Collagenase expression and activity in the stromal cells from giant cell tumour of bone

Evaluation of the multiple tissue factors in bone of primary osteoplasty and rhinoplasty in patients affected by cleft lip palate

Clefts of the lip and/or palate (CLP) are visible disruptions of standard facial structure. The aim of our study was to determine a relative number and appearance of the tissue factors in bone of patients with CLP during first time plastic alveolar osteoplasty or rhinoplasty. Immunohistochemistry was performed with matrix metalloproteinase-8 (MMP-8), matrix metalloproteinase-9 (MMP-9), osteopontin (OPN), osteocalcin (OC), Runt-related transcription factor 2 (Runx2), beta-defensin-2 (βdef-2), beta-defensin-3 (βdef-3), interleukin-1 alpha (IL-1α), and interleukin-10 (IL-10). The bone formation was observed by Masson-trichrome (Masson) staining. For the quantification of structures, the semi-quantitative census method was used. Spearman rank order correlation coefficient and Mann-Whitney U test were used for the statistical analysis. A significantly higher number of OPN positive osteocytes was observed in the CLP group when compared to the control group (p=0.002). The number of OC positive osteocytes (p=0.000) and βdef-2 positive osteocytes (p=0.003) was significantly lower in the CLP group in comparison to the control group. Strong, positive correlations between IL-10 and OC (rs=0.608; p=0.002), IL-1α and MMP-9 (rs=0.666; p=0.000), OPN and MMP-8 (rs=0.620; p=0.002) were detected in the CLP group. A tendency for the increased appearance of MMP-8, MMP-9 positive osteocytes of the patients with CLP, suggests elevated tissue remodelling properties. Increased appearance of OPN positive osteocytes in bone of the patients with CLP shows increased bone homeostasis based on seriously decreased mineralization, which may be a possible compensatory reaction to decreased quality of postsurgical bone.

Genome-Wide Transcriptome Profiling of the Neoplastic Giant Cell Tumor of Bone Stromal Cells by RNA Sequencing

Giant cell tumor of bone (GCTB) is the most common non-malignant primary bone tumor reported in Hong Kong. Failure of treatment in advanced GCTB with aggressive local recurrence remains a clinical challenge. In order to reveal the molecular mechanism underlying the pathogenesis of this tumor, we aimed to examine the transcriptome profiling of the neoplastic stromal cells of GCTB in this study. RNA-sequencing was performed on three GCTB stromal cell samples and one bone marrow-derived MSC sample and 174 differentially expressed genes (DEGs) were identified between these two cell types. The top five up-regulated genes are SPP1, F3, TSPAN12, MMP13, and LGALS3BP and further validated by qPCR and Western Blotting. Knockdown of SPP1 was found to induce RUNX2 and OPG expression in GCTB stromal cells but not the MSCs. Ingenuity pathway analysis (IPA) of the 174 DEGs revealed significant alternations in 23 pathways; variant calling analysis revealed 1915 somatic variants of 384 genes with high or moderate impacts. Interestingly, four canonical pathways were found overlapping in both analyses; from which VEGFA, CSF1, PLAUR, and F3 genes with somatic mutation were found up-regulated in GCTB stromal cells. The STRING diagram showed two main clusters of the DEGs; one cluster of histone genes that are down-regulated in GCTB samples and another related to osteoblast differentiation, angiogenesis, cell cycle progression, and tumor growth. The DEGs and somatic mutations found in our study warrant further investigation and validation, nevertheless, our study add new insights in the search for new therapeutic targets in treating GCTB. J. Cell. Biochem. 118: 1349-1360, 2017. © 2016 Wiley Periodicals, Inc.

