Impact of P16 Status on Pro- and Anti-angiogenesis Factors in Head and Neck Cancers

Background: Head and neck cancers (HNC) are aggressive tumours. Overexpression of p16 in HNC correlates with human papilloma virus (HPV)-associated HNC that carry a better prognosis than HPV-negative tumours. Angiogenesis is an important factor in tumour progression. Our aim was to dissect the impact of p16 expression on angiogenesis factors in HNC.

Methods: Eighteen newly diagnosed HNC patients and controls were analysed. Eleven pro- and anti-angiogenesis factors were quantified using multiplex ELISA in HNC patients and controls. Angiogenesis factors were analysed in tumour tissue using immunohistochemistry.

Results: Circulating levels of endostatin (anti-angiogenesis factor) were higher in the HNC group compared with healthy donors. Interestingly, the pro-angiogenesis factors angiopoietin-1 and vascular endothelial growth factor (VEGF) were significantly higher in patients with p16-negative compared with p16-positive HNC. Moreover, the major source of VEGF in p16-positive HNC tissue was tumour stromal cells. In contrast, both tumour cells and stromal cells expressed VEGF in p16-negative tissue.

Conclusions: We show that p16-negative tumours associate with increased circulating levels of pro-angiogenic VEGF and angiopoietin-1. Tissue expression of VEGF differs between p16-positive and p16-negative tumours. These findings may explain differences in the biological behaviour of p16-positive and p16-negative HNC. Better understanding of mechanisms by which the p16 status influences tumour angiogenesis may guide the development of targeted therapies.