Tumor-derived TGF-{beta} inhibits mitochondrial respiration to suppress IFN-{gamma} production by human CD4+ T cells

Transforming growth factor–β (TGF-β) is produced by tumors, and increased amounts of this cytokine in the tumor microenvironment and serum are associated with poor patient survival. TGF-β–mediated suppression of antitumor T cell responses contributes to tumor growth and survival. However, TGF-β also has tumor-suppressive activity; thus, dissecting cell type–specific molecular effects may inform therapeutic strategies targeting this cytokine. Here, using human peripheral and tumor-associated lymphocytes, we investigated how tumor-derived TGF-β suppresses a key antitumor function of CD4+ T cells, interferon- (IFN-) production. Suppression required the expression and phosphorylation of Smad proteins in the TGF-β signaling pathway, but not their nuclear translocation, and depended on oxygen availability, suggesting a metabolic basis for these effects. Smad proteins were detected in the mitochondria of CD4+ T cells, where they were phosphorylated upon treatment with TGF-β. Phosphorylated Smad proteins were also detected in the mitochondria of isolated tumor-associated lymphocytes. TGF-β substantially impaired the ATP-coupled respiration of CD4+ T cells and specifically inhibited mitochondrial complex V (ATP synthase) activity. Last, inhibition of ATP synthase alone was sufficient to impair IFN- production by CD4+ T cells. These results, which have implications for human antitumor immunity, suggest that TGF-β targets T ...
Source: Signal Transduction Knowledge Environment - Category: Science Authors: Tags: STKE Research Articles Source Type: news