ABSTRACT
Mutant isoforms of the KIT or PDGF receptors expressed by gastrointestinal stromal tumors (GISTs) are considered the therapeutic targets for STI571 (imatinib mesylate; Gleevec), a specific inhibitor of these tyrosine kinase receptors. Case reports of clinical efficacy of Gleevec in GISTs lacking the typical receptor mutations prompted a search for an alternate mode of action. Here we show that Gleevec can act on host DCs to promote NK cell activation. DC-mediated NK cell activation was triggered in vitro and in vivo by treatment of DCs with Gleevec as well as by a loss-of-function mutation of KIT. Therefore, tumors that are refractory to the antiproliferative effects of Gleevec in vitro responded to Gleevec in vivo in an NK cell-dependent manner. Longitudinal studies of Gleevec-treated GIST patients revealed a therapy-induced increase in IFN-gamma production by NK cells, correlating with an enhanced antitumor response. These data point to a novel mode of antitumor action for Gleevec.
Subject(s)
Enzyme Inhibitors/pharmacology , Killer Cells, Natural/metabolism , Protein-Tyrosine Kinases/antagonists & inhibitors , Proto-Oncogene Proteins c-kit/genetics , Proto-Oncogene Proteins c-kit/metabolism , Receptor Protein-Tyrosine Kinases/metabolism , Animals , Antineoplastic Agents/pharmacology , Benzamides , Case-Control Studies , Coculture Techniques , Dendritic Cells/drug effects , Dendritic Cells/metabolism , Female , Gastrointestinal Neoplasms/drug therapy , Gastrointestinal Neoplasms/genetics , Gastrointestinal Neoplasms/metabolism , Gastrointestinal Neoplasms/pathology , Gene Expression Regulation, Neoplastic , Humans , Imatinib Mesylate , Interferon-gamma/drug effects , Interferon-gamma/metabolism , Leukocytes, Mononuclear/metabolism , Longitudinal Studies , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, SCID , Mutation , Neutrophil Activation/drug effects , Piperazines/pharmacology , Proto-Oncogene Proteins c-kit/drug effects , Pyrimidines/pharmacology , Receptor Protein-Tyrosine Kinases/drug effects , Receptor Protein-Tyrosine Kinases/genetics , Receptors, Platelet-Derived Growth Factor/drug effects , Receptors, Platelet-Derived Growth Factor/genetics , Receptors, Platelet-Derived Growth Factor/metabolism , Stromal Cells/drug effectsABSTRACT
Dendritic cells (DC) regulate NK cell functions, but the signals required for the DC-mediated NK cell activation, i.e., DC-activated NK cell (DAK) activity, remain poorly understood. Upon acute inflammation mimicked by LPS or TNF-alpha, DC undergo a maturation process allowing T and NK cell activation in vitro. Chronic inflammation is controlled in part by Th2 cytokines. In this study, we show that IL-4 selectively confers to DC NK but not T cell stimulatory capacity. IL-4 is mandatory for mouse bone marrow-derived DC grown in GM-CSF (DC(GM/IL-4)) to promote NK cell activation in the draining lymph nodes. IL-4-mediated DAK activity depends on the KARAP/DAP12-triggering receptor expressed on myeloid cell 2 signaling pathway because: 1) gene targeting of the adaptor molecule KARAP/DAP12, a transmembrane polypeptide with an intracytoplasmic immunoreceptor tyrosine-based activation motif, suppresses the DC(GM/IL-4) capacity to activate NK cells, and 2) IL-4-mediated DAK activity is significantly blocked by soluble triggering receptor expressed on myeloid cell 2 Fc molecules. These data outline a novel role for Th2 cytokines in the regulation of innate immune responses through triggering receptors expressed on myeloid cells.
Subject(s)
Adaptor Proteins, Signal Transducing , Adaptor Proteins, Vesicular Transport/physiology , Cytotoxicity, Immunologic/immunology , Dendritic Cells/immunology , Interleukin-4/physiology , Killer Cells, Natural/immunology , Lymphocyte Activation/immunology , Membrane Glycoproteins/physiology , Receptors, Immunologic/physiology , Signal Transduction/immunology , Adaptor Proteins, Vesicular Transport/biosynthesis , Adoptive Transfer , Animals , Cell Communication/genetics , Cell Communication/immunology , Cells, Cultured , Coculture Techniques , Cytotoxicity, Immunologic/genetics , Dendritic Cells/metabolism , Dendritic Cells/transplantation , Female , Inflammation/genetics , Inflammation/immunology , Killer Cells, Natural/metabolism , Lipopolysaccharides/pharmacology , Lymphocyte Activation/genetics , Membrane Glycoproteins/genetics , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout , Mice, Nude , Mice, SCID , Receptors, Immunologic/biosynthesis , Receptors, Immunologic/genetics , Signal Transduction/genetics , Tumor Necrosis Factor-alpha/pharmacologyABSTRACT
Dendritic cells (DC) were originally found critical in the setting of cognate immune responses. We first demonstrated that DC can also induce mouse NK cell activation and NK cell dependent-antitumor effects in mice. Here we analyzed the dynamics between DC and NK cells in human in vitro model systems. In the absence of LPS, DC do not trigger resting NK cells. Conversely, in the presence of LPS, resting bulk NK cells interacting with DC acquire CD25 and CD69 surface expression, produce high levels of IFN-gamma and lyse DAUDI cells. On activated IL-2 dependent NK cell lines, regardless of their differentiation stage, DC maintain or enhance NK cell proliferation and effector functions in the absence of exogenous cytokines. While IL-12, IL-15 and IL-18 are not critical, a direct cell-to-cell contact is mandatory for NK activation by DC and required for optimal proliferation. These data imply that DC also modulate human NK cell innate effector functions.
