Assay Method Information
Assay Name:  GRE Agonist Assay
Description:  A reporter cell line (ChagoK1 18:7:2 s4/GRE) was established by stable transfection of the human bronchogenic carcinoma cell line, ChaGo K1 (ATCC: HTB 168) with a MMTV-GRE-LacZ reporter construct. The generated cell line allows for identification of compounds showing agonist activity at the human glucocorticoid receptor (GR) via induction of LacZ gene expression. Ligand-activated GR binds to the Glucocorticoid Response Element (GRE) in the promoter of the LacZ gene and transcription is initiated. The resulting beta-galactosidase activity is measured through a colour reaction (change in absorbance).Cryo-preserved ChagoK1 18:7:2 s4/GRE cells were suspended in RPMI medium with 10% FBS, 1% NEAA and 1% sodium pyruvate, and seeded as 50000 cells/200 ul/well in 96-well plates and cultured at 37° C. with 5% CO2 and 95% humidity for 24 hours. 1 μl compound was added at different concentrations to the cells and incubated for another 24 hours. Cells were washed once in PBS and lysed with 50 μl of 0.1% Triton-X for 10 min at room temperature. 40 μl of reaction mixture (2.5 mM MgCl2, 0.1 M β-mercapto ethanol, 1.7 mg/ml ONPG and 42.5 mM sodium phosphate, pH 7.5), was added to each well and kept at 37° C. for 60 min. The reaction was then terminated by addition of 100 μl stop solution (300 mM glycine, 15 mM EDTA, pH 11.3, adjusted with NaOH). The plates were measured at 420 nm for absorbance in a SpectraMax reader (Molecular Device).The relative efficacy (% effect) of a compound is calculated based on the full agonist effect of dexamethasone: % Effect=((Sample abs−min abs)/(max abs−min abs))×100To calculate EC50, max, min and slope factor for each compound, a concentration response curve is fitted by plotting % Effect versus compound concentration using the 4 parameter logistic equation: y=A+(B−A)/(1+((10C)/x)D)Where A=min Y, B=max Y, C=log EC50 and D=Slope factor.
Affinity data for this assay
 
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