Assay Method Information

Assay Name:  IDO1 Cell-Based Assay
Description:  HeLa cells were obtained from the American Type Culture Collection (ATCC) and maintained in DMEM media containing 10% FBS. Cells (7,000/well) were seeded onto a 384 well plate in 50 μL of media and incubated at 37° C., 5% CO2 overnight. Cell media was aspirated, fresh media containing 10 ng/mL IFNgamma was added, and cells were incubated in absence or presence of various concentrations of test compound (final 0.5% DMSO) for 24 hours. Aliquots of the cell conditioned media were removed from the cell plate, and mixed with an equal volume of 200 mM ZnSO4 to precipitate media containing proteins. Two volumes of acetonitrile were added, mixed, and samples were then centrifuged at 2250 G for 20 minutes at 4° C. Aliquots of the supernatant were diluted 1:10 in 0.1% formic acid containing 3 μM of deuterated Tryptophan as an internal standard.Samples were analyzed via RFMS to quantify N-Formyl Kynurenine (AUC) and L-tryptophan (AUC). A C18 cartridge was used with mobile phases of 0.1% Formic Acid and 80% ACN/0.1% Formic Acid under isocratic conditions. Dose-response curves were analyzed using IC50 regression curve fitting (GeneData Screener). Curves were plotted as percent of control and normalized by high controls without inhibitor (100%), and low controls (0%) containing 1 μM of epacadostat, a potent cell-permeable IDO1 inhibitor. Cell viability was also assessed using the Cell Titer Glo Kit (Promega) following manufacturer recommendation.
Affinity data for this assay
 

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