The role of innate immune signals in antitumor immunity

Innate immunity serves as a first line of defense against infectious agents, and germ-line-encoded pattern recognition receptors detect stressed and infected cells and elicit potent effector activities that accomplish efficient microbe containment. Recent evidence demonstrates that these pattern-sensing systems are also applicable to the recognition of tumor-derived stress-related factors. In particular, toll-like receptors and cytosolic sensors for DNA and RNA recognition utilize endogenous host elements containing microbial components, danger-associated molecules, and/or nucleic acids to stimulate innate signaling pathways and generate protective immune responses against nascent tumors in animal models and humans. In this review, we describe recent advances and perspectives about antitumor mechanisms and clinical application of innate immune signals and pathways.