Abstract:

Objective To explore the effect of zoledronate (ZOL) on the osteoclast adhesion and expression of integrin α_vand β₃ in vitro. Methods Mice RAW264.7 cells were used for osteoclast differentiation in vitro, and osteoclastogenesis was examined by tartrate-resistant acid phosphatase (TRAP) staining and dentin resorption lacunae examination. The cells were then divided into 2 groups, the control group and ZOL treatment group (treated with 1×10^-6 mol·L^-1 ZOL for 2 d). The adhesion ability of osteoclasts and mRNA and the protein expressions of integrin α_vand β₃were examined by crystal violet staining, real-time fluorescence quantitative polymerase chain reaction, Western blot analysis, and immunofluorescent chemistry. Results TRAP staining and dentin resorption lacunae examination revealed the formation of multi-nuclear osteoclasts. ZOL treatment significantly decreased the adhesion ability of osteoclasts (P<0.01). In the ZOL-treated group, the mRNA levels of integrin α_vand β₃ were 0.66±0.05 and 0.59±0.08, respectively. In the control group, the mRNA levels of integrin α_v and β₃were 1.01±0.01 and 1.01±0.02, respectively; these values were higher than those in the ZOL-treated group (P<0.01). The protein level of integrin α_vand β₃in the ZOL-treated group (31 934.84±112.91 and 18 812.79±194.13) was downregulated by approximately 39.19% and 40.17%, respectively, compared with those in the control group (52 517.81±211.72 and 31 441.93±456.87) (P<0.01). Immunofluorescent examination showed that the fluorescent intensities of integrinα^v and β³ in the ZOL-treated group (9.491±0.748 and 4.744±0.759) were also significantly decreased compared with those in the control group (15.159±1.143 and 11.418±1.095) (P<0.01). Conclusion ZOL significantly inhibits osteoclast adhesion and downregulates integrin α_vand β₃expression, thus contributing to the ZOL-induced inhibition of osteoclastmediated bone resorption.

Key words: zoledronate, osteoclast, cell adhesion, integrin αv and β3, sealing zone