Evidence for the role of matrix metalloproteinase-13 in bone resorption by giant cell tumor of bone

McMaster University, Hamilton, Ontario, Canada L8V 5C2.
Human pathology (Impact Factor: 2.77). 09/2010; 41(9):1320-9. DOI: 10.1016/j.humpath.2010.03.001
Source: PubMed


Giant cell tumor of bone (GCT) is an aggressively osteolytic primary bone tumor that is characterized by the presence of abundant multinucleated osteoclast-like giant cells, hematopoietic monocytes, and a distinct mesenchymal stromal cell component. Previous work in our laboratory has shown that matrix metalloproteinase (MMP)-13 is the principal proteinase expressed by the stromal cells of GCT. The release of cytokines, particularly interleukin-1beta, by the giant cells of GCT acts on stromal cells to stimulate a surge in MMP-13 secretion. The purpose of this study was to determine the bone resorption capabilities of the cellular elements of GCT and the significance of the MMP-13 expression involved in GCT bone resorption. We present a 3-dimensional histomorphometric technique developed to analyze resorption pit depth and yield an accurate measurement of bone resorption with a direct physical view of lacunae on bone slices. In this study, we demonstrate that the mesenchymal stromal cells and the multinucleated giant cells of GCT are independently capable of bone resorption. However, coculture of these 2 cell fractions shows a synergistic increase in bone resorption. In addition, inhibition of MMP-13 reduces resorptive activity of the cells indicating that MMP-13 likely plays an important role in this tumor. This cell-cell cooperation involves giant cell-derived cytokine up-regulation of MMP-13 in the stromal cells, which in turn assists the giant cells in bone resorption. Future research will involve elucidation of the role of cell-cell/matrix communication pathways in bone resorption and tumorigenesis in GCT.

