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)

Our previous work demonstrated that the inhibition of type I collagen synthesis by 1,25-dihydroxyvitamin D (1,25-(OH)2D3) in fetal rat calvaria and cultured rat osteosarcoma cells is accompanied by equivalent reduction in steady state levels of alpha 1(I) and alpha 2(I) collagen mRNA. To pursue the mechanism for this effect, we isolated and sequenced a 3.6-kilobase DNA fragment that contained the promoter for the rat alpha 1(I) collagen gene. This promoter fragment was fused to the chloramphenicol acetyltransferase gene and was introduced into ROS 17/2.8 cells by calcium phosphate co-precipitation. Expression of this construct was diminished by 1,25-(OH)2D3 to the same degree as the endogenous collagen gene in both transient expression assays and in permanently selected bone cells. However, a fibroblast cell line did not show a similar reduction in the activity of the transgene or the endogenous collagen gene. These experiments indicate that the alpha 1(I) promoter contains cis-active elements which are regulated by the 1,25-(OH)2D3 receptor in ROS 17/2.8 cells.
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PMID:Isolation and characterization of the rat alpha 1(I) collagen promoter. Regulation by 1,25-dihydroxyvitamin D. 820 63

Aluminum-induced osteomalacia is a frequent complication observed in patients on maintenance hemodialysis. However, it is not known whether there are direct effects of aluminum on osteoblasts, or alternatively, whether the observed changes are due to changes in PTH or other factors. We sought to determine the effect of micromolar levels of aluminum on osteoblasts using a well-defined cell line derived from a 32P induced osteosarcoma of rat, UMR 106-01, which is alkaline-phosphatase positive, responds to PTH, and synthesizes type I collagen. Aluminum exposure was controlled using tissue culture media with [Al ] less than 1 microgram/liter (40 nM), produced by precipitation of aluminum salts at pH 8.5. The effect of defined [Al ], from 20 to 800 micrograms/liter (0.7 to 30 microM), was then determined by adding back aluminum while measuring DNA and protein synthesis. We found that aluminum depressed DNA synthesis, as determined by 3H-thymidine incorporation, by 60%, with half maximal effect at 20 micrograms/liter (740 nM) in cells at a density of 20,000/cm2. Alternatively, protein synthesis, as determined by 3H-leucine incorporation, did not decline, and in some cases increased. However, qualitative analysis of matrix proteins produced with and without 800 micrograms/liter (30 mM) [Al ] showed no differences. Direct measurements of cell number and protein synthesis confirmed these findings. Al does not alter the PTH-induced cAMP response of these cells. Thus, aluminum has a direct effect on cell division, and probably on protein synthesis, in this osteoblast-like cell line. These effects occur at levels of aluminum below those commonly contaminating tissue culture media, and thus are seen reproducibly only in media of defined [Al ].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Micromolar aluminum levels reduce 3H-thymidine incorporation by cell line UMR 106-01. 254 94

Biochemical and molecular biological studies of osteoblastic cell function and hormonal regulation are frequently confounded by the inherent cellular heterogeneity and phenotypic instability of existing in vitro and in vivo model systems. A new technique (derived from Western blotting or antibody-based detection of protein molecules bound to nitrocellulose paper) is described for identification of individual cells which synthesize osteoblast-specific gene products (bone Gla-protein, type I collagen, and alkaline phosphatase) or produce cAMP in response to parathyroid hormone (PTH) or isoproterenol. Dispersed primary neonatal rat calvariae or osteogenic sarcoma cells were "plated" on Immobilon-P (a hydrophobic transfer membrane with very high protein-binding capacity) for 30 minutes to several hours, followed by agonist treatment, formalin fixation, hematoxylin staining, and immunostaining with a battery of antibodies specific for osteoblastic products. Individual cells and their secretory zones were visualized by light microscopy and counted. Treatment with PTH with or without isoproterenol resulted in increases in the percentages of osteoblastic cells elaborating cAMP, as well as the intensity of immunostaining, but had no effects on MCF-7 cells, a nonosteoblastic breast carcinoma control line. The percentage of cells within each primary osteoblastic cell population isolated or rat osteogenic sarcoma cell clone (G2 or C12) that elaborated bone-specific proteins or that generated cAMP in response to PTH varied with time and the individual cellular preparation, reconfirming the cellular heterogeneity of these systems. This method, in conjunction with techniques such as in vitro hybridization, should prove useful in characterizing discrete osteoblastic bone cell subpopulations and in clarifying mechanisms of hormonal regulation by local and systemic agents.
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PMID:Rapid, simple identification of individual osteoblastic cells and their specific products by cell blotting assay. 255 3

