In vitro activity: In a time-resolved fluorescence resonance energy transfer assay, TPCA-1 inhibits human IKK-2 activity with an IC50 of 17.9 nM. In addition, TPCA-1 is demonstrated to be ATP-competitive. Besides, TPCA-1 exhibits IC50 values of 400 nM and 3600 nM against IKK-1 and JNK3, respectively. TPCA-1 inhibits the production of TNF-α, IL-6, and IL-8 in a concentration-dependent manner, exhibiting IC50 values of 170, 290, and 320 nM, respectively. TPCA-1 inhibits glioma cell proliferation, as well as TNF-induced RelA (p65) nuclear translocation and NFκB-dependent IL8 gene expression. Importantly, TPCA-1 inhibits IFN-induced gene expression, completely suppressing MX1 and GBP1 gene expression, while having only a minor effect on ISG15 expression.

Kinase Assay: Recombinant human IKK-2 (residues 1-756) is expressed in baculovirus as an N-terminal GST-tagged fusion protein, and its activity is assessed using a time-resolved fluorescence resonance energy transfer assay. In brief, IKK-2 (5 nM final) diluted in assay buffer (50 mM HEPES, 10 mM MgCl2, 1 mM CHAPS, pH 7.4, with 1 mM DTT and 0.01% w/v BSA) is added to wells containing various concentrations of compound or dimethyl sulfoxide (DMSO) vehicle (3% final). The reaction is initiated by the addition of GST-IκBα substrate (25 nM final)/ATP (1 μM final), in a total volume of 30 μL. The reaction is incubated for 30 min at room temperature, then terminated by the addition of 15 μL of 50 mM EDTA. Detection reagent (15 μL) in buffer (100 mM HEPES, pH 7.4, 150 mM NaCl, and 0.1% w/v BSA) containing antiphosphoserine- IκBα-32/36 monoclonal antibody 12C2, labeled with W-1024 europium chelate, and an allophycocyanin-labeled anti-GST antibody is added, and the reaction is further incubated for 60 min at room temperature. The degree of phosphorylation of GST- IκBαis measured as a ratio of specific 665-nm energy transfer signal to reference europium 620-nm signal, using a Packard Discovery plate reader.

Cell Assay: Ten microliters of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) from stock solution (10 mg/mL) is added to each well of 96-well plates containing glioma cells and incubated at 37 °C for 2–4 h. Oxidized MTT is solubilized by adding 100 μL of 10% sodium dodecyl sulfate (SDS) in 0.01 N HCL, and plates are incubated at 37 °C for 4 h in a humidified chamber. Plates are read at 570 nm on a plate reader.

J Pharmacol Exp Ther. 2005 Jan;312(1):373-81; J Interferon Cytokine Res. 2012 Aug;32(8):368-77.