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Updated: Dec 15, 2025
In Vitro Tumor Cell Rechallenge For Predictive Evaluation of Chimeric Antigen Receptor T Cell Antitumor Function
Published on: February 27, 2019
Rewired signaling network in T cells expressing the chimeric antigen receptor (CAR)
Rui Dong1, Kendra A Libby2,3, Franziska Blaeschke4,5,6
1Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA.
Abstract:
The chimeric antigen receptor (CAR) directs T cells to target and kill specific cancer cells. Despite the success of CAR T therapy in clinics, the intracellular signaling pathways that lead to CAR T cell activation remain unclear. Using CD19 CAR as a model, we report that, similar to the endogenous T cell receptor (TCR), antigen engagement triggers the formation of CAR microclusters that transduce downstream signaling. However, CAR microclusters do not coalesce into a stable central supramolecular activation cluster (cSMAC). Moreover, LAT, an essential scaffold protein for TCR signaling, is not required for microcluster formation, immunological synapse formation, nor actin remodeling following CAR activation. However, CAR T cells still require LAT for an optimal production of the cytokine IL-2. Together, these data show that CAR T cells can bypass LAT for a subset of downstream signaling outputs, thus revealing a rewired signaling pathway as compared to native T cells.
Insights
Chimeric antigen receptor (CAR) T cells bypass a key protein, LAT, for initial signaling, unlike native T cells. However, LAT is still crucial for optimal cytokine IL-2 production in CAR T cell therapy.
Area of Science:
- Immunology
- Cell Biology
- Cancer Therapy
Background:
- Chimeric antigen receptor (CAR) T cell therapy shows promise in treating cancers.
- The precise intracellular signaling pathways governing CAR T cell activation are not fully understood.
- Understanding these pathways is crucial for optimizing CAR T cell efficacy and safety.
Purpose of the Study:
- To elucidate the intracellular signaling mechanisms downstream of CAR engagement.
- To compare CAR T cell signaling with the endogenous T cell receptor (TCR) pathway.
- To investigate the role of the scaffold protein LAT in CAR T cell activation.
Main Methods:
- Utilized a CD19 CAR T cell model system.
- Analyzed CAR microcluster formation and dynamics upon antigen engagement.
- Assessed the requirement of LAT for microcluster formation, synapse development, and cytokine production.
Main Results:
- CAR engagement induces microcluster formation, similar to TCR signaling.
- CAR microclusters do not form a stable central supramolecular activation cluster (cSMAC).
- LAT is dispensable for CAR-mediated microcluster formation, synapse assembly, and actin remodeling, but essential for optimal IL-2 production.
Conclusions:
- CAR T cells exhibit a rewired signaling pathway compared to native T cells, bypassing LAT for certain downstream events.
- This LAT-independent signaling contributes to CAR T cell activation.
- Despite bypassing LAT, optimal CAR T cell function, specifically IL-2 production, still relies on LAT.
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