CDK4/6 Inhibition Reverses MEIS2 Suppression of CRL4 ^CRBN to Enhance Immunomodulatory Drug Therapy in Multiple...

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Cereblon (CRBN) is crucial for immunomodulatory drugs (IMiDs) and CELMoDs in multiple myeloma.
• MEIS2 is a novel substrate of CRBN, but its role in myeloma was previously unknown.

Purpose of the Study:

• To investigate the function of MEIS2 in multiple myeloma.
• To explore the therapeutic potential of targeting MEIS2 and CDK4/6 in combination with IMiD therapy.

Main Methods:

• Biochemical identification of MEIS2 as a CRBN substrate.
• Analysis of MEIS2, CDK4/6, and CRBN expression in myeloma cells.
• Ex vivo studies of CDK4/6 inhibition (CDK4/6i) on myeloma cells.
• Mechanistic studies involving protein-protein interactions, protein degradation, and gene expression analysis.

Main Results:

• Aberrant MEIS2 expression in myeloma cells correlates with poor survival in IMiD-treated patients.
• CDK4/6i reprograms myeloma cells to enhance IMiD sensitivity by displacing MEIS2 from CRBN and destabilizing MEIS2.
• CDK4/6i increases CRBN levels, enhancing CRL4CRBN ubiquitination and degradation of IKZF3/IKZF1, leading to IRF4 loss and apoptosis.
• MEIS2 promotes BCMA expression, counteracting IMiD/CELMoD-mediated repression.

Conclusions:

• CDK4/6i reverses MEIS2-mediated inhibition of CRL4CRBN and mitigates MEIS2-driven BCMA signaling.
• Targeting MEIS2 and CDK4/6 represents a promising strategy to improve immunomodulatory drug therapy for multiple myeloma.