TGF-β modulates the functionality of tumor-infiltrating CD8+ T cells through effects on TCR signaling and Spred1 expression
- First Online:
- Cite this article as:
- di Bari, M.G., Lutsiak, M.E.C., Takai, S. et al. Cancer Immunol Immunother (2009) 58: 1809. doi:10.1007/s00262-009-0692-9
This study demonstrates that CD8+ T cells in the tumor microenvironment display reduced functionality and hyporesponsiveness. TGF-β contributed markedly to the tumor-infiltrating CD8+ T cells’ (TILs) reduced functionality, which could be reversed using a small molecule TGF-β inhibitor. Upon T-cell receptor (TCR) activation, the activation of ITK and ERK kinases were reduced in CD8+ TILs, as compared to splenic CD8+ T cells: TGF-β inhibitor could reverse this phenomenon. This study demonstrates for the first time the association of the Spred-1 gene, an inhibitor of the Ras/MAPK pathway, with CD8+ TILs and TGF-β activity. Spred-1 was upregulated in CD8+ TILs and TGF-β enhanced the expression of Spred-1 in effector/memory CD8+ T cells and not in rested/memory CD8+ T cells. Based on these findings, this study supports the hypothesis that TGF-β mediates an inhibitory mechanism on CD8+ TILs involving TCR-signaling blockade and the upregulation of Spred-1, thus implicating Spred-1 as a potential new target for future anti-tumor immune studies.