[Effect of zoledronate on the osteoclast adhesion and gene expression of integrin α(v) and β3]

To explore the effect of zoledronate (ZOL) on the osteoclast adhesion and expression of integrin α(v) and β3 in vitro.

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 x 10(-6) mol · L(-1) ZOL for 2 d). The adhesion ability of osteoclasts and mRNA and the protein expressions of integrin α(v) and β3 were examined by crystal violet staining, real-time fluorescence quantitative polymerase chain reaction, Western blot analysis, and immunofluorescent chemistry.

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(v) and β3 were 0.66 ± 0.05 and 0.59 ± 0.08, respectively. In the control group, the mRNA levels of integrin α(v) and β3, were 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(v) and β3 in 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 integrin α(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).

ZOL significantly inhibits osteoclast adhesion and downregulates integrin α(v) and β3, expression, thus contributing to the ZOL-induced inhibition of osteoclast- mediated bone resorption.