UMLS:C0265264 - FACTA Search

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Query: UMLS:C0265264 (HOS)
1,119 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The abilities of malignant tumor cells to bind and migrate through basement membranes are important steps in invasion and metastasis. Malignant tumor cells would therefore be expected to express receptors on their surfaces for basement membrane and stromal components, such as collagens, laminin, and fibronectin, although the pattern of expression of these receptors on the malignant cells may be different from that on their normal progenitors. We report here that chemically transformed tumorigenic human cells express an altered pattern of integrin receptors on their cell surfaces as compared with their untransformed nontumorigenic counterparts. Specifically, N-methyl-N'-nitro-N-nitrosoguanidine transformation of HOS cells into highly tumorigenic cells results in a significant specific increase in the expression of (in descending order of level of cell surface expression) the integrins alpha 6/beta 1, alpha 2/beta 1, and alpha 1/beta 1, which are receptors for laminin, collagens, and collagen type IV and laminin, respectively. The level of expression of two fibronectin receptor integrins, alpha 5/beta 1 and alpha 3/beta 1, are, however, unaltered, whereas the level of expression of vitronectin receptor integrin, alpha v/beta 3, is drastically reduced on the transformed cells. Consistent with the increased expression of laminin and collagen receptors and the decreased expression of vitronectin receptors on the transformed cells, these cells attached three- to fivefold more strongly to laminin and collagen but attached very poorly to vitronectin. The MNNG-HOS cells were also found to have a greater potential for invasion through reconstituted basement membrane, matrigel, the major components of which are laminin and type IV collagen. The invasion of both the HOS and MNNG-HOS cells was inhibited 45-50% by a polyclonal anti-fibronectin receptor antibody. However, although the invasion of HOS cells could be inhibited up to 75% by an anti-alpha 6 monoclonal antibody, a similar concentration of this antibody had no effect on the alpha 6-overproducing MNNG-HOS cells. A fivefold higher concentration of this antibody did result in partial inhibition of MNNG-HOS invasion. These data indicate a critical role for the alpha 6/beta 1 laminin receptor in the invasion of these cells through basement membranes and demonstrate that chemical transformation of nontumorigenic human cells to highly tumorigenic cells is associated with an altered pattern of integrin expression which may play a direct role in the increased capacity of these cells to bind and invade through basement membranes.
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PMID:Alterations in integrin receptor expression on chemically transformed human cells: specific enhancement of laminin and collagen receptor complexes. 168 58

The contraction of floating collagen gels is suggested to mimic the reorganization of collagenous matrix during development and tissue healing. Here, we have studied two osteogenic cell lines, namely MG-63 and HOS, and a chemically transformed subclone of HOS cells, HOS-MNNG. Transforming growth factor-beta (TGF-beta), a putative regulator of bone fracture healing, increased collagen gel contraction by MG-63 and HOS-MNNG, but not by HOS cells. Our data show that TGF-beta-induced fibronectin synthesis is not sufficient for the process. Instead, anti-beta 1 integrin antibodies could prevent the contraction. There are three different integrin heterodimers that are known to mediate the cell-collagen interaction, namely alpha 1 beta 1, alpha 2 beta 1, and alpha 3 beta 1. In MG-63 cells TGF-beta increased the expression of alpha 2 beta 1 integrin and decreased the expression of alpha 3 beta 1 integrin, whereas alpha 1 beta 1 integrin is not expressed. HOS cells had no alpha 2 beta 1 integrin, neither did TGF-beta induce its expression. However, HOS-MNNG cells expressed more alpha 2 beta 1 integrin when treated with TGF-beta. Thus, we suggest that the mechanism of the enhanced collagen gel contraction by TGF-beta is the increased expression of alpha 2 beta 1 integrin heterodimer. To further test this hypothesis, we expressed a full-length alpha 2 integrin cDNA in HOS cells and in MG-63 cells. We obtained HOS cell clones that expressed alpha 2 beta 1 heterodimer, and the ability of these cells to contract collagen gels was greatly enhanced. Furthermore, the contraction by MG-63 cells transfected with alpha 2 integrin cDNA was enhanced, and the contraction by cells transfected with antisense oriented alpha 2 integrin cDNA was decreased. Thus, both in MG-63 and HOS cells the increased alpha 2 integrin expression alone was sufficient for the enhanced contraction of collagen gels. Furthermore, the amount of alpha 2 integrin is critical for the process, and its decrease leads to diminished ability to contract gels.
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PMID:Transforming growth factor-beta regulates collagen gel contraction by increasing alpha 2 beta 1 integrin expression in osteogenic cells. 752 33

