SMAD4 Regulates the Expression of LCK Affecting Chimeric Antigen Receptor-T Cells Proliferation Through PI3K/Akt...

Area of Science:

• Immunology
• Molecular Biology
• Cancer Therapy

Background:

• CAR-T cell proliferation is limited in solid tumors.
• The regulatory mechanisms governing CAR-T cell proliferation remain incompletely understood.

Purpose of the Study:

• To elucidate the molecular mechanisms regulating CAR-T cell proliferation.
• To identify key factors involved in CAR-T cell expansion and function.

Main Methods:

• Recombinant CD19CAR expression in T cells.
• Overexpression and knockdown of LCK and SMAD4.
• Cell cycle analysis and apoptosis assays.
• Western blotting for PI3K/Akt pathway activation.
• Chromatin immunoprecipitation to assess SMAD4 binding to LCK promoter.

Main Results:

• CD19CAR expression increased basal and LCK activation in CAR-T cells.
• LCK and SMAD4 are essential for CAR-T cell proliferation, with overexpression promoting and knockdown inhibiting it.
• Knockdown of LCK or SMAD4 led to increased apoptosis and cell cycle arrest.
• Overexpression of LCK or SMAD4 enhanced PI3K/Akt phosphorylation, while inhibitors blocked this effect.
• SMAD4 directly binds to the LCK promoter, regulating its expression.

Conclusions:

• SMAD4 regulates LCK expression, which in turn influences CAR-T cell proliferation through the PI3K/Akt signaling pathway.
• This study reveals a novel regulatory axis for CAR-T cell expansion, offering potential therapeutic targets for enhancing CAR-T cell efficacy in solid tumors.