Interplay between Partial EMT and Cisplatin Resistance as the Drivers for Recurrence in HNSCC

This study aims to investigate the role of partial epithelial to mesenchymal transition (pEMT)-related proteins in modulating Cisplatin resistance in head and neck squamous cell carcinoma (HNSCC). SCC-25 cells were pre-treated with TGF-beta1 followed by transient Krüppel-like Factor 4 (KLF4)-overexpression and Cisplatin treatment. Cell growth, cell morphological changes and cell migration were assessed using Juli BR live cell video-microscopy. In addition, Ki-67 and Slug immunostaining and follow-up image cytometric analysis of primary and recurrent HNSCC tumors were performed to evaluate the proliferation index (PI) and the EMT-like phenotype. We observed that proliferating and Slug-positive tumor cells expand after therapy in HNSCC. Subsequently, protein analysis revealed the stabilization of Slug, upregulation of Vimentin and phospho-p38 (p-p38) in Cisplatin-resistant SCC-25 cells. Moreover, KLF4-overexpression contributed to Cisplatin sensitivity by reduction of Slug at the protein level. This work strongly suggests that an pEMT-like pathway is activated in recurrent and Cisplatin-resistant HNSCC. Finally, stable KLF4-overexpression might sensitize HNSCC tumor cells for Cisplatin treatment.