The distribution of type I, II, III, IV, V and VI collagens in 20 cases of osteosarcoma was demonstrated immunohistochemically using monospecific antibodies to different collagen types. In addition, biochemical analysis was made on collagenous proteins synthesized by tumor cells in short-term cultures obtained from seven representative cases and compared with dermal fibroblasts. In osteoblastic areas, most of the tumor osteoid consisted exclusively of type I collagen. Type V collagen was associated in some of them. Type III and type VI collagens were mainly localized in the perivascular fibrous stroma. Cultured tumor cells from osteoblastic osteosarcomas produced type I collagen exclusively and small amount of type V collagen constantly, while the synthetic activity of type III collagen was extremely low. In contrast, fibroblastic areas were characterized by the codistribution of type I, III, VI collagens and chondroblastic areas by type I, V, VI collagens as well as type II. Furthermore, type IV collagen was demonstrated in the stroma, other than the basement membrane region of blood vessels, in fibroblastic, intramedullary well-differentiated and telangiectatic osteosarcomas. In vitro, the production of variable amounts of type IV collagen, which was not detected in cultured dermal fibroblasts, was also recognized in the osteoblastic, fibroblastic, undifferentiated and intramedullary well-differentiated osteosarcomas examined. These findings suggest that the immunohistochemical approach using monospecific antibodies to different collagen types is useful not only in identifying some specific organoid components, such as tumor osteoid, but also in disclosing the biological properties of osteosarcoma cells with diverse differentiation.
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PMID:Immunohistochemical and biochemical studies on the collagenous proteins of human osteosarcomas. 257 16

Our previous studies have demonstrated that 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3)] reduces type I collagen synthesis and steady state levels of procollagen mRNA in cultured fetal rat calvaria and rat osteosarcoma cells. To determine whether 1,25-(OH)2D3 regulates transcription of type I collagen genes, transcription rates were measured directly in nuclei isolated from ROS 17/2.8 cells using a nuclear run-off assay. Transcription was allowed to proceed in the presence of [32P]UTP for 20 min, at which time incorporation of radiolabeled UTP into trichloroacetic acid-precipitable material was maximal. UTP incorporation was inhibited 90% by 3 micrograms/ml actinomycin-D and 40% by 1 microgram/ml alpha-amanitin. Treatment of ROS 17/2.8 cells with 1,25-(OH)2D3 inhibited procollagen gene transcription in a concentration and time dependent manner. Procollagen transcription was reduced by approximately 50% of the control rate by 10 nM 1,25-(OH)2D3, and this inhibition was maximal after 24 h of 1,25-(OH)2D3 treatment. The inhibition of procollagen transcription was specific for collagen, since total RNA synthesis and beta-actin transcription were not inhibited by 1,25-(OH)2D3. The magnitude of the decrease of procollagen transcription by 1,25-(OH)2D3 was comparable to its inhibition of steady state procollagen mRNA levels, suggesting that transcription is the predominant mechanism by which 1,25-(OH)2D3 regulates collagen gene expression in bone cells.
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PMID:1,25-Dihydroxyvitamin D3 inhibits transcription of type I collagen genes in the rat osteosarcoma cell line ROS 17/2.8. 273 51

