Abstract 2104: NK cell immunosurveillance of tumors is regulated by NFAT1 and NFAT2

Abstract

NK cells are lymphoid components of innate immunity and play an important role in tumor immunosurveillance. One of the major transcriptional regulators in lymphoid cells is NFAT (Nuclear Factor of Activated T cells), controlling lymphocyte development and activity. However, while the role of NFAT signaling is well defined in T cells, the cytotoxic lymphocytes of adaptive immunity, surprisingly little is known regarding the relevance of this transcription factor family in NK cells as effector cells of innate immunity. Available data indicate that NFAT activity is dispensable for development of NK cells. However, several lines of evidence including reports on the effects of the immunosuppressive drugs cyclosporin A and tacrolimus, which mediate their effects through inhibition of calcineurin and consecutively NFAT, implicate an involvement of the NFAT family in NK cell function. We here employed different genetic mouse models to unravel the role of NFAT1 (NFATc2) and NFAT2 (NFATc1) in NK cell reactivity. When NK cells with knockout (KO) of NFAT1 or NFAT2 compared to NK cells of control mice (WT) were employed in in vitro analyses, lack of either NFAT was found to surprisingly result in enhanced NK cell degranulation as well as increased production of granzyme B and perforin upon stimulation of activating receptors like NK1.1 or Nkp46 or upon co-culture with different leukemia and solid tumor tumor cells. In line, cytotoxicity assays revealed increased lysis of YAC-1 and B16F10 tumor cells by both NFAT1- and NFAT2-deficient NK cells as compared to WT controls. The inhibitory effect of NFAT transcription factors on NK cell effector function could also be confirmed in vivo by employing WT and NFAT KO animals in syngeneic B16F10 melanoma and RMA-S flank tumor models, which revealed a significantly reduced tumor burden in NFAT1 and NFAT2 KO mice. Comparative analyses with single NFAT as well as NFAT1+NFAT2 double KO and WT animals further confirmed the inhibitory effect of NFAT1 and NFAT2 and pointed to additive effects of NFAT1 and NFAT2 in NK cell tumor immunosurveillance. Taken together, our results provide the first evidence for the direct functional involvement of NFAT1 and NFAT2 in NK cell antitumor reactivity and, in contrast to T and B cells, identify NFAT as a negative regulator of NK cell function. Citation Format: Melanie Märklin, Samuel Holzmayer, Kübra Kaban, Martin R. Müller, Helmut R. Salih. NK cell immunosurveillance of tumors is regulated by NFAT1 and NFAT2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2104.

Simulated Microgravity Impairs Human NK Cell Cytotoxic Activity Against Space Radiation-Relevant Leukemic Cells

“…Exposure to sµG also led to a signi cant up-regulation of the following transcripts (Fig. 7): 1) CD3D (p = 1.14e − 3 ), which is consistent with the recently described NK2.4 subset of memory-like NK cells that accumulates with aging and exhibits low expression of the TCR complex 48 ; 2) CD5 (p = 6.6e − 3 ), a cell surface protein that has an inhibitory function in antigen receptor signaling and is not normally expressed on NK cells and would be expected to impair NK functionality [49][50][51] ; 3) decay-accelerating factor/CD55 (p = 8.53e − 3 ), a molecule whose expression has been shown to inhibit human NK cell cytotoxicity against hematological cancers 52 ; 4) CD84 (p = 0.01), engagement of which signi cantly dampens NK cell cytotoxicity 53 ; 5) CD200 (p = 0.02), the shedding of which in the tumor microenvironment leads to NK cell dysfunction and apoptosis 54 ; 6) CD47 (p = 0.05), a nding of particular relevance to the anti-tumor function of NK cells, since prior studies have shown that CD47 may play an inhibitory role in NK cell-mediated cytotoxicity against cancer cells 55 ; 7) LAIR1 (p = 0.01), a potent inhibitor of NK cytotoxicity 56 ; 8) NFATC1 (p = 0.02), a negative regulator of NK cell tumor immunosurveillance 57 ; and 9) CD34 (p = 7.6e − 3 ), an antigen only present on the earliest precursors of the NK lineage 58 , suggesting that microgravity may provoke a regression of NK cells to an immature, undifferentiated stem-like state, as has been reported with other cell types grown in microgravity 59,60 .…”