Reciprocal leukemia-stroma VCAM-1/VLA-4-dependent activation of NF-κB mediates chemoresistance

Area of Science:

• Hematology
• Cell Biology
• Molecular Oncology

Background:

• Leukemia cells interact with bone marrow mesenchymal stromal cells (BM-MSCs), conferring protection against chemotherapy-induced apoptosis.
• The precise mechanisms underlying this stromal-mediated chemoresistance remain incompletely understood.

Purpose of the Study:

• To elucidate the molecular mechanisms by which BM-MSCs protect leukemia cells from chemotherapy.
• To investigate the role of nuclear factor-kappa B (NF-κB) signaling in stroma-mediated chemoresistance.

Main Methods:

• Genome-wide gene expression profiling of BM-MSCs co-cultured with leukemia cells.
• In vitro and in vivo studies involving blockade of NF-κB activation using chemical agents and inhibitor κB-α (IκBα) overexpression.
• Utilizing a unique in vivo model of the human leukemia bone marrow microenvironment.
• Investigating the role of vascular cell adhesion molecule 1 (VCAM-1) and very late antigen-4 (VLA-4) interactions.

Main Results:

• Co-culture with leukemia cells upregulated NF-κB signaling pathway genes in BM-MSCs.
• Primary BM-MSCs from leukemia patients showed higher NF-κB target gene expression compared to normal BM-MSCs.
• Inhibition of NF-κB activation in BM-MSCs significantly reduced chemoresistance in leukemia cells, both in vitro and in vivo.
• VCAM-1/VLA-4 interaction was identified as crucial for NF-κB activation in both stromal and leukemia cells.

Conclusions:

• Reciprocal NF-κB activation between BM-MSCs and leukemia cells is critical for promoting chemoresistance.
• Targeting the NF-κB pathway or the VLA-4/VCAM-1 signaling axis presents a promising therapeutic strategy to overcome stroma-mediated chemoresistance in leukemia.