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Suppression of experimental choroidal neovascularization utilizing KDR selective receptor tyrosine kinase inhibitor
Atsunobu Takeda1, Yasuaki Hata, Satomi Shiose
1Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, 812-8582 Fukuoka, Japan.
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).
Conclusion:
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.
Insights
Vascular Endothelial Growth Factor (VEGF) and its receptor KDR are crucial in choroidal neovascularization (CNV). A KDR-selective inhibitor, SU5416, effectively reduced CNV development and thickness in experimental models, suggesting therapeutic potential.
Area of Science:
- Ophthalmology
- Angiogenesis Research
- Molecular Biology
Background:
- Choroidal neovascularization (CNV) is a significant cause of vision loss.
- The VEGF-VEGF receptor 2 (KDR) system plays a key role in CNV development.
- Targeting KDR offers a potential therapeutic strategy for CNV.
Purpose of the Study:
- To investigate the role of the VEGF-KDR system in CNV.
- To evaluate the therapeutic potential of a KDR-selective inhibitor (SU5416) for CNV.
Main Methods:
- In vitro studies using bovine choroidal endothelial cells (BCECs) to assess VEGF-induced signaling.
- In vitro proliferation and tube formation assays.
- An experimental CNV model in rats induced by laser photocoagulation.
- Evaluation of SU5416 efficacy using fluorescein angiography and histology.
Main Results:
- SU5416 inhibited VEGF-induced KDR and p44/p42 MAPK phosphorylation in BCECs.
- SU5416 dose-dependently suppressed VEGF-induced proliferation and in vitro tube formation.
- SU5416 significantly reduced fluorescein leakage and CNV membrane thickness in the experimental model.
Conclusions:
- The VEGF-KDR system is critical for CNV development.
- KDR-selective inhibitors like SU5416 demonstrate anti-angiogenic efficacy against CNV.
- KDR inhibitors hold promise for treating intraocular angiogenic diseases, including age-related macular degeneration.