microRNA and Bone Cancer

MicroRNA molecules have a variety of roles in cellular development and proliferation processes, including normal osteogenesis. These effects are exerted through post-translational inhibition of target genes. Altered miRNA expression has been demonstrated in several cancers, both in the tumor tissue and in the peripheral circulation. This may influence carcinogenesis if the specific miRNA targets are encoded by tumor suppressor genes or oncogenes. To date, most research investigating the role of microRNAs and primary bone tumors has focused on osteosarcoma and Ewing sarcoma. Several microRNAs including the miR-34 family have been implicated in osteosarcoma tumorigenesis via effects on the Notch signaling pathway. Progression, invasion, and metastasis of osteosarcoma tumor cells is also influenced by microRNA expression. In addition, microRNA expression may affect the response to chemotherapy in osteosarcoma and thus hold potential for future use as either a prognostic indicator or a therapeutic target. The EWS-FLI1 fusion protein produced in Ewing sarcoma has been shown to induce changes in miRNA expression. MicroRNA expression profiling may have some potential for prediction of disease progression and survival in Ewing sarcoma. There is limited evidence to support a role for microRNAs in other primary bone tumors, either malignant or benign; however, early work is suggestive of involvement in chondrosarcoma, multiple osteochondromatosis, and giant cell tumors of bone.

MiR-126-5p regulates osteoclast differentiation and bone resorption in giant cell tumor through inhibition of MMP-13

Giant cell tumor (GCT) of bone is an aggressive skeletal tumor characterized by localized bone resorption. Matrix metalloproteinase-13 (MMP-13) is the principal proteinase expressed by the stromal cells of GCT (GCTSCs) and also considered to play a crucial role in formation of the osteolytic lesion in GCT. However, the exact mechanism of the regulation of MMP-13 expression in GCTSCs was unknown. In this study, we identified miR-126-5p was significantly downregulated in GCTSCs and affect osteoclast (OC) differentiation and bone resorption by repressing MMP-13 expression at the post-transcriptional level. Thus, our studies show that miR-126-5p plays an important physiological role in multinucleated giant cell formation and osteolytic lesion in GCT.

Titanium particles up-regulate the activity of matrix metalloproteinase-2 in human synovial cells

PURPOSE

Wear debris particle-induced osteolysis and subsequent aseptic loosening is one of the major causes of failure of total joint replacement. The purpose of this study was to investigate the effect of titanium implant material and inflammatory cytokines on human synovial cells and the development to osteolysis and aseptic loosening.

METHODS

This study investigated the effect of titanium implant material on the ECM-degraded MMP-2 in human synovial cells and analyzed the contribution of synovial cells in osteolysis and aseptic loosening.

RESULTS

When human synovial cells are exposed to titanium materials, MMP-2 activity is induced by 1.72 ± 0.14-fold with Ti disc and 3.95 ± 0.10-fold with Ti particles, compared with that of the controls, respectively. Inflammatory cytokines TNFα and IL-1β are also shown to induce MMP-2 activity by 3.65 ± 0.28-fold and 6.76 ± 0.28-fold, respectively. A combination of Ti particles and cytokines induces MMP-2 activities to a higher level (10.54 ± 0.45-fold). Inhibitors of various signal pathways involved in MMP-2 reverse Ti particle-induced MMP-2 activities.

CONCLUSIONS

Synovial cells surrounding the bone-prosthesis interface may contribute to production of MMP-2, and NFκB inhibitors may be explored as potential therapeutics to alleviate wear debris-induced osteolysis and aseptic loosening.

Downregulation of ERK signaling impairs U2OS osteosarcoma cell migration in collagen matrix by suppressing MMP9 production

The present study investigated the role of extracellular signal-regulated kinase (ERK) activation in the migratory phenotype of human U2OS osteosarcoma (OS) cells in a collagen matrix. The activation of ERK was inhibited by PD98059, a specific inhibitor of ERK kinase. Additionally, no significant differences were observed in the adhesion and proliferation of the cells with or without PD98059 treatment in collagen-coated dishes. The migratory capacity of the U2OS cells was then examined in non-coated and collagen-coated dishes, and the results depicted that collagen I enhanced the migration of the U2OS cells, the effect of which was significantly blocked by the treatment of the cells with PD98059. Furthermore, enhanced gene and protein expression of matrix metalloproteinase 9 (MMP9), but not MMP2, was observed to be involved in the enhanced migratory phenotype of the U20S cells in the collagen-coated plates. This effect was partially abolished by the treatment of the cells in the collagen-coated dishes with ERK inhibitor. Collectively, the data demonstrate that ERK signaling is important for the migration of U2OS cells through the extracellular matrix (ECM), which is comprised mostly of collagen, by enhancing MMP9 production. These results may contribute to the regulation of MMP9 production in metastatic OS.

