Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0029463 (osteosarcoma)
 16,637 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several receptors for the extracellular matrix protein collagen have been described which belong to the superfamily of receptors collectively known as integrins. Although several integrins have been shown to interact with extracellular matrix molecules via a common recognition site, arginine-glycine-aspartic Acid (RGD), within the beta 1 integrin subfamily, only the fibronectin receptor (alpha 5 beta 1) has been convincingly shown to interact with RGD. In the present study, we tested whether a collagen receptor could interact with RGD. Adhesion of an osteosarcoma cell line, MG-63, to immobilized collagen I was inhibited by the cyclic RGD-containing peptide, C*GRGDSPC* (where C* indicates that Cys participates in disulfide), and not by the linear GRGDSP or the non-RGD-containing cyclic peptide, C*GKGESPC*. Similarly, using collagen-Sepharose affinity chromatography, a heterodimeric protein could be specifically eluted from the column by the cyclic RGD peptide. Immunoprecipitations of the eluted material with monoclonal antibodies showed reactivity with the collagen receptor alpha 2 beta 1 and not alpha 3 beta 1. Our data demonstrate that RGD peptides can interact with the collagen receptor, and the differences seen with the linear and cyclic peptide suggest that the cyclic C*GRGDSPC* has a higher avidity for the receptor than the more flexible linear GRGDSP. In this paper, we provide supportive evidence that one possible mode of collagen interaction with alpha 2 beta 1 is via the RGD recognition sequence.
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PMID:The collagen receptor alpha 2 beta 1, from MG-63 and HT1080 cells, interacts with a cyclic RGD peptide. 133 Oct 77

The influence of 1,25-dihydroxyvitamin D-3 on the cAMP response to parathyroid hormone was studied in the osteoblast-like rat osteosarcoma cells ROS 17/2.8. The stimulation by parathyroid hormone of cAMP production in intact cells and of adenylate cyclase activity in isolated plasma membranes was attenuated by 1,25-dihydroxyvitamin D-3 treatment. This was associated with a reduction of the stimulatory guanine nucleotide regulatory protein, as demonstrated by a lower response to NaF and guanosine 5'-[beta, gamma-imido]triphosphate, and by a lower activity of solubilized plasma membrane extracts in the reconstitution assay. 1,25-dihydroxyvitamin D-3 blunted also the cAMP response to parathyroid hormone in cells incubated with the glucocorticoid dexamethasone, where a higher activity of the adenylate cyclase catalytic unit was observed. Thus, the two steroids appear to affect distinct levels of the adenylate cyclase system. Furthermore, the two hormones also showed an antagonistic effect upon the production of osteocalcin, an osteoblast-specific extracellular matrix protein. The release of this non-collagenous matrix protein by ROS 17/2.8 cells was increased by 1,25-dihydroxyvitamin D-3 and decreased by dexamethasone.
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PMID:Heterologous desensitization by 1,25-dihydroxyvitamin D-3 of cyclic AMP response to parathyroid hormone in osteoblast-like cells and the role of the stimulatory guanine nucleotide regulatory protein. 301 22

In this study we describe a human sulfated 30 kD protein (sp30) that is recognized by a monoclonal antibody raised against human vitronectin (mAb 8E6). Another monoclonal antibody raised against human vitronectin, mAb MaSp, and a polyclonal antiserum against vitronectin did not react detectably with sp30. Sp30, unlike vitronectin, is synthesized by a variety of non-hepatic human cell lines in culture, including cells of lymphoid origin. It is synthesized in sulfated form as indicated by metabolic labeling of MG-63 human osteosarcoma cells with 35SO4. Sp30 is an extracellular matrix protein as indicated by its association with the matrix of MG-63 cells after removal of the cells with EDTA and its fibrillar pattern by immunofluorescence of non-permeabilized confluent MG-63 cell monolayers detected with mAb 8E6. This antibody also stained short fibrils in human embryonic tissue. This pattern was distinct from the fainter diffuse staining obtained with mAb MaSp and the polyclonal antiserum to vitronectin, suggesting that the 8E6 staining in embryonic tissues was mostly due to sp30 rather than vitronectin. A polyclonal antiserum against bovine microfibril associated glycoprotein (MAGP) precipitated a [35SO4]-30 kD protein from [35SO4]-labeled MG-63 medium that co-migrated with a band precipitated by mAb 8E6. Double-labeling immunofluorescence studies of embryonic tissues showed an identical distribution of anti-bovine MAGP antiserum and mAb 8E6 staining. These data indicate that sp30 is the human homolog of bovine MAGP. Distinction between sp30 and vitronectin will be important in ascertaining the localization and function of both proteins. The findings that sp30 is sulfated and synthesized and secreted by a variety of cells in culture should aid in defining its role in microfibrillogenesis. That sp30 is secreted by cells of lymphoid origin suggests that it might also have a heretofore unsuspected role in immune responses.
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PMID:A 30 kD sulfated extracellular matrix protein immunologically crossreactive with vitronectin. 768 99

