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)

The binding capacity and sub-cellular distribution of beta 2 adrenergic receptors was explored in rat osteosarcoma cells (ROS 17/2.8) following short-term (20 min) and long-term (24 hr) agonist treatment. ROS cells express about 27,000 beta 2 adrenergic receptors per cell, nearly 90% of which appear plasma membrane-associated by radioligand binding analysis. When cells were treated with isoproterenol for 20 min, lysed, and the lysate centrifuged over a gradient of sucrose, beta-adrenergic receptors in the plasma membrane fraction were found to decline from approximately 90% to 50%, while those in a lower-density "light" vesicle fraction increased from approximately 10% to 50%. Immunoblotting with specific antisera against the beta 2 adrenergic receptor revealed, in sharp contrast, that 60% of receptor was distributed in the plasma membrane-enriched fraction, 40% in the light vesicle fraction of untreated cells. A 20-min exposure to agonist caused the 60:40 distribution of immunoreactive receptor between the two fractions (plasma membrane:light vesicle) to shift to 35:65. The distribution of immunoreactive G beta 1-subunit (36,000-M(r)) between the two fractions was 80:20 and not influenced by exposure of cells to agonist. A 24 hr-exposure to agonist changed markedly the distribution of immunoreactive receptor from 60:40 to 90:10 (plasma membrane: light vesicle). Receptor content as determined by radioligand binding, in contrast, was nondetectable in either fraction prepared from ROS cells stimulated by agonist for 24 hr. Immunoblotting of post-nuclear, supernatant fractions of whole-cell lysates revealed no change in receptor content after 24 hr of agonist treatment. Furthermore, SDS-polyacrylamide gel electrophoresis and immunoblotting revealed no prominent proteolytic degradation of receptor in response to agonist stimulation at 20 min or 24 hr. Indirect immunofluorescence of beta adrenergic receptors in fixed, intact ROS cells probed only cell surface-associated receptor and yielded equivalent epifluorescence signals for untreated cells and cells treated with isoproterenol for either 20 min, or 24 hr. The immunological results confirm the phenomenon of agonist-induced receptor sequestration, but reveal several new insights: (i) beta adrenergic receptor protein content and subcellular distribution may not be accurately reflected by radioligand binding; (ii) receptor down-regulation (loss of binding) after 24 hr exposure to agonist cannot be explained by enhanced receptor degradation; (iii) the cell surface complement of receptor is not altered at 20 min or 24 hr following stimulation of cells with agonist; and (iv) lateral sequestration of receptors to separate domains of the cell membrane occurs when ROS 17/2.8 cells are exposed to beta-agonist for a short time (20 min).
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PMID:Agonist regulation of beta-adrenergic receptors: immunoblotting and indirect immunofluorescence reveal agonist-induced lateral sequestration and loss of binding. 890 7

Human osteosarcoma cells secrete a novel C-X-C chemokine called granulocyte chemotactic protein-2 (GCP-2), which was previously identified by amino acid sequencing of the purified natural protein. In order to understand the role of this new protein in inflammatory reactions, we cloned GCP-2 DNA sequences to generate recombinant protein and specific DNA probes and primers. By means of PCR on cloned cDNA of osteosarcoma cells induced by interleukin-1 beta and fibroblasts induced by lipopolysaccharide plus dsRNA, the complete coding domain of GCP-2 was isolated. This sequence was cloned into the bacterial expression vector pHEN1 and, after induction, GCP-2 was secreted into the periplasm of Escherichia coli. Recombinant GCP-2 (rGCP-2) was purified and characterized by SDS/PAGE as a monomeric 6.5-kDa protein and by amino-terminal sequencing. The chemoattractive potency of GCP-2 for neutrophilic granulocytes was about 10-times less than that of interleukin-8 and the minimal effective dose was 10 ng/ml. However, at optimal dose (100 ng/ml) the maximal chemotactic response was comparable with that of interleukin-8. Both characteristics correspond with those of natural GCP-2. In addition, intracellular calcium release in neutrophils by recombinant GCP-2 was achieved with as little as 10 ng/ml. Quantitation studies using reverse transcriptase and the polymerase chain reaction revealed higher GCP-2 mRNA production in normal fibroblasts than in tumor cells. When compared with epithelial-cell-derived neutrophil-activating peptide-78 (ENA-78) mRNA, the GCP-2 mRNA levels were higher in all cell lines tested. In addition, GCP-2 and ENA-78 expression seem to be differentially regulated in that phorbol ester and lipopolysaccharide have opposing effects on their mRNA induction in diploid fibroblasts and epithelial cells, respectively. Interleukin-1 was demonstrated to be a general inducer for both chemokines, while interferon-gamma down-regulates their mRNA expression. The availability of recombinant GCP-2 together with the quantitation studies on mRNA expression will help to further elucidate the biological role of GCP-2 during the inflammatory response.
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PMID:Cloning, bacterial expression and biological characterization of recombinant human granulocyte chemotactic protein-2 and differential expression of granulocyte chemotactic protein-2 and epithelial cell-derived neutrophil activating peptide-78 mRNAs. 905 43

