Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00369 (ROS)
 19,271 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A proinflammatory cytokine cascade, including IL-1 alpha, IL-1 beta, TNF-alpha, IL-6, and IL-8, is activated in response to infection or immunologic insult. Besides their immunologic effects, several of these mediators stimulate bone resorption and inhibit bone formation. Osteocalcin, the most abundant noncollagenous protein present in bone, is an osteoblast-specific product whose production closely correlates with bone formation, and which has also been implicated in control of bone resorption. IL-1 and TNF have previously been shown to down-regulate osteocalcin production in vitro and in vivo, although the mechanism of this inhibition is unknown. In the present studies, IL-1 beta and TNF-alpha both inhibited 1,25-dihydroxyvitamin D3-stimulated production of osteocalcin protein and mRNA by ROS 17/2.8 osteosarcoma cells, whereas IL-6 had no effect on protein and only weakly inhibited mRNA. To determine if down-regulation was exerted at the transcriptional level, an osteocalcin promoter-chloramphenicol acetyltransferase (CAT) fusion gene was constructed (PHOC-CAT). After transient transfection of PHOC-CAT into ROS 17/2.8 osteosarcoma cells, reporter CAT activity was up-regulated by vitamin D at concentrations above 10(-12) M. In screening studies, TNF-alpha (-57%) and IL-6 (-37%) inhibited vitamin D-stimulated osteocalcin transcription, whereas IL-1 alpha, IL-1 beta, and IL-8 had no effect. Other immune cytokines and growth factors, including IL-2, IL-3, IL-7, and M-CSF, also failed to regulate osteocalcin transcription. Despite their lack of promoter regulation, IL-1 alpha and IL-1 beta also stimulated PGE2 production by ROS 17/2.8, further confirming the ability of the host cell to respond to these mediators. In dose-response experiments, down-regulation by TNF-alpha was significant at concentrations as low as 0.14 pM (0.1 U/ml), whereas approximately 10(4)-fold higher concentration of IL-6 was required to exert a similar effect. TNF-alpha-mediated down-regulation was unaffected by indomethacin. These data demonstrate that of these cytokines, TNF-alpha alone potently down-regulates osteocalcin promoter function, whereas IL-1 acts post-transcriptionally, possibly by reducing mRNA stability. Heterogeneity therefore exists among the proinflammatory cytokines with respect to the level at which control of osteocalcin expression is exerted.
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PMID:Proinflammatory cytokines tumor necrosis factor-alpha and IL-6, but not IL-1, down-regulate the osteocalcin gene promoter. 130 41

Interleukin 6 (IL-6) exerts well-established effects on cells of the immune system as well as on various other cell types. It has been implicated in the control of connective tissue cells in such conditions as rheumatoid arthritis and osteoporosis. We have investigated the effects of recombinant human interleukin-6 (rhIL-6) on human osteoblastlike cells derived from explants of trabecular bone. ROS 17/2.8 cells were used as an additional osteoblastlike cell model system. We were unable to identify any effects of rhIL-6 (5-5000 pg/ml) on the proliferation, alkaline phosphatase activity. osteocalcin production, or release of cytokines or prostaglandins by either osteoblastlike cell model system. Since we have shown previously that these cells release IL-6 in culture, we used a sheep anti-human IL-6 antibody to investigate the possibility that (1) action of added exogenous IL-6 could be masking endogenous production, and (2) endogenous IL-6 may regulate the effects of osteotropic agents on the osteoblastlike cells. Presence of the antibody exerted no detectable effects on 1,25-(OH)2D3-stimulated alkaline phosphatase or on proliferation or TNF production enhanced by IL-1. Thus IL-6 does not appear to be involved in the regulation of osteoblast activity.
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PMID:Human osteoblastlike cells do not respond to interleukin-6. 170 32

