Zoledronic acid monohydrate Ras inhibitor

Zoledronic acid inhibits osteoclast maturation indirectly by increasing OPG protein secretion and decreasing transmembrane RANKL expression in human osteoblasts. Treatment of primary human OB-like cells with the potent nitrogen-containing BP, zoledronic acid (ZOL), resulted in a downregulation of membrane-associated RANKL protein expression. In addition to direct effects on cells of the osteoclast lineage, zoledronic acid may inhibit bone resorption by reducing transmembrane RANKL expression and increasing OPG secretion in osteoclast (OB)-like cells[1]. Zoledronic acid induces growth inhibition (IC50:10–50 μM) and apoptotic death of human pancreatic cancer cells. The proapoptotic effect was correlated to cleavage/activation of caspase-9 and poly(ADP)-ribose polymerase, but not of caspase-3. It interferes with growth and survival pathways downstream to p21^Ras[2]. Zoledronic acid is also a potent inhibitor of angiogenesis. In vitro, zoledronic acid inhibits proliferation of human endothelial cells stimulated with fetal calf serum, basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (IC50 values 4.1, 4.2, and 6.9 μM, respectively), and modulates endothelial cell adhesion and migration. In cultured aortic rings and in the chicken egg chorioallantoic membrane assay, zoledronic acid reduces vessel sprouting. ZOL also exerted a concentration-dependent, biphasic effect on the adhesion and migration of HUVEC in vitro. ZOL concentrations of 1 and 3 μM increased cell adhesion but inhibited it at 30 and 100 μM. Similarly, cell migration was stimulated by 0.3 to 10 μM ZOL, whereas 30 μM completely inhibited it. These findings suggest that ZOL could interfere with cytoskeletal function in endothelial cells[4].

Zoledronic acid affects breast cancer metastasis to visceral organs as well as bone[3]. When administered systemically to mice, zoledronic acid potently inhibits the angiogenesis induced by subcutaneous implants impregnated with bFGF [ED50, 3 μg/kg (7.5 nmol/kg) s.c.][4]. In mice transplanted with osteosarcoma (OS) cells, ZOL administration prevented osteolysis and significantly reduced the amount of OS-induced bone formation while has no effect on tumour burden at the primary site. ZOL failed to reduce lung metastasis and in some cases was associated with larger and more numerous metastatic lesions[5].