Cell lines were established from three spontaneous osteosarcoma and one fibrosarcoma of aging mice. They were studied for tumorigenicity, osteoblastic features, and other in vitro cellular characteristics, by a combination of histological, morphological, biochemical, and molecular approaches. It was found that all cell lines formed tumors in vivo, whereas in vitro, only the fibrosarcoma-derived cell line grew efficiently in soft agar. Three out of the four cell lines produced mouse endogenous retroviruses, but none were classical sarcoma viruses. Type I collagen was expressed by all the cell lines, as was another extracellular matrix protein, osteonectin. The osteosarcoma-derived cell lines, however, exhibited different degrees of osteogenic differentiation. Only one line (OSA), and its clonal subline (1G11), consistently gave rise to mineralized tumors after transplantation into syngeneic mice, and these cells expressed high levels of alkaline phosphatase and bone-specific osteocalcin mRNA in vitro. Expression of these biochemical markers of osteoblasts occurred to a lesser extent in a second line (OSC) and was undetectable in the third line (OSB). The clonal 1G11 cell line exhibits the phenotype of a fully mature osteoblast and thus may serve as a particularly useful model for studies of bone cell function and regulation. Studies of cells which display a wide spectrum of osteogenic potential may further our understanding of the mechanisms involved in bone cell differentiation and tumorigenicity.
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PMID:Spectrum of osteoblastic differentiation in new cell lines derived from spontaneous murine osteosarcomas. 815 8

Osteocalcin (OC) is a bone-specific extracellular matrix protein expressed by mature osteoblasts during late stages of differentiation. Previous studies have shown that forskolin, an activator of adenylate cyclase, stimulated OC production. Because PTH has been shown to activate several intracellular signal transduction pathways including cAMP, inositol phosphate and intracellular calcium mobilization, we investigated whether PTH action on cAMP accumulation leads to OC promoter activation. The rat OC promoter (1095 bp) was cloned into the promoterless luciferase gene reporter vector. The transcriptional activity of the rat OC promoter was evaluated after transfection of SaOS-2, an osteosarcoma cell line, with the OC promoter followed by treatment with PTH. Maximal OC promoter activity was observed within 4-8 h after the addition of 10(-8) M PTH, whereas very little induction was seen after 24 and 48 h of treatment. The induction of OC promoter activity by PTH was concentration dependent. PTH analogs (PTH 1-84, PTH 1-34, and PTH 1-31) that stimulate intracellular cAMP accumulation, induced OC promoter activity, whereas other PTH analogs (PTH 3-34, PTH 7-34, PTH 13-34, and PTH 53-84) that do not stimulate cAMP production had no effect on OC promoter activation. Furthermore, PTH activation of the OC promoter was significantly enhanced in the presence of 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor. Inactivation of cAMP-dependent protein kinase A activity by either a selective protein kinase A inhibitor, H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5 isoquinolinesulfonamide), or antisense oligonucleotide directed against the regulatory subunit of cAMP-dependent protein kinase A, led to a corresponding loss of OC promoter activation by PTH. 5' deletion analysis of the OC promoter demonstrated that the promoter (1095 bp) exhibited the greatest response to PTH, whereas the -198 bp construct of the OC promoter, containing only one cAMP response element and OC box, was no longer responsive. The constructs with further deletions (-120, -92, and -74) retained PTH responsiveness, but to a lesser extent. In summary, our results indicate that PTH activation of the OC promoter is a rapid event and mediated by the cAMP-dependent protein kinase A pathway. Although the novel cAMP response region overlapping the OC box is required for activation, full activation may require several cis-acting cAMP response elements or other response elements.
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PMID:Parathyroid hormone (PTH 1-34) regulation of rat osteocalcin gene transcription. 923 53

