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)

Until now, many extracellular matrix proteins, e.g. osteopontin and osteonectin, have been used to determine a cell's osteogenic maturation. The disadvantage in evaluation of these proteins is their relative wide-ranging appearance throughout the osteogenic differentiation process. Thus, the aim of this study was to establish an immunohistochemical setup using E11, a marker that binds selectively to cells of the late osteogenic cell lineage. In addition, the histochemical expression of the bone matrix proteins osteonectin, osteopontin and fibronectin was compared to that of E11 using monoclonal antibodies. For light microscopical detection of osteogenic markers in cultured cells we developed a simple paraffin technique using a fibrin glue as embedding medium. This allows the handling of cultured cells such as a tissue sample and includes the use of stored biological specimens for further immunohistochemical experiments. We used newborn rat calvariae for whole tissue preparations and for isolation and cultivation of bone cells. In addition, we included the rat osteosarcoma cell line ROS 17/2.8 in this study. For the first time, we have localised E11 in osteocytes of rat calvaria preparations at the electron microscopical level. E11 was detected at plasma membranes of osteocytes and their processes, but not at those of osteoblasts. Accompanying experiments with cultured newborn rat calvaria cells and ROS 17/2.8 cells revealed E11 reactivity on a subset of cells. The results obtained confirm the suitability of the differentiation marker E11 as a sensitive instrument for the characterisation of bone cell culture systems.
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PMID:Immunohistochemical investigations on the differentiation marker protein E11 in rat calvaria, calvaria cell culture and the osteoblastic cell line ROS 17/2.8. 993 Aug 85

Osteosarcomas produce an extracellular matrix (ECM), called tumor osteoid, which is also the microscopic hallmark of these tumors. It can be difficult to differentiate tumor osteoid from other formations of ECM in intra-and extraskeletal soft tissue tumors, so that problems in differential diagnosis arise. Conventional special stainings provide a means to increase the reliability of the differential diagnosis, but do not identify the type of tumor conclusively as they only reflect physiochemical features and do not identify the molecular components of the matrix. The key to the solution of this problem is the immunohistochemical use of antibodies against bone matrix components. Matrix-immunohistochemistry using polyclonal and monoclonal antibodies against COL-I-C-peptide, Osteopontin, Osteonectin, Osteocalcin, and Decorin have proved to be a useful tool for the differentiation of osteoid in a series of 20 osteosarcomas with different variants of osteoid formation. For the detection of undifferentiated tumors, however, this method has not proved useful, since the cytoplasmatic immunoreactivity is variable. Molecular methods appear to be a more promising tool. Since the expression of Osteocalcin is known to be the last step of the osteoblastic differentiation, we have established a method to detect osteocalcin mRNA by RT-PCR. First studies of our group on the identification of the osteoblastic differentiation at the molecular level have revealed that Osteocalcin mRNA can be detected both in osteosarcoma cells and in non-skeletal tumor cell lines. In order to provide a reliable means of molecular tumor characterisation, thorough comparative studies on fresh and paraffin material of larger tumor series are in progress.
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PMID:[Bone matrix production in osteosarcoma]. 1009 26

Bone sialoprotein (BSP) and osteopontin (OPN) are secreted glycoproteins with a conserved Arg-Gly-Asp (RGD) integrin-binding motif and are expressed predominantly in bone. The RGD tripeptide is commonly present in extracellular attachment proteins and has been shown to mediate the attachment of osteosarcoma cells and osteoclasts. To determine the origin and incidence of BSP and OPN mRNA expression in primary tumor, a cohort of archival, primary invasive breast carcinoma specimens was analyzed. BSP transcripts were detected in 65% and OPN transcripts in 77% of breast cancers examined. In general, BSP and OPN transcripts were detected in both invasive and in situ carcinoma components. The transcripts were not detected in surrounding stromal cells or in peritumoral macrophages. Despite its abundance in carcinomas, BSP expression was not detected in a panel of 11 human breast cancer cell lines (MCF-7, T47D, SK-Br-3, MDA-MB-453, MDA-MB-231, MDA-MB-436, BT549, MCF-7ADR, Hs578T, MDA-MB-435, and LCC15-MB) and OPN expression was detected only in two of these (MDA-MB-435 and LCC15-MB). To examine the possibility that expression of these genes was down-regulated in cell culture, several cell lines were grown as nude mouse xenografts in vivo; however, these tumors also failed to express BSP. OPN expression was identified in all cell lines grown as nude mouse xenografts. Our data suggest that in human primary breast tumors, the origin of BSP and OPN mRNA is predominantly the breast cancer cells and that expression of these transcripts is influenced by the tumor environment.
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PMID:Tumor cells are the source of osteopontin and bone sialoprotein expression in human breast cancer. 1041 27