ETV5 as a regulator of matrix metalloproteinase 2 in human chondrosarcoma

Chondrosarcoma is a unique type of bone cancer in that it does not respond to chemotherapy or radiation therapy, and therefore many affected patients die from metastatic disease. Metastasis has been correlated with the upregulation of the matrix metalloproteinase (MMP) family of proteases, which can degrade extracellular components. ETV5 is a transcription factor which has shown to be overexpressed in various types of invasive tumors. We hypothesized that ETV5 regulates MMP2 in human chondrosarcoma with the protease acting as a downstream effector. Gene knock-down of ETV5 in human chondrosarcoma cells reduces MMP2 mRNA expression as well as decreased protein production and significantly decreased MMP2 activity. With plasmid transfected ETV5 upregulation, MMP2 expression is similarly upregulated at the gene expression and protein levels. Data from our bone resorption studies revealed that when a matrix metalloproteinase-2 inhibitor is added to the growth media of chondrosarcoma cells, collagen released from bone chips incubated with the cells decreased by 27%. This data suggests that ETV5 has a significant role in regulating MMP2 expression and therefore matrix resorption in human chondrosarcoma, and thus may be a targetable upstream effector of the metastatic cascade in this cancer.

Giant cell tumor of bone: a basic science perspective

Comprehending the pathogenesis of giant cell tumor of bone (GCT) is of critical importance for developing novel targeted treatments for this locally-aggressive primary bone tumor. GCT is characterized by the presence of large multinucleated osteoclast-like giant cells distributed amongst mononuclear spindle-like stromal cells and other monocytes. The giant cells are principally responsible for the extensive bone resorption by the tumor. However, the spindle-like stromal cells chiefly direct the pathology of the tumor by recruiting monocytes and promoting their fusion into giant cells. The stromal cells also enhance the resorptive ability of the giant cells. This review encompasses many of the attributes of GCT, including the process of giant cell formation and the mechanisms of bone resorption. The significance of the receptor activator of nuclear factor-κB ligand (RANKL) in the development of GCT and the importance of proteases, including numerous matrix metalloproteinases, are highlighted. The mesenchymal lineage of the stromal cells and the origin of the hematopoietic monocytes are also discussed. Several aspects of GCT that require further understanding, including the etiology of the tumor, the mechanisms of metastases, and the development of an appropriate animal model, are also considered. By exploring the current status of GCT research, this review accentuates the significant progress made in understanding the biology of the tumor, and discusses important areas for future investigation.

Matrix Metalloproteinase 1 promotes tumor formation and lung metastasis in an intratibial injection osteosarcoma mouse model

Proteolytic degradation of the extracellular matrix (ECM) is an important process during tumor invasion. Matrix Metalloproteinase 1 (MMP-1) is one of the proteases that degrade collagen type I, a major component of bone ECM. In the present study, the biological relevance of MMP-1 in osteosarcoma (OS) tumor growth and metastasis was investigated in vitro and in vivo. Human OS cells in primary culture expressed MMP-1 encoding mRNA at considerably higher levels than normal human bone cells. In addition, MMP-1 mRNA and protein expression in the highly metastatic human osteosarcoma 143-B cell line was remarkably higher than in the non-metastatic parental HOS cell line. Stable shRNA-mediated downregulation of MMP-1 in 143-B cells impaired adhesion to collagen I and anchorage-independent growth, reflected by a reduced ability to grow in soft agar. Upon intratibial injection into SCID mice, 143-B cells with shRNA-downregulated MMP-1 expression formed smaller primary tumors and significantly lower numbers of lung micro- and macrometastases than control cells. Conversely, HOS cells stably overexpressing MMP-1 showed an enhanced adhesion capability to collagen I and accelerated anchorage-independent growth compared to empty vector-transduced control cells. Furthermore, and most importantly, individual MMP-1 overexpression in HOS cells enabled the formation of osteolytic primary tumors and lung metastasis while the HOS control cells did not develop any tumors or metastases after intratibial injection. The findings of the present study reveal an important role of MMP-1 in OS primary tumor and metastasis formation to the lung, the major organ of OS metastasis.