Transforming growth factor-beta (TGF-beta) stimulates new bone formation when administered locally in vivo. The extracellular matrix protein tenascin-C, which is secreted by osteoblasts but absent from mineralized bone matrix, supports differentiation of cultured osteoblast-like cells. The current study was undertaken to determine whether expression patterns of tenascin-C in TGF-beta-treated bone cells are in agreement with a role for this protein as a mediator of TGF-beta-stimulated new bone formation. Expression of tenascin-C was investigated by immunohistochemistry in calvarial bones of mice to which TGF-beta had been locally administered. Three days after initiation of daily TGF-beta treatment, strong staining for tenascin-C was seen in regions where periosteal osteoprogenitor cells were undergoing proliferation in response to TGF-beta; by comparison, staining of periosteal surfaces of control bones was weak and discontinuous. Seven days after initiation of a course of five daily injections of TGF-beta, tenascin-C staining was still enhanced in treated bones. The ability of TGF-beta to regulate expression of tenascin-C in osteoblast-like cells in vitro was investigated using an osteosarcoma-derived cell line (ROS 17/2.8). TGF-beta caused a small but significant increase in secretion of tenascin-C into the medium, as determined by a solid phase dot immunoassay quantitated by densitometry. Western and northern blot analysis indicated that TGF-beta did not influence the pattern of expression of tenascin-C splice variants. These results indicate that TGF-beta stimulates osteoblastic tenascin-C expression and suggest that tenascin-C may act as a mediator of TGF-beta-induced new bone formation.
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PMID:Regulation of tenascin-C expression in bone cells by transforming growth factor-beta. 955 28

Osteosarcoma, fibrous dysplasia, and myositis ossificans contain osteoid-producing cells that are not necessarily morphologically typical osteoblasts. Nevertheless, these pathologic cells may share differentiation steps with osteoblasts at the molecular level. Osteocalcin, a bone-specific extracellular matrix protein, is a marker of mature osteoblasts. Osteocalcin is upregulated by the transcription factor core-binding factor alpha 1, which is responsible for commitment to the osteoblastic lineage, and is downregulated by MSX2, a homeobox-containing transcription factor expressed during the early proliferative phase of osteoblast differentiation. Semiquantitative reverse transcription-polymerase chain reaction was used to compare expression levels of osteocalcin, core-binding factor alpha 1, and MSX2 in 34 osteosarcoma, five fibrous dysplasia, and five myositis ossificans specimens, as well as in seven normal cortical bone samples. Despite normal or elevated levels of core-binding factor alpha-1 expression in most specimens, osteocalcin expression was low or undetectable in most cases of osteosarcoma (25 of 34) and myositis ossificans (4 of 5). Single-strand conformation polymorphism and sequencing did not identify any mutations in the DNA-binding domain of core-binding factor alpha 1. However, a high level of MSX2 expression was demonstrated in these lesions, which may inhibit osteocalcin transcription. The presence of moderate levels of osteocalcin in fibrous dysplasia may contribute to the characteristic disconnected appearance of trabeculae in that entity because osteocalcin is a negative regulator of bone formation.
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PMID:Expression of osteocalcin and its transcriptional regulators core-binding factor alpha 1 and MSX2 in osteoid-forming tumours. 1056 70

Cell culture in collagen lattice is known to be a more physiological model than monolayer for studying the regulation of extracellular matrix protein deposition. The synthesis of sulfated glycosaminoglycans (GAG) and dermatan sulfate (DS) proteoglycans by 3 cell strains were studied in confluent monolayers grown on plastic surface, in comparison to fully retracted collagen lattices. Cells were labelled with 35S-sulfate, followed by GAG and proteoglycan analysis by cellulose acetate and SDS-polyacrylamide gel electrophoresis, respectively. The 3 cell strains contracted the lattice in a similar way. In monolayer cultures, the major part of GAG was secreted into culture medium whereas in lattice cultures of dermal fibroblasts and osteosarcoma MG-63 cells but not fibrosarcoma HT-1080 cells, a higher proportion of GAGs, including dermatan sulfate, was retained within the lattices. Small DS proteoglycans, decorin and biglycan, were detected in fibroblasts and MG-63 cultures. They were preferentially trapped within the collagen gel. In retracted lattices, decorin had a higher Mr than in monolayer. Biglycan was detected in monolayer and lattice cultures of MG-63 cells but in lattice cultures only in the case of fibroblasts. In this last case, an up regulation of biglycan mRNA steady state level and down regulation of decorin mRNA was observed, in comparison to monolayers, indicating that collagen can modulate the phenotypical expression of small proteoglycan genes.
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PMID:Modulation of sulfated glycosaminoglycan and small proteoglycan synthesis by the extracellular matrix. 1082 30