Prior studies have demonstrated that the pineal hormone, melatonin, can stimulate chloramphenicol acetyltransferase activity in Drosophila SL-3 cells transfected with a chloramphenicol acetyltransferase reporter construct containing the response element of rat bone sialoprotein (BSP). Based on these findings, studies were performed to determine whether melatonin could similarly modulate the expression of BSP in two cell lines, the MC3T3-E1(MC3T3) pre-osteoblast and rat osteoblast-like osteosarcoma 17/2.8 cell. Initial studies demonstrated that MC3T3 cells grown in the presence of 50 nM melatonin underwent cell differentiation and mineralization by day 12 instead of the 21-day period normally required for cells grown in untreated media. Melatonin increased gene expression of BSP and the other bone marker proteins, including alkaline phosphatase (ALP); osteopontin; secreted protein, acidic and rich in cysteine; and osteocalcin in MC3T3 cells in a concentration-dependent manner. Levels of melatonin as low as 10 nM were capable of stimulating transcription of these genes when cells were grown in the presence of beta-glycerophosphate and ascorbic acid. Under these conditions, melatonin induced gene expression of the bone marker proteins; however, this does not occur until the 5th day after seeding the culture dishes. Thereafter, MC3T3 cells responded to melatonin within 2 h of treatment. The fully differentiated rat osteoblast-like osteosarcoma 17/2.8 cells responded rapidly to melatonin and displayed an increase in the expression of BSP, ALP, and osteocalcin genes within 1 h of exposure to the hormone. To determine whether melatonin-induced osteoblast differentiation and bone formation are mediated via the transmembrane receptor, MC3T3 cells were treated in the presence and absence of melatonin with either luzindole, a competitive inhibitor of the binding of melatonin to the transmembrane receptors, or pertussis toxin, an uncoupler of G(i) from adenylate cyclase. Both luzindole and pertussis toxin were shown to reduce melatonin-induced expression of BSP and ALP. These results demonstrate, for the first time, that the pineal hormone, melatonin, is capable of promoting osteoblast differentiation and mineralization of matrix in culture and suggest that this hormone may play an essential role in regulating bone growth.
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PMID:Melatonin promotes osteoblast differentiation and bone formation. 1041 30

Integrin heterodimers sharing the common alphaV subunit are receptors for adhesion glycoproteins such as vitronectin and fibronectin. They are suggested to play an essential role in cell anchoring, differentiation, and survival. Here, we describe the construction of an expression plasmid coding for an intracellular single-chain antibody against alphaV integrin subunit. Saos-2 osteosarcoma cells transfected with this DNA construct showed an approximately 70-100% decrease in the cell surface expression of alphaVbeta3 and alphaVbeta5 integrins as shown by flow cytometry. Intracellular antibody expression had no effect on the mRNA levels of alphaV integrin. Pulse chase experiments of metabolically labeled integrins showed that the translation of precursor alphaV integrin subunit was not affected. However, the maturation of alphaV integrins as glycoproteins was slow suggesting that the transport from endoplasmic reticulum to Golgi complex was partially prevented. Depletion of alphaV integrins from Saos-2 cells led to a decreased ability to spread on fibronectin and vitronectin. Furthermore, the expression of osteoblast differentiation marker genes, alkaline phosphatase and osteopontin, was induced and concomitantly the expression of matrix metalloproteinase-2 decreased. Thus, alphaV integrins seem to be important regulators of osteosarcoma cell phenotypes. Our data also indicate that the expression of intracellular antibodies is an effective strategy to study the significance of specific integrins for cell phenotype and differentiation.
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PMID:Depletion of alphaV integrins from osteosarcoma cells by intracellular antibody expression induces bone differentiation marker genes and suppresses gelatinase (MMP-2) synthesis. 1042 43

