CD44 interacts with EGFR and promotes head and neck squamous cell carcinoma initiation and progression

SummaryObjectivesCD44 is a promising target for therapy in head and neck squamous cell carcinoma (HNSCC) and has two defined roles in tumorigenesis: it is a cancer stem cell (CSC) marker and it promotes migration and proliferation through interaction with many signaling molecules. The purpose of this study was to investigate the role of CD44 in HNSCC carcinogenesis.Materials and methodsThe effects of CD44 in cell proliferation, migration, apoptosis and cisplatin resistance were studied by its overexpression in HNSCC cells. We also evaluated the effect of CD44 on tumor progression by siRNA methodology, immunohistochemistry (IHC) and western blot analysis. CD44 and EGFR colocalization were examined in CAL 27 cells by laser scanning confocal microscopy. The interaction between CD44 and EGFR was analyzed by immunoprecipation.ResultsOverexpression of CD44 enhances cell proliferation and migration and correlates with increased cisplatin resistance and apoptosis inhibition in SCC25 cells. Downregulation of CD44 in CAL27 cells inhibited constitutive EGFR phosphorylation and significantly reduced tumor growth in nude mice. CD44 and EGFR colocalized in CAL 27 cells. CD44 coimmunoprecipated with EGFR in CAL 27 cells, indicating that these proteins interact with each other.ConclusionCD44 therapy in HNSCC may target the CSC population and alter EGFR signaling.