Quercetin Inhibits Breast Cancer Stem Cells via Downregulation of Aldehyde Dehydrogenase 1A1 (ALDH1A1), Chemokine Receptor Type 4 (CXCR4), Mucin 1 (MUC1), and Epithelial Cell Adhesion Molecule (EpCAM)

BACKGROUND: Quercetin, nature’s most common flavonoid, possesses anticarcinogenic properties against various forms of cancer. The aim of this study was to investigate the effect of quercetin on breast cancer stem cells in the MDA-MB-231 cell line, and to elucidate the possible mechanisms for those effects. MATERIAL/METHODS: We evaluated breast cancer stem cell proliferation, clone generation, and mammosphere formation to determine the effect of quercetin treatment on breast cancer stem cells. RESULTS: In our study, quercetin suppressed breast cancer stem cell proliferation, self-renewal, and invasiveness. It also lowered the expression levels of proteins related to tumorigenesis and cancer progression, such as aldehyde dehydrogenase 1A1, C-X-C chemokine receptor type 4, mucin 1, and epithelial cell adhesion molecules. CONCLUSIONS: These results indicate that quercetin targets and destroys breast cancer stem cells, making it a potential novel drug in the fight against cancer.