Reprogrammed marrow adipocytes: an unexpected role in the genesis of myeloma-induced bone disease (ChIP-Seq)

Multiple myeloma is characterized by osteolytic lesions caused by osteoclast-mediated bone resorption and reduced bone formation. A unique feature of myeloma is a failure of bone healing following successful treatment. Identification of increased adipocyte numbers in marrow of successfully treated patients led us to demonstrate that normal marrow adipocytes, when co-cultured with myeloma cells, are reprogrammed and produce adipokines that activate osteoclastogenesis and suppress osteoblastogenesis. These adipocytes have reduced expression of peroxisome proliferator-activated receptor  (PPAR) mediated by recruitment of polycomb-repressive complex 2 (PRC2) via specificity protein 1, which modifies PPAR promoter methylation at trimethyl lysine-27 histone H3. We confirmed the importance of PPAR methylation by demonstrating that adipocyte-specific knockout of EZH2, a member of the PRC2, prevents adipocyte reprogramming and reverses bone changes in vivo. These results define a heretofore unrecognized role for adipocytes in genesis of myeloma-associated bone disease and that reversal of adipocyte reprogramming has therapeutic implications. Define a heretofore unrecognized role for adipocytes in genesis of myeloma-associated bone disease