Transgenic αβ TCR tonic signaling is leukemogenic while strong stimulation is leukemia suppressive

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• T cell receptor (TCR) and TCR complexes are common in T cell acute lymphoblastic leukemia (T-ALL).
• Previous studies suggested TCR expression promotes T-ALL, but recent findings show TCR signaling can suppress leukemia.
• The dual role of TCR signaling in leukemogenesis requires further investigation.

Purpose of the Study:

• To determine if a specific αβ TCR complex has a dual role in T-ALL development based on stimulus type.
• To investigate the mechanisms underlying TCR-mediated leukemogenesis and suppression.

Main Methods:

• Utilized transgenic mouse models expressing specific αβ TCRs (Marilyn and OT-I).
• Analyzed T-ALL development in genetically modified mice (e.g., Rag2-deficient, β2-microglobulin knockout).
• Assessed leukemic cell apoptosis and mouse survival upon exposure to agonist antigens or peptides.

Main Results:

• Transgenic Marilyn αβ TCR expression induced T-ALL in female mice, characterized by Notch1 mutations and immature immunophenotype.
• T-ALL development occurred independently of Rag2-mediated recombination but required MHC class I for the OT-I model.
• Leukemic cells expressing CD5 indicated tonic TCR signaling, which was leukemogenic.
• Exposure to agonist antigens or peptides triggered T-ALL apoptosis and prolonged survival, demonstrating strong TCR stimulation's suppressive effect.

Conclusions:

• The same αβ TCR complex exhibits a dual role in T-ALL: tonic stimulation promotes leukemogenesis, while strong stimulation induces apoptosis.
• This study highlights the critical influence of TCR signaling context on T-ALL development and progression.
• Findings provide insights into therapeutic strategies targeting TCR signaling in T-ALL.