TET2 promotes anti-tumor immunity by governing G-MDSCs and CD8⁺ T-cell numbers

Area of Science:

• Immunology
• Cancer Biology
• Epigenetics

Background:

• The host immune response is vital for controlling cancer progression.
• TET2 (ten-eleven translocation 2) is a DNA demethylase and a known tumor suppressor.
• The precise mechanisms by which TET2 influences anti-tumor immunity are not fully understood.

Purpose of the Study:

• To investigate the role of TET2 in host anti-tumor immunity.
• To elucidate the molecular pathways linking TET2 to immune responses against tumors.
• To explore therapeutic strategies targeting the TET2-mediated pathway.

Main Methods:

• Utilized Tet2 knockout mouse models for syngeneic tumor challenges.
• Measured cytokine levels (e.g., IL-6) and immune cell populations (e.g., CD8+ T cells, G-MDSCs).
• Employed antibody-based therapies targeting PD-1, Ly6g, and IL-6 to modulate immune responses.

Main Results:

• Tet2 deletion in mice led to elevated IL-6 levels following tumor challenge.
• High IL-6 promoted the expansion of immunosuppressive granulocytic myeloid-derived suppressor cells (G-MDSCs).
• G-MDSCs suppressed CD8+ T cell activity, resulting in accelerated tumor growth, which was partially reversed by anti-PD-1 therapy.
• Depletion of G-MDSCs or blockade of IL-6 restored CD8+ T cell numbers and anti-tumor activity.

Conclusions:

• TET2 plays a critical role in maintaining host anti-tumor immunity through a pathway involving IL-6 and G-MDSCs.
• This study reveals a cell non-autonomous mechanism for TET2 tumor suppression.
• Targeting the IL-6/G-MDSCs axis represents a potential therapeutic strategy for enhancing anti-tumor immunity in TET2-deficient cancers.