Abstract 4056: Recognition of tumor cells by Dectin-1 orchestrates innate immune cells for anti-tumor responses

Abstract

Abstract The eradication of cancer cells requires communication between cells which constitute the complex immune system. Natural killer (NK) cells are essential tumor-killing effector cells of the innate arm of the immune system; however, little is known about whether or how other immune cells recognize tumor cells to assist NK cells. In addition, although signal-transducing pattern recognition receptors are known to play important roles in innate immune responses against invading pathogens through recognition of pathogen-associated molecular patterns (PAMPs), it is still enigmatic whether and how these receptors contribute to anti-tumor immune responses. In this study, we show that the innate immune pattern recognition receptor Dectin-1 expressed on dendritic cells (DCs) and macrophages is critical to NK-mediated killing of tumor cells. We also show that tumor cell-mediated Dectin-1 signaling is instigated by the receptor recognition of N-glycan structures on tumor cells, which we term tumor-associated molecular patterns (TAMPs). As such, the TAMP-Dectin-1 signaling causes activation of the Interferon Regulatory Factor 5 (IRF5) transcription factor and subsequent induction of genes required for the full-blown killing activity of NK cells. The importance of these events is underscored by the observation of massive tumor metastasis in mice genetically deficient in either Dectin-1 or IRF5. Thus, these results reveal a hitherto unrecognized facet of pattern recognition receptors in the orchestration of anti-tumor innate immune responses; recognition of TAMPs. This study is the first demonstration that an innate immune pattern recognition receptor potentiates anti-tumor immune responses, offering new insight into anti-tumor activity of the innate immune system with implications for anti-tumor immunotherapy. Citation Format: Hiroaki IKUSHIMA, Tadatsugu TANIGUCHI. Recognition of tumor cells by Dectin-1 orchestrates innate immune cells for anti-tumor responses. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4056. doi:10.1158/1538-7445.AM2015-4056