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)

Cyclic AMP production by freshly isolated cells, from a 32P-induced transplantable rat osteogenic sarcoma, was stimulated by PGE1, PGE2 and to a less extent by PGF2alpha and PGA2. In the case of PGE2, the cyclic AMP content of cells was maximal within 5 min. The 13,14-dihydroderivatives of PGE1, PGE2 and PGF2alpha had approximately 40% of the activity of the parent prostaglandin whilst, in every case, the metabolites (15-keto and 13,14-dihydro-15-keto) had very little activity. Two prostaglandin endoperoxide analogues (U44069 and U46619) had only 10% of the activity of an equimolar dose of PGE2. The data presented in this paper demonstrates similarities between the responses of these cells and cells derived from bony tissue in terms of the ability of prostaglandins to stimulate bone resorption in tissue culture.
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PMID:Rat osteogenic sarcoma cells:effects of some prostaglandins, their metabolites and analogues on cyclic AMP production. 19 86

Adenylate cyclase activity in particulate fractions from a transplantable rat osteogenic sarcoma was stimulated in a dose-dependent manner by prostaglandins E1 and E2 (PGE1 and PGE2) and parathyroid hormone (PTH). Prostaglandin F2alpha was active at a high concentration (3 x 10(-4) mol/l). Pretreatment of membranes with collagenase plus hyaluronidase reduced the magnitude of the PTH effect but did not affect the size of the PGE1 effect. Guanosine 5'-triphosphate and its synthetic analogue 5'-guanylylimidodiphosphate (Gpp(NH)p) activated adenylate cyclase in particulate preparations from the osteogenic sarcoma. The latter agent produced much larger effects, although the concentrations required for half-maximal enzyme activation were the same for both agonists (approximately 2 x 10(-6) mol/l). The effects of PTH and Gpp(NH)p were supra-additive at some concentrations of hormone. The effects of PGE1 and Gpp(NH)p were supra-additive at all hormone concentrations tested. Pre-incubation of membrane particles for 6 min with PTH produced an enzyme activation which was not reversed by dilution through washing; pre-incubation with PGE1 did not produce this effect. The response of membrane adenylate cyclase to Gpp(NH)p (10(-4) mol/l) was 75% greater in preparations pre-incubated with PTH than in membranes pre-incubated in buffer alone or in buffer containing PGE1. The basal rate of cyclic AMP production in the adenylate cyclase assay system decreased over a 35 min incubation period. This decrease was prevented by addition of PTH or PGE1. Addition of NaF or Gpp(NH)p produced a steady increase in the rate of production of cyclic AMP with time. Membrane preparations did not reduce the biological activity of PTH and did not degrade 125I-labelled PTH. The results demonstrate that the PTH- and PGE-responsive adenylate cyclases of the osteogenic sarcoma have distinctly different properties and that particulate preparations of the tumour do not metabolize PTH.
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PMID:Membranes from a transplantable osteogenic sarcoma responsive to parathyroid hormone and prostaglandins: regulation of adenylate cyclase and of hormone metabolism. 27 36

To gain insight into the cellular regulation of bovine leukemia virus (BLV) trans activation, a lambda-gt11 cDNA library was constructed with mRNA isolated from a BLV-induced tumor and the recombinant proteins were screened with an oligonucleotide corresponding to the tax activation-responsive element (TAR). Two clones (called TAR-binding protein) were isolated from 750,000 lambda-gt11 plaques. The binding specificity was confirmed by Southwestern (DNA-protein) and gel retardation assays. Nucleotide sequence analysis revealed that TAR-binding protein is very similar to the CREB2 protein. It contains a leucine zipper structure required for dimerization, a basic amino acid domain, and multiple potential phosphorylation sites. A vector expressing CREB2 was transfected into D17 osteosarcoma cells. In the absence of the tax transactivator, the CREB2 protein and the cyclic AMP-dependent protein kinase A activate the BLV long terminal repeat at a basal expression level: trans activation reached 10% of the values obtained in the presence of tax alone. These data demonstrate that CREB2 is a cellular factor able to induce BLV long terminal repeat expression in the absence of tax protein and could thus be involved in the early stages of viral infection. In addition, we observed that in vitro tax-induced trans activation can be activated or inhibited by CREB2 depending on the presence or absence of protein kinase A. These data suggest that the cyclic AMP pathway plays a role in the regulation of viral expression in BLV-infected animals.
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PMID:A cyclic AMP-responsive DNA-binding protein (CREB2) is a cellular transactivator of the bovine leukemia virus long terminal repeat. 130 10

