RESUMO
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.
Assuntos
Inibidores Enzimáticos/farmacologia , Células Matadoras Naturais/metabolismo , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-kit/genética , Proteínas Proto-Oncogênicas c-kit/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Animais , Antineoplásicos/farmacologia , Benzamidas , Estudos de Casos e Controles , Técnicas de Cocultura , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/metabolismo , Feminino , Neoplasias Gastrointestinais/tratamento farmacológico , Neoplasias Gastrointestinais/genética , Neoplasias Gastrointestinais/metabolismo , Neoplasias Gastrointestinais/patologia , Regulação Neoplásica da Expressão Gênica , Humanos , Mesilato de Imatinib , Interferon gama/efeitos dos fármacos , Interferon gama/metabolismo , Leucócitos Mononucleares/metabolismo , Estudos Longitudinais , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos SCID , Mutação , Ativação de Neutrófilo/efeitos dos fármacos , Piperazinas/farmacologia , Proteínas Proto-Oncogênicas c-kit/efeitos dos fármacos , Pirimidinas/farmacologia , Receptores Proteína Tirosina Quinases/efeitos dos fármacos , Receptores Proteína Tirosina Quinases/genética , Receptores do Fator de Crescimento Derivado de Plaquetas/efeitos dos fármacos , Receptores do Fator de Crescimento Derivado de Plaquetas/genética , Receptores do Fator de Crescimento Derivado de Plaquetas/metabolismo , Células Estromais/efeitos dos fármacosRESUMO
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.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Proteínas Adaptadoras de Transporte Vesicular/fisiologia , Citotoxicidade Imunológica/imunologia , Células Dendríticas/imunologia , Interleucina-4/fisiologia , Células Matadoras Naturais/imunologia , Ativação Linfocitária/imunologia , Glicoproteínas de Membrana/fisiologia , Receptores Imunológicos/fisiologia , Transdução de Sinais/imunologia , Proteínas Adaptadoras de Transporte Vesicular/biossíntese , Transferência Adotiva , Animais , Comunicação Celular/genética , Comunicação Celular/imunologia , Células Cultivadas , Técnicas de Cocultura , Citotoxicidade Imunológica/genética , Células Dendríticas/metabolismo , Células Dendríticas/transplante , Feminino , Inflamação/genética , Inflamação/imunologia , Células Matadoras Naturais/metabolismo , Lipopolissacarídeos/farmacologia , Ativação Linfocitária/genética , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Nus , Camundongos SCID , Receptores Imunológicos/biossíntese , Receptores Imunológicos/genética , Transdução de Sinais/genética , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
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.