PTHrP increases RANKL expression by stromal cells from giant cell tumor of bone

Giant cell tumor of bone (GCT) presents with numerous osteoclast-like multinucleated giant cells that are principally responsible for the extensive bone resorption by the tumor. Although the precise etiology of GCT remains uncertain, the accumulation of giant cells is partially due to the high expression of the receptor activator of nuclear factor-κB ligand (RANKL) from the neoplastic stromal cells. Here, we have investigated whether parathyroid hormone-related protein (PTHrP) plays a role in the pathogenesis of GCT. Immunohistochemistry results revealed PTHrP expression in the stromal cells of the tumor, and that its receptor, the parathyroid hormone type 1 receptor (PTH1R), is expressed by both the stromal cells and giant cells. PCR and Western blot analyses confirmed the expression of PTHrP and PTH1R by isolated stromal cells from five patients presenting with GCT. Treatment of GCT stromal cells with varying concentrations of PTHrP (1-34) significantly increased both RANKL gene expression and the number of multinucleated cells formed from RAW 264.7 cells in co-culture experiments, whereas inhibition of PTHrP with a neutralizing antibody decreased RANKL gene expression. These results suggest that PTHrP is expressed within GCT by the stromal cells and can contribute to the abundant RANKL expression and giant cell formation within the tumor.

An MMP13-selective inhibitor delays primary tumor growth and the onset of tumor-associated osteolytic lesions in experimental models of breast cancer

We investigated the effects of the matrix metalloproteinase 13 (MMP13)-selective inhibitor, 5-(4-{4-[4-(4-fluorophenyl)-1,3-oxazol-2-yl]phenoxy}phenoxy)-5-(2-methoxyethyl) pyrimidine-2,4,6(1H,3H,5H)-trione (Cmpd-1), on the primary tumor growth and breast cancer-associated bone remodeling using xenograft and syngeneic mouse models. We used human breast cancer MDA-MB-231 cells inoculated into the mammary fat pad and left ventricle of BALB/c Nu/Nu mice, respectively, and spontaneously metastasizing 4T1.2-Luc mouse mammary cells inoculated into mammary fat pad of BALB/c mice. In a prevention setting, treatment with Cmpd-1 markedly delayed the growth of primary tumors in both models, and reduced the onset and severity of osteolytic lesions in the MDA-MB-231 intracardiac model. Intervention treatment with Cmpd-1 on established MDA-MB-231 primary tumors also significantly inhibited subsequent growth. In contrast, no effects of Cmpd-1 were observed on soft organ metastatic burden following intracardiac or mammary fat pad inoculations of MDA-MB-231 and 4T1.2-Luc cells respectively. MMP13 immunostaining of clinical primary breast tumors and experimental mice tumors revealed intra-tumoral and stromal expression in most tumors, and vasculature expression in all. MMP13 was also detected in osteoblasts in clinical samples of breast-to-bone metastases. The data suggest that MMP13-selective inhibitors, which lack musculoskeletal side effects, may have therapeutic potential both in primary breast cancer and cancer-induced bone osteolysis.

The role of TWIST as a regulator in giant cell tumor of bone

Giant cell tumor of bone (GCT) is an aggressive tumor consisting of multinucleated osteoclast-like giant cells and proliferating osteoblast-like stromal cells. Our group has reported that the stromal cells express high levels of the bone resorbing matrix metalloproteinase (MMP)-13, and that this expression is regulated by the osteoblast transcription factor Runx2. The purpose of this study was to determine the upstream regulation of Runx2 in GCT cells. Using GCT stromal cells obtained from patient specimens, we demonstrated that TWIST, a master osteogenic regulator, was highly expressed in all GCT specimens. TWIST overexpression downregulated Runx2 expression whereas TWIST siRNA knockdown resulted in Runx2 and MMP-13 upregulation. Interestingly, cells obtained from a GCT lung metastasis showed a reverse regulatory pattern between TWIST and Runx2. In mutational analysis, we revealed a point mutation (R154S) at the Helix2 domain of TWIST. This TWIST mutation may be an essential underlying factor in the development and pathophysiology of these tumors in that they lead to inappropriate TWIST downregulation of Runx2, arrested osteoblastic differentiation, and the maintenance of an immature and neoplastic phenotype.

PTHrP induces autocrine/paracrine proliferation of bone tumor cells through inhibition of apoptosis

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 parathryroid 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 metastsis 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.

