TGF-beta modulates the functionality of tumor-infiltrating CD8+ T cells through effects on TCR signaling and Spred1 expression.
This study demonstrates that CD8+ T cells in the tumor microenvironment display reduced functionality and hyporesponsiveness. TGF-beta contributed markedly to the tumor-infiltrating CD8+ T cells' (TILs) reduced functionality, which could be reversed using a small molecule TGF-beta 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-beta 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-beta activity. Spred-1 was upregulated in CD8+ TILs and TGF-beta 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-beta 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.
di Bari
Maria Giovanna
MG
Laboratory of Tumor Immunology and Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 10 Center Drive, Room 8B09, MSC 1750, Bethesda, MD 20892, USA.
Lutsiak
M E Christine
ME
Takai
Shinji
S
Mostböck
Sven
S
Farsaci
Benedetto
B
Semnani
Roshanak Tolouei
RT
Wakefield
Lalage M
LM
Schlom
Jeffrey
J
Sabzevari
Helen
H