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Systemic activation of the vascular endothelial growth factor receptor KDR/flk-1 selectively triggers endothelial
Abstract:
The hypothesis that tumor growth is angiogenesis dependent has been documented by a considerable body of direct and indirect experimental data. A prerequisite for the development of novel anti-angiogenic agents is the design of drugs that would be active only on those endothelial cells with an angiogenic phenotype. We took advantage of the anti-idiotypic strategy to obtain circulating agonists specific for the vascular endothelial growth factor receptor KDR/flk-1 (J-IgG). They induced in the absence of VEGF cell proliferation in vitro and angiogenesis in the corneal pocket assay either through local or systemic delivery. Intraperitoneal injections of J-IgG in nude mice grafted with a prostatic adenocarcinoma led to tumor enlargement associated with an increase in both tumor vascularization and proliferation. In contrast KDR/flk-1 overstimulation had no detectable effect on normal tissues. These data underline that KDR/flk-1 is a functional marker of the angiogenic phenotype of endothelial cells.
Insights
Novel anti-angiogenic drugs target specific endothelial cells. Researchers developed agonists for the vascular endothelial growth factor receptor KDR/flk-1, which stimulated tumor growth and vascularization in mice without affecting normal tissues.
Area of Science:
- Oncology
- Vascular Biology
- Drug Development
Background:
- Tumor growth is dependent on angiogenesis, the formation of new blood vessels.
- Developing targeted anti-angiogenic therapies requires drugs specific to angiogenic endothelial cells.
- The vascular endothelial growth factor receptor KDR/flk-1 is a key target in angiogenesis.
Purpose of the Study:
- To develop agonists specific for the KDR/flk-1 receptor using an anti-idiotypic strategy.
- To investigate the effect of KDR/flk-1 overstimulation on tumor growth and vascularization.
- To determine if KDR/flk-1 stimulation has differential effects on tumor versus normal tissues.
Main Methods:
- Utilized an anti-idiotypic strategy to generate circulating agonists (J-IgG) specific for KDR/flk-1.
- Assessed in vitro cell proliferation and in vivo angiogenesis using the corneal pocket assay.
- Administered J-IgG intraperitoneally to nude mice bearing prostatic adenocarcinoma.
Main Results:
- J-IgG induced endothelial cell proliferation in vitro and angiogenesis in the corneal pocket assay.
- Intraperitoneal J-IgG administration led to increased tumor growth, vascularization, and proliferation in mice.
- Overstimulation of KDR/flk-1 had no observable effects on normal tissues.
Conclusions:
- KDR/flk-1 is a functional marker for the angiogenic phenotype of endothelial cells.
- Targeted stimulation of KDR/flk-1 can promote tumor angiogenesis and growth.
- This approach offers a potential strategy for developing targeted anti-angiogenic therapies.