Lack of differences in radiation-induced immunogenicity parameters between HPV-positive and HPV-negative human HNSCC cell lines.

Abstract

Clinical studies indicate that patients with HPV/p16-associated head & neck squamous cell carcinoma (HNSCC) represent a subgroup with a better prognosis and improved response to conventional radiotherapy. Involvement of immune-based factors has been hypothesized. In the present study, we investigated radiation-induced differences in release of damage associated molecular patterns (DAMPs), cytokines and activation of dendritic cells (DCs) in HPV-positive and negative HNSCC cancer cell lines. Calreticulin (CRT) exposure was detected on cancer cell surface. ATP, HMGB1 and cytokines were measured in culture supernatants. Maturation marker CD83 surface exposure was determined on DCs after co-incubation with irradiated tumor cells. There was no increase in DAMPs and cytokine profiles after radiation treatment and no difference between HPV+ and HPV- cell lines. The HPV/p16-positive SCC90 cells showed a trend for increased total CRT, HMGB1, and number of cytokines compared to all other cell lines. None of the irradiated cancer cell lines could affect DC maturation. Radiation treatment did not increase immunogenicity of HNSCC cell lines assessed by membrane CRT, ATP, HMGB1, cytokines production, and by activation of immature DCs. There was no difference between HPV-positive and HPV-negative cell lines.