title: Over-expression of parathyroid hormone Type 1 receptor confers an aggressive phenotype in osteosarcoma.
abstract: Osteosarcoma is the most common primary bone malignancy in children and is associated with rapid bone growth. Parathyroid hormone-related peptide (PTHrP) signaling via parathyroid hormone Type 1 receptor (PTHR1) is important for skeletal development and is involved in bone metastases in other tumors. The aim of this study was to investigate the status of PTHrP/PTHR1 and its possible role in osteosarcoma. In a preliminary screening, a higher level of PTHR1 mRNA, but not PTHrP, was found in 4 osteosarcoma xenografts as compared with 4 standard cell lines, or 5 patient derived cell lines (p < 0.05) using quantitative RT-PCR. It was therefore extended to 55 patient specimens, in which a significantly higher level of PTHR1 mRNA was detected in metastatic or relapsed samples than those from primary sites (p < 0.01). Cell behavior caused by PTHR1 overexpression was further studied in vitro using PTHR1 transfected HOS cell line as a model. Over-expression of PHTR1 resulted in increased proliferation, motility and Matrigel invasion without addition of exogenous PTHrP suggesting an autocrine effect. Importantly, the aggressiveness in PTHR1-expressing cells was completely reversed by RNAi mediated gene knockdown. In addition, PTHR1 over-expression led to delayed osteoblastic differentiation and upregulation of genes involved in extracellular matrix production, such as TGF-beta1 and connective tissue growth factor. When cocultured with bone marrow derived monocytes, PTHR1 transfected HOS cells induced a greater number of osteoclasts. This study suggests that PTHR1 over-expression may promote osteosarcoma progression by conferring a more aggressive phenotype, and forming a more favorable microenvironment.
authors.affiliation: Department of Pediatrics and Molecular Pharmacology, The Albert Einstein College of Medicine, The Children's Hospital at Montefiore, Bronx, NY, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Yang
authors.forename: Bang H
authors.initials: BH
authors.lastname: Hoang
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Kubo
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Kawano
authors.forename: Alexander
authors.initials: A
authors.lastname: Chou
authors.forename: Rebecca
authors.initials: R
authors.lastname: Sowers
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Huvos
authors.forename: Paul A
authors.initials: PA
authors.lastname: Meyers
authors.forename: John H
authors.initials: JH
authors.lastname: Healey
authors.forename: Richard
authors.initials: R
authors.lastname: Gorlick
mesh_terms: D001483:Base Sequence; D049109:Cell Proliferation; D017931:DNA Primers; D018076:DNA, Complementary; D006801:Humans; D009362:Neoplasm Metastasis; D010010:Osteoclasts / Q000473:pathology; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D010641:Phenotype; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053773:Transforming Growth Factor beta1 / Q000235:genetics
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D044168:Receptor, Parathyroid Hormone, Type 1; D053773:Transforming Growth Factor beta1