We previously described Na+-Ca2+ exchange in osteoblastic rat osteosarcoma cells (UMR-106) and demonstrated that Na+-dependent Ca2+ transport was inhibited by 24-hour treatment of cells with parathyroid hormone (PTH), prostaglandin E2 (PGE2), or 1,25(OH)2D3. To determine whether this inhibition of Na+-Ca2+ exchange is at the level of exchanger protein synthesis we have examined exchanger protein levels using immunoblot analysis. UMR-106 cells were treated for 24 hours with or without PTH, PGE2, or 1,25(OH)2D3. Plasma membrane fractions (7500 g) were obtained and proteins were separated by SDS-PAGE, transferred to nylon membranes, and immunoblotted with a polyclonal antibody to the canine cardiac Na+-Ca2+ exchanger. In rat cardiac membranes, we detected 125 and 75 kD bands, similar to findings for the canine exchanger. In the osteoblastic UMR cell membranes, a specific band was detected at 90 kD that decreased 65% after treatment of cells with PTH. Inhibition by PTH was dose dependent, was maximal with 10(-7) M PTH, and required 16-24 hour treatment time. Similar inhibition was observed after a 24 hour treatment with 10(-6) M PGE2 or 10(-8) M 1,25(OH)2D3. These results demonstrate the presence of a specific protein in UMR cells that cross-reacts with antibody directed against the cardiac Na+-Ca2+ exchanger. Thus, the previously reported inhibition of Na+-Ca2+ exchange activity by calcemic agents in osteoblasts appears to be due to regulation of exchanger protein levels in these osteoblastic cells.
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PMID:Parathyroid hormone, prostaglandin E2, and 1,25-dihydroxyvitamin D3 decrease the level of Na+-Ca2+ exchange protein in osteoblastic cells. 911 67

We recently demonstrated that basic fibroblast growth factor (FGF-2) and platelet-derived growth factor-BB (PDGF-BB) mainly activated extracellular signal-regulated kinase 2 (ERK2) in normal human osteoblastic (HOB) and bone marrow stromal (HBMS) cells by an "in-gel" MAP kinase assay, although both ERK1 and ERK2 proteins were present. In the present study, we examined whether ERK1 is also activated by growth factors by using three different MAPK assay procedures, an "in-gel MAP kinase assay," an immune-complex kinase assay, and western blotting with anti-active MAPK antibody which recognizes specifically activated forms of both ERK1 and ERK2. Results have demonstrated that in addition to ERK2, ERK1 is activated by FGF-2 and PDGF-BB in normal HOB and HBMS cells. The human ERK1 moved faster on SDS-polyacrylamide gel compared to rat and mouse, revealing differences in the apparent molecular weight of FRK1 in normal human osteoblastic and bone marrow osteoprogenitor cells, human (TE-85) and rat (ROS 17/2.8 and UMR-106) osteosarcoma, and mouse (MC3T3E1) osteoblastic cells. ERK1 is less stable in the in-gel renaturation process compared to ERK2; thus, in-gel MAP kinase assay does not provide an accurate estimation of ERK1 activity. Results also showed that anti-active MAPK antibody can be used reliably and accurately to measure the activation of ERK1 and ERK2 in osteoblastic cells.
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PMID:Activation of extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2) by FGF-2 and PDGF-BB in normal human osteoblastic and bone marrow stromal cells: differences in mobility and in-gel renaturation of ERK1 in human, rat, and mouse osteoblastic cells. 929 66

