BCG immune activation reduces growth and angiogenesis in an in vitro model of head and neck squamous cell carcinoma

Abstract

Head and neck squamous cell carcinoma (HNSCC) is one of the most frequent cancers worldwide and is associated with poor survival and significant treatment morbidity. The immune profile in patients with HNSCC is immunosuppressive and presents cytokine-mediated adaptive immune responses, triggered apoptosis of T cells, and alterations in antigen processing machinery. Bacille Calmette-Guerin (BCG) immunotherapy has been used successfully as a treatment for several types of cancer. In the present study, we sought to determine the antitumor effect of soluble mediators from peripheral blood mononuclear immune cells (PBMCs) activated with BCG vaccine in a three-dimensional coculture model of HNSCC growth using FaDu hypopharynx carcinoma squamous cells. BCG activation of PBMCs led to an increase in CD4+ and CD8+ lymphocyte subsets concomitant with an elevation in the levels of the antitumor cytokines IL-6, TNF-α and IFN-γ, and a EGFR in FaDu cells. In addition, coculture with BCG-activated PBMCs reduced FaDu proliferation and increased cytotoxicity and apoptosis in parallel with an increase in caspase-3 activity and p53 expression. Finally, conditioned medium from BCG-activated PBMCs reduced the levels of the angiogenic factors vascular endothelial growth factor and angiopoietin-2 produced by human aortic endothelial cells (HAECs), and inhibited their proliferation and differentiation into capillary-like structures. Taken together, these results demonstrate that BCG vaccination induces antitumor responses in an HNSCC in vitro model and suggest that the BCG vaccine could be an effective alternative therapy for the treatment of HNSCC.