Interleukin 6 (IL-6) probably plays a central role in the acute phase response and in haemopoiesis and may be involved in the control of bone turnover. We have studied the release of IL-6 from human trabecular bone cells treated with a variety of stimuli using a specific bioassay. In serum free medium, unstimulated human osteoblast-like cells produced IL-6 in the range of 1000-2050 pg/ml/24 h. Recombinant human interleukin 1 (IL-1 alpha) (10(-13)-10(-11) M), tumor necrosis factor alpha (TNF alpha) (10(-9)-10(-7) M) and lipopolysaccharide (5-500 ng/ml) all stimulated release of IL-6 from human bone cells. Maximal levels of 17,000 pg/ml were observed using the highest concentration of IL-1. 1,25(OH)2D3 and PTH did not stimulate IL-6 release. Using a specific sheep antihuman IL-6 antibody, all IL-6 activity could be neutralized. In parallel studies, ROS 17/2.8 rat osteosarcoma cells released around 50 pg/ml of IL-6 under basal conditions which were increased to a maximum of 900 pg/ml by treatment with PTH (10(-9) M). The cytokines were less effective and 1,25(OH)2D3 again had no effect. Modulation of expression of IL-6 mRNA in human osteoblast cells was examined using a human complementary deoxyribonucleic acid probe. The mRNA was constitutively expressed, and IL-1 (10(-11) M) and TNF (10(-7) M) induced further mRNA expression within 2 h, which was sustained over 24 h. 1,25(OH)2D3 (10(-7) M), IL-6 (2000 pg/ml), and PTH (10(-9) M) exerted no effects at any time point. Dexamethasone (10(-6) M) suppressed both basal and IL-1- and TNF-induced IL-6 mRNA expression. IL-6 receptor mRNA was constitutively expressed but was not regulated by any of the above agents. It is clear that rodent and human osteoblasts differ in their production of IL-6 and its modulation. These data support the hypothesis that IL-6 is produced locally in human bone by osteoblasts under the direction of other cytokines. This could have implications in bone remodeling, haemopoiesis, and systemic responses to local injury.
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PMID:The modulation of the expression of IL-6 and its receptor in human osteoblasts in vitro. 171 33

Tumor necrosis factor-alpha (TNF alpha), a 17,000 mol wt protein, mediates a variety of immunological and inflammatory events. TNF alpha is a potent inhibitor of bone collagen synthesis and stimulator of osteoclastic bone resorption, the net effect of which is to cause bone loss. We have previously reported that TNF alpha inhibits the synthesis of collagen by osteoblastic cells in culture out of proportion to effects on total protein synthesis, suggesting that inhibition of bone formation by TNF alpha may be due to selective inhibition of matrix protein synthesis. To further test this hypothesis and to evaluate the mechanism of TNF alpha action, we studied the effect of TNF alpha on synthesis of the osteoblast-specific bone Gla protein (BGP) by ROS 17/2.8 cells, which have the osteoblast phenotype. Cells were cultured with 10 nM 1,25-dihydroxyvitamin D3 to stimulate BGP secretion, followed by the addition of TNF alpha (1-100 ng/ml) in 1,25-dihydroxyvitamin D3-containing medium. TNF alpha (10 ng/ml) inhibited BGP secretion to 42 +/- 5%, 19 +/- 10%, and 15 +/- 3% of control values after 24, 48, and 72 h of treatment. After 48 h, inhibition of BGP secretion was observed with 2 ng/ml TNF alpha and was maximum with 100 ng/ml. To determine the effect of TNF alpha on total protein synthesis, cells were pulse labeled with [14C]leucine during the last 4 h of TNF alpha treatment, and incorporation of radioactivity into trichloroacetic acid-precipitable protein in cell layer and medium was determined. The TNF alpha inhibition of BGP secretion was independent of changes in [14C]leucine incorporation, suggesting that TNF alpha did not have a general inhibitory effect on total protein synthesis. Cell number was not affected by TNF alpha. Northern analysis of steady state BGP mRNA revealed a dose-dependent decrease in the BGP/cyclophilin mRNA hybridization signal intensity after 24 h of treatment. The maximum inhibitory effect was 41 +/- 5% of the control value with 100 ng/ml TNF alpha. The effect of TNF alpha on steady state BGP mRNA levels was not prevented by treatment of cells with cycloheximide, suggesting that TNF-induced new protein synthesis was not required for TNF alpha action. These results suggest that the mechanism of TNF alpha inhibition of BGP synthesis includes a pretranslational site and support the hypothesis that TNF alpha inhibits bone formation by a selective inhibition of matrix protein production.
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PMID:Tumor necrosis factor-alpha inhibits 1,25-dihydroxyvitamin D3-stimulated bone Gla protein synthesis in rat osteosarcoma cells (ROS 17/2.8) by a pretranslational mechanism. 201 66

