| In Vitro | In vitro activity: E7080, as a potent inhibitor of in vitro angiogenesis, shows a significantly inhibitory effect on VEGF/KDR and SCF/Kit signaling. According to the in vitro receptor tyrosine and serine/threonine kinase assays, E7080 inhibits Flt-1, KDR, Flt-4 with IC50 of 22, 4.0 and 5.2 nM, respectively. In addition to these kinases, E7080 also inhibits FGFR1 and PDGFR tyrosine kinases with IC50 value of 46, 51 and 100 nM for FGFR1, PDGFRα and PDGFRβ, respectively. E7080 potently inhibits phosphorylation of VEGFR2 (IC50, 0.83 nM) and VEGFR3 (IC50, 0.36 nM) in HUVECs which is stimulated by VEGF and VEGF-C, respectively. A recent study shows that E7080 treatment (both at 1 μM and 10 μM) results in a significant inhibition of cell migration and invasion by inhibiting FGFR and PDGFR signaling.
Kinase Assay: Tyrosine kinase assays are performed by HTRF (KDR, VEGFR1, FGFR1, c-Met, EGFR) and ELISA (PDGFRβ), using the recombinant kinase domains of receptors. In both assays, 4 μL of serial dilutions of E7080 are mixed in a 96-well round plate with 10 μL of enzyme, 16 μL of poly (GT) solution (250 ng) and 10 μL of ATP solution (1 μM ATP) (final concentration of DMSO is 0.1%). In wells for blanks, no enzyme is added. In control wells no test article is added. The kinase reaction is initiated by adding ATP solution to each well. After 30-minute incubation at 30°C, the reaction is stopped by adding 0.5 M EDTA (10 μL/well) to the reaction mixture in each well. Dilution buffer adequate to each kinase assay is added to the reaction mixture. In the HTRF assay, 50 μL of the reaction mixture is transferred to a 96-well 1/2 area black EIA/RIA plate, HTRF solution (50 μL/well) is added to the reaction mixture, and then kinase activity is determined by measurement of fluorescence with a time-resolved fluorescence detector at an excitation wavelength of 337 nm and an emission wavelengths of 620 and 665 nm. In the ELISA, 50 μL of the reaction mixture is incubated in avidin coated 96-well polystyrene plates at room temperature for 30 minutes. After washing with wash buffer, PY20-HRP solution (70 μL/well) is added and the reaction mixture is incubated at room temperature for 30 minutes. After washing with wash buffer, TMB reagent (100 μL/well) is added to each well. After several minutes (10–30 minutes), 1 M H3PO4 (100 μL/well) is added to each well. Kinase activity is determined by measurement of absorbance at 450 nm with a microplate reader.
Cell Assay: HUVECs (1,000 cells in each well in serum-free medium containing 2% fetal bovine serum) and L6 rat skeletal muscle myoblasts (5,000 cells in each well in serum-free DMEM) are dispensed in a 96-well plate and incubated overnight. E7080 and either VEGF (20 ng/mL) or FGF-2 (20 ng/mL) containing 2% fetal bovine serum and PDGFβ (40 ng/mL) are added to each well. Cells are incubated for 3 days and then the ratios of surviving cells are measured by WST-1 reagent. For proliferation assay, samples are duplicated and three separate experiments are done. |
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