WH-4-023  (Synonyms: Dual LCK/SRC inhibitor)

The Lck HTRF kinase assay involves ATP-dependent phosphorylation of a biotinylated substrate peptide of gastrin in the presence or absence of inhibitor compound. The final concentration of gastrin is 1.2 μM. The final concentration of ATP is 0.5 μM (K_m app =0.6±0.1 μM), and the final concentration of Lck (a GST-kinase domain fusion (AA 225−509)) is 250 pM. Buffer conditions are as follows: 50 mM HEPES pH=7.5, 50 mM NaCl, 20 mM MgCl₂, 5 mM MnCl₂, 2 mM DTT, 0.05% BSA. The assay is quenched and stopped with 160 μL of detection reagent. Detection reagents are as follows: Buffer made of 50 mM Tris, pH=7.5, 100 mM NaCl, 3 mM EDTA, 0.05% BSA, 0.1% Tween20. Prior to reading, Streptavidin allophycocyanin (SA-APC) is added at a final concentration in the assay of 0.0004 mg/mL, along with europilated anti-phosphotyrosine Ab (Eu-anti-PY) at a final conc of 0.025 nM. The assay plate is read in a Discovery fluorescence plate reader with excitation at 320 nm and emission at 615 and 655 nm^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

The purpose of this assay is to test the potency of T cell receptor (TCR; CD3) and CD28 signaling pathway inhibitors in human T cells. T cells are purified from human peripheral blood lymphocytes (hPBL) and preincubated with or without compound prior to stimulation with a combination of an anti-CD3 and an anti-CD28 antibody in 96-well tissue culture plates (1×10⁵ T cells/well). Cells are cultured for ~20 h at 37°C in 5% CO₂ and then secreted IL-2 in the supernatants is quantified by cytokine ELISA. The cells remaining in the wells are then pulsed with ³H-thymidine overnight to assess the T cell proliferative response. Cells are harvested onto glass fiber filters and ³H-thymidine incorporation into DNA is analyzed by liquid scintillation counter. For comparison purposes, phorbol myristic acid (PMA) and calcium ionophore are used in combination to induce IL-2 secretion from purified T cells. Potential inhibitor compounds are tested for inhibition of this response as described above for anti-CD3 and -CD28 antibodies. Human whole-blood anti-CD3/CD28-induced IL-2 secretion assays are run in a similar fashion as described above using whole blood from normal volunteers diluted 50% in tissue culture medium prior to stimulation^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

• [1]. Martin MW, et al. Novel 2-aminopyrimidine carbamates as potent and orally active inhibitors of Lck: synthesis, SAR, and in vivo antiinflammatory activity. J Med Chem. 2006 Aug 10;49(16):4981-91.  [Content Brief]