Tumor necrosis factor-alpha (TNF alpha) and interferon-gamma (IFN gamma) have potent effects on bone resorption and collagen synthesis in cultured rat long bones. Since the effects of TNF alpha and IFN gamma may result from interaction with multiple cell types, we studied the effects of these cytokines on the synthesis of DNA and collagen in one cell type with osteoblast phenotype, cloned rat osteosarcoma cells (ROS 17/2.8). Recombinant human TNF alpha did not affect DNA synthesis after 48 h with concentrations of 10(-11)-10(-8) M and inhibited DNA synthesis slightly at 10(-6) M. Recombinant rat IFN gamma (5-500 U/ml) caused a dose-dependent inhibition of DNA synthesis. Coincubation with TNF alpha and IFN gamma inhibited DNA synthesis more than maximal doses of either cytokine alone. This enhanced inhibitory effect was due to the induction of a response to TNF alpha by IFN gamma, since preexposure of cells to IFN gamma for 24 h, followed by incubation with TNF alpha alone for an additional 48 h, also resulted in increased inhibition of DNA synthesis. Preexposure to TNF alpha for 24 h, followed by IFN gamma alone, did not increase the inhibition of DNA synthesis. Incubation with either IFN gamma (5-500 U/ml) or TNF alpha (10(-10)-10(-6) M) inhibited the incorporation of [3H]proline into collagen. Coincubation with intermediate concentrations of both cytokines resulted in an inhibitory effect greater than that produced by maximal concentrations of either alone. The results indicate that 1) IFN gamma and TNF alpha have direct actions on osteoblast-like cells in vitro; 2) IFN gamma modulates the DNA response to TNF alpha; and 3) the greater responses to combined cytokines than to high doses of either alone suggest that these cytokines act, at least in part, through different pathways.
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PMID:Inhibitory effects of tumor necrosis factor-alpha and interferon-gamma on deoxyribonucleic acid and collagen synthesis by rat osteosarcoma cells (ROS 17/2.8). 249 7

Transcripts coding for transcription factors (RB, P53, FOS, MYC, MYB, ERBA, REL), growth factors (FGF1, FGF2, INT2, TGFA, TGFB, PDGF, IGF1, IGF2), interleukins, (IL1, IL2, IL3, IL4, IL6, TNF), growth-factor receptors or cytosolic protein kinases (RAF, PIM, FES, MET, SRC, ROS, TRK, KIT, CSFR, IGFR, PDGFR, EGFR, NEU) were quantified in cultured human mammary fibroblasts from normal tissues, benign tumours, carcinomas and post-radiation fibrosis lesions by slot-blot autoradiography and image analysis. The effects of a differentiating agent (cholera toxin) and of a tumour promoter (12-O-tetradecanoyl-phorbol-13-acetate) were also examined. The drugs modulated the levels of the anti-oncogene transcripts (RB, P53) and of ERBA, REL, RAF, MET, ROS, TRK, CSFR, EGFR, NEU, FGF1, INT2, IGF1, IL1, IL2, IL4 and IL6. Apart from this variation, there were multiple differences in gene expression among normal and pathological cells (concerning all but P53, TGFB and interleukin transcripts) and between sub-types defined by the presence of alpha-sm-actin (myofibroblasts) or EDB-fibronectin (RAF, ROS, FES, KIT, IGFR, NEU, INT2, TGFB, PDGF, IGFs, ILs). It appears, therefore, that mammary stroma progress irreversibly along with the epithelium during tumoral development, and that breast cancer is not only a multi-gene but also a multi-tissue phenotype.
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PMID:Quantitative variation of proto-oncogene and cytokine gene expression in isolated breast fibroblasts. 776 44

Tumor necrosis factor-alpha (TNF alpha) is one of several autocrine/paracrine factors known to exert potent inhibitory effects on bone. We have shown that TNF alpha inhibition of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]-stimulated synthesis of the bone-specific protein osteocalcin (OC) occurs by decreasing steady state levels of OC mRNA, suggesting a pretranslational mechanism. In many genes, TNF alpha action is mediated by the transcription factor NF kappa B. Analysis of OC 5'-flanking DNA revealed a sequence structurally homologous to the previously described NF kappa B-binding site and, thus, a potential TNF alpha response element. Deletion analysis was performed to identify the sequences mediating the response to TNF alpha in osteoblastic ROS 17/2.8 cells by transient transfection with reporter constructs containing rat OC 5'-flanking DNA [chloramphenicol acetyltransferase (CAT)] that retained or deleted homologous NF kappa B sites or a previously defined 1,25-(OH)2D3 response element (VDRE). Transfection with all reporter constructs resulted in low basal CAT activity, measured 72 h after transfection. 1,25-(OH)2D3 stimulated CAT activity 2.8- to 4.5-fold in cells transfected with constructs that included the VDRE. TNF alpha inhibited 1,25-(OH)2D3-stimulated, but not basal, CAT activity. Deletion analysis localized the effect of TNF alpha to a sequence between -522 and -306 relative to the OC transcription start site, an area that included the VDRE but deleted a homologous NF kappa B element. Transfection of cells with a heterologous reporter containing one copy of the OC VDRE inserted in correct orientation or two copies in inverse orientation was sufficient to confer a response to TNF alpha. Gel mobility shift analysis of DNA-nuclear protein interaction revealed that 1,25-(OH)2D3 stimulated an increase in binding of nuclear proteins to an OC 32P-VDRE probe. Preincubation of nuclear extract with specific monoclonal antibodies confirmed that the proteins binding the VDRE included the vitamin D receptor and retinoid-X receptor. TNF alpha treatment of cells inhibited the 1,25-(OH)2D3-stimulated increase in nuclear protein binding to the VDRE. These results suggest 1) the VDRE is sufficient to confer a response to the inhibitory effect of TNF alpha on 1,25-(OH)2D3-stimulated rat OC gene transcription; 2) the action of TNF alpha does not require homologous NF kappa B response elements; and 3) the mechanism of TNF alpha inhibition of 1,25-(OH)2D3-stimulated OC gene expression includes modulation of binding of the vitamin D receptor/retinoid-X receptor heterodimer to the VDRE.
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PMID:A single up-stream element confers responsiveness to 1,25-dihydroxyvitamin D3 and tumor necrosis factor-alpha in the rat osteocalcin gene. 811 49

