Epidermal growth factor-induced COX-2 regulates metastasis of head and neck squamous cell carcinoma through upregulation of angiopoietin-like 4

Epidermal growth factor receptor (EGFR) expression and activation are the major causes of metastasis in cancers such as head and neck squamous cell carcinoma (HNSCC). However, the reciprocal effect of EGF-induced COX-2 and angiopoietin-like 4 (ANGPTL4) on HNSCC metastasis remains unclear. In this study, we revealed that the expression of ANGPTL4 is essential for COX-2-derived prostaglandin E₂ (PGE₂)-induced tumor cell metastasis. We showed that EGF-induced ANGPTL4 expression was dramatically inhibited with the depletion and inactivation of COX-2 by knockdown of COX-2 and celecoxib treatment, respectively. Prostaglandin E₂ induced ANGPTL4 expression in a time- and dose-dependent manners in various HNSCC cell lines through the ERK pathway. In addition, the depletion of ANGPTL4 and MMP1 significantly impeded the PGE₂-induced transendothelial invasion ability of HNSCC cells and the binding of tumor cells to endothelial cells. The induction of molecules involved in the regulation of epithelial-mesenchymal transition was also dependent on ANGPTL4 expression in PGE₂-treated cells. The depletion of ANGPTL4 further blocked PGE₂-primed tumor cell metastatic seeding of lungs. These results indicate that the EGF-activated PGE₂/ANGPTL4 axis enhanced HNSCC metastasis. The concurrent expression of COX-2 and ANGPTL4 in HNSCC tumor specimens provides insight into potential therapeutic targets for the treatment of EGFR-associated HNSCC metastasis.