Zoledronate inhibits alpha v beta 3 and alpha v beta 5 integrin cell surface expression in endothelial cells

Zoledronate exhibits antiangiogenic properties in vitro and in vivo. Integrins alpha v beta 3 and alpha v beta 5 are involved in angiogenesis. Because zoledronate inhibits endothelial cell adhesion, the authors explored the hypothesis that it could alter these integrins recruitment to focal adhesion sites. Human umbilical vein endothelial cells ( HUVECs) were treated with zoledronate or with mevalonate pathway intermediates geranylgeraniol ( GGOH) and farnesol (FOH). Zoledronate generated a significant decrease in alpha v beta 3 and alpha v beta 5 expression at HUVEC cell surface using flow cytometry and immunofluorescence. This inhibition was reversed by GGOH but not by FOH. Cells cotreated with zoledronate and GGOH were able to attach to vitronectin through alpha v beta 3 and alpha v beta 5, as confirmed by the use of specific function-blocking antibodies. The authors showed that zoledronate alters endothelial cell integrin-mediated adhesion. This effect is likely to contribute to the previously demonstrated antiangiogenic effect of zoledronate. Whether this mechanism of action also applies to metastatic tumor cells is under investigation.