Treatment for osteosarcoma is problematic because there are no prognostic markers. Diagnosis is primarily limited to cytologic grading. Oncogenesis alters cell structure therefore osteoblast tissue matrix proteins (extracellular matrix, cytoskeletal, intermediate filament, and nuclear matrix proteins), components of the cell substructure, are candidates for osteosarcoma markers. Structural proteins of the extracellular matrix, e.g. the collagens, are useful for diagnosis but not for tumors that produce little osteoid. To identify principal cellular tissue matrix proteins that distinguish normal from transformed human osteoblasts, their expression in normal osteoblasts, two osteosarcoma cell lines, and three primary osteosarcoma tumors were compared. The tumors were graded as (i) intermediate, (ii) high, and (iii) high grade recurrent. The 1-D SDS/PAGE profiles of the major components of the nuclear matrix and intermediate filament fractions from normal osteoblasts did not vary with biopsy site, age, or sex of patients. These profiles included known cytoskeletal proteins and OB250, a approximately 250 kD protein(s) observed in the intermediate filament fraction. A loss of protein bands, including OB250, was observed in the osteosarcoma cell lines and tumors. The intermediate and high grade tumors exhibited nearly identical protein profiles including potential tumor-specific proteins and collagen, consistent with the presence of intracellular collagen fibers in osteosarcoma. A microsequence was obtained for OT25, a novel low molecular weight protein observed in osteosarcoma cell lines. Fibrinogen gamma-chain, a protein that mediates cell adhesion was recovered from the high grade recurrent tumor.
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PMID:Tissue matrix protein expression in human osteoblasts, osteosarcoma tumors, and osteosarcoma cell lines. 940 69

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

To investigate the long-term efficacy of irradiated recombinant human osteogenic protein 1 (hOP-1) in bone regeneration and morphogenesis, hOP-1 was combined with a bovine collagenous matrix carrier (0, 0.1, 0.5, and 2.5 mg hOP-1/g of matrix), sterilized with 2.5 Mrads of y-irradiation, and implanted in 80 calvarial defects in 20 adult baboons (Papio ursinus). The relative efficacy of partially purified bone-derived baboon bone morphogenetic proteins (BMPs), known to contain several osteogenic proteins, was compared with the recombinant hOP-1 device in an additional four baboons. Histology and histomorphometry on serial undecalcified sections prepared from the specimens harvested on day 90 and day 365 showed that gamma-irradiated hOP-1 devices induced regeneration of the calvarial defects by day 90, although with reduced bone area compared with a previous published series of calvarial defects treated with nonirradiated hOP-1 devices. One year after application of the irradiated hOP-1 devices, bone and osteoid volumes and generated bone tissue areas were comparable with nonirradiated hOP-1 specimens. Moreover, 365 days after healing regenerates induced by 0.5 mg and 2.5 mg of irradiated hOP-1 devices showed greater amounts of bone and osteoid volumes when compared with those induced by nonirradiated hOP-1 devices. On day 90, defects treated with 0.1 mg and 0.5 mg of bone-derived baboon BMPs, combined with irradiated matrix, showed significantly less bone compared with defects receiving irradiated devices containing 0.1 mg and 0.5 mg hOP-1; 2.5 mg of partially purified BMPs induced bone and osteoid volumes comparable with the 0.1-mg and 0.5-mg hOP-1 devices. Control specimens of y-irradiated collagenous matrix without hOP-1 displayed a nearly 2-fold reduction in osteoconductive bone repair when compared with nonirradiated controls. These findings suggest that the reduction in bone volume and bone tissue area on day 90 may be caused by a reduced performance of the irradiated collagenous matrix substratum rather than to a reduction in the biological activity of the irradiated recombinant osteogenic protein. This is supported by the results of in vitro and in vivo studies performed to determine the structural integrity of the recovered gamma-irradiated hOP-1 before application in the baboon. Recoveries by high-performance liquid chromatography (HPLC) and sodium dodecyl sulfate/ polyacrylamide gel electrophoresis (SDS/PAGE)/immunoblot analyses indicated that doses of 2.5-3 Mrads of gamma-irradiation did not significantly affect the structural integrity of the recovered hOP-1. Biological activity of the recovered hOP-1 was confirmed in vitro by showing induction of alkaline phosphatase activity in rat osteosarcoma cells (ROS) and in vivo by de novo endochondral bone formation in the subcutaneous space of the rat. These findings in the adult primate indicate that a single application of gamma-irradiated hOP-1 combined with the irradiated xenogeneic bovine collagenous matrix carrier is effective in regenerating and maintaining the architecture of the induced bone at doses of 0.5 mg/g and 2.5 mg/g of carrier matrix.
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PMID:Long-term evaluation of bone formation by osteogenic protein 1 in the baboon and relative efficacy of bone-derived bone morphogenetic proteins delivered by irradiated xenogeneic collagenous matrices. 1097 99

