Assay Method Information

Assay Name:  Inhibiting SOS1-Mediated GTP Nucleotide Exchange by Blocking Mant-GDP Exchange
Description:  Table 24: This Example illustrates that exemplary compounds of the present invention prevent KRas-mediated GTP nucleotide exchange mediated by SOS1 to inhibit KRas activity thereby inhibiting the generation of the downstream effector pERK. MKN1 cells (15,000/w) or H358 (30,000/w) were seeded in a black clear flat bottom 96-well cell culture plate (Corning, #3904) and incubated at 37° C. overnight. Assay day 1, cells were dosed with compounds of Formula (I) with a 10 μm starting concentration and serially diluted 3× for a total of 9 concentrations. The cells were incubated for approximately 0.5-1 hour with the compounds solubilized in DMSO at 37° C. Cells were immediately fixed by adding 50 μL of 4% formaldehyde to all wells in a fume hood and the plates were incubated for 20 minutes at room temperature. The formaldehyde was discarded from the plates and 150 μL of ice-cold methanol was added to permeabilize the cells for 10 minutes at −20° C. The methanol was discarded from each of the plates and any liquid remaining in the plate by tapping the plate against paper towels. Cells were then blocked with 150 μL of Odyssey blocking buffer (LI-COR Biosciences #927-50010) using 0.05% Tween for 1 hour at room temperature on a shaker. The blocking buffer was discarded and 50 μL of primary antibodies pERK (cell signaling Technology #9101L; Rabbit, 1:500) and GapDH (Millipore #MAB34; Mouse, 1:5000) diluted in Odyssey blocking buffer was added. The plates were incubated overnight at 4° C. on a shaker. On Assay Day 2, the primary antibody solution was removed. Each plate was washed 3× times with 150 μL of 1×PBST (PBS+0.1% Tween 20) and incubated with 50 μL of secondary antibodies: Anti-Rabbit (LI-COR Biosciences #926-32211) and Anti-Mouse (LI-COR Biosciences #68070) at 1:800 dilution in Odyssey blocking buffer with Tween at room temperature on a shaker for 2 hours (protected from light). The secondary antibody solution as removed and each plate was washed with PBST 3× times. Any liquid remaining was discarded and the plate was imaged using the Licor Odyssey machine according to the manufacturer's instruction, using a set focus length at 3 mm and both 800 nm and 700 nm filters. The GAPDH normalized scan values for each well were divided by the average of vehicle wells to get the % of pERK inhibition. The IC50 values were then calculated with the Graph pad Prism software.
Affinity data for this assay
 

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