Potential autocrine function of vascular endothelial growth factor in head and neck cancer via vascular endothelial growth factor receptor-2

Vascular endothelial growth factor is a peptide with well-defined actions on the vasculature and fundamental role in tumor angiogenesis. Its action in vascular endothelium is exerted in a paracrine manner. The immunohistochemical expression of this protein by cancer cells in head and neck squamous cell carcinoma was correlated with increased tumor aggressiveness and poor survival in previous studies. In the past years, an increasing amount of studies demonstrated potential autocrine action of vascular endothelial growth factor in various neoplasms. However, the existence and the impact of such autocrine action in head and neck cancer have not been demonstrated yet. In this retrospective study, we evaluated the expression of vascular endothelial growth factor and its receptors in neoplastic cells, in a cohort of patients with head and neck squamous cell carcinoma, and compared this expression with tumor aggressiveness, clinicopathologic parameters and outcome. High expression of vascular endothelial growth factor was strongly correlated with high expression of vascular endothelial growth factor receptor-2 (but not vascular endothelial growth factor receptor-1) on the cancer cells (P<0.001). The co-overexpression of both the protein and vascular endothelial growth factor receptor-2 was associated with higher tumor proliferation rate (P<0.001). The above co-overexpression also correlated with worse survival (log rank P<0.05) in patients with oral-larynx squamous cell carcinoma. Our results suggest that an autocrine vascular endothelial growth factor loop, mediated via vascular endothelial growth factor receptor-2, probably exists in head and neck squamous cell carcinoma. These observations support the hypothesis that the use of vascular endothelial growth factor receptor-2 inhibitors as adjuvant antiangiogenic therapy might have beneficial effects for these patients, by disrupting both paracrine (endothelial-dependent) and autocrine actions of vascular endothelial growth factor.