Quercetin in elimination of tumor initiating stem-like and mesenchymal transformation property in head and neck cancer

Background. Previously, we enriched a subpopulation of head and neck cancer-derived tumor initiating cells (HNC-TICs) presented high tumorigenic, chemo-radioresistant, and coupled with epithelial-mesenchymal transition (EMT) properties. The purpose of this study was to investigate the therapeutic effect and molecular mechanisms of quercetin on HNC-TICs. Method. ALDH1 activity of head and neck cancer cells with quercetin treatment was assessed by the Aldefluor assay flow cytometry analysis. Self-renewal, invasiveness, and EMT capability of HNC-TICs with different doses of quercetin was presented. Results. We first observed that the treatment of quercetin significantly downregulated the ALDH1 activity of head and neck cancer cells in a dose-dependent manner (p < .05). Moreover, quercetin reduced self-renewal property and stemness signatures expression in head and neck cancer-derived sphere cells. The migration ability of head and neck cancer-derived sphere cells was lessened under quercetin treatment partially due to the decreased productions of Twist, N-cadherin, and vimentin. Conclusion. Quercetin suppressing HNC-TICs characteristics may therefore be valuable therapeutics clinically in combination with standard treatment modalities. (C) 2012 Wiley Periodicals, Inc. Head Neck 35: 413-419, 2013