Abstract 4816: Potent inhibition of the cell proliferation and induction of apoptosis in lymphoma cells by the anthelminthic drug niclosamide:in vitrodata

Background: Niclosamide, an anthelminthic drug, has demonstrated anti-cancer potential in variety of malignancies. However only a limited number of studies have been performed in lymphoma models, therefore we hypothesized that niclosamide may also have anti-cancer potential on B-cell lymphomas. Materials and Methods: Established B lymphoma cell lines were exposed to different concentrations of niclosamide and IC50 was calculated using GraphPad Prism 6.0 software. Cell viability and proliferation were assessed by CellTiter-Blue and trypan blue exclusion assays. Apoptosis was assessed by flow cytometry following Annexin-V/ propidium iodide staining. Gene expression changes were studied using GeneChip Human Transcriptome Array 2.0. Colony forming assays were performed in methylcellulose. Ultrastructural cellular changes were studied with electron microscopy. Peripheral blood mononuclear cells (PBMCs) from individuals without active cancer and from patients with different hematologic disorders, were also exposed with niclosamide. Results: Treatment with niclosamide resulted in time-and dose- dependent apoptosis, cytotoxicity and inhibition of proliferation in different lymphoma cell lines including vincristine-refractory cell line. The IC50 of lymphoma cells lines is as follows: Daudi: 0.33 iM; HBL-2: 0.57 iM; KOPN-8: 0.72 iM; Ramos: 0.53 iM and SU-DHL4-VR: 0.45 iM. Niclosamide also inhibited clonal growth in semi-solid media. Gene expression changes were studied in Daudi and KOPN-8 cells treated with 2.5 iM Niclosamide for 3 and 6 hours. 96 genes were consistently overexpressed, 59 down-regulated. 10 genes involved in the tumor necrosis factor (TNF) pathway and 10 genes involving the DNA damage pathway were overexpressed. 13 out of the 59 down-regulated genes were involved in mitochondrial function. Electron microscopy showed that filopodia increased and lipid vacuoles developed whereas mitochondria were less numerous in KOPN-8 cells. The viability of PBMCs from 8 individuals without lymphoma was unchanged when incubated with niclosamide, whereas niclosamide showed significant cytotoxicity in a patient with mantle cell lymphoma (MCL). Conclusion: Niclosamide effectively inhibits the proliferation of B lymphoma cell lines, including vincristine-refractory lymphoma cells, and induces apoptosis at concentrations non-toxic to PBMCs. Interestingly, niclosamide exhibited cytotoxic activity against MCL cells - a finding worth testing further in this difficult-to-treat disease. The mechanism of action of Niclosamide may involve the TNF receptor pathway, mitochondrial function and DNA damage response pathway. We plan to elucidate further specific mechanism(s) of action, and evaluate synergistic effects with other antineoplastic agents, and perform in vivo studies. Citation Format: Junaid Ansari, Hazem El-Osta, Paula Polk, Jeffrey J. Aufman, Guillermo A. Herrera, James Cardelli, Rodney E. Shackelford, Glenn M. Mills, Magdalena L. Circu, Felicity N. E. Gavins, Reinhold Munker. Potent inhibition of the cell proliferation and induction of apoptosis in lymphoma cells by the anthelminthic drug niclosamide: in vitro data. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4816.