Radiosensitization of human triple-negative breast cancer MDA-MB-231 cells by antihelminthic niclosamide

Abstract

Objective To investigate the radiosensitization effect of antihelminthic niclosamide on human triple-negative breast cancer MDA-MB-231 cells and the potential mechanism related to Wnt/β-catenin signaling pathway.Methods Four methyl thiazolyl tetrazolium(MTT) assay was used to measure the effect of niclosamide on cell viability at different concentrations and 50％ inhibitory concentration(IC50)value was calculated.MDA-MB-231 cells were divided into 4 groups:untreated control,niclosamide treatment alone group,radiation alone group and niclosamide plus radiation treatment group.The cells with or without 1.0 and 1.5 μmol/L niclosamide pre-treatment were irradiated with 137Cs γ-rays at doses of 0,2,4 and 6 Gy.Cell survival was assayed with the colony formation method,radiation-induced γH2AX foci was analyzed with immunofluorescence,cell cycle progression was assayed with flow cytometry,and the changes of phospho-and non-phospho-β-catenin and Cyclin D1 protein expressions were measured with Western blot.Results Niclosamde obviously inhibited the viability of MDA-MB-231 cells in a dosedependent manner with a IC50 value of 13.63 μmol/L.Pretreatment of cells with 1.0 and 1.5 μmol/L niclosamide evidently enhanced the radiosensitivity of MDA-MB-231 cells to γ-rays,and the values of SER were 1.37 and 1.62,respectively.Niclosamide pretreatment significantly increased radiation-induced γH2AX foci formation(t =3.91,P ＜0.05),diminished the radiation-induced G2/M arrest(t =8.05,P ＜0.01),and inhibited radiation-induced expressions of phospho-β-catenin (S675),non-phospho-β-catenin and Cyclin D1 proteins in MDA-MB-231 cells.Conclusions Niclosamide significantly can enhance the sensitivity of MDA-MB-231 cells to γ-ray irradiation through inhibiting Wnt/β-catenin signaling pathway,which results in the inhibition of DNA DSBs repair and the reduction of radiation-induced G2/M arrest.Wnt/β-catenin signaling pathway may serve as an ideal molecular target for radiosensitization of triplenegative breast cancer. Key words: Niclosamide; Radiosensitization; β-catenin; MDA-MB-231 cells