The aim of this study was to perform a systematic comparison of two widely used osteosarcoma cell lines and ascertain their relevance as experimental models for investigating osteoblast function. We have therefore compared growth, differentiated cell function, integrin expression and adhesive profiles of MG-63, HOS TE85, and human bone derived cells. Both osteosarcoma cell lines proliferated more rapidly than osteoblast-like cells with HOS cells exhibiting the shortest doubling time. HOS cells expressed higher levels of alkaline phosphatase than MG-63 cells under basal conditions but only MG-63 cells showed the increased enzyme activity following 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) administration, which is characteristic of bone derived cells. Osteocalcin was not detected in supernatants from any cells under basal conditions but levels produced by MG-63 cells on addition of 1,25(OH)2D3 were comparable with those of osteoblast-like cells. alpha 1, alpha 2, alpha 3, alpha 5, alpha V, and beta 1 integrin subunits were detected on all cells and there was no staining for alpha L, alpha M, beta 2, and beta 3. alpha 3 and beta 1 were the major subunits detected on MG-63, HOS, and bone derived cells but relative concentrations of other alpha subunits were dependent on cell type; alpha 4 and alpha 6 subunits could only be detected on osteosarcoma cell lines. Short term, serum-free cell adhesion assays showed that the three cell types adhered in a saturable manner to collagen I, fibronectin, and laminin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Are MG-63 and HOS TE85 human osteosarcoma cell lines representative models of the osteoblastic phenotype? 787 86

We describe the development of flowcytometrical methods to analyse human primary osteoblast-like cultures obtained from trabecular bone explants in comparison to the human osteosarcoma cell line HOS 58. Two antigens typical of osteoblasts were studied: bone alkaline phosphatase and collagen/procollagen I; the non-specific attachment protein fibronectin served as control. The morphology of all different antigens is shown by immunocytochemistry before flowcytometrical analysis. The establishment of flowcytometry is described in detail. While all antigens tested were nearly 100% positive in the HOS 58 cells in immunocytochemistry and flowcytometry, in primary osteoblast-like cells results varied widely between both methods. Cell permeabilisation before flowcytometry improved the homogeneity of results, probably by increasing the accessibility of the specific antibody to intracellular compartments. Though up to 80% of cells were lost during preparation the ratio of positive versus negative cells in specific experiment was not dependent on the cell recovery. Therefore, the cells finally analysed seemed to be representative of the total population.
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PMID:Analysis of human primary bone cells by fluorescence activated cell scanning: methodological problems and preliminary results. 964 53

