In vitro activity: Niclosamide (< 5 μM) dose dependently inhibits STAT3-mediated luciferase reporter activity with IC50 of 0.25 μM in HeLa cells. Niclosamide(< 2 μM) dose dependently inhibits the phosphorylation of STAT3 in Du145 cells. Niclosamide (1 μM) inhibits the EGF-induced nuclear translocation of STAT3 in Du145 cells. Niclosamide(< 2 μM) dose dependently inhibits the transcription of STAT3 downstream genes in Du145 cells. Niclosamide(< 10 μM) dose dependently induces G0/G1 arrest and apoptosis of Du145 cancer cells. Niclosamide is able to inhibit SARS-CoV replication at a micromolar concentration in Vero E6 cells infected with SARS-CoV. Niclosamide(< 7.5 μM) promotes Frizzled1 endocytosis, downregulates Dishevelled-2 protein, and inhibits Wnt3A-stimulated beta-catenin stabilization and LEF/TCF reporter activity in U2OS cells. Niclosamide inhibits the TNF-induced NF-κB reporter activity in a dose- and time-dependent manner in U2OS cells. Niclosamide(125 nM) inhibits NF-κB activation induced by p65, IKKα, IKKβ, IKKγ, and TAK1 in U2OS cells. Niclosamide(< 500 nM) completely block the time- and dose-dependent TNFα-induced alteration of the NF-κB–DNA complex in HL-60 cells. Niclosamide(< 10 nM) inhibits constitutive NF-κB activation in U266 cells. Niclosamide inhibits TNF-induced degradation of IκBα and relocation of p65 in a dose- and time-dependent manner in HL-60, Molm13, or AML primary cells. Niclosamide(500 nM) decreases TNF-induced NF-κB–dependent gene products involved in cell survival in HL-60 cells. Niclosamide dose dependently inhibits the growth and induces robust apoptosis of AML cells associated with decreased Mcl-1 and XIAP levels and increased intracellular ROS levels.

Kinase Assay: Assay for 22 different proteins kinases is carried out by ProQinase Gmbh. All of the protein kinases are expressed either in Sf9 insect cells or in E.coli as recombinant GST-fusion proteins or His-tagged proteins. Protein kinases are purified by affinity chromatography using either GSH-agarose or Ni_NTH-agarose. A radiometric protein kinase assay is used for measuring the kinase activity of the 22 protein kinases. Briefly, for each protein kinase, 50 μL reaction cocktail containing 60 mM HEPES-NaOH, 3 mM MgCl2, 3 mM MnCl2, 3 μM Na-orthovanadate, 1.2 mM DTT, 50 μg/mL PEG20000, 1 μM [γ-33P]-ATP, Niclosamide, adequate amount of enzyme and its substrate. The PKC-alpha assay additionally contain 1 mM Cacl2, 4 mM EDTA, 5 μg/mL phosphatidylserine and 1 μg/mL 1, 2-Dioleyl-glycerol. The reaction cocktails are incubated at 37 °C for 60 minutes and stop with 50 μL 2% (v/v) H3PO4. Incorporation of 33Pi is determined with a microplate scintillation counter. The activities and the IC50 values are calculated using Quattro Workflow V2.28.

Cell Assay: Cells are plated in 96-well culture plates with cell density of 3-4 × 103 cells/well and treat with Niclosamide by adding 100 μL medium containing Niclosamide of various concentrations on the second day. After 72-hour's treatment, MTT is added to each well and incubated for additional 4-5 hours, and the absorbance is measured on a microplate reader at 570nm. Cell growth inhibition is evaluated as the ratio of the absorbance of the sample to that of the control. The results are representative of at least 3 independent experiments.

Antimicrob Agents Chemother. 2004 Jul;48(7):2693-6; Cancer Res. 2010 Mar 15;70(6):2516-27.