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    • "Although the giant cells are primarily responsible for the osteolysis typical in GCT, evidence suggests that the osteoblast-like stromal cell is the true neoplastic component of this neoplasm [5]. Previous work in our lab has shown that many factors, including growth factors, transcription factors, and cytokines play important roles regulating the neoplastic properties of the stromal cells of GCT [6] [7] [8] [9] [10]. One factor that we have found to be particularly important is parathyroid hormone-related protein (PTHrP), which we have found to be highly expressed in GCT, both in vivo and in vitro [10] [11]. "
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    ABSTRACT: Parathyroid-hormone-related protein (PTHrP) has been shown to be an important factor in osteolysis in the setting of metastatic carcinoma to bone. However, PTHrP may also be central in the setting of primary bone tumors. Giant Cell Tumor of Bone (GCT) is an aggressive osteolytic bone tumor characterized by osteoclast-like giant cells that are recruited by osteoblast-like stromal cells. The stromal cells of GCT are well established as the only neoplastic element of the tumor, and we have previously shown that PTHrP is highly expressed by these cells both in vitro and in vivo. We have also found that the stromal cells exposed to a monoclonal antibody to PTHrP exhibited rapid plate detachment and quickly died in vitro. Therefore, PTHrP may serve in an autocrine manner to increase cell proliferation and promote invasive properties in GCT. The purpose of this study was to use transcriptomic microarrays and functional assays to examine the effects of PTHrP neutralization on cell adhesion, migration and invasion. Microarray and proteomics data identified genes that were differentially expressed in GCT stromal cells under various PTHrP treatment conditions. Treatment of GCT stromal cells with anti-PTHrP antibodies showed a change in the expression of 13 genes from the integrin family relative to the IgG control. Neutralization of PTHrP reduced cell migration and invasion as evidenced by functional assays. Adhesion and anoikis assays demonstrated that although PTHrP neutralization inhibits cell adhesion properties, cell detachment related to PTHrP neutralization did not result in associated cell death, as expected in mesenchymal stromal cells. Based on the data presented herein, we conclude that PTHrP excreted by GCT stromal cells increases bone tumor cell local invasiveness and migration.
    Bone 03/2013; 55(1). DOI:10.1016/j.bone.2013.02.020 · 3.97 Impact Factor
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    • "Following several successive passages, the mesenchymal stromal cells became the homogeneous cell type whereas the multinucleated giant cells were eliminated from culture. Primary cultures of the proliferating homogenous stromal tumor cell population obtained after the fifth or sixth passage (without any hematopoietic markers) and up to the tenth passage were used for experiments [30], [31]. GCT-stromal cells were incubated in media containing 50 nmol/L ascorbic acid, 3 mM inorganic phosphate (NaH2PO4) and a range of dilution from 10 to 40 ng/ml of FGF-2 (Minneapolis, MN). "
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    ABSTRACT: Giant cell tumor of bone (GCT) is an aggressive bone tumor consisting of multinucleated osteoclast-like giant cells and proliferating osteoblast-like stromal cells. The signaling mechanism involved in GCT stromal cell osteoblastic differentiation is not fully understood. Previous work in our lab reported that GCT stromal cells express high levels of TWIST1, a master transcription factor in skeletal development, which in turn down-regulates Runx2 expression and prevents terminal osteoblastic differentiation in these cells. The purpose of this study was to determine the upstream regulation of TWIST1 in GCT cells. Using GCT stromal cells obtained from patient specimens, we demonstrated that fibroblast growth factor receptor (FGFR)-2 signaling plays an essential role in bone development and promotes differentiation of immature osteoblastic cells. Fibroblast growth factor (FGF)-2 stimulates FGFR-2 expression, resulting in decreased TWIST1 expression and increased Runx2, alkaline phosphastase (ALP) and osteopontin (OPN) expression. Inhibition of FGFR-2 through siRNA decreased the expression of ALP, Runx2 and OPN in GCT stromal cells. Our study also confirmed that FGF-2 ligand activates downstream ERK1/2 signaling and pharmacological inhibition of the ERK1/2 signaling pathway suppresses FGF-2 stimulated osteogenic differentiation in these cells. Our results indicate a significant role of FGFR-2 signaling in osteoblastic differentiation in GCT stromal cells.
    PLoS ONE 10/2012; 7(10):e46769. DOI:10.1371/journal.pone.0046769 · 3.23 Impact Factor
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    • "Previous work in our lab has shown that the osteoblastic transcription factor Runx2 and AP-1 plays an important role in regulating protein expression in the neoplastic cells stromal cells of GCT. [6], [7], [8], [9]. Among these proteins, we have found that parathyroid hormone-related protein (PTHrP) and its receptor are constitutively expressed in this tumor [10]. "
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    ABSTRACT: Giant Cell Tumor of Bone (GCT) is an aggressive skeletal tumor characterized by local bone destruction, high recurrence rates and metastatic potential. Previous work in our lab has shown that the neoplastic cell of GCT is a proliferating pre-osteoblastic stromal cell in which the transcription factor Runx2 plays a role in regulating protein expression. One of the proteins expressed by these cells is parathyroid hormone-related protein (PTHrP). The objectives of this study were to determine the role played by PTHrP in GCT of bone with a focus on cell proliferation and apoptosis. Primary stromal cell cultures from 5 patients with GCT of bone and one lung metastasis were used for cell-based experiments. Control cell lines included a renal cell carcinoma (RCC) cell line and a human fetal osteoblast cell line. Cells were exposed to optimized concentrations of a PTHrP neutralizing antibody and were analyzed with the use of cell proliferation and apoptosis assays including mitochondrial dehydrogenase assays, crystal violet assays, APO-1 ELISAs, caspase activity assays, flow cytometry and immunofluorescent immunohistochemistry. Neutralization of PTHrP in the cell environment inhibited cell proliferation in a consistent manner and induced apoptosis in the GCT stromal cells, with the exception of those obtained from a lung metastasis. Cell cycle progression was not significantly affected by PTHrP neutralization. These findings indicate that PTHrP plays an autocrine/paracrine neoplastic role in GCT by allowing the proliferating stromal cells to evade apoptosis, possibly through non-traditional caspase-independent pathways. Thus PTHrP neutralizing immunotherapy is an intriguing potential therapeutic strategy for this tumor.
    PLoS ONE 05/2011; 6(5):e19975. DOI:10.1371/journal.pone.0019975 · 3.23 Impact Factor
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