TET2 promotes tumor antigen presentation and T cell IFN-γ, which is enhanced by vitamin C
Meng Cheng, … , Yue Xiong, Albert S. Baldwin
Meng Cheng, … , Yue Xiong, Albert S. Baldwin
Published October 10, 2024
Citation Information: JCI Insight. 2024;9(22):e175098. https://doi.org/10.1172/jci.insight.175098.
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Research Article Immunology Oncology

TET2 promotes tumor antigen presentation and T cell IFN-γ, which is enhanced by vitamin C

Abstract

Immune evasion by tumors is promoted by low T cell infiltration, ineffective T cell activity directed against the tumor, and reduced tumor antigen presentation. The TET2 DNA dioxygenase gene is frequently mutated in hematopoietic malignancies and loss of TET enzymatic activity is found in a variety of solid tumors. We showed previously that vitamin C (VC), a cofactor of TET2, enhances tumor-associated T cell recruitment and checkpoint inhibitor therapy responses in a TET2-dependent manner. Using single-cell RNA sequencing (scRNA-seq) analysis performed on B16-OVA melanoma tumors, we have shown here that an additional function for TET2 in tumors is to promote expression of certain antigen presentation machinery genes, which is potently enhanced by VC. Consistently, VC promoted antigen presentation in cell-based and tumor assays in a TET2-dependent manner. Quantifying intercellular signaling from the scRNA-seq dataset showed that T cell–derived IFN-γ–induced signaling within the tumor and tumor microenvironment requires tumor-associated TET2 expression, which is enhanced by VC treatment. Analysis of patient tumor samples indicated that TET activity directly correlates with antigen presentation gene expression and with patient outcomes. Our results demonstrate the importance of tumor-associated TET2 activity as a critical mediator of tumor immunity, which is augmented by high-dose VC therapy.

Authors

Meng Cheng, Angel Ka Yan Chu, Zhijun Li, Shiyue Yang, Matthew D. Smith, Qi Zhang, Nicholas G. Brown, William F. Marzluff, Nabeel Bardeesy, J. Justin Milner, Joshua D. Welch, Yue Xiong, Albert S. Baldwin

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Figure 5

VC increases tumor cell antigen presentation and T cell activation as well as T cell–induced tumor cell killing.

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VC increases tumor cell antigen presentation and T cell activation as we...
(A) WT or 2 TET2-KO clones were cultured in 6-well plates in DMEM. Then, 500 μM VC or 100 ng/mL IFN-γ or PBS control were added as indicated for 24 hours before running flow cytometry experiments to determine OVA antigen levels on the tumor cell surface. Data are quantified on the right, with mean ± SD (n = 4). P values were calculated by unpaired, 2-tailed Student’s t test, with multiple comparisons corrected using Bonferroni’s method. (B) WT or TET2-KO B16-OVA tumor cells (2 × 105 each) were transplanted into 6-week-old C57BL/6J syngeneic mice and i.v. 1 g/kg VC or PBS treatment was given daily from day 7 to the date of harvesting tumor tissue. Then, single cells were isolated from tumor tissue for flow cytometry experiments to detect OVA antigen presentation or the B2M component of the MHC I complex on the tumor cell surface. Data are quantified on the right, with mean ± SD (n = 4). P values were calculated by unpaired, 2-tailed Student’s t test, with multiple comparisons corrected using Bonferroni’s method. (C) WT or TET2-KO B16-OVA cells were cultured in 6-well plates with RPMI medium. Then, 1 × 106 isolated OT-I T cells were cocultured with B16-OVA cells and 500 μM VC or PBS was added as indicated above for the coculture experiments in the presence of 1 × 105 isolated dendritic cells as the antigen-presenting cell. After 16 hours, OT-I T cells were collected for flow cytometry experiments to determine T cell activation using the CD69 marker. (D) T cells isolated from WT or TET2-KO B16-OVA syngeneic mice treated with PBS or VC as described in B were collected for flow cytometry assays to determine CD69+ activated T cell ratio and the results were calculated and summarized (E). The error bars indicate 5 replicates in each group and data are represented as mean ± SD. P values were calculated by unpaired, 2-tailed Student’s t test. (F) WT or TET2-KO B16-OVA cells were transfected with EGFP plasmid and then cocultured with isolated OT-I T cells as described in C. After 16-hour treatment with PBS or 500 μM VC, cells were washed 3 times with PBS before acquiring images. Scale bars: 100 μm. (G) The quantification of live cells from F was summarized and data are represented as mean ± SD (n = 4). P values were calculated by unpaired, 2-tailed Student’s t test, with multiple comparisons corrected using Bonferroni’s method. **P < 0.01; ***P < 0.001; ****P < 0.0001.