RESUMO
The tumor microenvironment restrains conventional T cell (Tconv) activation while facilitating the expansion of Tregs. Here we showed that Tregs' advantage in the tumor milieu relies on supplemental energetic routes involving lipid metabolism. In murine models, tumor-infiltrating Tregs displayed intracellular lipid accumulation, which was attributable to an increased rate of fatty acid (FA) synthesis. Since the relative advantage in glucose uptake may fuel FA synthesis in intratumoral Tregs, we demonstrated that both glycolytic and oxidative metabolism contribute to Tregs' expansion. We corroborated our data in human tumors showing that Tregs displayed a gene signature oriented toward glycolysis and lipid synthesis. Our data support a model in which signals from the tumor microenvironment induce a circuitry of glycolysis, FA synthesis, and oxidation that confers a preferential proliferative advantage to Tregs, whose targeting might represent a strategy for cancer treatment.
Assuntos
Ácidos Graxos/imunologia , Glicólise/imunologia , Neoplasias Experimentais/imunologia , Linfócitos T Reguladores/imunologia , Microambiente Tumoral/imunologia , Animais , Linhagem Celular Tumoral , Ácido Graxo Sintase Tipo I/genética , Ácido Graxo Sintase Tipo I/imunologia , Ácidos Graxos/genética , Humanos , Camundongos , Camundongos Transgênicos , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/imunologia , Neoplasias Experimentais/genética , Neoplasias Experimentais/patologia , Oxirredução , Linfócitos T Reguladores/patologia , Microambiente Tumoral/genéticaRESUMO
Since it was suggested that cobalt chloride (CoCl(2)) could mimic the O(2) sensing role of mitochondria by increasing reactive oxygen species (ROS) generation during normoxia, we studied the correlation between CoCl(2)-generation of free radicals and the induction of a hypoxic cellular response in myogenic cell lines. In both L6C5 and C2C12 cell lines, exposure to CoCl(2) induced an increase of intracellular oxidants, the accumulation of HIF-1alpha protein, and the expression of vascular endothelial growth factor (VEGF) and/or iNOS genes. On the other hand, only ascorbic acid, but not trolox, was effective in lowering the CoCl(2) gene up-regulation. Neither the cytotoxicity nor the apoptosis induced by CoCl(2) in skeletal muscle cells were modified by culture supplementation with either ascorbic acid or trolox. Thus, CoCl(2) treatment of myogenic cell lines may represent a useful and convenient in vitro model to study gene modulation induced by hypoxia in skeletal muscle, although cellular loss induced by this metal may involve mechanisms other than HIF-1alpha stabilization. It is unlikely, however, that ROS would represent the main mediators of CoCl(2) effects on muscle cells.