Salinomycin Can Effectively Inhibit The Proliferation, Invasion Of Breast Cancer Cells And Kill Breast Cancer Stem Cells

Background: The invasion, recurrence and metastasis of breast cancer cells areimportant for the prognostic of breast cancer. The existence of cancer stem cells results inthe failure of cancer treatments. Researchers have identified that an antibiotic, calledsalinomycin, can effectively inhibit the growth of breast cancer stem cells and thetumor of mice. However, the exact mechanism has not been clear yet.Objective: To study the effects of salinomycin on breast cancer cells and to investigatethe mechanism of these effects.Materials and methods： The human breast cancer cells MCF-7, MCF-7/ADRand MDA-MB-231,were treated with epirubicin, docetaxel and salinomycin. Cellviability was determined by Cell Counting Kit8. The invasive ability of tumor cells wasevaluated by Transwell chamber assay. The mRNA levels of ETS1and MMP-1weredetected by real-time quantitative PCR, protein levels were detected by Western blotting,respectively.Fraction of ALDH1+cell subpopulations was assessed by Flow Cytometricanalysis. The formation of mammospheres was completed by suspension culture inserum-free DMEM-F12, supplemented with B27, bFGF and EGF.Results: Salinomycin significantly inhibited the proliferation of breast cancer cells,justlike epirubicin and docetaxel did; The inhibition got stronger when salinomycin wascombined with epirubicin or docetaxel; The invasion capacity of breast cancer cells wassignificantly reduced by salinomycin. Salinomycin inhibited the ability ofmammospheres formation and reduced the proportion of cancer stem cells in theMCF-7/ADR cells, at the same time, downregulated the level of ETS1.Conclusion: Salinomycin can inhibit the proliferation of breast cancer cells, increase thesensitivity to chemotherapy，reduce the invasion capacity and kill breast cancer stemcells.Conclusively, salinomycin may become a new choice for the treatments ofbreast cancer in the future.