title: Suramin interacts with RANK and inhibits RANKL-induced osteoclast differentiation.
abstract: Suramin is a naphthalene trisulfonic acid derivative that inhibits osteoclast differentiation and bone resorption in vitro and in vivo; however, the mechanisms underlying this activity have not been studied. Receptor activator of NF-kB (RANK) ligand (RANKL) is a key regulator of osteoclast differentiation and function and this study evaluated the ability of suramin, which has been shown to disrupt protein-protein interactions, to interfere with RANKL functional activity and binding to RANK. Suramin inhibited osteoclastic bone resorption in a calvarial model and inhibited osteoclast differentiation in RANKL-stimulated murine spleen cells and RAW264.7 cells. RANKL-induced second messenger signaling (AKT and p38 MAP Kinase phosphorylation) was completely blocked by 100 microM suramin. The ability of RANKL to bind to recombinant human RANK-Fc (rhRANK-Fc) was reduced 50% by suramin in an in vitro binding assay. Surface plasmon resonance technology and nuclear magnetic resonance (NMR) were used to evaluate the ability of suramin to bind to rhRANK-Fc. Suramin was found to selectively interact with immobilized rhRANK-Fc chimera in a concentration-dependent manner by Biacore 3000 analysis. Similar results were obtained using saturation transfer difference NMR spectroscopy to demonstrate that suramin binds to rhRANK-Fc, but not IgG1Fc or sRANKL. In summary, these findings demonstrate that suramin inhibits sRANKL-induced osteoclast differentiation and suggest that these effects are mediated by suramin binding to RANK and blocking the ability of sRANKL to induce second messenger signaling.
authors.affiliation: Lilly Research Labs, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, USA.
authors.forename: Ajit
authors.initials: A
authors.lastname: Regmi
authors.forename: Tina
authors.initials: T
authors.lastname: Fuson
authors.forename: Xuhao
authors.initials: X
authors.lastname: Yang
authors.forename: Joanne
authors.initials: J
authors.lastname: Kays
authors.forename: Christopher
authors.initials: C
authors.lastname: Moxham
authors.forename: Edward
authors.initials: E
authors.lastname: Zartler
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Chandrashekhar
authors.forename: Rachelle J Sells
authors.initials: RJ
authors.lastname: Galvin
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors* / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006023:Glycoproteins / Q000378:metabolism*; D006131:Growth Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000502:physiology*; D051379:Mice; D008813:Mice, Inbred ICR; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D053244:Osteoprotegerin; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D013498:Suramin / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D002352:Carrier Proteins; D006023:Glycoproteins; D006131:Growth Inhibitors; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; D013498:Suramin