Expression of Osteoclast Differentiation Signals by Stromal Elements of Giant Cell Tumors

Authors

  • Gerald J. Atkins,

    1. Department of Orthopaedics and Trauma, University of Adelaide, Adelaide, South Australia 5000, Australia
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  • David R. Haynes,

    1. Department of Pathology, University of Adelaide, Adelaide, South Australia 5000, Australia
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  • Stephen E. Graves,

    1. Department of Orthopaedics and Trauma, University of Adelaide, Adelaide, South Australia 5000, Australia
    2. Department of Orthopaedic Surgery, Flinders Medical Centre and Repatriation General Hospital, Daw Park, South Australia 5041, Australia
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  • Andreas Evdokiou,

    1. Department of Orthopaedics and Trauma, University of Adelaide, Adelaide, South Australia 5000, Australia
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  • Shelley Hay,

    1. Department of Orthopaedics and Trauma, University of Adelaide, Adelaide, South Australia 5000, Australia
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  • Stelios Bouralexis,

    1. Department of Orthopaedics and Trauma, University of Adelaide, Adelaide, South Australia 5000, Australia
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  • David M. Findlay Ph.D.

    Corresponding author
    1. Department of Orthopaedics and Trauma, University of Adelaide, Adelaide, South Australia 5000, Australia
    • Department of Orthopaedics and Trauma University of Adelaide Royal Adelaide Hospital, North Terrace Adelaide, South Australia, 5000, Australia
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Abstract

The mechanisms by which primary tumors of the bone cause bone destruction have not been elucidated. Unlike most other lytic bone tumors, osteoclastomas, otherwise known as giant cell tumors (GCT), contain osteoclast-like cells within the tumor stroma. A new member of the TNF-ligand superfamily member, osteoclast differentiation factor (ODF/OPGL/RANKL/TRANCE), was recently identified. ODF was shown to directly stimulate osteoclastogenesis, in the presence of M-CSF. In this study, the expression of ODF was examined in a number of tumor samples associated with bone lysis in vivo. In addition, we investigated expression of the ODF receptor on osteoclast precursors, RANK, as well as the ODF inhibitor osteoprotegerin (OPG), and another TNF-ligand superfamily member, TRAIL, previously shown to abrogate the inhibitory effects of OPG. We report here the novel finding that GCT stromal cells contain abundant ODF mRNA, whereas the giant cell population exclusively expresses RANK mRNA. These results are consistent with the osteoclast-mediated bone destruction by these tumors. We also report the expression of OPG and TRAIL mRNA in GCT samples. A comparison with other lytic and nonlytic tumors of bone showed that GCT express more ODF and TRAIL mRNA relative to OPG mRNA. In addition, GCT were found to express a number of cytokines previously reported to play central roles in osteoclastogenesis, namely, IL-1, −6, −11, −17, as well as TNF-α. Importantly, GCT were also found to express high levels of M-CSF mRNA, a cytokine shown to be an essential cofactor of ODF, and a survival factor for mature and developing osteoclasts. Furthermore, expression of these molecules by stromal cells isolated from GCT continued in vitro. Thus GCT constitutively express all of the signals that are currently understood to be necessary for the differentiation of osteoclasts from precursor cells.

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