NK cells promote cancer immunoediting through tumor-intrinsic loss of interferon-stimulated gene expression

Abstract

Natural killer (NK) cells are innate lymphocytes that constantly patrol host tissues against transformed cells in a process known as cancer immunosurveillance. Previous evidence in mice has demonstrated that NK cell-derived IFN-{gamma} can promote immunoevasion by sculpting the immunogenicity of developing tumors in a process known as cancer immunoediting. This process involves the elimination of highly immunogenic "unedited" tumor cells followed by the eventual escape of less immunogenic "edited" tumor cell variants that are able to escape recognition or elimination by the immune system. Here, we show that NK cell-edited fibrosarcomas decrease the expression of 17 conserved IFN-{gamma}-inducible genes compared to unedited tumor cells. High expression of 3 of these identified genes (Psmb8, Trim21, Parp12) in human tumor samples correlates with enhanced survival in breast cancer, melanoma, and sarcoma patients. While NK cell-edited fibrosarcomas displayed resistance to IFN-{gamma} growth suppression in vitro, functional knockouts of individual interferon stimulated genes (ISGs) were not required for outgrowth of unedited tumor cell lines in vitro and in vivo compared to complete loss of IFN signaling. Furthermore, knockout of IFN-{gamma}-intrinsic signaling via deletion of Ifngr in edited B16 F10 and E0771 LMB metastatic cancer cell lines did not impact host survival following lung metastasis. Together, these results suggest that unedited tumors can be selected for decreased IFN-{gamma} signaling to evade immune responses in vivo, and as a consequence, tumor-extrinsic IFN signaling may be more important for potentiating durable anti-tumor responses to advanced solid tumors.