Regulation of MMP-9 (92 kDa type IV collagenase/gelatinase B) expression in stromal cells of human giant cell tumor of bone

Protein Expression Profiling of Giant Cell Tumors of Bone Treated with Denosumab

Giant cell tumors of bone (GCTB) are locally aggressive osteolytic bone tumors. Recently, some clinical trials have shown that denosumab is a novel and effective therapeutic option for aggressive and recurrent GCTB. This study was performed to investigate the molecular mechanism underlying the therapeutic effect of denosumab. Comparative proteomic analyses were performed using GCTB samples which were taken before and after denosumab treatment. Each expression profile was analyzed using the software program to further understand the affected biological network. One of identified proteins was further evaluated by gelatin zymography and an immunohistochemical analysis. We identified 13 consistently upregulated proteins and 19 consistently downregulated proteins in the pre- and post-denosumab samples. Using these profiles, the software program identified molecular interactions between the differentially expressed proteins that were indirectly involved in the RANK/RANKL pathway and in several non-canonical subpathways including the Matrix metalloproteinase pathway. The data analysis also suggested that the identified proteins play a critical functional role in the osteolytic process of GCTB. Among the most downregulated proteins, the activity of MMP-9 was significantly decreased in the denosumab-treated samples, although the residual stromal cells were found to express MMP-9 by an immunohistochemical analysis. The expression level of MMP-9 in the primary GCTB samples was not correlated with any clinicopathological factors, including patient outcomes. Although the replacement of tumors by fibro-osseous tissue or the diminishment of osteoclast-like giant cells have been shown as therapeutic effects of denosumab, the residual tumor after denosumab treatment, which is composed of only stromal cells, might be capable of causing bone destruction; thus the therapeutic application of denosumab would be still necessary for these lesions. We believe that the protein expression patterns and the results of the network analysis will provide a better understanding of the effects of denosumab administration in patients with GCTB.

Differential Expression of ADAM23, CDKN2A (P16), MMP14 and VIM Associated with Giant Cell Tumor of Bone

Though benign, giant cell tumor of bone (GCTB) can become aggressive and can exhibit a high mitotic rate, necrosis and rarely vascular invasion and metastasis. GCTB has unique histologic characteristics, a high rate of multinucleated cells, a variable and unpredictable growth potential and uncertain biological behavior. In this study, we sought to identify genes differentially expressed in GCTB, thus building a molecular profile of this tumor. We performed quantitative real-time polymerase chain reaction (qPCR), immunohistochemistry and analyses of methylation to identify genes that are putatively associated with GCTB. The expression of the ADAM23 and CDKN2A genes was decreased in GCTB samples compared to normal bone tissue, measured by qPCR. Additionally, a high hypermethylation frequency of the promoter regions of ADAM23 and CDKN2A in GCTB was observed. The expression of the MAP2K3, MMP14, TIMP2 and VIM genes was significantly higher in GCTB than in normal bone tissue, a fact that was confirmed by qPCR and immunohistochemistry. The set of genes identified here furthers our understanding of the molecular basis of GCTB.

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.

Modern interpretation of giant cell tumor of bone: predominantly osteoclastogenic stromal tumor

Owing to striking features of numerous multinucleated cells and bone destruction, giant cell tumor (GCT) of bone, often called as osteoclastoma, has drawn major attractions from orthopaedic surgeons, pathologists, and radiologists. The name GCT or osteoclastoma gives a false impression of a tumor comprising of proliferating osteoclasts or osteoclast precursors. The underlying mechanisms for excessive osteoclastogenesis are intriguing and GCT has served as an exciting disease model representing a paradigm of osteoclastogenesis for bone biologists. The modern interpretation of GCT is predominantly osteoclastogenic stromal cell tumors of mesenchymal origin. A diverse array of inflammatory cytokines and chemokines disrupts osteoblastic differentiation and promotes the formation of excessive multi-nucleated osteoclastic cells. Pro-osteoclastogenic cytokines such as receptor activator of nuclear factor kappa-B ligand (RANKL), interleukin (IL)-6, and tumor necrosis factor (TNF) as well as monocyte-recruiting chemokines such as stromal cell-derived factor-1 (SDF-1) and monocyte chemoattractant protein (MCP)-1 participate in unfavorable osteoclastogenesis and bone destruction. This model represents a self-sufficient osteoclastogenic paracrine loop in a localized area. Consistent with this paradigm, a recombinant RANK-Fc protein and bisphosphonates are currently being tried for GCT treatment in addition to surgical excision and conventional topical adjuvant therapies.

