Vascular endothelial growth factor is an in vivo survival factor for tumor endothelium in a murine model of colorectal carcinoma liver metastases.
BACKGROUND
Recent studies have suggested that vascular endothelial growth factor (VEGF), in addition to its proangiogenic properties, also functions as a survival factor for endothelial cells. The authors hypothesized that inhibition of VEGF activity by blockade of VEGF receptor-2 (R-2) function prevents angiogenesis and decreases tumor growth in colon carcinoma liver metastases.


METHODS
Spleens of mice were injected with human colon carcinoma cells producing liver metastases. After 7 days of tumor growth, groups of mice received either antibody to VEGFR-2 (DC101) or phosphate-buffered saline (control). In a follow-up experiment, a similar treatment regimen was followed except that mice were sacrificed at 1-week intervals to assess the time course of endothelial cell and tumor cell apoptosis.


RESULTS
After 21 days of therapy, the authors observed a significant decrease in vessel counts in liver metastases from human colon carcinoma in nude mice after therapy with VEGFR-2 antibody. Tumor cell apoptosis was increased significantly in the tumors of mice receiving DC101. Temporal studies with immunofluorescent double staining for the microvasculature and apoptotic cells revealed an increase in endothelial cell apoptosis that preceded an increase in tumor cell apoptosis. In vitro, treatment of human umbilical vein endothelial cells with antibody to VEGFR-2 produced a > 2.5-fold increase in endothelial cell apoptosis.


CONCLUSIONS
Therapy targeting the VEGFR-2 inhibited tumor growth in a murine model of colon carcinoma liver metastasis. Surprisingly, this therapy did not only inhibit angiogenesis but also led to endothelial cell death. These findings suggest that VEGF, via VEGFR-2 signaling, functions as a survival factor for tumor endothelial cells in liver metastases from colon carcinoma.
Bruns
C J
CJ
Department of Cancer Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Liu
W
W
Davis
D W
DW
Shaheen
R M
RM
McConkey
D J
DJ
Wilson
M R
MR
Bucana
C D
CD
Hicklin
D J
DJ
Ellis
L M
LM
D020533:Angiogenesis Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003110:Colonic Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D016228:Endothelial Growth Factors / Q000037:antagonists & inhibitors / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000378:metabolism / Q000556:secondary*; D008222:Lymphokines / Q000037:antagonists & inhibitors / Q000378:metabolism; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D017978:Receptors, Growth Factor / Q000037:antagonists & inhibitors*; D040262:Receptors, Vascular Endothelial Growth Factor; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D016228:Endothelial Growth Factors; D008222:Lymphokines; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D018809:Proliferating Cell Nuclear Antigen; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor