title: Expression of parathyroid hormone-related protein (PTHrP), osteoclast differentiation factor (ODF)/receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoclastogenesis inhibitory factor (OCIF)/osteoprotegerin (OPG) in ameloblastomas.
abstract: BACKGROUND
  To clarify the roles of osteoclast regulatory factors in progression of odontogenic tumors, expression of parathyroid hormone-related protein (PTHrP), osteoclast differentiation factor (ODF)/receptor activator of nuclear factor-kappaB ligand (RANKL), and osteoclastogenesis inhibitory factor (OCIF)/osteoprotegerin (OPG) were analyzed in ameloblastomas as well as tooth germs.
  
  
  METHODS
  Tissue specimens of nine tooth germs and 36 benign and one malignant ameloblastomas were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry for the expression of PTHrP, ODF/RANKL, and OCIF/OPG.
  
  
  RESULTS
  Expression of PTHrP, ODF/RANKL, and OCIF/OPG mRNA was detected in all tooth germ and ameloblastoma samples. Immunohistochemical reactivity for PTHrP was recognized in both normal and neoplastic odontogenic epithelial cells. In ameloblastomas, PTHrP reactivity in peripheral columnar or cuboidal cells was stronger than that in central polyhedral cells, and keratinizing cells showed increased PTHrP reactivity. ODF/RANKL and OCIF/OPG were expressed predominantly in mesenchymal cells rather than in odontogenic epithelial cells in both tooth germs and ameloblastomas. Epithelial ODF/RANKL and OCIF/OPG expression was slightly lower in ameloblastomas than in tooth germs. Tumor cells in plexiform ameloblastomas showed slightly higher reactivity for PTHrP and ODF/RANKL than tumor cells in follicular ameloblastomas.
  
  
  CONCLUSIONS
  Expression of PTHrP, ODF/RANKL and OCIF/OPG in tooth germs and ameloblastomas suggests that these factors might locally regulate bone metabolism and dynamics in tooth development as well as in progression of ameloblastomas. These factors might also be involved in tumor cell differentiation and/or tumor tissue structuring in ameloblastomas.
authors.affiliation: Department of Oral Medicine and Surgery, Tohoku University Graduate School of Dentistry, Sendai, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kumamoto
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ooya
mesh_terms: D000564:Ameloblastoma / Q000473:pathology*; D002352:Carrier Proteins / Q000032:analysis*; D002454:Cell Differentiation; D004847:Epithelial Cells / Q000473:pathology; D006023:Glycoproteins / Q000032:analysis*; D006801:Humans; D015603:Keratinocytes / Q000473:pathology; D008024:Ligands; D008562:Membrane Glycoproteins / Q000032:analysis*; D008648:Mesoderm / Q000473:pathology; D016328:NF-kappa B / Q000032:analysis*; D009805:Odontogenesis; D010010:Osteoclasts / Q000473:pathology*; D053244:Osteoprotegerin; D044162:Parathyroid Hormone-Related Protein / Q000032:analysis*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis*; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis*; D018709:Statistics, Nonparametric; D014083:Tooth Germ / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis*
chemical_list: D002352:Carrier Proteins; D006023:Glycoproteins; D008024:Ligands; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D053244:Osteoprotegerin; D044162:Parathyroid Hormone-Related Protein; 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; D014409:Tumor Necrosis Factor-alpha