Antineoplastic Mechanisms of Niclosamide in Acute Myelogenous Leukemia Stem Cells: Inactivation of the NF-κB Pathway and Generation of Reactive Oxygen Species

Abstract

NF-κB may be a potential therapeutic target for acute myelogenous leukemia (AML) because NF-κB activation is found in primitive human AML blast cells. In this report, we initially discovered that the potent antineoplastic effect of niclosamide, a Food and Drug Administration-approved antihelminthic agent, was through inhibition of the NF-κB pathway in AML cells. Niclosamide inhibited the transcription and DNA binding of NF-κB. It blocked tumor necrosis factor-induced IκBα phosphorylation, translocation of p65, and expression of NF-κB-regulated genes. Niclosamide inhibited the steps TAK1→IκB kinase (IKK) and IKK→IκBα. Niclosamide also increased the levels of reactive oxygen species (ROS) in AML cells. Quenching ROS by the glutathione precursor N-acetylcysteine attenuated niclosamide-induced apoptosis. Our results together suggest that niclosamide inhibited the NF-κB pathway and increased ROS levels to induce apoptosis in AML cells. On translational study of the efficacy of niclosamide against AML, niclosamide killed progenitor/stem cells from AML patients but spared those from normal bone marrow. Niclosamide was synergistic with the frontline chemotherapeutic agents cytarabine, etoposide, and daunorubicin. It potently inhibited the growth of AML cells in vitro and in nude mice. Our results support further investigation of niclosamide in clinical trials of AML patients. Cancer Res; 70(6); 2516-27. ©2010 AACR.

Ponatinib Induces Apoptosis in Imatinib-Resistant Human Mast Cells by Dephosphorylating Mutant D816V KIT and Silencing β-Catenin Signaling

“…For detection of AIF and cytochrome c, cytosolic fraction was prepared with digitonin extraction buffer (28). Extracts of subcellular cytoplasmic, mitochondrial, and nuclear fractions were separated as previously described (23).…”

“…The MTS assay (CellTiter 96 Aqueous One Solution reagent; Promega) was used to evaluate cell viability as described previously (23,28). Synergism of combinational drugs was evaluated by the median-effect method of Chou and Talalay (28).…”

“…Synergism of combinational drugs was evaluated by the median-effect method of Chou and Talalay (28).…”

“…One week later, the number of colony-forming units was evaluated with microscope according to the standard criteria (28 (25). The cells were then exposed to ponatinib and subjected to cell death assay and Western blotting analysis.…”

“…The dual luciferase reporter assay was performed according to the manufacturer's instructions (Promega; ref. 28). …”