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Updated: Mar 8, 2026
Multiplexed Immunofluorescence Analysis and Quantification of Intratumoral PD-1+ Tim-3+ CD8+ T Cells
Published on: February 8, 2018
SATB1 Expression Governs Epigenetic Repression of PD-1 in Tumor-Reactive T Cells
Tom L Stephen1, Kyle K Payne1, Ricardo A Chaurio1
1Tumor Microenvironment and Metastasis Program, The Wistar Institute, Philadelphia, PA 19104, USA.
Abstract:
Despite the importance of programmed cell death-1 (PD-1) in inhibiting T cell effector activity, the mechanisms regulating its expression remain poorly defined. We found that the chromatin organizer special AT-rich sequence-binding protein-1 (Satb1) restrains PD-1 expression induced upon T cell activation by recruiting a nucleosome remodeling deacetylase (NuRD) complex to Pdcd1 regulatory regions. Satb1 deficienct T cells exhibited a 40-fold increase in PD-1 expression. Tumor-derived transforming growth factor β (Tgf-β) decreased Satb1 expression through binding of Smad proteins to the Satb1 promoter. Smad proteins also competed with the Satb1-NuRD complex for binding to Pdcd1 enhancers, releasing Pdcd1 expression from Satb1-mediated repression, Satb1-deficient tumor-reactive T cells lost effector activity more rapidly than wild-type lymphocytes at tumor beds expressing PD-1 ligand (CD274), and these differences were abrogated by sustained CD274 blockade. Our findings suggest that Satb1 functions to prevent premature T cell exhaustion by regulating Pdcd1 expression upon T cell activation. Dysregulation of this pathway in tumor-infiltrating T cells results in diminished anti-tumor immunity.
Insights
Special AT-rich sequence-binding protein-1 (Satb1) prevents T cell exhaustion by controlling programmed cell death-1 (PD-1) expression. Tumor-derived TGF-β disrupts this, impairing anti-tumor immunity.
Area of Science:
- Immunology
- Molecular Biology
- Cancer Research
Background:
- Programmed cell death-1 (PD-1) inhibits T cell effector activity, but its expression regulation is unclear.
- T cell exhaustion limits anti-tumor immunity.
Purpose of the Study:
- Investigate the role of special AT-rich sequence-binding protein-1 (Satb1) in regulating PD-1 expression.
- Elucidate the mechanisms by which tumor microenvironments affect T cell exhaustion.
Main Methods:
- Chromatin immunoprecipitation assays to identify Satb1 and NuRD complex binding sites.
- Quantitative PCR and Western blotting to assess gene and protein expression levels.
- In vivo tumor models and T cell adoptive transfer experiments.
Main Results:
- Satb1 restrains PD-1 expression by recruiting the NuRD complex to Pdcd1 regulatory regions.
- Satb1-deficient T cells show a 40-fold increase in PD-1 expression.
- Tumor-derived TGF-β reduces Satb1 expression, releasing PD-1 from repression and promoting T cell exhaustion.
Conclusions:
- Satb1 acts as a crucial regulator preventing premature T cell exhaustion.
- Dysregulation of the Satb1-PD-1 axis in tumor-infiltrating T cells diminishes anti-tumor immunity.
- Targeting Satb1 or its downstream pathways may enhance cancer immunotherapy.
