Zoledronate inhibits endothelial cell adhesion, migration and survival through the suppression of multiple, prenylation-dependent signaling pathways.
BACKGROUND
Recent evidence indicates that zoledronate, a nitrogen-containing bisphosphonate used to treat conditions of increased bone resorption, may have anti-angiogenic activity. The endothelial cells signaling events modulated by zoledronate remain largely elusive.


OBJECTIVE
The aim of this work was to identify signaling events suppressed by zoledronate in endothelial cells and responsible for some of its biological effects.


METHODS
Human umbilical vein endothelial cells (HUVEC) were exposed to zoledronate, isoprenoid analogs (i.e. farnesol and geranylgeraniol) and various inhibitors of signaling, and the effect on adhesion, survival, migration, actin cytoskeleton and signaling events characterized.


RESULTS
Zoledronate reduced Ras prenylation, Ras and RhoA translocation to the membrane, and sustained ERK1/2 phosphorylation and tumor necrosis factor (TNF) induced JNK phosphorylation. Isoprenoid analogs attenuated zoledronate effects on HUVEC adhesion, actin stress fibers and focal adhesions, migration and survival. Isoprenoid analogs also restored Ras prenylation, RhoA translocation to the membrane, sustained FAK and ERK1/2 phosphorylation and prevented suppression of protein kinase B (PKB) and JNK phosphorylation in HUVEC exposed to TNF in the presence of zoledronate. Pharmacological inhibition of Rock, a RhoA target mediating actin fiber formation, phosphatidylinositol 3-kinase, an activator of PKB, MEK1/2, an activator of ERK1/2, and JNK, recapitulated individual zoledronate effects, consistent with the involvement of these molecules and pathways and their inhibition in the zoledronate effects.


CONCLUSIONS
This work has demonstrated that zoledronate inhibits HUVEC adhesion, survival, migration and actin stress fiber formation by interfering with protein prenylation and has identified ERK1/2, JNK, Rock, FAK and PKB as kinases affected by zoledronate in a prenylation-dependent manner.
Hasmim
M
M
Division of Experimental Oncology, Centre Pluridisciplinaire d'Oncologie, Lausanne Cancer Center, Epalinges, Switzerland.
Bieler
G
G
Rüegg
C
C
D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D050071:Bone Density Conservation Agents / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects*; D002465:Cell Movement / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004164:Diphosphonates / Q000494:pharmacology*; D004224:Diterpenes / Q000494:pharmacology; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005204:Farnesol / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017368:Protein Prenylation / Q000187:drug effects*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000633:toxicity; D014471:Umbilical Veins; D000077211:Zoledronic Acid; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D020533:Angiogenesis Inhibitors; D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D004224:Diterpenes; D007093:Imidazoles; D047908:Intracellular Signaling Peptides and Proteins; D047428:Protein Kinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; D005204:Farnesol; D000077211:Zoledronic Acid; C017338:geranylgeraniol; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D054460:rho-Associated Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D048670:MAP Kinase Kinase 4; D020742:rhoA GTP-Binding Protein