BTK induces CAM-DR through regulation of CXCR4 degradation in multiple myeloma

Area of Science:

• Oncology
• Hematology
• Molecular Biology

Background:

• Cellular adhesion-mediated drug resistance (CAM-DR) is a significant challenge in treating relapsed or refractory multiple myeloma (MM).
• Bruton's tyrosine kinase (BTK) is implicated in MM progression and drug resistance, with a known association with CXCR4, a cell adhesion molecule.

Purpose of the Study:

• To elucidate the precise mechanism by which BTK contributes to CAM-DR in multiple myeloma.
• To investigate the therapeutic potential of targeting BTK in MM treatment.

Main Methods:

• Investigated the effect of BTK expression on MM cell adherence to extracellular matrix (ECM) and stromal cells in vitro and in vivo.
• Examined the relationship between BTK, CXCR4 expression, and ubiquitination.
• Evaluated the synergistic effects of a BTK inhibitor and bortezomib in a 5TMM3VT MM mouse model.

Main Results:

• Increased BTK expression promoted MM cell adherence to ECM and stromal cells, contributing to CAM-DR.
• BTK enhances CXCR4 expression and may prevent its degradation by inhibiting ubiquitination.
• Separating MM cells from ECM or stromal cells reversed CAM-DR.
• A BTK inhibitor showed synergistic effects with bortezomib in a preclinical MM model.

Conclusions:

• BTK plays a novel role in mediating cellular adhesion and drug resistance in multiple myeloma.
• Targeting BTK represents a promising therapeutic strategy for overcoming CAM-DR in MM.
• Combined therapy with BTK inhibitors and bortezomib may offer improved clinical outcomes for MM patients.