RESUMO
Dendritic cell (DC) targeting in vivo has recently been shown to confer strong and protective cytotoxic T lymphocyte (CTL)-based immunity in tumor murine models. Our group has recently demonstrated in preclinical models that the infusion of genetically modified lymphocytes (GMLs) expressing the self/tumor antigen TRP-2 is able to elicit functional TRP-2-specific effectors with antitumor activity by targeting DCs in vivo. Here we have analyzed vaccine- and tumor-specific immune responses of 10 melanoma patients treated with autologous GMLs expressing the cancer germline gene MAGE-A3. Three of 10 patients treated with MAGE-A3-GML showed an increase of circulating anti-MAGE-A3 T cells, and developed skin delayed-type hypersensitivity to MAGE-A3. Interestingly, in 2 of these patients, with progressive and measurable tumors at study entry, anti-MAGE-A3 T cells were detected not only in the blood but also within tumors resected after vaccination. These results demonstrate that the infusion of MAGE-A3-GML elicits antitumor T cells, which are capable of trafficking to inflamed tissues and of infiltrating tumors. Clinical studies on a larger group of patients are needed to evaluate the clinical efficacy of such a strategy.
Assuntos
Antígenos de Neoplasias/genética , Antígenos de Neoplasias/imunologia , Vacinas Anticâncer/administração & dosagem , Terapia Genética/métodos , Melanoma/terapia , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/imunologia , Neoplasias Cutâneas/terapia , Transferência Adotiva , Animais , Células COS , Vacinas Anticâncer/efeitos adversos , Linhagem Celular Tumoral , Chlorocebus aethiops , Humanos , Hipersensibilidade Tardia/imunologia , Melanoma/imunologia , Melanoma/patologia , Estadiamento de Neoplasias , Projetos Piloto , Neoplasias Cutâneas/imunologia , Neoplasias Cutâneas/patologia , Linfócitos T/citologia , Linfócitos T/fisiologia , Linfócitos T/transplante , Timidina Quinase/genética , Timidina Quinase/imunologia , TransfecçãoRESUMO
The exploitation of the physiologic processing and presenting machinery of DCs by in vivo loading of tumor-associated antigens may improve the immunogenic potential and clinical efficacy of DC-based cancer vaccines. Here we show that lymphocytes genetically modified to express self/tumor antigens, acting as antigen carriers, efficiently target DCs in vivo in tumor-bearing mice. The infusion of tyrosinase-related protein 2-transduced (TRP-2-transduced) lymphocytes induced the establishment of protective immunity and long-term memory in tumor-bearing mice. Analysis of the mechanism responsible for the induction of such an immune response allowed us to demonstrate that cross-presentation of the antigen mediated by the CD11c(+)CD8alpha(+) DC subset had occurred. Furthermore, we demonstrated in vivo and in vitro that DCs had undergone activation upon phagocytosis of genetically modified lymphocytes, a process mediated by a cell-to-cell contact mechanism independent of CD40 triggering. Targeting and activation of secondary lymphoid organ-resident DCs endowed antigen-specific T cells with full effector functions, which ultimately increased tumor growth control and animal survival in a therapeutic tumor setting. We conclude that the use of transduced lymphocytes represents an efficient method for the in vivo loading of tumor-associated antigens on DCs.
Assuntos
Antígenos de Neoplasias/genética , Autoantígenos/genética , Células Dendríticas/imunologia , Neoplasias/imunologia , Linfócitos T/imunologia , Animais , Apresentação de Antígeno , Células Apresentadoras de Antígenos/imunologia , Antígenos CD40/imunologia , Comunicação Celular , Linhagem Celular Tumoral , Movimento Celular , Oxirredutases Intramoleculares/genética , Camundongos , Camundongos Transgênicos , Fagocitose , Linfócitos T/transplanteRESUMO
p73 is a member of the p53 family often overexpressed in human cancer. Its regulation, particularly following DNA damage, is different from that of p53. Following DNA damage, we found induction of p73 at both the protein and mRNA levels. Furthermore, by using different p73 promoter fragments, we found a role for E2F1 in mediating transcription of p73. However, this observation alone does not account for the observed DNA damage-induced activation of p73 in the cells used in these experiments. By analyzing the p73 promoter sequence, we revealed a new mechanism of p73 induction associated with the removal of transcriptional repression from the p73 promoter. We found, in fact, that treatment of cells with DNA damaging agents induced nuclear export of the transcription factor C-EBPalpha and blockage of this export abolished drug-induced p73 activation. We also show that C-EBPalpha has a direct repressive activity on transfactor E2F1, and for this repression the binding of C-EBPalpha to its consensus sequence in the DNA is required. These data suggest that in normal conditions a repressor complex involving C-EBPalpha, E2F1 and perhaps other proteins is present on the p73 promoter. This repressor complex is destroyed following damage by removal of C-EBPalpha from nuclei.