RESUMEN
BACKGROUND: Epithelial to mesenchymal transition (EMT) promotes therapy resistance in head and neck cancer (HNC) cells. In this study, EMT was quantified in HNC tumor samples by the cellular co-localization of cytokeratin/vimentin, Ecadherin/ßcatenin and by Slug expression. METHODS: Tissue samples from HNC patients were stained with antibody pairs against cytokeratin/vimentin and E-cadherin/ß-catenin. Epithelial-mesenchymal co-localization was quantified using immunofluorescence multichannel image cytometry. Double positivity was confirmed using confocal microscopy. Slug was semi-quantified by 2 specialists and quantified by bright field image cytometry. RESULTS: Tumor samples of 102 patients were investigated. A loss of E-cadherin positive cells (56.9 ± 2.6% vs. 97.9 ± 1.0%; p < 0.0001) and E-cadherin/ß-catenin double positive cells (15.4 ± 5.7% vs. 85.4 ± 1.2%; p < 0.0001) was observed in tumor samples. The percentage of Slug positive cells was increased in tumor samples (12.1 ± 3.6% vs. 3.2 ± 2.6%; p = 0.001). Ordinal Slug scores judged by two specialists closely correlated with percentage of Slug-positive cells (Spearman's rho = 0.81; p < 0.001). Slug score correlated negatively with the percentage of E-cadherin positive cells (r = 0.4; p = 0.006), the percentage of E-cadherin/ß-catenin positive cells (r = 0.5; p = 0.001) and positively with cytokeratin/vimentin positive cells (r = 0.4, p = 0.003). CONCLUSION: EMT can be assessed in HNC tumor probes by cytokeratin/vimentin co-expression and loss of E-cadherin/ß-catenin co-expression. Slug score provides a convenient surrogate marker for EMT.
RESUMEN
Epithelial mesenchymal crosstalk (EMC) describes the interaction of the tumor stroma and associated fibroblasts with epithelial cancer cells. In this study we analysed the effects of EMC on head and neck cancer cells. In tumor cell lines EMC was induced using media conditioned from a mix-culture of cancer cells and fibroblasts. Cell proliferation and chemotherapy response were assessed using direct cell counting. Flow cytometry, immunohistochemistry of markers of epithelial-mesenchymal transition (EMT) and subsequent TissueFaxs™ acquisition and quantification and western blot analysis were performed. Holotomographic microscopy imaging was used to visualize the effects of EMC on Cisplatin response of SCC-25 cells. EMC induced a hybrid epithelial-mesenchymal phenotype in SCC-25 cells with co-expression of vimentin and cytokeratin. This hybrid phenotype was associated with chemotherapy resistance and increased proliferation of the cells. The EMC conditioned medium led to an activation of the IL-6/STAT3 pathway with subsequent phosphorylation of STAT3. EMC induced a hybrid epithelial-mesenchymal phenotype in HNSCC cells accompanied by increased therapy resistance and cell proliferation. The IL-6/STAT3 pathway might be one of the major pathways involved in these EMC-related effects.