Suppression of experimental choroidal neovascularization utilizing KDR selective receptor tyrosine kinase inhibitor.
BACKGROUND
We investigated the role of the VEGF-VEGF receptor 2 (KDR) system in the development of choroidal neovascularization (CNV) and its possibility as a therapeutic target utilizing KDR selective receptor tyrosine kinase (RTK) inhibitor (SU5416) both in vitro and in an experimental CNV model.


METHODS
VEGF-induced phosphorylation of KDR and p44/p42 MAPK in cultured bovine choroidal endothelial cells (BCECs) was determined by Western blot analysis. The proliferation and in vitro tube formation were analyzed by [3H]thymidine uptake and three-dimensional collagen gel model. For experimental CNV model, intense fundus laser photocoagulation was performed on pigmented rats. The anti-angiogenic efficacy of intraperitoneally injected SU5416 on experimental CNV was evaluated by fluorescein angiography and histology. The extent of fluorescein leakage on late-phase angiograms was scored, and the thickness of CNV membrane was histologically measured under a light microscope.


RESULTS
VEGF-induced KDR phosphorylation in cultured BCECs was inhibited by SU5416 in a dose-dependent manner (0-3 microM) with IC50 of 0.29 +/- 0.071 microM. SU5416 treatment also resulted in a dose-dependent prohibition of VEGF-induced p44/p42 MAPK phosphorylation, [3H]thymidine uptake and in vitro tube formation with corresponding concentrations that inhibited KDR phosphorylation. The leakage score on fluorescein angiography for experimental CNV was significantly lower in the SU5416-treated group than in the control group (P<0.01). Histologically, the CNV membranes in the SU5416-treated group were 31.6% thinner than those in the control group (P<0.01).


CONCLUSIONS
These results strengthen the evidence for a critical role of the VEGF-KDR system in the development of CNV, indicating that KDR selective inhibitor might be beneficial for the treatment of intraocular angiogenic diseases, including age-related macular degeneration.
Takeda
Atsunobu
A
Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, 812-8582 Fukuoka, Japan.
Hata
Yasuaki
Y
Shiose
Satomi
S
Sassa
Yukio
Y
Honda
Masae
M
Fujisawa
Kimihiko
K
Sakamoto
Taiji
T
Ishibashi
Tatsuro
T
D000818:Animals; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D020256:Choroidal Neovascularization / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D004728:Endothelium, Corneal / Q000098:blood supply / Q000166:cytology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011758:Pyrroles / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors* / Q000378:metabolism
D004791:Enzyme Inhibitors; D005419:Flavonoids; D007211:Indoles; D011758:Pyrroles; D042461:Vascular Endothelial Growth Factor A; C116890:Semaxinib; D011505:Protein-Tyrosine Kinases; D040301:Vascular Endothelial Growth Factor Receptor-2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one