title: Functional osteoclast-like transformation of cultured human myeloma cell lines.
abstract: Hyperactive osteoclastogenesis is a hallmark of multiple myeloma, a B cell neoplasia homing to bone marrow and resulting in multiple osteolytic lesions and skeleton devastation. We provide evidence that myeloma cells can themselves act as osteoclasts in vitro. By extending standard cultures of U-266 and MCC-2 myeloma cell lines, we found that subsets of adherent cells also expressed the osteoclast phenotype, including multinuclear morphology, cytoplasmic tartrate-resistant acid phosphatase, the calcitonin receptor and a specific osteoclast antigen. These subsets resorbed bone substrates by producing osteoclast enzymes as well as the characteristic redistribution of F-actin in their cytoskeleton, thus forming the sealing zone that is adopted by adherent osteoclasts to generate the acidified environment essential for bone resorption. Neither the phenotype nor the functional properties of osteoclasts were detected in parental non-adherent cells. In adherent cultures osteoclastogenesis was associated with deregulated expression of both receptor activator of nuclear transcription factor (NF)-kappaB (RANK) and its ligand RANK-L, which triggers cell maturation in osteoclast precursors. Resorption of bone substrates was prevented by a neutralising anti-RANK-L antibody. Our data indicate that osteoclast-like transformation of both U-266 and MCC-2 cellular models of human myeloma is dependent on RANK-L stimulation.
authors.affiliation: Department of Internal Medicine and Clinical Oncology, University of Bari, Bari, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Calvani
authors.forename: Paola
authors.initials: P
authors.lastname: Cafforio
authors.forename: Franco
authors.initials: F
authors.lastname: Silvestris
authors.forename: Franco
authors.initials: F
authors.lastname: Dammacco
mesh_terms: D000199:Actins / Q000378:metabolism; D001857:Bone Matrix / Q000473:pathology; D001862:Bone Resorption; D002352:Carrier Proteins / Q000378:metabolism; D002448:Cell Adhesion; D003599:Cytoskeleton / Q000378:metabolism; D006801:Humans; D016130:Immunophenotyping; D008562:Membrane Glycoproteins / Q000378:metabolism; D009101:Multiple Myeloma / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D010010:Osteoclasts / Q000473:pathology*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014407:Tumor Cells, Cultured
chemical_list: D000199:Actins; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human