Toll-like receptor modulation in head and neck cancer

Toll-like receptors (TLRs) are the archetypal pattern recognition receptors that have emerged as key mediators of immune functions. Activation of TLRs is a first line of defense of the immune system, leading to the activation and recruitment of different types of immune cells to sites of infection and malignant cell growth. Cells of human cancers, such as head and neck squamous cell carcinoma (HNSCC), are known to develop numerous molecular strategies to escape from efficient antitumor immune responses. It is supposed that tumor production of various immunosuppressive mediators contributes to impaired and altered immune functions in cancer patients. The molecular mechanisms responsible for these immunomodulatory processes and the biosynthesis of the immunosuppressive HNSCC microenvironment remain mostly unknown. Recently, different studies have shown that tumor cells are able to modulate the expression and function of TLR proteins in different kinds of immune cells. In this review, we present recent progress in these studies on the modulation of TLR expression and signaling through malignant head and neck cancer.