title: RANKL/RANK/OPG: new therapeutic targets in bone tumours and associated osteolysis.
abstract: The emergence of the molecular triad osteoprotegerin (OPG)/Receptor Activator of NF-kB (RANK)/RANK Ligand (RANKL) has helped elucidate a key signalling pathway between stromal cells and osteoclasts. The interaction between RANK and RANKL plays a critical role in promoting osteoclast differentiation and activation leading to bone resorption. OPG is a soluble decoy receptor for RANKL that blocks osteoclast formation by inhibiting RANKL binding to RANK. The OPG/RANK/RANKL system has been shown to be abnormally regulated in several malignant osteolytic pathologies such as multiple myeloma [MM, where enhanced RANKL expression (directly by tumour cells or indirectly by stromal bone cells or T-lymphocytes)] plays an important role in associated bone destruction. By contrast, production of its endogenous counteracting decoy receptor OPG is either inhibited or too low to compensate for the increase in RANKL production. Therefore, targeting the OPG/RANK/RANKL axis may offer a novel therapeutic approach to malignant osteolytic pathologies. In animal models, OPG or soluble RANK was shown both to control hypercalcaemia of malignancy and the establishment and progression of osteolytic metastases caused by various malignant tumours. To this day, only one phase I study has been performed using a recombinant OPG construct that suppressed bone resorption in patients with multiple myeloma or breast carcinoma with radiologically confirmed bone lesions. RANK-Fc also exhibits promising therapeutic effects, as revealed in animal models of prostate cancer and multiple myeloma. If the animal results translate to similar clinical benefits in humans, using RANK-Fc or OPG may yield novel and potent strategies for treating patients with established or imminent malignant bone diseases and where standard therapeutic regimens have failed.
authors.affiliation: Physiopathologie de la Résorption Osseuse et Thérapie des Tumeurs Osseuses Primitives, Faculté de Médecine, INSERM ESPRI, 1 rue Gaston Veil, 44035 Nantes cedex 1, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Wittrant
authors.forename: S
authors.initials: S
authors.lastname: Théoleyre
authors.forename: C
authors.initials: C
authors.lastname: Chipoy
authors.forename: M
authors.initials: M
authors.lastname: Padrines
authors.forename: F
authors.initials: F
authors.lastname: Blanchard
authors.forename: D
authors.initials: D
authors.lastname: Heymann
authors.forename: F
authors.initials: F
authors.lastname: Rédini
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000503:physiopathology* / Q000556:secondary; D002352:Carrier Proteins / Q000494:pharmacology*; D002471:Cell Transformation, Neoplastic; D006023:Glycoproteins / Q000494:pharmacology*; D006801:Humans; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000503:physiopathology*; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; D015398:Signal Transduction
chemical_list: D000970:Antineoplastic Agents; D002352:Carrier Proteins; D006023:Glycoproteins; 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