Vascular endothelial growth factor (VEGF)-C differentially affects tumor vascular function and leukocyte recruitment : Role of VEGF-receptor 2 and host VEGF-A

Unlike vascular endothelial growth factor (VEGF)-A, the effect of VEGF-C on tumor angiogenesis, vascular permeability, and leukocyte recruitment is not known. To this end, we quantified in vivo growth and vascular function in tumors derived from two VEGF-C-overexpressing (VC+) and mock-transfected cell lines (T241 fibrosarcoma and VEGF-A-/- embryonic stem cells) grown in murine dorsal skinfold chambers. VC+ tumors grew more rapidly than mock-transfected tumors and exhibited parallel increases in tumor angiogenesis. Furthermore, VEGF-C overexpression elevated vascular permeability in T241 tumors, but not in VEGF-A-/- tumors. Surprisingly, unlike VEGF-A, VEGF-C did not increase leukocyte rolling or adhesion in tumor vessels. Administration of VEGF receptor (VEGFR)-2 neutralizing antibody DC101 reduced vascular density and permeability of both VC+ and mock-transduced T241 tumors. These data suggest that VEGFR-2 signaling is critical for tumor angiogenesis and vascular permeability and that VEGFR-3 signaling does not compensate for VEGFR-2 blockade. An alternate VEGFR, VEGFR-1 or neuropilin-1, may modulate adhesion of leukocytes to tumor vessels.