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.

Varying Ti-6Al-4V surface roughness induces different early morphologic and molecular responses in MG63 osteoblast-like cells

Osteoblast response to Ti implants depends not only on the chemistry of the implant but also on the physical properties of the implant surface, such as microtopography and roughness. This study was undertaken to examine early changes in cell morphology and gene expression during the early phase of osteoblast interaction with titanium alloy (Ti-6Al-4V) surfaces of two different roughnesses. MG63 osteoblast-like cells were cultured for 2, 6, 24, and 72 h on smooth (Ra=0.18+/-0.03 microm) and rough (Ra=2.95+/-0.23 microm) Ti-6Al-4V surfaces. Changes in cell proliferation were assessed by measuring cell number after 72 h in culture. Morphological characteristics were observed by scanning electron microscopy after 2, 6, and 24 h of culture. Changes in gene expression for extracellular signal-regulated kinase 2 (Erk2), type I collagen (alpha2[I] collagen), phospholipase C-gamma2 (Plc-gamma2), and beta-actin were measured by RT-PCR after 6 and 24 h in culture. Cell number was significantly higher on the smooth surface. In scanning electron micrographs, cells on smooth Ti-6Al-4V were spherical and raised up from the surface after 2 h in culture. In contrast, cells on the rough surface adopted an irregular, elongated shape that spanned across pits in the surface. At 24 h, cells on the smooth surface had flattened, become elongate, and covered the surface. In contrast, cells on the rough surface appeared more differentiated in shape and the margins of the cells were irregular, with many processes extending out, following the contour of the surface. Of the genes examined, only Erk2 and beta-actin showed a change in expression with surface roughness. Both genes were upregulated (p<0.05) on the rough surface at 6 h. These results indicate that Ti-6Al-4V surface roughness affects osteoblast proliferation, morphology, and gene expression, and that these effects can be measured after periods as short as 2-6 h.

Expression and localization of extracellular matrix metalloproteinase inducer in giant cell tumor of bone

Matrix metalloproteinases (MMPs) are regarded as a significant regulator in tumor invasion and metastasis. Previous studies have shown that extracellular matrix metalloproteinase inducer (EMMPRIN) in tumor cells induces the synthesis of MMPs. EMMPRIN is abundantly present on the surface of tumor cells and stimulate adjacent stromal cells to synthesize MMPs to induce tumor progression. Giant cell tumor (GCT) of bone is a benign but locally aggressive primary neoplasm of bone. The spindle-shaped mononuclear stromal cells are considered to be the tumor components of GCT, which are capable of inducing osteoclast formation by recruiting the circulating monocyte and macrophage. In this study, we proposed that EMMPRIN is associated with the biological progression and aggressiveness of GCT. We have conducted semi-quantitative RT-PCR to determine the correlation of EMMPRIN expression with the clinical stage of GCT. We have also examined the cellular localization of EMMPRIN in GCT using in-situ hybridization (ISH) and Immunohistochemistry (IH). The results showed that EMMPRIN was present in GCT and its mRNA levels were associated with the clinical stage of GCT. Higher expression level of EMMPRIN was observed in GCT with advanced stage (stage III). There was a great significance (P < 0.05) of EMMPRIN expression between stage I & II and stage III GCTs. Both ISH and IH demonstrated that EMMPRIN is present at the multinuclear osteoclast-like giant cells of GCT, with strong immunostaining on the cell membrane. The stromal-like tumor cells were also positively stained but the intensity was weaker. Interestingly, the production of EMMPRIN in osteoclast-like cells of GCT seems to be regulated by stromal-like tumor cells. Receptor activator of NF-kappaB ligand (RANKL), which has been previously shown to be produced by the stromal-like tumor cells for the recruitment of osteoclast-like giant cells in GCT, enhanced the expression of EMMPRIN mRNA during the differentiation of macrophage-like RAW(264.7) cells into osteoclasts. In short, our studies suggest that EMMPRIN may be an important regulatory factor involved in the biological behaviors of GCT.