MG-63 human osteosarcoma cells were selected for attachment and growth in increasing concentrations of a synthetic peptide containing the cell attachment-promoting Arg-Gly-Asp (RGD) sequence derived from the cell-binding region of fibronectin. Cells capable of attachment and growth in 5 mM concentrations of a peptide having the sequence Gly-Arg-Gly-Asp-Ser-Pro overproduce the cell surface receptor for fibronectin. No increase in fibronectin receptor gene copy number was detected by Southern blot analysis. The peptide-resistant MG-63.3A cells look very different from the MG-63 cells and resemble osteocytes. The resistant cells also grow more slowly than MG-63 cells. The enhanced expression of the fibronectin receptor on the resistant cells indicates that cells can regulate the amount of this receptor on their surface in response to environmental factors and that this may affect the phenotypic properties of the cell. MG-63.3A cells differ from MG-63 cells in their ability to form a calcified matrix in vitro and in their increased synthesis of type I collagen. The MG-63.3A cells synthesize 50-100-fold less prostaglandin E2, a mediator of bone resorption, than MG-63 cells. There is an overall down-regulation of chondroitin sulphate proteoglycans in MG-63.3A cells. These results are consistent with the hypothesis that such proteoglycans interfere with calcium phosphate deposition and with the observation that chondroitin sulphate is increased in a wide variety of neoplasms but is absent or in small amounts in normal tissue. We conclude that MG-63.3A cells represent a more differentiated cell type with osteoblast-like properties.
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PMID:An adhesion variant of the MG-63 osteosarcoma cell line displays an osteoblast-like phenotype. 306 6

This study analyzed the transforming potential of murine viruses in organ cultures of mouse fetal condylar cartilage: Finkel-Biskis-Jinkins-Murine sarcoma virus (FBJ-MuSV) and Finkel-Biskis-Reilly-Murine sarcoma virus (FBR-MuSV). It was only the FBR-MuSV isolated from a radiation-induced osteosarcoma, that induced morphological changes as early as 24 hours following the infection. The latter manifested itself by a marked enlargement of the number of progenitor cells concomitant with an accumulation of spindle-like cells, giant cells, and pleomorphic cells along with large bone spicules and heavy mineralization of the remaining cartilage. The newly formed tissue synthesized type I collagen and revealed profound invasive characteristics. By day 7, FBR-MuSV-infected cultures acquired the appearance of an osteosarcomatouslike lesion. Electron microscopy examinations revealed that both the matrix and the osteogenic cells in the induced tumors differed markedly from that encountered in normal mammalian osseous tissue. To determine which cells within the condylar tissue served as the target for the FBR-MuSV, we used antibodies against viral P30 protein for an indirect immunoperoxidase reaction. The chondroprogenitor cells were the only ones that reacted positively for the virus-specific protein. Further, the in vitro-induced tumor was tumorigenic in syngeneic mice, hence, brought about the development of osteo-fibrosarcoma subcutaneously. By contrast to FBR-MuSV, the FBJ-MuSV did not elicit similar transformative effects in vitro. Since both viruses possess the fos oncogene, it has been suggested that the unique tumorigenic potential of the FBR-MuSV may be linked to structural alterations in the fos oncogene product.
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PMID:In vitro induction of osteosarcomalike lesion by transformation of differentiating skeletal precursor cells with FBR murine osteosarcoma virus. 311 76

The growth of human osteosarcoma xenografts in nude mice can be inhibited by human interferon-alpha (IFN-alpha). Histologic examination of growth-inhibited tumors has revealed mineralization and partial replacement of the tumor by normal bone tissue. We have investigated whether the normal bone tissue was formed by differentiated tumor cells or by induction of host stroma to differentiate into bone tissue. Employing antibodies to both murine and human type I collagen, it was found that the normal bone produced in IFN-inhibited osteosarcomas was host derived. These results suggest that IFN induced the osteosarcoma cells to produce a bone-inductive agent that interacts with the host cells, and leads to the formation of mature normal bone tissue in a heterotopic site.
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PMID:Interferon-inhibited human osteosarcoma xenografts induce host bone in nude mice. 321 16

