Myeloma cells and bone marrow osteoblast interactions: role in the development of osteolytic lesions in multiple myeloma.

Bone destruction is the hallmark of multiple myeloma (MM) due to the high capacity of malignant plasma cells to induce a severe imbalance of bone remodeling. Growing evidences suggest that MM cell interactions with bone marrow (BM) osteoblast have a critical role in the pathophysiology of osteolytic lesions. Indeed histomorphometric studies have demonstrated that MM patients with osteolytic bone lesions have lower numbers of osteoblasts and decreased bone formation together with osteoclast activation. Recently, the biological mechanisms involved in the osteoblast inhibition induced by MM cells have begun to be elucidated, underlying the main role of the block of osteoblast differentiation in the development of bone lesions. In this article, we summarize the main mechanisms regulating MM cell and osteoblast interactions.