Hydroxyapatite (HA) is an osteoconductive implant material. We previously demonstrated that RGD peptides regulate the spreading of HOS cells on HA but not on titanium, speculating that the osteoconductivity of HA might be attributed to this RGD domain-dependent spreading of osteoblasts. To confirm this hypothesis, the molecules which regulate the spreading of HOS cells on HA and on titanium were investigated. The 50% effective dose (ED50) of RGD peptide for the spreading on HA was five fold lower comparing to titanium. Anti-alphaV integrin antibody, vitronectin, and fibronectin inhibited the spreading on HA but not on titanium. In Western blot analysis, vitronectin and fibronectin were found in components adsorbed to HA but not to titanium. Taken together, the spreading of HOS cells on HA but not on titanium requires the interaction of alphaV integrin and its ligands. The ED50 of the RGD peptides on titanium but not on HA was remarkably reduced by neuraminidase treatment, that by itself could not inhibit the spreading on both materials. This phenomenon suggests that RGD domain and sialic acid cooperatively but not independently mediate the spreading of HOS cells on titanium. Collectively, the molecules regulating the spreading on HA are apparently different from those on titanium. The spreading of osteoblasts mediated by RGD domain of vitronectin and fibronectin might contribute to the osteoconductive ability of HA.
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PMID:Diverse mechanisms of osteoblast spreading on hydroxyapatite and titanium. 1081 64

Tissue transglutaminase (tTG) is a calcium-dependent and guanosine 5'-triphosphate (GTP) binding enzyme, which catalyzes the post-translational modification of proteins by forming intermolecular epsilon(gamma-glutamyl)lysine cross-links. In this study, human osteoblasts (HOBs) isolated from femoral head trabecular bone and two osteosarcoma cell lines (HOS and MG-63) were studied for their expression and localization of tTG. Quantitative evaluation of transglutaminase (TG) activity determined using the [1,4 14C]-putrescine incorporation assay showed that the enzyme was active in all cell types. However, there was a significantly higher activity in the cell homogenates of MG-63 cells as compared with HOB and HOS cells (p < 0.001). There was no significant difference between the activity of the enzyme in HOB and HOS cells. All three cell types also have a small amount of active TG on their surface as determined by the incorporation of biotinylated cadaverine into fibronectin. Cell surface-related tTG was further shown by preincubation of cells with tTG antibody, which led to inhibition of cell attachment. Western blot analysis clearly indicated that the active TG was tTG and immunocytochemistry showed it be situated in the cytosol of the cells. In situ extracellular enzyme activity also was shown by the cell-mediated incorporation of fluorescein cadaverine into extracellular matrix (ECM) proteins. These results clearly showed that MG-63 cells have high extracellular activity, which colocalized with the ECM protein fibronectin and could be inhibited by the competitive primary amine substrate putrescine. The contribution of tTG to cell surface/matrix interactions and to the stabilization of the ECM of osteoblast cells therefore could by an important factor in the cascade of events leading to bone differentiation and mineralization.
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PMID:Characterization of tissue transglutaminase in human osteoblast-like cells. 1149 70

We used an adhesion assay for cells cultured under high dynamic strain to measure human osteoblast-like HOS cell adherence to immobilized type I collagen, fibronectin, and vitronectin. These conditions were designed to model the increased forces present at unstable fractures or loose joint prostheses. At a constant, low protein-coating density (1000 molecules/microm2) and 20% cyclic strain for 24 h, type I collagen, fibronectin, and vitronectin supported 24.6 +/- 2%, 16.7 +/- 3%, and 1.1 +/- 1% adherence, respectively, which paralleled the relative number of integrin-binding sites in each protein. Thus, when the number of available binding sites was limited, strain resistance was proportional to the number of integrin-ligand interactions. In contrast, at high protein-coating densities (> or = 2,500 molecules/microm2), vitronectin supported greater adherence (45.7 +/- 2%) when compared with type I collagen (37 +/- 2%) or fibronectin (34.8 +/- 2%) and directed constitutive expression of osteopontin (OPN), which suggested that there exist discrete signals on vitronectin receptor occupancy that promoted cell adherence and survival under strain. Integrin-mediated binding was necessary for resistance to strain, as evidenced by the low levels of strain resistance observed when cells were adherent in a nonintegrin-dependent manner. These findings support the utilization of at least two distinct mechanisms (i.e., tensegrity and integrin-mediated signal transduction) by HOS cells to remain adherent and viable on exposure to mechanical forces.
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PMID:A comparison of type I collagen, fibronectin, and vitronectin in supporting adhesion of mechanically strained osteoblasts. 1187 39

