ABSTRACT
Objective:To investigate the effects of doxorubicin(DOX) on osteoblast differentiation of rat bone marrow mesenchymal stem cells(BMSCs) and osteoclast differentiation of bone marrow monocytes(BMMs) in vitro.Methods:Rat BMSCs were treated with various concentrations of DOX in osteogenic medium. The cell viability was detected by CCK-8 assay. Alizarin red staining and alkaline phosphatase(ALP) activity were used to detect the effect of DOX on osteogenic differentiation. Expressions of osteogenic differentiation-related genes were detected by real-time quantitative PCR, Western blot, and immunofluorescence. Similarly, BMMs were treated with various concentrations of DOX and its effects on cell viability and osteoclast differentiation were measured. Finally, the expressions of osteoclast-related genes were detected.Results:DOX treatment inhibited the ALP activity during BMSCs differentiation into osteoblasts and reduced the number of calcium nodules, along with decreased expressions of osteogenic-related genes(ALP, collagen-Ⅰ, and osteocalcin, P<0.05). DOX suppressed the expressions of Smad 1/5/9, bone morphogenetic protein 2(BMP-2), Osterix, and core binding factor α1(Runx2). BMP-2 supplement antagonized the effect of DOX on ALP activity. DOX promoted receptor activator of NF-κB ligand(RANKL) expression and inhibited osteoprotegerin expression. DOX promoted the osteoclast formation and expressions of osteoclast-related genes such as tartrate-resistant acid phosphatase, nuclear factor of activated T cells c1(NFATc1), and c-Fos in a direct and indirect manner. Conclusion:DOX inhibits BMSCs differentiation into osteoblasts through BMP-2/Smads signaling pathway while promotes RANKL-induced BMMs differentiation into osteoclasts in vitro.