The effect of four different neuropeptides and norepinephrine (NE) on cyclic AMP formation in four different osteoblastic cell lines and in isolated neonatal mouse calvarial bone cells has been examined. In the rat osteosarcoma cell line UMR-106-01, vasoactive intestinal polypeptide (VIP, 0.001-1 microM), calcitonin gene-related peptide (CGRP, 0.3-30 nM), and NE (0.1-300 microM), but not neuropeptide Y (NPY, 0.001-1 microM) or substance P (SP, 0.1-10 microM), caused a dose-dependent stimulation of cyclic AMP formation. The stimulatory effects were synergistically potentiated by forskolin (0.1-3 microM). The effects of NE and VIP were time dependent, with an optimal effect seen at 5 minutes. The amount of cyclic AMP accumulated in cells stimulated with NE and VIP was in the same range. The amplitude of the cyclic AMP response induced by CGRP was smaller than that caused by VIP and NE. In the human osteosarcoma cell line Saos-2, NE (0.1 microM) and VIP (0.3 microM) stimulated cyclic AMP formation, and the effect was synergistically potentiated by forskolin. In the absence of forskolin, no effect of CGRP (30 nM) could be seen in the Saos-2 cells, but in the presence of forskolin (3 microM) a stimulatory effect was observed. SP and NPY did not change basal cyclic AMP levels in Saos-2 cells. In the osteoblastic osteosarcoma cell line of rat, ROS 17/2.8, NE (0.1 microM) caused a significant stimulatory action on cyclic AMP formation that was synergistically potentiated by forskolin (3 microM), VIP, CGRP, and SP did not affect the cellular content of cyclic AMP in ROS 17/2.8.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Neuroendocrine regulation of cyclic AMP formation in osteoblastic cell lines (UMR-106-01, ROS 17/2.8, MC3T3-E1, and Saos-2) and primary bone cells. 138 76

Parathyroid hormone (PTH) and PTH-related protein (PTHrP) act via PTH receptors in bone to stimulate bone resorption. Bone resorption is also stimulated by certain cytokines, which are produced in bone and bone marrow. The effects of such cytokines on the PTH-receptor system were studied in the osteoblast-like osteosarcoma cell line UMR 106-06. 125I-labelled PTHrP-(1-84)-peptide bound specifically to the cells, and PTHrP-(1-34) and -(1-84) competed with equimolar affinity for binding to UMR 106-06 cells. The specific binding of 125I-PTHrP-(1-84) could be completely blocked by PTH. Therefore 125I-PTHrP-(1-84) bound to a classical receptor in UMR 106-06 cells. Preincubation for 3 days with either tumour necrosis factor alpha (TNF alpha) or retinoic acid (RA) both decreased the specific binding of 125I-PTHrP-(1-84) to about 40% of control levels. These effects were specific for PTH binding, since there was little effect on 125I-salmon-calcitonin binding. Both TNF alpha and RA required 24 h exposure to cells to produce a measurable effect. The decrease in 125I-PTHrP-(1-84) binding was due to a reduced number of binding sites, with little apparent change in affinity. Half-maximal effects were seen with 1 ng of TNF alpha/ml, whereas 1 microM-RA was needed to observe the loss of PTH receptors. Combinations of RA and TNF alpha produced a greater effect than that of either agonist alone. The loss of PTH receptors was accompanied by a specific loss of PTH-stimulated cyclic AMP production. Preincubation with TNF alpha increased the basal plasminogen activator (PA) activity in the cells and decreased the amplitude of the response of PA activity to PTH compared with control cells. Furthermore TNF alpha decreased sensitivity to PTH (50% stimulation of PA activity with 0.1 nM-PTH in control cells versus 50% stimulation with 0.3 nM-PTH in TNF alpha-treated cells). In contrast, TNF alpha pretreatment increased the amplitude of the response of PA activity to calcitonin, whereas sensitivity to calcitonin was not altered. These data are consistent with a specific down-regulation of PTH receptors in osteoblast-like UMR 106-06 cells after exposure to TNF alpha or RA. The loss of PTH receptors is accompanied by a decreased responsiveness to PTH, as measured with the PA system in these cells. A loss of PTH receptors could modulate PTH responses in osteoblasts, either in the local control of bone formation and resorption, or in pathological conditions such as humoral hypercalcaemia of malignancy.
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PMID:Specific down-regulation of parathyroid hormone (PTH) receptors and responses to PTH by tumour necrosis factor alpha and retinoic acid in UMR 106-06 osteoblast-like osteosarcoma cells. 166 Jul 13

