title: Expression of receptor activator of nuclear factor kappa-B ligand (RANKL) in neoplasms of dogs and cats.
abstract: BACKGROUND
  Receptor activator of nuclear factor kappa-B (RANK), RANK-ligand (RANKL), and the soluble decoy receptor osteoprotegerin (OPG) form a key axis modulating osteoclastogenesis. In health, RANKL-expressing bone stromal cells and osteoblasts activate osteoclasts through RANK ligation, resulting in homeostatic bone resorption. Skeletal tumors of dogs and cats, whether primary or metastatic, may express RANKL and directly induce malignant osteolysis.
  
  
  OBJECTIVE
  Bone malignancies of dogs and cats may express RANKL, thereby contributing to pathologic bone resorption and pain. Furthermore, relative RANKL expression in bone tumors may correlate with radiographic characteristics of bone pathology.
  
  
  METHODS
  Forty-two dogs and 6 cats with spontaneously-occurring tumors involving bones or soft tissues were evaluated.
  
  
  METHODS
  A polyclonal anti-human RANKL antibody was validated for use in canine and feline cells by flow cytometry and immunocytochemistry. Fifty cytologic specimens were collected from bone and soft tissue tumors of 48 tumor-bearing animals and assessed for RANKL expression. In 15 canine osteosarcoma (OSA) samples, relative RANKL expression was correlated with radiographic characteristics of bone pathology.
  
  
  RESULTS
  Expression of RANKL by neoplastic cells was identified in 32/44 canine and 5/6 feline tumor samples. In 15 dogs with OSA, relative RANKL expression did not correlate with either radiographic osteolysis or bone mineral density as assessed by dual energy x-ray absorptiometry.
  
  
  CONCLUSIONS
  In dogs and cats, tumors classically involving bone and causing pain, often may express RANKL. Confirming RANKL expression in tumors is a necessary step toward the rational institution of novel therapies targeting malignant osteolysis via RANKL antagonism.
authors.affiliation: Department of Pathobiology, University of Illinois at Urbana-Champaign, USA. abarger@uiuc.edu
authors.forename: Anne M
authors.initials: AM
authors.lastname: Barger
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Fan
authors.forename: Louis-Philippe
authors.initials: LP
authors.lastname: de Lorimier
authors.forename: Ian T
authors.initials: IT
authors.lastname: Sprandel
authors.forename: Kristen
authors.initials: K
authors.lastname: O'Dell-Anderson
mesh_terms: D000818:Animals; D015519:Bone Density; D001859:Bone Neoplasms / Q000378:metabolism / Q000662:veterinary; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000662:veterinary; D002371:Cat Diseases / Q000378:metabolism*; D002415:Cats; D045744:Cell Line, Tumor; D002813:Chondrosarcoma / Q000378:metabolism / Q000662:veterinary; D004283:Dog Diseases / Q000378:metabolism*; D004285:Dogs; D005260:Female; D005354:Fibrosarcoma / Q000378:metabolism / Q000662:veterinary; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D006801:Humans; D008297:Male; D010014:Osteolysis / Q000378:metabolism; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism*
chemical_list: D053245:RANK Ligand