Over-expression of parathyroid hormone Type 1 receptor confers an aggressive phenotype in osteosarcoma.
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.
Yang
Rui
R
Department of Pediatrics and Molecular Pharmacology, The Albert Einstein College of Medicine, The Children's Hospital at Montefiore, Bronx, NY, USA.
Hoang
Bang H
BH
Kubo
Tadahiko
T
Kawano
Hirotaka
H
Chou
Alexander
A
Sowers
Rebecca
R
Huvos
Andrew G
AG
Meyers
Paul A
PA
Healey
John H
JH
Gorlick
Richard
R
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
D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D044168:Receptor, Parathyroid Hormone, Type 1; D053773:Transforming Growth Factor beta1