The protein kinase C-(PKC) activating phorbol esters 12-O-tetradecanoylphorbol-13-acetate (TPA; 100 nmol/l) and phorbol 12,13-dibutyrate (PDBU; 100 nmol/l) enhanced basal cyclin AMP accumulation in cultured neonatal mouse calvaria. The cyclic AMP response to parathyroid hormone (PTH; 10 nmol/l) and the adenylate cyclase activators forskolin (1-3 mumol/l) and choleratoxin (0.1 mumg/ml) was potentiated in a more than additive manner by TPA and PDBU. In contrast, phorbol 13-monoacetate (phorb-13; 100 nmol/l), a related compound but inactive on PKC, had no effect on basal or stimulated cyclic AMP accumulation. In the presence of indomethacin (1 mumol/l), TPA and PDBU had no effect on cyclic AMP accumulation in calvarial bones per se, but were still able to cause a significant enhancement of the response to PTH, forskolin and choleratoxin. PTH-, forskolin- and choleratoxin-stimulated cyclic AMP accumulation in rat osteosarcoma cells UMR 106-01 was synergistically potentiated by TPA and PDBU, but not by phorb.-13. These data indicate that PKC enhances cyclic AMP formation and that the level of interaction may be at, or distal to, adenylate cyclase.
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PMID:Protein kinase C activating phorbolesters enhance the cyclic AMP response to parathyroid hormone, forskolin and choleratoxin in mouse calvarial bones and rat osteosarcoma cells. 166 87

We have investigated the effects of PTH-induced desensitization on second messenger interactions in the rat osteosarcoma cell line ROS 17/2.8. Adenylate cyclase activation was assessed by accumulation of immunoassayable cAMP, and cytosolic calcium ion ([Ca2+]i) concentrations were measured in adherent perifused cells loaded with the Ca2(+)-sensitive bioluminescent protein aequorin. Preexposure to rat PTH-(1-34) [rPTH-(1-34); 10(-8) M for 48 h, then 10(-7) M for 24 h] dramatically reduced (by 85%) the cAMP response to fresh challenge [2 min; 10(-9)-10(-7) M rPTH-(1-34)], but the peak PTH-induced rise of [Ca2+]i was not diminished significantly (0-20%). Nevertheless, we did observe other changes in the PTH-induced [Ca2+]i response. Exposure of treated cells to (Bu)2cAMP nearly abolished the [Ca2+]i response to PTH (greater than 80% reduction), but had much less effect on the PTH-stimulated [Ca2+]i increment of the naive cells (less than 35% reduction). Treated cells also had a blunted [Ca2+]i response to PTH in the presence of low extracellular calcium (greater than 60% reduction), but in the naive cells, low extracellular Ca2+ did not significantly diminish the peak PTH-induced [Ca2+]i rise, although low extracellular Ca2+ dramatically reduced the area under this [Ca2+]i transient (greater than 50%). Low extracellular Ca2+ had no influence on the peak [Ca2+]i responses of treated cells to bradykinin or prostaglandin F2 alpha. Although the peak PTH-stimulated [Ca2+]i rise of treated cells in normal Ca2+ medium was not significantly attenuated, the time to half-maximum [Ca2+]i concentration was significantly increased (greater than 100%), and the area under the [Ca2+]i transient was diminished. These alterations in the [Ca2+]i response of treated cells were not observed upon challenge with bradykinin or prostaglandin F2 alpha. Thus, 1) the cAMP and [Ca2+]i responses of ROS 17/2.8 cells to rPTH-(1-34) are not obligatorily coupled; 2) the response of naive cells to PTH includes both the release of Ca2+ from intracellular stores and the entry of extracellular Ca2+; and 3) pretreatment of these cells with rPTH-(1-34) augments the dependence on Ca2+ entry during hormone rechallenge. We propose that the preserved PTH-stimulated [Ca2+]i rise in treated cells results partly from loss of cAMP-mediated inhibition of extracellular Ca2+ entry.
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PMID:Desensitization of rat osteoblast-like cells (ROS 17/2.8) to parathyroid hormone uncouples the adenosine 3',5'-monophosphate and cytosolic ionized calcium response limbs. 184 74

