On June 19, 2025, a team led by Hang Yin from Tsinghua University published a research paper in Cell Chemical Biology titled "EGR2 O-GlcNAcylation orchestrates the development of protumoral macrophages to limit CD8⁺ T cell antitumor responses," revealing a novel mechanism by which glucose metabolic reprogramming in the tumor microenvironment regulates macrophage fate through O-GlcNAcylation.

In a tumor microenvironment abundant in GM-CSF, O-GlcNAc transferase (OGT) promotes the differentiation of tumor-associated macrophages (TAMs) towards a pro-tumor phenotype through O-GlcNAcylation of the transcription factor EGR2.

These TAMs express markers such as TREM2 and MERTK, inhibiting the cytotoxicity of CD8⁺ T cells and promoting their exhaustion (PD-1⁺), thereby weakening the anti-tumor immune response.

Key Findings

The authors discovered that O-GlcNAcylation of the glucose-driven transcription factor EGR2 reprograms TAMs, suppressing anti-tumor immunity by CD8⁺ T cells. This study reveals how metabolic reprogramming in the tumor microenvironment shapes immunosuppressive macrophages, providing new insights into targeting macrophage plasticity to enhance Cancer Immunotherapy.

Research Highlights

• O-GlcNAcylationregulates the differentiation and function of pro-tumor TAMs.
• O-GlcNAcylationin TAMs weakens the killing ability of CD8⁺ T cells and promotes tumor progression.
• EGR2 undergoes O-GlcNAcylationat serine 299, promoting Trem2 transcription.
• EGR2 O-GlcNAcylationregulates GM-CSF-induced macrophage differentiation and function.

Abstract

TAMs exhibit high Glucose uptake. This study reports that glucose metabolism-driven protein O-GlcNAcylation is elevated in TAMs and shapes their differentiation and pro-tumor function. Deletion of OGT in TAMs reduces the proportion of C1QC⁺ F4/80⁺ TREM2⁺ MerTK⁺ TAMs and Trem2 expression, thereby preserving the cytotoxic function of effector CD8⁺ T cells and reducing their exhaustion characteristics. Mechanistically, O-GlcNAcylation targets the macrophage-specific transcription factor EGR2, enhancing its transcriptional activity. Transcriptomic analysis showed that OGT increased the accessibility of EGR2-related motifs in TAMs. O-GlcNAcylation of EGR2 at serine 299 enhances its binding to myeloid cell differentiation-related genes (including Trem2), thus promoting the pro-tumor function of TAMs in GM-CSF-rich tumors.

Fig. 1 EGR2 O-GlcNAcylation orchestrates the development of protumoral macrophages to limit CD8⁺ T cell antitumor responses. (Zhang, et al. 2025)

Introduction

• Tumor-associated macrophages (TAMs) constitute a large proportion of tumor-infiltrating immune cells in various cancers and are often associated with poor prognosis.
• TAMs are highly plastic and can be reprogrammed by the tumor microenvironment into an immunosuppressive phenotype.
• TAMs exhibit the highest glucose uptake capacity, but the molecular mechanisms underlying their metabolic reprogramming and pro-tumorigenic state remain unclear.
• O-GlcNAc modification is a nutrient-sensitive signaling modification involved in the regulation of various immune cells.
• The transcription factor EGR2 plays an important role in the immune system, but its function in TAMs is not yet clear.

Main Results

1. OGT deficiency inhibits tumor growth in macrophages

• Levels of glucose metabolites (such as UDP-GlcNAc) are elevated in TAMs.
• Tumor growth of MC38, Panc02, and MMTV-PyMTis slowed in Myeloid-Specific Ogt Knockout (Ogt-cKO) Mice.
• The proportion of F4/80⁺CD64⁺ TAMs decreases, and CD45⁺ leukocyte infiltration increases in tumors of Ogt-cKO mice.

2. OGT deficiency enhances the anti-tumor response of CD8⁺T cells

• The proportion of CD8⁺T cells increases, the proportion of effector T cells (Teff) increases, and the proportion of exhausted T cells (Tex) decreases in tumors of Ogt-cKO mice.
• The ability of CD8⁺T cells to produce TNF, IFN-γ, and Gzmb is enhanced, and PD-1 expression is decreased.
• The inhibitory capacity of Ogt-cKO TAMs on T cell proliferation is weakened.

3. OGT deficiency reduces the proportion of pro-tumorigenic C1QC⁺TAMs

• Single-cell RNA sequencing shows a decrease in the proportion of MAC-2 (C1QC⁺TAMs) in Ogt-cKO mice.
• Ligand-receptor interaction analysis shows a shift from immunosuppression to immunostimulation in the interaction between Ogt-cKO TAMs and CD8⁺T cells.

4. OGT regulates the differentiation and immunosuppressive characteristics of TAMs

• The expression of genes such as Trem2, C1qb, C1qc, Mgl2, and Mertk is decreased in Ogt-cKO TAMs.
• RNA-seq shows that myeloid cell differentiation-related pathways are downregulated, and immune response-related pathways are upregulated in Ogt-cKO TAMs.

5. OGT enhances the accessibility of the EGR2 motif

• ATAC-seq shows that the accessibility of the EGR2 motif is decreased in Ogt-cKO TAMs.
• EGR2 is highly expressed in TAMs and its expression is elevated in various human tumors.

6. OGT deficiency impairs EGR2-dependent Trem2 transcription

• ChIP-seq and CUT&Tag show that EGR2 binds to the Trem2 promoter region, and Ogt deficiency reduces its binding ability.
• In GM-CSF-induced macrophages (GM-MACs), Ogt-cKO leads to decreased Trem2 expression and weakened T cell inhibitory capacity.

7. EGR2 O-GlcNAcylationenhances the pro-tumor function of macrophages.

• EGR2 interacts with OGT and undergoes O-GlcNAcylationat multiple sites, with S299 being a key site.
• S299A mutation or mutation of all sites (MutAll) significantly reduces the transcriptional activity and O-GlcNAcylationlevel of EGR2.
• Overexpression of EGR2-WT restores Trem2 expression and T cell inhibitory capacity, while S299A or MutAll does not have this effect.

Discussion

• EGR2 O-GlcNAc modification drives the differentiation of GM-CSF-induced TAMs by promoting Trem2 transcription, promoting CD8⁺ T cell exhaustion, and accelerating tumor progression.
• EGR2 is an evolutionarily conserved transcription factor, and its O-GlcNAcylationsites are highly conserved between humans and mice.
• GM-CSF is highly expressed in MC38 tumors and is a key factor in inducing EGR2 expression and TAM differentiation.

Limitations

• The contribution of other proteins besides EGR2 to O-GlcNAcylationhas not been verified.
• The cytokine network regulating OGT activity in the TME has not been fully explored.
• The interaction between O-GlcNAcylationand other post-translational modifications has not been studied.
• Mouse Models cannot fully simulate human tumor heterogeneity.

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Reference

1. Zhang, Y., et al. (2025). EGR2 O-GlcNAcylation orchestrates the development of protumoral macrophages to limit CD8⁺ T cell antitumor responses. Cell Chemical Biology. DOI: 1016/j.chembiol.2025.05.007.