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Published on: October 27, 2020
T-cell TGF-β signaling abrogation restricts medulloblastoma progression
David Gate1, Moise Danielpour2, Javier Rodriguez3
1Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089;Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048;
Abstract:
Cancer cell secretion of TGF-β is a potent mechanism for immune evasion. However, little is known about how central nervous system tumors guard against immune eradication. We sought to determine the impact of T-cell TGF-β signaling blockade on progression of medulloblastoma (MB), the most common pediatric brain tumor. Genetic abrogation of T-cell TGF-β signaling mitigated tumor progression in the smoothened A1 (SmoA1) transgenic MB mouse. T regulatory cells were nearly abolished and antitumor immunity was mediated by CD8 cytotoxic T lymphocytes. To define the CD8 T-cell subpopulation responsible, primed CD8 T cells were adoptively transferred into tumor-bearing immunocompromised SmoA1 recipients. This led to generation of CD8(+)/killer cell lectin-like receptor G1 high (KLRG1(hi))/IL-7R(lo) short-lived effector cells that expressed granzyme B at the tumor. These results identify a cellular immune mechanism whereby TGF-β signaling blockade licenses the T-cell repertoire to kill pediatric brain tumor cells.
Insights
Blocking TGF-β signaling in T cells stops pediatric brain tumor growth. This approach eliminates regulatory T cells and activates CD8 cytotoxic T lymphocytes to eradicate medulloblastoma.
Area of Science:
- Immunology
- Oncology
- Neuroscience
Background:
- Cancer cells, including those in the central nervous system, often use TGF-β to evade immune detection.
- The mechanisms by which brain tumors, specifically medulloblastoma, resist immune attack are not fully understood.
Purpose of the Study:
- To investigate the effect of blocking T-cell TGF-β signaling on medulloblastoma progression.
- To identify the specific T-cell populations involved in anti-tumor immunity against medulloblastoma.
Main Methods:
- Utilized the smoothened A1 (SmoA1) transgenic mouse model for medulloblastoma.
- Genetically abrogated T-cell TGF-β signaling.
- Performed adoptive transfer of primed CD8 T cells into tumor-bearing mice.
Main Results:
- Blocking T-cell TGF-β signaling significantly reduced medulloblastoma progression.
- T regulatory cells were depleted, and anti-tumor immunity was driven by CD8 cytotoxic T lymphocytes.
- Identified a specific CD8 T-cell subset (KLRG1(hi)/IL-7R(lo)) expressing granzyme B at the tumor site.
Conclusions:
- T-cell TGF-β signaling blockade is a viable strategy to overcome immune evasion in pediatric brain tumors.
- This blockade promotes the generation of effective anti-tumor CD8 T cells, leading to tumor eradication.
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