We have examined the effects of parathyroid hormone (PTH) and PTH-related peptide (PTH-rP) on intracellular calcium (Ca2+i) in a rat osteogenic sarcoma cell line, UMR106. Synthetic bovine (b)PTH(1-34) caused a small inconsistent rise in Ca2+i in UMR106 cells, whilst cells pretreated with retinoic acid (RA, 1 mumol/l) for 18 h exhibited reproducible, significant and dose-dependent increases in Ca2+i levels in response to bPTH. The effect of RA on PTH-induced changes in Ca2+i were dependent upon both dose and time. Purified human (h)PTH-rP(1-34) increased Ca2+i in the absence of RA in the same cells. However, RA increased the magnitude of PTH-rP-stimulated changes in Ca2+i without affecting the concentration required for a maximal response. RA also prolonged the delay before the Ca2+i response was observed. Maximal responses to PTH-rP were greater in magnitude than those to PTH. These changes appeared not to be due to cyclic AMP (cAMP), since neither dibutyryl cAMP (1 mmol/l) nor forskolin (15 mumol/l) affected Ca2+i. PTH- and PTH-rP-mediated Ca2+i transients were not completely abolished by the absence of extracellular calcium, and both peptides increased basal levels of inositol trisphosphate. PTH and PTH-rP were subject to mutual desensitization, but were not desensitized by prostaglandin E2. PTH(7-34) antagonized PTH- but not PTH-rP-mediated Ca2+i transients. We conclude that there may be some important differences in the mechanism of action of PTH and PTH-rP.
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PMID:The effect of retinoic acid on parathyroid hormone- and parathyroid hormone-related peptide-induced intracellular calcium in a rat osteosarcoma cell line, UMR106. 203 Mar 32

Aluminum intoxication is associated with low osseous remodeling rate and peripheral resistance to parathyroid hormone (PTH). The pathophysiological mechanism of these aluminum induced changes was investigated using cultured clonal osteoblastic UMR-106 cells as well as dog renal cortical membrane. Both systems possess high-affinity PTH receptors that are coupled to adenylate cyclase. The UMR-106 cells have typical osteoblastic features, including receptors for the tissue-specific hormones, formation and mineralization of a bone-like ground substance and exclusive synthesis of type 1 collagen. The results show that aluminum at a concentration of 4 microM and 40 microM significantly inhibits the cyclic AMP responses to PTH challenge in UMR-106 cells, and this is associated with significant decrease in the binding to the PTH receptor. At 200 microM, no PTH-responsive adenylate cyclase or binding to receptor can be demonstrated. The effect of aluminum on UMR-106 rat osteosarcoma cells is not due to changes in cell number, cell viability or rate of mitogenesis. Similar results are obtained with dog kidney membrane. At a concentration of 10 microM and 400 microM, there is significant inhibition of the binding of PTH to kidney membrane and proportional decrease in PTH-stimulated adenylate cyclase. With higher concentration of aluminum, no response or binding can be demonstrated. In conclusion, aluminum at concentrations of 4 to 400 microM is associated with a decrease in affinity of PTH receptor and concomitant suppression of PTH-stimulated adenylate cyclase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of aluminum on the parathyroid hormone receptors of bone and kidney. 215 49

The influence of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on adenylate cyclase responsiveness in cultured osteoblastic cells was studied using a human osteosarcoma cell line SaOS-2. 1,25(OH)2D3 treatment had no effect on cell growth, cell protein and alkaline phosphatase activity. 1,25(OH)2D3 did not alter the basal production of cyclic AMP (cAMP) in intact cells, but the cAMP formation in response to parathyroid hormone (PTH), isoproterenol (ISO) and cholera toxin was attenuated by 1,25(OH)2D3. The response to forskolin, however, was unaffected by 1,25(OH)2D3 treatment. Islet activating protein failed to modify these 1,25(OH)2D3 effect. In cell free experiments, 1,25(OH)2D3 showed similar effect--that is, PTH and ISO-stimulated adenylate cyclase activity were attenuated, but forskolin-stimulated adenylate cyclase was unaffected. 1,25(OH)2D3 treatment had no effect on the kinetics of PTH binding to PTH receptor and on the ADP ribosylation of GTP stimulatory binding protein (Gs) in SaOS-2 cells. According to these results, 1,25(OH)2D3 appeared to change the coupling of Gs with adenylate cyclase, but does not affect receptor, Gs and adenylate cyclase themselves, nor GTP inhibitory binding protein.
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PMID:The effect of 1,25-dihydroxyvitamin D3 on human osteoblast-like osteosarcoma cell: modification of response to PTH. 216 Dec 22


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