In this study, we examined in vitro histogenesis by murine K8 osteosarcoma cells maintained in three-dimensional (3D) collagen sponges. We tested the hypothesis that perfusion of medium enhances cell viability and their biosynthetic activity as assessed by expression of the osteoblastic phenotype and mineral deposition. At intervals, samples were harvested and analyzed histologically, biochemically, and by Northern hybridization for type I collagen, osteopontin (OPN), osteocalcin (OC), and core binding factor alpha 1 (Cbfa1). Histologic evaluation showed greater viability, more alkaline phosphatase (ALP)-positive cells, and more mineralized tissue in the perfused sponges after 21 days. Immunohistological assessment of proliferating cell nuclear antigen revealed 5-fold more proliferating cells in the perfused sponges compared with the controls (p = 0.0201). There was 3-fold more ALP activity in the perfused sponges than the controls at 6 days and 14 days (p = 0.0053). The perfused sponges contained twice the DNA and eight times more calcium than the nonperfused controls after 21 days (p < 0.0001 for both). Northern hybridization analysis revealed more mRNA for collagen type I (2-fold) and 50% more for OC at 14 days and 21 days, whereas OPN and Cbfa1 mRNA expression remained unaffected by the medium perfusion. These results show that medium perfusion had beneficial effects on the proliferation and biosynthetic activity of this osteosarcoma cell line. This system mimics the 3D geometry of bone tissue and has the potential for revealing mechanisms of regulation of osteogenesis.
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PMID:Medium perfusion enhances osteogenesis by murine osteosarcoma cells in three-dimensional collagen sponges. 1062 71

Connective tissue growth factor/hypertrophic chondrocyte-specific gene product Hcs24 (CTGF/Hcs24) promotes the proliferation and differentiation of chondrocytes and endothelial cells which are involved in endochondral ossification (Shimo et al., 1998, J Biochem 124:130-140; Shimo et al., 1999, J Biochem 126:137-145; Nakanishi et al., 2000, Endocrinology 141:264-273). To further clarify the role of CTGF/Hcs24 in endochondral ossification, here we investigated the effects of CTGF/Hcs24 on the proliferation and differentiation of osteoblastic cell lines in vitro. A binding study using (125)I-labeled recombinant CTGF/Hcs24 (rCTGF/Hcs24) disclosed two classes of specific binding sites on a human osteosarcoma cell line, Saos-2. The apparent dissociation constant (Kd) value of each binding site was 17.2 and 391 nM, respectively. A cross-linking study revealed the formation of (125)I-rCTGF/Hcs24-receptor complex with an apparent molecular weight of 280 kDa. The intensity of (125)I-rCTGF/Hcs24-receptor complex decreased on the addition of increasing concentrations of unlabeled rCTGF/Hcs24, but not platelet-derived growth factor-BB homodimer or basic fibroblast growth factor. These findings suggest that osteoblastic cells have specific receptor molecules for CTGF/Hcs24. rCTGF/Hcs24 promoted the proliferation of Saos-2 cells and a mouse osteoblast cell line MC3T3-E1 in a dose- and time-dependent manner. rCTGF/Hcs24 also increased mRNA expression of type I collagen, alkaline phosphatase, osteopontin, and osteocalcin in both Saos-2 cells and MC3T3-E1 cells. Moreover, rCTGF/Hcs24 increased alkaline phosphatase activity in both cells. It also stimulated collagen synthesis in MC3T3-E1 cells. Furthermore, rCTGF/Hcs24 stimulated the matrix mineralization on MC3T3-E1 cells and its stimulatory effect was comparable to that of bone morphogenetic protein-2. These findings indicate that CTGF/Hcs24 is a novel, potent stimulator for the proliferation and differentiation of osteoblasts in addition to chondrocytes and endothelial cells. Because of these functions, we are re-defining CTGF/Hcs24 as a major factor to promote endochondral ossification to be called "ecogenin: endochondral ossification genetic factor."
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PMID:Effects of CTGF/Hcs24, a hypertrophic chondrocyte-specific gene product, on the proliferation and differentiation of osteoblastic cells in vitro. 1086 44

