EGFR antisense treatment of human HNSCC cell lines down-regulates VEGF expression and endothelial cell migration

Overexpression of the epidermal growth factor receptor (EGFR) is thought to play a key role in the development of head and neck squamous cell carcinoma (HNSCC) primarily through its effect on promoting uncontrolled cell proliferation. Blocking EGFR ligand binding might also inhibit angiogenesis and down-regulate the production of angiogenic factors. Angiogenesis is increased in various human tumors, including head and neck squamous cell carcinoma (HNSCC), and correlates with tumor progression and metastasis. The vascular endothelial growth factor (VEGF) is thought to be the most important angiogenic factor. We determined whether VEGF antisense oligonucleotide treatment can decrease angiogenic activity of HNSCC cell lines in vitro. By using a 21-mer antisense phosphorothioate oligonucleotide targeting the translation start site of human EGFR mRNA, we examined modulation of VEGF expression in cell line supernatants by capture ELISA, and in cell lysates by Western blotting. Human umbilica vein endothelial cells (HUVEC) were grown in conditioned medium produced from the treated tumor cells. Endothelial cell migration was measured using a modified Boyden chamber. EGFR antisense oligonucleotide treatment resulted in a significant reduction of VEGF protein expression compared to sense oligonucleotide control. Addition of conditioned medium from EGFR antisense-treated tumor cells resulted in decreased endothelial cell migration. In conclusion, therapeutic strategies targeting EGFR signaling in head and neck cancer might have an antitumor effect mediated in part by inhibition of tumor angiogenesis.