Recombinant canstatin inhibits VEGF‐A‐induced lymphangiogenesis and metastasis in an oral squamous cell carcinoma SCC‐VII animal model

We describe the inhibitory effects of recombinant canstatin on tumor growth and lymphangiogenesis induced by an oral squamous cell carcinoma (SCC) using an orthotropic oral SCC animal model. Recombinant canstatin treatment decreased final tumor volumes and weights, as well as densities of blood and lymphatic vessels. Lung metastasis of oral SCC was significantly reduced in recombinant canstatin‐treated animals. Recombinant canstatin reduced vascular endothelial growth factor (VEGF)‐A expression in SCC‐VII cells treated with the hypoxia mimetic agent, CoCl(2). VEGF‐A induced in vivo lymphatic vessel formation in a Matrigel plug, but this was remarkably reduced in a recombinant canstatin‐treated Matrigel. Recombinant canstatin suppressed the expression of vascular endothelial growth factor receptors (VEGFR)‐1 and ‐2 stimulated by VEGF‐A. Based on immunohistochemical analysis, recombinant canstatin significantly reduced the expression of VEGF‐A, VEGFR‐1, and ‐2 in SCC‐VII‐induced tumors. Recombinant canstatin did not affect the expression of VEGF‐C or VEGFR‐3. In addition, recombinant canstatin suppressed the VEGF‐A‐induced phosphorylation of VEGFR‐1 and ‐2. Our results indicate that recombinant canstatin exhibits antitumoral and antilymphangiogenic activities against oral SCC cells. Antilymphangiogenic signaling by recombinant canstatin is probably mediated by the suppression of the integrin αvβ3/VEGFR‐1 and/or ‐2 signaling induced by VEGF‐A. Our results also suggest that recombinant canstatin has a high potential to inhibit oral SCC‐induced tumors and lymphatic metastasis.