BackgroundHead and neck squamous cell carcinoma (HNSCC) tumors are often therapy resistant and may originate from cancer stem cells or tumor cells with an epithelial-to-mesenchymal transition (EMT) phenotype. The aim of this study was to characterize HNSCC cell lines with regard to EMT profile and to investigate the influence of EMT on the response to treatment. MethodsmRNA expression of the EMT-associated genes CDH1 (E-cadherin), CDH2 (N-cadherin), FOXC2, TWIST1, VIM (vimentin), and FN1 (fibronectin) was determined using quantitative real-time PCR. Cell morphology and migration were investigated by phase-contrast microscopy and Boyden chamber assay, respectively. The cell surface expression of CD44 and epidermal growth factor receptor (EGFR) was examined by flow cytometry. The response to radiotherapy, cetuximab, and dasatinib was assessed by crystal violet staining. ResultsA total of 25 cell lines investigated differed greatly with regard to EMT phenotype. Cell lines with an EMT expression profile showed a mesenchymal morphology and a high migratory capacity. In addition, they exhibited a high cell surface expression of CD44 and a low expression of EGFR, a pattern previously associated with stemness. When the EMT inducer transforming growth factor- (TGF-) was added to non-EMT cells, changes in treatment responses were observed. Moreover, the expression of TWIST1 was found to correlate with radioresistance. ConclusionsThe data presented in this report suggest that EMT is associated with a CD44(high)/EGFR(low) phenotype and possibly negative impact on radiotherapy response in HNSCC cell lines.