Increased expression of MMP-2, MMP-9 (type IV collagenases/gelatinases), and MT1-MMP in canine X-linked Alport syndrome (XLAS)

BACKGROUND

Alport syndrome is a group of genetic disorders resulting from mutations in either the alpha3(IV), alpha4(IV) or alpha5(IV) collagen chains. The disease is characterized by a progressive glomerulonephritis, usually associated with a high-frequency specific sensorineural hearing loss, dot and fleck retinopathy, and lens abnormalities. Dogs with naturally occurring genetic disorders of basement membrane collagen (type IV) may serve as animal models of Alport syndrome. In this study, a well-characterized naturally occurring canine model was employed to demonstrate a potential role for matrix metalloproteinases (MMPs) in Alport renal disease pathogenesis.

METHODS

Adolescent male dogs that developed renal failure were euthanized and necropsied. Clinicopathologic features of the disease were characterized, and kidneys from normal and Alport dogs were analyzed by gelatin zymography, Western blotting, in situ zymography, immunohistology, and by reverse transcription polymerase chain reaction (RT-PCR) for expression of MMP-2, MMP-9, and membrane type 1-MMP (MT1-MMP).

RESULTS

Affected dogs developed proteinuria and rapidly progressive juvenile-onset chronic renal failure. The activities of MMP-2 and MMP-9 were significantly induced in Alport kidney. In situ zymography confirmed elevated active metalloproteinases in kidney cryosections of affected dogs. The mRNAs encoding MMP-2, MMP-9 and MT1-MMP were also increased in Alport dogs suggesting that elevated expression of MMPs reflects events in the progression of Alport syndrome in dogs.

CONCLUSION

Elevated expression of MMP-2, MMP-9, and MT1-MMP is observed in fibrotic renal cortex from X-linked Alport syndrome dogs. These findings suggest that MMPs may play an important role in matrix accumulation associated with progressive renal scarring in this model.

Matrix metalloproteinase inhibitors: do they have a place in anticancer therapy?

Matrix metalloproteinases (MMPs) are a family of enzymes involved in degradation of extracellular matrix. An imbalance between MMPs and naturally occurring MMP inhibitors may cause excess extracellular matrix destruction, allowing cancer cells to invade surrounding tissues and metastasize, and permitting angiogenesis to occur. Inhibition of certain key MMPs may prevent angiogenesis, tumor growth, invasion, and metastasis. Gelatinases MMP-2 and MMP-9 are expressed during carcinogenesis and angiogenesis. Synthetic MMP inhibitors were designed to target these enzymes and potentially prevent the tumor growth and metastases associated with cancer.

Analysis of mechanisms underlying BRMS1 suppression of metastasis

Introduction of normal, neomycin-tagged human chromosome 11 (neo11) reduces the metastatic capacity of MDA-MB-435 human breast carcinoma cells by 70-90% without affecting tumorigenicity. Differential display comparing MDA-MB-435 and neo11/435 led to the discovery of a human breast carcinoma metastasis suppressor gene, BRMS1, which maps to chromosome 11q13.1-q13.2. Stable transfectants of MDA-MB-435 and MDA-MB-231 breast carcinoma cells with BRMS1 cDNA still form progressively growing, locally invasive tumors when injected in mammary fat pads of athymic mice but exhibit significantly lower metastatic potential (50-90% inhibition) to lungs and regional lymph nodes. To begin elucidating the mechanism(s) of action, we measured the ability of BRMS1 to perturb individual steps of the metastatic cascade modeled in vitro. Consistent differences were not observed for adhesion to extracellular matrix components (laminin, fibronectin, type IV collagen, type I collagen, Matrigel); growth rates in vitro or in vivo; expression of matrix metalloproteinases, heparanase, or invasion. Likewise. BRMS1 expression did not up regulate expression of other metastasis suppressors, such as NM23, Kai1, KiSS1 or E-cadherin. Motility of BRMS1 transfectants was modestly inhibited (30-60%) compared to parental and vector-only transfectants. Ability to grow in soft agar was also decreased in MDA-MB-435 cells by 80-89%, but the decrease for MDA-MB-231 was less (13-15% reduction). Also, transfection and re-expression of BRMS1 restored the ability of human breast carcinoma cells to form functional homotypic gap junctions. Collectively, these data suggest that BRMS1 suppresses metastasis of human breast carcinoma by complex, atypical mechanisms.