Synthesis of type I and III collagens has been examined in MG-63 human osteosarcoma cells after treatment with the steroid hormone, 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3). Analysis of total [3H]proline-labeled proteins and pepsin-derived collagens revealed that 1,25-(OH)2D3 selectively stimulated synthesis of alpha 1I and alpha 2I components of type I collagen after 6-12 h. Consistent with previous reports (Franceschi, R. T., Linson, C. J., Peter, T. C., and Romano, P. R. (1987) J. Biol. Chem. 262, 4165-4171), parallel increases in fibronectin synthesis were also observed. Hormonal effects were maximal (2- to 2.5-fold versus controls) after 24 h and persisted for at least 48 h. In contrast, synthesis of the alpha 1III component of type III collagen was not appreciably affected by hormone treatment. Of several vitamin D metabolites (1,25-(OH)2D3, 25-dihydroxyvitamin D3, and 24R,25-dihydroxyvitamin D3) tested for activity in stimulating type I collagen synthesis, 1,25-(OH)2D3 was found to be the most active. Analysis of collagen mRNA abundance by Northern blot hybridization indicated that both types I and III procollagen mRNAs were increased 4-fold after a 24-h exposure to 1,25-(OH)2D3. Pro alpha 1I mRNA remained elevated through the 48-h time point while pro alpha 2I and pro alpha 1III mRNAs returned to control values. These results indicate that the regulation of collagen synthesis by 1,25-(OH)2D3 is complex and may involve changes in translational efficiency as well as mRNA abundance. 1,25-(OH)2D3 also caused at least a 20-fold increase in levels of the bone-specific calcium-binding protein, osteocalcin. These results are consistent with the hypothesis that 1,25-(OH)2D3 is stimulating partial differentiation to the osteoblast phenotype in MG-63 cells.
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PMID:Regulation of type I collagen synthesis by 1,25-dihydroxyvitamin D3 in human osteosarcoma cells. 326 82

To isolate collagen-binding cell surface proteins, detergent extracts of surface-iodinated MG-63 human osteosarcoma cells were chromatographed on affinity matrices of either type I collagen-Sepharose or Sepharose carrying a collagen-like triple-helical peptide. The peptide was designed to be triple helical and to contain the sequence Arg-Gly-Asp, which has been implicated as the cell attachment site of fibronectin, vitronectin, fibrinogen, and von Willebrand factor, and is also present in type I collagen. Three radioactive polypeptides having apparent molecular masses of 250 kD, 70 kD, and 30 kD were distinguishable in that they showed affinity toward the collagen and collagen-like peptide affinity columns, and could be specifically eluted from these columns with a solution of an Arg-Gly-Asp-containing peptide, Gly-Arg-Gly-Asp-Thr-Pro. These collagen-binding polypeptides associated with phosphatidylcholine liposomes, and the resulting liposomes bound specifically to type I collagen or the collagen-like peptide but not to fibronectin or vitronectin or heat-denatured collagen. The binding of these liposomes to type I collagen could be inhibited with the peptide Gly-Arg-Gly-Asp-Thr-Pro and with EDTA, but not with a variant peptide Gly-Arg-Gly-Glu-Ser-Pro. We conclude from these data that these three polypeptides are membrane molecules that behave as a cell surface receptor (or receptor complex) for type I collagen by interacting with it through the Arg-Gly-Asp tripeptide adhesion signal. The lack of binding to denatured collagen suggests that the conformation of the Arg-Gly-Asp sequence is important in the recognition of collagen by the receptor complex.
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PMID:A cell surface receptor complex for collagen type I recognizes the Arg-Gly-Asp sequence. 346 4


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