correlations of these protein expression with Ki-67 labeling indices were noted (Spearman ρ = 0.88-0.40). Among them, VEGFR-3 showed the highest correlation coefficient. These results suggest that not only VEGFR-2-mediated signal but also VEGFR-3-mediated signal may contribute to proliferation of vascular tumor cells as autocrine and paracrine signaling factors.