Determination of imbalance between MMP-2 and TIMP-2 in human neuroblastoma by reverse-transcription polymerase chain reaction and its correlation with tumor progression

BACKGROUND/PURPOSE

The matrix metalloproteinases (MMPs) and their specific tissue inhibitors (TIMPs) have been implicated in tumor invasion and metastasis. Net matrix degradation and proteolysis depend on the critical local balance between MMPs/TIMP-2. We attempted to determine their expression balance and to evaluate its importance with tumor progression.

METHODS

Expressions of MMP-2, MMP-9, and TIM P-2 mRNAs was quantified by reverse-transcription polymerase chain reaction (RT-PCR) in tumor tissues from 25 neuroblastoma patients.

RESULTS

MMP-2, MMP-9, and TIMP-2 expression was observed in all the samples but with different trends. Increased expressions of MMP-2 mRNA was evident in advanced stages (Evans' stage III and IV; P = .02; unpaired ttest), and in patients who died of progressive disease (P = .0001). Whereas, the expressions of MMP-9 and TIMP-2 had no such significant association with clinical stages and prognosis. The ratio of MMP-2/TIMP-2 mRNAs was significantly higher in the advanced stages versus early stages (mean +/- SD = 1.66+/-0.65 and 1.11+/-0.34, respectively; P = .02) and in patients who died of progressive disease versus alive patients (mean = 2.13+/-0.78 and 1.21+/-0.36, respectively; P = .0006).

CONCLUSIONS

Coexpression of MMPs and TIMP-2 in neuroblastoma indicates the need to evaluate their expression balance. Significantly higher expression of MMP-2 mRNA and increased ratio of MMP-2 and TIMP-2 mRNAs in advanced stages or patients who have died of progressive disease suggests an association between elevated MMP-2 expression and poor prognosis. To establish the role of enzyme to inhibitor mRNA ratio as a reliable predictor, cohort studies with significant number of cases may be carried out.

Interleukin-1beta upregulates MMP-9 expression in stromal cells of human giant cell tumor of bone

Giant cell tumor (GCT) of bone is a progressive, potentially malignant process that destroys skeletal tissue. It consists of multinucleated giant cells, which are hypothesized to be derived from a monocyte/macrophage lineage and mononuclear stromal cells, and the precise relationship of these cells is not fully understood. Recently, we demonstrated that the production of matrix metalloproteinase-9 (MMP-9) in GCT stromal cells is regulated by certain factor(s) secreted by the multinucleated giant cells. In the present study, we evaluated for the presence of interleukin-1beta (IL-1beta) and attempted to establish its possible role for the induction of MMP-9 in GCT stromal cells. Using enzyme-linked immunosorbent assay (ELISA), we have demonstrated that the primary GCT cultures secrete both IL-1beta and MMP-9. The addition of monoclonal antibody (mAb) against IL-1beta partially abrogated, but did not abolish, MMP-9 expression. Our results on gelatin zymography, reverse transcriptase-polymerase chain reaction (RT-PCR), and immunofluorescence showed that GCT stromal cells did not express MMP-9, although treatment with IL-1beta induced MMP-9 expression in a dose-dependent manner, and the secretion peaked 24 h after stimulation and then plateaued. Studies with cycloheximide, a protein synthesis inhibitor, demonstrated that de novo protein synthesis is required for IL-1beta induced MMP-9 expression. Moreover, nuclear run-on analysis has revealed that IL-1beta significantly increased MMP-9 gene transcription in GCT stromal cells. The data suggest that IL-1beta secreted by the multinucleated giant cells in GCT may be one of the factors responsible for the induction of MMP-9 at the transcriptional level in GCT stromal cells in vivo. We conclude that GCT has a self-stimulatory system for the production of MMP-9, and the ability of stromal cells to produce MMP-9 with appropriate stimuli, such as IL-1beta, and possibly in concert with other cytokines may contribute to the aggressive and potentially malignant behavior of GCT.

