Toll-like receptors and cancer, particularly oral squamous cell carcinoma

Abstract

It is becoming increasingly apparent that the tumor microenvironment plays an important role in the progression of cancer. The microenvironment may promote tumor cell survival and proliferation or, alternatively may induce tumor cell apoptosis. Toll-like receptors (TLRs) are transmembrane proteins, expressed on immune cells and epithelial cells, that recognize exogenous and endogenous macromolecules. Once activated, they initiate signaling pathways leading to the release of cytokines and chemokines, which recruit immune cells inducing further cytokine production, the production of angiogenic mediators and growth factors, all of which may influence tumor progression. This paper examines the actions of TLRs in carcinogenesis with particular emphasis on their role in oral squamous cell carcinoma.

Keywords: NF-κB; TLR; oral squamous cell carcinoma; toll-like receptors.

Figure 1

Diagram showing how TLRs can mediate pro- and anti-tumor pathways.

Figure 2

Photomicrograph showing TLR2⁺ cells with a dusky red cell membrane and cytoplasmic staining (black arrow) with the morphology of macrophages in OSCC (ȕ100, bar: 100 μm).