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Flk-1 as a target for tumor growth inhibition
1SUGEN, Inc., Redwood City, California 94063, USA.
Abstract:
A number of growth factor receptor tyrosine kinases have been implicated in angiogenesis, including epidermal growth factor receptor, fibroblast growth factor receptor, platelet-derived growth factor receptor, Flk-1/KDR, Flt-1, Tie-1, and Tek/Tie-2. Flk-1/KDR, a receptor for vascular endothelial growth factor (VEGF), is expressed exclusively in endothelial cells. Using dominant-negative methods, Flk-1 was shown to play a role in angiogenesis and the growth of a variety of tumor types. Because of this, a drug discovery effort was established to identify Flk-1 kinase inhibitors. For initial screening, an ELISA in, a 96-well format was used to measure VEGF-induced Flk-1 tyrosine phosphorylation in whole cells. Compounds that inhibited ligand-induced receptor autophosphorylation were confirmed by antiphosphotyrosine immunoblotting. Inhibition of VEGF-stimulated DNA synthesis in human endothelial cells was also assessed. Inhibitors were further evaluated for their effects on vessel formation using the chorioallantoic membrane assay. Using these methods, antiangiogenesis compounds that inhibit Flk-1 tyrosine kinase activity, endothelial cell mitogenesis, and blood vessel formation in the chorioallantoic membrane assay have been found.
Insights
Researchers identified compounds that inhibit Flk-1 tyrosine kinase activity, crucial for blood vessel formation. These anti-angiogenesis drugs target vascular endothelial growth factor (VEGF) signaling, offering potential cancer therapies.
Area of Science:
- Molecular Biology
- Oncology
- Biochemistry
Background:
- Growth factor receptor tyrosine kinases are key regulators of angiogenesis.
- Vascular Endothelial Growth Factor (VEGF) receptor Flk-1/KDR is exclusively expressed in endothelial cells and plays a critical role in angiogenesis.
- Flk-1 signaling is implicated in tumor growth, making it a target for anti-cancer drug discovery.
Purpose of the Study:
- To identify inhibitors of Flk-1 tyrosine kinase activity.
- To develop novel anti-angiogenesis compounds for potential therapeutic applications.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) for screening VEGF-induced Flk-1 tyrosine phosphorylation.
- Antiphosphotyrosine immunoblotting for confirmation of kinase inhibition.
- Assessment of VEGF-stimulated DNA synthesis in endothelial cells.
- Chorioallantoic membrane assay to evaluate effects on blood vessel formation.
Main Results:
- Identified compounds that inhibit Flk-1 tyrosine kinase activity.
- Confirmed inhibition of ligand-induced receptor autophosphorylation.
- Demonstrated inhibition of endothelial cell mitogenesis and blood vessel formation in vivo.
Conclusions:
- Flk-1 tyrosine kinase inhibitors were successfully identified using a multi-assay approach.
- These compounds exhibit anti-angiogenic properties by inhibiting Flk-1 kinase activity, endothelial cell proliferation, and blood vessel formation.
- The identified inhibitors represent promising candidates for anti-cancer drug development targeting angiogenesis.