AP-1 as a Regulator of MMP-13 in the Stromal Cell of Giant Cell Tumor of Bone

Matrix-metalloproteinase-13 (MMP-13) has been shown to be an important protease in inflammatory and neoplastic conditions of the skeletal system. In particular, the stromal cells of giant cell tumor of bone (GCT) express very high levels of MMP-13 in response to the cytokine-rich environment of the tumor. We have previously shown that MMP-13 expression in these cells is regulated, at least in part, by the RUNX2 transcription factor. In the current study, we identify the expression of the c-Fos and c-Jun elements of the AP-1 transcription factor in these cells by protein screening assays and real-time PCR. We then used siRNA gene knockdown to determine that these elements, in particular c-Jun, are upstream regulators of MMP-13 expression and activity in GCT stromal cells. We conclude that there was no synergy found between RUNX2 and AP-1 in the regulation of the MMP13 expression and that these transcription factors may be independently regulated in these cells.

Overexpression of matrix metalloproteinase (MMP)-1 and -9 in central giant cell lesions of the jaws: implications for clinical behavior

OBJECTIVE

The aim of this study was to investigate the relationship between the immunohistochemical expression of MMP-1 and MMP-9 with the clinical behavior of central giant cell lesions (CGCLs) of the jaws.

STUDY DESIGN

Paraffin-embedded tissue from 30 aggressive and 12 nonaggressive CGCLs was assessed for the expression of MMP-1 and MMP-9 using immunohistochemistry.

RESULTS

Although cellular immunolocalization patterns of MMP-1 and MMP-9 were similar, mean values of expression estimation/SID scores of each protease were significantly higher in aggressive CGCLs in comparison with nonaggressive lesions. Moreover, linear regression analysis showed that there was a reasonably good correlation not only between the expression estimation but also among SID scores of the 2 proteolytic enzymes.

CONCLUSION

The findings of this study suggest a role for MMP-1 and MMP-9 in the resorptive activity of different cellular groups in CGCLs and indicate that differences in immunoreactivity of these 2 proteolytic enzymes may underlie the distinct clinical behavior.

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

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.

Matrix Metalloproteinase Activity in the Stromal Cell of Giant Cell Tumor of Bone

Giant cell tumor of bone (GCT) is a destructive and potentially metastatic bone tumour in which the characteristic giant cells have classically been considered the culprits in bone destruction. However, the neoplastic element of the tumour consists of propagative osteoblast-like stromal cells that may play a role in bone resorption. The objectives of this study were to determine the expression and activity of the gelatinases, matrix metalloproteinase (MMP)-2 and -9, in GCT stromal cells, and to determine if these cells have bone-resorbing capabilities. We performed immunohistochemistry on clinical specimens, and real-time polymerase chain reaction (PCR) and zymography on cell lysates and conditioned media from cultured clinical GCT specimens in order to evaluate the expression and activity of MMP-2 and-9 in GCT stromal cells. Our results support the fact that GCT stromal cells express MMP-2 and MMP-9 and are capable of gelatin degradation in vitro. These cells may therefore play a role in bone destruction in GCT.

Upregulation of MMP-13 via Runx2 in the stromal cell of Giant Cell Tumor of bone

Giant Cell Tumor of bone (GCT) is an aggressively osteolytic and cytokine-rich bone tumor. Previous work in our lab has shown that matrix metalloproteinase-13 (MMP-13) is the principal proteinase expressed by the mesenchymal stromal cells of GCT. The Runx2 transcription factor is known to have a binding site in the MMP-13 promoter region, and we have previously found this transcription factor to be constitutively expressed in GCT stromal cells. The purpose of this study was to determine the role of Runx2 in MMP-13 regulation in GCT stromal cells. Following in vitro stimulation of GCT stromal cells with incremental concentrations of cytokine IL-1beta or TNF-alpha, the level of MMP-13 mRNA expression increased dramatically over 100-fold with a concomitant increase in MMP-13 protein expression. Inhibition of the ERK and JNK signaling pathways inhibited the upregulation of MMP-13 in these cells. Runx2 siRNA knockdown resulted in MMP-13 knockdown, and this effect was amplified following cytokine stimulation. Our study provides the first evidence that Runx2 may play a crucial role in cytokine-mediated MMP-13 expression in GCT stromal cells.