Isolated limb perfusion (ILP) with TNF alpha, IFN gamma and melphalan causes impressive tumour reduction in patients with irresectable soft tissue sarcomas with a high limb salvage rate. Since this therapy could be of value in patients with progressive osteosarcoma, we performed a study in an osteosarcoma tumour model in the rat. The ROS-1 osteosarcoma was implanted s.c. in the hind leg of WAG rats. Rats were divided in four groups: rats that underwent ILP with perfusate alone, TNF alpha alone, melphalan alone or their combination. Almost all rats, treated with a sham ILP or a perfusion with 40 micrograms melphalan, showed progressive disease (PD) (6/6 and 5/6). After perfusion with 50 micrograms TNF alpha alone a varied response was observed: 2/6 PD, 2/6 no change (NC) and 2/6 a complete remission (CR). After combined perfusion: 3/6 rats had a partial remission and 3/6 a CR. The best and most consistent responses are obtained by combining TNF alpha and melphalan. The discrepancy with the in vitro sensitivity of ROS-1 indicates that indirect effects are important in this tumour model.
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PMID:Isolated limb perfusion with TNF alpha and melphalan in a rat osteosarcoma model: a new anti-tumour approach. 860 32

Inflammation provides those searching in the field with a number of "models" allowing them to study, in vivo, in humans and in animals, the regulation and the functions of HSP, which are being considered as a new and promising marker for the severity and the prognosis of inflammatory diseases. HSP are differentially regulated according to the type of inflammation, whether acute or chronic, whether self-limiting (inflammatory cell elimination by apoptosis) or self-perpetuating (inflammatory cell death by necrosis). We propose that mitochondria are a key organelle in determining the outcome of inflammation, because they are both the cellular "switchboard" for apoptosis and a selective target for the protective effects of HSP against the cytotoxic effects of TNF alpha and ROS. On the other hand, HSP exert multiple protective effects in inflammation, including self/non-self discrimination, enhancement of immune responses, immune protection, thermotolerance and protection against the cytotoxicity of inflammatory mediators. The latter protective effects against the deleterious effects of the mediators of inflammation, including ROS and cytokines, open new avenues for the development of original anti-inflammatory therapies, such as non-toxic inducers of a complete HS response. It may well be that the "beneficial effects of fever" already described by Hippocrates actually relate to increased HSP expression during fever, and to their protective effects....
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PMID:Stress proteins in inflammation. 885 86

TNF is produced during inflammation and induces, among other activities, cell death in sensitive tumour cells. We previously reported an increased generation of ROS in TNF-treated L929 fibrosarcoma cells prior to cell death. These ROS are of mitochondrial origin and participate in the cell death process. Presently, we focus on the identification of parameters that control ROS production and subsequent cytotoxicity. From the cytotoxic properties and susceptibility to scavenging of TNF-induced ROS as compared to pro-oxidant-induced ROS we conclude that TNF-mediated ROS generation and their lethal action are confined to the inner mitochondrial membrane. Oxidative substrates, electron-transport inhibitors, glutathione and thiol-reactive agents but also caspase inhibitors modulate TNF-induced ROS production and imply the existence of a negative regulator of ROS production. Inactivation of this regulator by a TNF-induced reduction of NAD(P)H levels and/or formation of intraprotein disulfides would be responsible for ROS generation.
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PMID:Redox regulation of TNF signaling. 1060 76


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