[Mechanisms of myeloma-induced bone disease]

Multiple myeloma(MM)develops and expands almost exclusively in the bone marrow, and generates devastating bone destruction. MM cells produce a variety of cytokines to stimulate RANKL-mediated osteoclastogenesis and suppress osteoblastic differentiation from bone marrow stromal cells, leading to extensive bone destruction with rapid loss of bone. Furthermore, osteocyte apoptosis has been demonstrated to be induced in parallel with enhanced osteoclast recruitment and osteoclastogenesis in myeloma bone lesions. Of note, osteocytes physically interact with myeloma cells to skew their signaling pathways and thereby production of mediators responsible for exacerbated bone resorption and suppressed bone formation in myeloma. The role of osteocytes in myeloma-induced bone lesions remains to be further clarified.