Silencing Human NKG2D, DAP10, and DAP12 Reduces Cytotoxicity of Activated CD8+ T Cells and NK Cells

Abstract

Human CD8+ T cells activated and expanded by TCR cross-linking and high-dose IL-2 acquire potent cytolytic ability against tumors and are a promising approach for immunotherapy of malignant diseases. We have recently reported that in vitro killing by these activated cells, which share phenotypic and functional characteristics with NK cells, is mediated principally by NKG2D. NKG2D is a surface receptor that is expressed by all NK cells and transmits an activating signal via the DAP10 adaptor molecule. Using stable RNA interference induced by lentiviral transduction, we show that NKG2D is required for cytolysis of tumor cells, including autologous tumor cells from patients with ovarian cancer. We also demonstrated that NKG2D is required for in vivo antitumor activity. Furthermore, both activated and expanded CD8+ T cells and NK cells use DAP10. In addition, direct killing was partially dependent on the DAP12 signaling pathway. This requirement by activated and expanded CD8+ T cells for DAP12, and hence stimulus from a putative DAP12-partnered activating surface receptor, persisted when assayed by anti-NKG2D Ab-mediated redirected cytolysis. These studies demonstrated the importance of NKG2D, DAP10, and DAP12 in human effector cell function.

DNAX-activating protein 10 co-stimulation enhances the anti-tumor efficacy of chimeric antigen receptor T cells

“…Our data is consistent with previous report demonstrating that activation of NKG2D and DAP10 can directly elicit T cell killing or enhance their cytotoxcity against target cells, 37–39 and bystander activated memory CD8 T cells control early pathogen load through NKG2. 40 In contrast, silencing NKG2D and DAP10 can reduce the cytotoxcity of T and NK cell, 41 and NKG2D dysfunction impairs anti-tumor activities of memory CD8 + T cell. 42 Besides, activation of NKG2D and DAP10 also enhance the inflammatory cytokine production by murine CD8 + T cells as reported previousl, 43,44 and NKG2D signaling are also able to promote T cell infiltration and accumulation in tumors and live, 45,46 which are consistent with our in vivo results obtained from lung cancer PDX mouse model.…”

Role of NKG2D and its ligands in the anti‐infectious activity of Vγ9Vδ2 T cells against intracellular bacteria

“…1 T cells and NK cells [39]. Moreover, the recruitment of NKG2D with ULBP1 or ULBP2 triggers PKB phosphorylation, a substrate of PI3K, while a PI3K inhibitor pretreatment impairs all biological responses.…”

“…Nevertheless, this result does not allow us to totally exclude a role of DAP12 in NKG2D-mediated signaling pathways and biological responses. Indeed, another study provided evidence that DAP10 although obligatory is not sufficient for optimal cytolysis of tumor cells mediated by NKG2D and DAP12 is also required by CD81 T cells and NK cells [39]. Moreover, the recruitment of NKG2D with ULBP1 or ULBP2 triggers PKB phosphorylation, a substrate of PI3K, while a PI3K inhibitor pretreatment impairs all biological responses.…”

HMBOX1 negatively regulates NK cell functions by suppressing the NKG2D/DAP10 signaling pathway

“…Cytokines, such as IL-2, 23 IL-12, 24 IL-15 25 and IFN-a, 26 can promote NKG2D expression; IL-21, 27 TGF-b 28 and IFN-c 29 have a repressive effect. In addition, the expression of NKG2D adapter proteins DAP10 or DAP12 30 and chronic exposure to soluble or membrane-bound NKG2D ligands such as major histocompatibility complex class I-related chain A (MICA) could also influence the expression of NKG2D on NK cells. 31 However, the transcriptional factor that influences NKG2D expression remains unknown.…”