Abstract: Objective To observe the effect of bortezomib on the receptor of NF-κB ligand(RANKL) mediated osteoclast differentiation and function in vitro. Methods Osteoclast precursors from peripheral blood mononuclear cells of MM patients were cultured in the presence of RANKL and M-CSF. Osteoclast function was quantified with the extent of the bony resorption and TRAP activity in culture supernatants. Sub-apoptotic concentrations of bortezomib used were 0.5, 1, 2.5 and 5 nmol/L. Results Bortezomib could result in reduction of osteoclast differentiation by the detected less formation quantity of osteoclast and the decreased activity level of TRAP in treatment group. Osteoclast resorption capacity was decreased too, reflecting bortezomib can inhibit the function of osteoclast. Conclusion Bortezomib acts on osteoclast differentiation and function at low concentrations and should be considered as potential drug for the treatment of myeloma bone diseases.

Key words: multiple myeloma, bortezomib, osteoclast