Anticancer function of polyinosinic-polycytidylic acid

Polyinosinic-polycytidylic acid (polyi:c) is a synthetic analog of double-stranded RNA and an agonist of toll-like receptor (TLR) 3 and retinoic acid inducible gene I (RIG-I)-like receptors (RLRs), including RIG-I and melanoma differentiation-associated gene 5 (MDA5). The effect of polyi:c on tumor immunotherapy has been well explored for several decades. The accumulated evidence suggests that polyi:c could be used as a vaccine adjuvant to enhance innate and adaptive immune responses, and to alter the tumor microenvironment. Recent studies have also shown that activation of TLR3 and RLR signaling by polyi:c can directly trigger apoptosis in some cancer cells. This review focuses on polyi:c-induced signaling pathways and the applications of polyi:c in cancer treatment.