Hepatitis B virus infection is primarily mediated by the interaction of the preS region of the viral envelope protein with its still unknown cellular receptor. Using recombinantly expressed preS proteins, the distribution of preS-binding receptors on cell lines from extrahepatic origins was determined by immunofluorescence and flow cytometry. In contrast to human liver cell lines, most cell lines from extrahepatic origins did not bind preS proteins. Nevertheless, exceptions were found in the bone marrow-derived cell line, KG-1, and the osteogenic sarcoma cell line SaOS-2, as well as in the previously reported EBV-transformed B-cell line, Wa. To determine the biochemical nature of these receptors, Wa-cells were cell surface biotinylated and the preS-binding receptors were isolated by immunoprecipitation. A specific band with a molecular weight of approximately 30 kDa was identified in a SDS-polyacrylamide gel, which further characterization is expected to provide clues regarding the infection mechanism of HBV in hepatic- and extra-hepatic cells.
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PMID:Detection of cellular receptors specific for the hepatitis B virus preS surface protein on cell lines of extrahepatic origin. 1102 70

Oxidative damage to mitochondria is a central mechanism of apoptosis induced by many toxic chemicals. Thioredoxin family proteins share a conserved Cys-X-X-Cys motif at their active center and play important roles in control of cellular redox state and protection against oxidative damage. In addition to the well studied cytosolic and extracellular form (Trx1), rat and avian mitochondrial forms of thioredoxin (mtTrx) have been reported. In this study, we cloned the full-length human mtTrx cDNA and performed localization and functional studies in 143B human osteosarcoma cells. The coding sequence of human mtTrx consists of a region with homology to Trx1 as well as a putative mitochondrial localization signal (MLS) at its N terminus. In stably transfected cell lines, mtTrx had a mitochondrial localization as measured by subcellular fractionation studies and by confocal fluorescence microscopy. Deletion of the MLS rendered mtTrx to be solely expressed in the cytosolic fraction. On SDS-PAGE, transfected mtTrx had the same apparent molecular weight as the MLS truncated form, indicating that the leader sequence is cleaved during or after mitochondrial import. Treatment with the oxidant tert-butylhydroperoxide induced apoptosis in 143B cells. This oxidant-induced apoptosis was inhibited by overexpressing the full-length mtTrx in 143B cells. Thus, human mtTrx is a member of the thioredoxin family of proteins localized to mitochondria and may play important roles in protection against oxidant-induced apoptosis.
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PMID:Overexpressed human mitochondrial thioredoxin confers resistance to oxidant-induced apoptosis in human osteosarcoma cells. 1203 45

Growth hormone (GH) treatment has been used in children with intrauterine growth retardation (IUGR) to promote growth with success in several short- and long-term clinical trials. Intermittent GH therapy has also been advocated in children with IUGR. This study was designed to evaluate the growth of children with IUGR after discontinuation of a two-year trial of GH treatment. Sixteen children (12 F, 4 M) who had received GH (Genotropin) at age 5.3 (1.3) years at a dose of 0.2 IU/kg/day for 2 years (Group 1) and 10 (6 F, 4 M) controls of age 4.3 (1.7) years without treatment (Group 2) were followed after completion of the trial over a median period of 4 years. Height SDS of the GH-treated group showed an increase from -3.0 (0.5) to -1.9 (0.7) (p <0.001) over 2 years of therapy. Off therapy, height SDS decreased to -3.5 (0.5) at a mean age of 11.2 (1.6) years. The difference between the initial and recent height SDS in this group was significantly different (p = 0.02). Height SDS of the control group, -2.7 (1.4) initially, did not change over the two-year observation period. At follow-up, seven control children received GH in a similar fashion for one year. In spite of an insignificant increase in height SDS on one year of GH, it decreased to -2.9 (1.6) at age 11.0 (2.1) years at the latest visit. There was no significant difference between the recent heights of the two groups at final examination. One girl in Group 1 developed acanthosis nigricans and type 2 diabetes mellitus at age 13.3 years, after the follow-up period. A second patient developed osteosarcoma in the left tibia at age 9.9 years, for which she received chemotherapy and surgery. In conclusion, height SDS showed a significant increase on GH therapy for 2 years in children with IUGR; however, it decelerated after discontinuation of therapy. At the final visit, GH therapy did not seem to have had any effect on height prognosis. This finding shows that GH should be given continuously to improve final height in children with IUGR.
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PMID:Follow-up height after discontinuation of growth hormone treatment in children with intrauterine growth retardation. 1209 89


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