HIV particles are detected extracellularly in lymphoid tissues, a major reservoir of the virus. We previously reported that a polymerized form of fibronectin (FN), superfibronectin (sFN), as well as a fragment of FN, III1-C, enhanced infection of primary CD4(+) T cells by HIV-1IIIB. We now show that sFN enhances infection of primary CD4(+) T cells by both R5 and X4 strains of HIV-1. Using HIV pseudotyped with different envelope glycoproteins (gp120) and HOS cells transfected with various chemokine receptors alone or in combination with the CD4 molecule, we show that sFN-mediated enhancement requires the CD4 receptor and does not alter the specificity of gp120 for different chemokine receptors. Because the III1-C fragment also resulted in enhancement, we asked whether proteolysis of FN generated fragments capable of enhancing HIV infection. We found that progressive proteolysis of FN by chymotrypsin correlates with an enhancement of HIV infection in both primary CD4(+) T cells and the IG5 reporter cell line. Furthermore, incubation of HIV with sFN significantly prolonged infectivity at 37 degrees C compared with dimeric FN or BSA. In conclusion, these results indicate that polymerized (matrix) or degraded (inflammation-associated), but not dimeric (plasma), FN are capable of enhancing infection by HIV-1, independent of the coreceptor specificity of the strains. Moreover, virions bound to matrix FN maintain infectivity for longer periods of time than do virions in suspension. This study suggests that matrix proteins and their conformational status may play a role in the pathogenesis of HIV.
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PMID:Matrix fibronectin increases HIV stability and infectivity. 1202 72

We investigated the effect of the proinflammatory cytokine interleukin 17 (IL-17) on the lysis of osteosarcoma cells by human NK cells. NK cells and U-2 OS, MG-63, HOS osteosarcoma cell lines express the IL-17 receptor, the highest amount being found on U-2 OS. Pre-incubation of NK cells with IL-17 did not affect the cytotoxicity against osteosarcomas, that was increased when U-2 OS were pre-incubated with IL-17. In IL-17 treated U-2 OS osteosarcoma cells FACS analysis demonstrated an increased expression of fibronectin among the panel of adhesion molecules assayed, and the treatment with anti-fibronectin antibodies decreased the NK cytotoxicity. The comparison between interferon gamma (IFN-gamma) treated and IFN-gamma/IL-17-treated U-2 OS showed a decreased susceptibility to NK lysis associated with a reduced expression of CD49f on U-2 OS treated with IFN-gamma/IL-17. IL-17 appears to be a modulator of NK adhesion molecules on U-2 OS cells but antagonizes with IFN-gamma on NK lysis.
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PMID:IL-17 enhances the susceptibility of U-2 OS osteosarcoma cells to NK cell lysis. 1293 Mar 59

Soluble glasses are considered to be of potential clinical value in orthopaedic and dental surgery. However, the biological response to these materials is not well understood. To determine the effects of these glasses, two human osteoblast cell lines, MG63 and HOS (TE85), were incubated in vitro in the presence of increasing concentrations of extracts of the glasses. The effects of the extracts on cell growth was measured using the MTT assay and an ELISA assay was used to measure the expression of bone sialoprotein (BSP), osteonectin (ON) and fibronectin (FN), antigens which play a fundamental part in the integrity and function of hard connective tissue. The results showed that the proliferation of the cells was adversely affected only by the more soluble glasses, which also down-regulated the expression of the bone-associated proteins. In contrast, the extract of the glass with the lowest dissolution rate, which contains relatively elevated levels of Ca2+, was found to enhance bone cell growth and antigen expression. These findings suggest that the compositions of these glasses at least partly determine the response of cells and thus, that the glasses could be modified to elicit a more optimal biological response and clinical efficacy.
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PMID:Development of soluble glasses for biomedical use Part II: the biological response of human osteoblast cell lines to phosphate-based soluble glasses. 1534 85

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