Metastasis is a major cause of mortality and morbidity in osteosarcoma (OS) patients. To monitor tumor dissemination, we assessed the circulating tumor burden in OS patients by semiquantitative reverse transcription-PCR using osteocalcin, osteonectin, osteopontin, and type I collagen (COLL) mRNAs as molecular markers. We distinguished levels of the mRNAs in peripheral blood between OS patients and healthy subjects using an OS-derived cell line (Saos-2) as a reference standard. We prospectively analyzed 40 peripheral blood samples from 11 OS patients at diagnosis and 29 healthy subjects. In all 29 (100%) healthy subjects, we detected osteocalcin, osteonectin, and osteopontin mRNAs that were most likely attributed to illegitimate transcription in normal hematopoietic cells. In contrast, we found low COLL mRNA levels in only 35% (10 of 29) of healthy subjects, but significantly higher COLL mRNA levels in 91% (10 of 11) of OS patients (P < 0.0001). The reverse transcription-PCR assay for COLL mRNA was sensitive down to the detection of 10 Saos-2 cells among 10(6) normal peripheral blood nucleated cells. The upper limit of COLL mRNA determined among the healthy subjects was found exceeded by six OS patients. The substantially elevated COLL mRNA levels in peripheral blood seemed to originate from circulating malignant cells in these six OS patients, all of whom subsequently developed clinical metastases within 12 months of diagnosis (P = 0.002). Conversely, no metastases were detected in the remaining OS patients with normal COLL mRNA levels. Quantification of COLL mRNA may prove valuable for diagnosing OS micrometastasis and assessing prognosis.
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PMID:Quantitative analysis of circulating tumor cells in peripheral blood of osteosarcoma patients using osteoblast-specific messenger RNA markers: a pilot study. 1087 67

The effects of growing the Saos-2 human osteosarcoma cell line onto surfaces containing -CH(3), -OH, -COOH, -NH(2), and C6H5 groups obtained by silane modification were examined. These cells were used because of the great importance of bone cells in many aspects of biomaterials research. Silane-modified surfaces were characterized by contact angle measurements and, subsequently, surface energies were calculated. Cells grown on clean glass, as well as those grown on glass surfaces containing the functional groups cited above, were examined by light and scanning electron microscopy and assessed for their growth characteristics (i.e., determination of cell number and Ki67 antigen expression). The data presented seemed to indicate that if Saos-2 cells are grown on silane-modifed surfaces containing the methyl (CH(3)), hydroxyl (OH), and phenyl (C6H5) functional groups, their proliferation is slowed down while growth of these cells on glass surfaces modified with amino (NH(2)) and carboxyl (COOH) groups did not significantly affect growth. Once it was demonstrated that these three functional groups induce significant variations in proliferation, cells grown on these surfaces were also tested for apoptosis and expression of important markers of bone cell differentiation (i.e., osteonectin and osteopontin) by flow cytometry and eventual rearrangement of these markers by fluorescence microscopy. The data suggested that growth of Saos-2 cells on CH(3) induces the most evident morphological changes while growth of these cells on OH and C6H5 brings about the greater variations in osteonectin and osteopontin. We hypothesized that these changes are indicative of an increase in differentiation of Saos-2 cells when grown on the OH and C6H5 groups.
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PMID:Modulation of osteosarcoma cell growth and differentiation by silane-modified surfaces. 1125 87

Local growth of osteosarcoma involves destruction of host bone by proteolytic mechanisms and/or host osteoclast activation. Osteoclast formation and activity are regulated by osteoblast-derived factors such as the osteoclast differentiating factor, receptor activator of NF-kappaB ligand (RANKL) and the inhibitor osteoprotegerin (OPG). We have investigated the in vitro effects of bisphosphonates on a clonal rat osteosarcoma cell line. The aminobisphosphonate pamidronate was added to UMR 106-01 cell cultures (10(-8)M to 10(-4)M up to 5 days). The non-aminobisphosphonate clodronate was administered for the same time periods (10(-6)M to 10(-2)M). Cell proliferation, apoptosis and mRNA expression was assessed. Both agents inhibited cell proliferation in a time- and dose-dependent manner. ELISA analysis demonstrated an increase in DNA fragmentation although there was no significant dose-related difference between the doses studied. Bisphosphonate-treated cultures had a greater subpopulation of cells exhibiting morphological changes of apoptosis. Expression of mRNA for osteopontin and RANKL was down-regulated by both agents, while the expression of mRNA for alkaline phosphatase, pro-alpha1(I) collagen and OPG was not altered. Out in vitro work suggests the bisphosphonates not only have direct effects on osteosarcoma cell growth and apoptosis, but also, by altering the relative expression of osteoclast-regulating factors, they may inhibit the activity of osteoclasts and their recruitment.
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PMID:Bisphosphonates regulate cell growth and gene expression in the UMR 106-01 clonal rat osteosarcoma cell line. 1128 76


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