Genetically engineered human osteosarcoma cells containing developmental endothelial locus-1 (del-1) gene were studied for production of Del-1, a protein that has the properties of an extracellular matrix protein and can regulate vascular morphogenesis and remodeling. Del-1 has been studied as a potential anti-angiogenesis drug targeting solid tumors. In this study, osteosarcoma cells were cultured in a fibrous-bed bioreactor (FBB) to continuously produce Del-1. The FBB was constructed by packing a polyester fibrous matrix into a 1.5-l spinner flask. The effects of media composition, including the serum content in the medium, and dilution rate on cell growth, metabolism, and Del-1 production were studied. A gradual reduction of serum content from 10% (v/v) to 0.5% (v/v) caused no loss in Del-1 production. However, the production of Del-1 decreased significantly in a serum-free medium, suggesting some nutrients present in the serum were important to culture viability and Del-1 production. The continuous FBB culture was stable for long-term production of Del-1, with a higher Del-1 titer than that normally obtained in T-flask cultures and overall productivity similar to the total production from 300 25-cm(2) T-flasks. Reducing geneticin in the medium from 250 microg ml(-1) to zero at later culturing stages had no significant effect on Del-1 production. The FBB was operated for a period of more than 4 months without any notable degeneration, and reached a final cell density of 3 x 10(8) cells ml(-1) of packing volume with >90% cell viability. The good reactor performance can be attributed to the three-dimensional environment provided by the fibrous matrix that allows for efficient mass transfer and cell immobilization and growth. Scanning electron microscopic and confocal scanning laser microscopic studies of the cell-matrix showed that cells formed large aggregates in the fibrous matrix and cell density was relatively uniform in the matrix.
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PMID:A fibrous-bed bioreactor for continuous production of developmental endothelial locus-1 by osteosarcoma cells. 1205 80

Matrix extracellular phosphoglycoprotein (MEPE) is an extracellular matrix protein that was first detected in tumor-induced osteomalacia (TIO). Investigations in mice revealed that MEPE is expressed in bone and teeth in a maturation-dependent manner, reaching its maximum during mineralization. However, from knockout experiments, although it has become clear that MEPE might function as a mineralization inhibitor, the exact mechanism of action is still unclear. Even less is known about the regulation of MEPE in men. Therefore, we have studied the time- and maturation-dependent expression of MEPE in two human osteoblast culture systems, the osteosarcoma cell line HOS 58 and primary trabecular osteoblasts. Cells were cultured for up to 29 days, and the influence of beta-glycerophosphate (bGP), ascorbate, transforming growth factor beta (TGF-beta), BMP-2, and dexamethasone was studied. HOS 58 cells showed no significant effect on MEPE gene expression up to 5.0 mM, but a significant inhibition was revealed at 10 and 20 mM, when osteocalcin (OC) expression was maximal. Under the same conditions, primary human osteoblasts showed no effect on MEPE gene expression. However, when cultured in the presence of 5 mM beta-glycerophosphate, ascorbate, and dexamethasone for 29 days, which are similar conditions to those described by Owen in his differentiation model in rat osteoblasts, a progressive inhibition of MEPE gene expression to 20% of the maximum was observed. Increasing osteocalcin expression indicated advancing differentiation. In conclusion, in contrast to the results in mice, when MEPE was maximally expressed during mineralization, in the human system, this factor seems to be maximally active in the proliferation and early matrix maturation phase. It was, however, strongly suppressed, associated with the mineralization phase.
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PMID:Evidence of downregulation of matrix extracellular phosphoglycoprotein during terminal differentiation in human osteoblasts. 1526 10


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