Expression and role of matrix metalloproteinases MMP-2 and MMP-9 in human spinal column tumors

Matrix metalloproteinases (MMPs) have been implicated in the process of tumor invasion and metastasis formation. Thus, we determined the expression of MMPs in various primary and metastatic spinal tumors in order to assess the role of these enzymes in spinal invasion. MMP expression was examined by immunohistochemical localization, and quantitative evaluation of MMP protein content was determined by enzyme-linked immunosorbant assay (ELISA) and Western blotting. MMP enzyme activity was determined by gelatin zymography. Lung carcinomas and melanomas metastatic to the spine were shown to have higher levels of MMP-9 activity than those of breast, thyroid, renal metastases and primary spinal tumors. Immunohistochemical analysis revealed similar difference in expression of MMP-9 in tissue samples. When the tissue samples were subjected to gelatin zymography for examination of MMP-2 and MMP-9 activity and to ELISA and Western blotting for quantitative estimation of protein content, the most striking results were obtained for lung carcinomas and melanomas relative to the other tumors. Lung carcinomas and melanomas metastatic to the spine had considerably higher levels of MMP-9 activity than those of primary spinal tumor or breast, thyroid, and renal carcinoma metastases. Within the metastatic tumor category, neoplasms that are known to be associated with the shortest overall survival rates and most aggressive behavior, such as lung carcinomas and melanomas, had the highest levels of MMP-2 and MMP-9 activity compared to those less aggressive metastatic tumors such as breast, renal cell, and thyroid carcinomas. Our results suggest that MMPs may contribute to the metastases to the spinal column, and overexpression of these enzymes may correlate with enhanced invasive properties of both primary and metastatic spinal tumors.

Accelerated linear growth and advanced bone age in Sotos syndrome is not associated with abnormalities of collagen metabolism

OBJECTIVES

To investigate whether the advanced bone age in Sotos syndrome is associated with alterations in type I collagen metabolism in bone.

DESIGN AND METHODS

The metabolism of collagen was studied by analyzing the production, gene expression and degradation of type I collagen in dermal fibroblast strains from patients with Sotos syndrome and comparing them with fibroblasts from age-matched healthy subjects. Collagen production was determined as collagenase digestible radioactivity and collagen mRNA levels were measured by RT-PCR. Collagen degradation was assessed by specific collagenase assay and gelatin zymography. To determine the structural defects in type I collagen, the newly synthesized proteins were analyzed by SDS-PAGE before and after proteolytic digestion with pepsin.

RESULTS

In the present study, we have demonstrated that the collagen production, secretion and degradation in Sotos syndrome is comparable to controls. In addition, no qualitative differences in mRNA transcripts for type I collagen were detected between the control and Sotos syndrome fibroblasts. The secretion and intracellular accumulation of procollagen is also comparable to controls. The analysis of both procollagen and collagen on SDS-PAGE did not exhibit any major structural changes as compared with controls.

CONCLUSIONS

Our results on several aspects of collagen metabolism have demonstrated for the first time that collagen, the most abundant of mammalian proteins and the major constituent of bone, is normal in patients with Sotos syndrome. Therefore, it appears that the advanced bone age and accelerated linear growth seen in patients with Sotos syndrome may not be attributed to inherent abnormalities of collagen metabolism. The etiology and the pathogenesis of Sotos syndrome still remains unclear.