Humanized Bone Model Identifies BMP6 as a Multifunctional Regulator in Myeloma Bone Disease

Area of Science:

• Bone Biology and Disease
• Cancer Therapeutics
• Stem Cell Biology

Background:

• Multiple myeloma (MM) disrupts bone homeostasis by inhibiting bone formation and increasing bone resorption.
• Current MM therapies primarily target tumor cells and osteolysis, neglecting bone restoration strategies.
• Mesenchymal stromal cells (MSCs) are crucial for bone formation but are suppressed in the MM microenvironment.

Purpose of the Study:

• To investigate osteoinductive strategies for restoring bone formation in multiple myeloma.
• To evaluate the therapeutic potential of bone morphogenetic protein 6 (BMP6) in the MM bone microenvironment.
• To establish a humanized model for studying tumor-stroma interactions in MM.

Main Methods:

• Utilized a human bone marrow-like scaffold model for in vivo evaluation of MM-stroma interactions.
• Performed transcriptomic profiling of MM-primed mesenchymal stromal cells (MSCs).
• Assessed the effects of BMP6 on osteogenesis, osteoclastogenesis, MSC phenotype, and MM cell proliferation.

Main Results:

• MM cells suppress the osteogenic potential of MSCs by downregulating key bone morphogenetic protein (BMP) signaling mediators, including small leucine-rich proteoglycans (SLRPs).
• BMP6 potently induced osteogenesis, upregulated SLRPs, and selectively promoted bone formation without increasing osteoclast activity.
• BMP6 attenuated inflammatory and tumor-supportive MSC phenotypes, directly inhibited MM cell proliferation, and suppressed IL6-induced MM cell growth.

Conclusions:

• BMP6 is a multifunctional regulator that restores bone formation and exhibits direct anti-myeloma activity.
• BMP6 represents a promising therapeutic candidate for treating bone disease associated with multiple myeloma.
• The developed humanized model is valuable for dissecting complex tumor-bone interactions in MM.