The <i>NOTCH4</i> – <i>HEY1</i> Pathway Induces Epithelial–Mesenchymal Transition in Head and Neck Squamous Cell Carcinoma

Abstract

<b>Purpose:</b> Recently, several comprehensive genomic analyses demonstrated <i>NOTCH1</i> and <i>NOTCH3</i> mutations in head and neck squamous cell carcinoma (HNSCC) in approximately 20% of cases. Similar to other types of cancers, these studies also indicate that the <i>NOTCH</i> pathway is closely related to HNSCC progression. However, the role of <i>NOTCH4</i> in HNSCC is less well understood.<b>Experimental Design:</b> We analyzed <i>NOTCH4</i> pathway and downstream gene expression in the TCGA data set. To explore the functional role of <i>NOTCH4</i>, we performed <i>in vitro</i> proliferation, cisplatin viability, apoptosis, and cell-cycle assays. We also compared the relationships among <i>NOTCH4, HEY1</i>, and epithelial-mesenchymal transition (EMT)-related genes using the TCGA data set and <i>in vitro</i> assays.<b>Results:</b><i>HEY1</i> is specifically upregulated in HNSCC compared with normal tissues in the TCGA data set. <i>NOTCH4</i> is more significantly related to <i>HEY1</i> activation in HNSCC in comparison with other <i>NOTCH</i> receptors. <i>NOTCH4</i> promotes cell proliferation, cisplatin resistance, inhibition of apoptosis, and cell-cycle dysregulation. Furthermore, <i>NOTCH4</i> and <i>HEY1</i> upregulation resulted in decreased <i>E-cadherin</i> expression and increased <i>Vimentin, Fibronectin, TWIST1</i>, and <i>SOX2</i> expression. <i>NOTCH4</i> and <i>HEY1</i> expression was associated with an EMT phenotype as well as increased invasion and cell migration.<b>Conclusions:</b> In HNSCC, the <i>NOTCH4-HEY1</i> pathway is specifically upregulated, induces proliferation and cisplatin resistance, and promotes EMT. <i>Clin Cancer Res; 24(3); 619-33. ©2017 AACR</i>.