TLR and Cancer: The Enigmatic Cross Talk

Abstract

The connection between inflammation and cancer has been well recognized at the epidemiological, biological, and pharmacological levels. Unresolved chronic inflammation is implicated in most stages of cancer development and thus can induce certain solid tumors. The molecular regulators of these linkages are emerging and should be well-decorticated. Toll-like receptors (TLRs) recognize pathogen/microbe-associated molecular patterns (PAMPs/MAMPs) and death–associated molecular patterns (DAMPs) secreted from dying or damaged cells of the host. TLRs can be pro and anti-tumorigenic depending on the type of TLR signaling, cancer, and its stage. Therefore, comprehensive studies are required in this direction. The current chapter supplies a concise schematic concerning the biology and the characteristics of TLRs and summarizes the major findings of the enigmatic role of TLRs and their associated signaling in the pathogenesis of human cancers. On one hand and in some neoplastic contexts, TLR activation mediates proliferation invasion, migration and correlates with poor prognosis and metastasis, and inhibits apoptosis, leading to cancer progression. On the other hand and depending on other neoplastic context, TLRs agonists enhance radiosensitivity and chemotherapy, apoptosis, immune cell infiltration, and raise the antitumor effect of T cells.