Molecular Profile of Tumor-Specific CD8+ T Cell Hypofunction in a Transplantable Murine Cancer Model

Abstract

Mechanisms of self-tolerance often result in CD8+ tumor-infiltrating lymphocytes (TIL) with a hypofunctional phenotype incapable of tumor clearance. Using a transplantable colon carcinoma model, we found that CD8+ T cells became tolerized in less than 24 hours in an established tumor environment. To define the collective impact of pathways suppressing TIL function, we compared genome-wide mRNA expression of tumor-specific CD8+ T cells from the tumor and periphery. Notably, gene expression induced during TIL hypofunction more closely resembled self-tolerance than viral-exhaustion. Differential gene expression was refined to identify a core set of genes that defined hypofunctional TIL; these data comprise the first “molecular profile” of tumor-specific TIL that are naturally responding and represent a polyclonal repertoire. The molecular profile of TIL was further dissected to determine the extent of overlap and distinction between pathways that collectively restrict T cell functions. As suggested by the molecular profile of TIL, protein expression of inhibitory receptor LAG-3 was differentially regulated throughout prolonged late-G1/early-S phase of the cell cycle. Our data may accelerate efficient identification of combination therapies to boost anti-tumor function of TIL specifically against tumor cells.

The EGR2 targets LAG-3 and 4-1BB describe and regulate dysfunctional antigen-specific CD8+ T cells in the tumor microenvironment

“…To further examine functional alterations during tumor progression we tested for protein levels of IL-2, IFN-γ, and TNF after TCR stimulation. As the loss of the ability of CD8 + TILs to produce cytokines is suggested to be a temporal process initiated after entry into the tumor microenvironment ( Schietinger et al, 2016 ; Waugh et al, 2016 ), or progressively after 30 d in the chronic LCMV model ( Wherry et al, 2007 ), we tested for cytokine production on day 7, 14, 21, and 28. The 4-1BB + LAG-3 + population lost the capacity to produce IL-2 as early as day 7, whereas the 4-1BB – LAG-3 + population lost IL-2 production between day 7 and 14 ( Fig.…”

Chromatin states define tumour-specific T cell dysfunction and reprogramming

“…10e ). The rapid induction of dysfunction early during tumorigenesis without progression through an effector state resembles peripheral tolerance induction 31 , 32 . We identified core elements shared between murine fixed dysfunctional TST and human PD1 hi TIL.…”

LAG3 (CD223) as a cancer immunotherapy target

“…In mice, LAG3 co‐expresses with PD1 on tumor‐infiltrating CD4 + and CD8 + T cells in melanoma (B16‐F10), colon adenocarcinoma (MC38), and fibrosarcoma (Sa1N) tumors . CD8 + T cells expressing both LAG3 and PD1 are also the dominant tumor‐infiltrating lymphocyte (TIL) population in CT26, a colon carcinoma in which LAG3 was shown to control T‐cell proliferation/cell cycle progression—resulting in a state of hypofunction …”