Increased response to ionizing radiation in human papillomavirus-associated head and neck squamous cell carcinoma : contributing to unravel the physiopathology

Head and neck squamous cell carcinoma (HNSCC) is the seventh most common cancer worldwide. An important risk factor in addition to heavy tobacco and alcohol consumption is infection with the human papillomavirus (HPV). HPV prevalence is increasing, especially in squamous cell carcinoma of the oropharynx. Clinical studies have shown that patients with HPV-associated oropharyngeal cancer are a subgroup with a better prognosis and improved response to conventional radiotherapy. The involvement of both intrinsic radiosensitivity (DNA repair capacity) and extrinsic factors (immune system) was hypothesized. In this context, we investigated the infiltration of immune cells in human HNSCC and their relation to overall survival after radiotherapy. We further investigated radiation-induced differences in the release of damage-associated molecular patterns, cytokines, and activation of dendritic cells in HPV-related and unrelated head and neck cancer cell lines. Finally, we investigated the DNA damage repair efficiency by homologous recombination in HPV-related and E6-transduced human cancer cell lines.