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)

Recombinant human parathyroid hormone (hPTH) was expressed in Escherichia coli harboring a plasmid containing a synthetic human parathyroid hormone gene under the control of the E. coli lac promoter. Three major forms of the hormone were isolated by acid extraction and purified to homogeneity by high performance liquid chromatography. By amino acid analysis and NH2-terminal sequencing, these were identified as hPTH-(1-84), formyl-methionyl-hPTH-(1-84), and hPTH-(8-84). The recombinant hPTH-(1-84) was immunologically indistinguishable from a World Health Organization standard of extracted native hPTH-(1-84). Recombinant hPTH-(1-84) was also bioactive in renal and skeletal adenylate cyclase assays. In the skeletal bioassay performed in UMR 108 osteosarcoma cells its activity was identical to that of an hPTH-(1-84) standard. In this bioassay, formyl-methionyl-hPTH-(1-84) had 10% of the activity of hPTH-(1-84) and hPTH-(8-84) was inactive. The results demonstrate the importance of isolating hPTH-(1-84) from other recombinant forms and metabolites to achieve full hormonal bioactivity and indicate that purified recombinant hPTH-(1-84) can thereby be obtained which should be a useful source of hormone for both basic and clinical studies.
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PMID:Recombinant human parathyroid hormone synthesized in Escherichia coli. Purification and characterization. 327 65

A number of factors have been proposed as potential mediators of the syndrome of humoral hypercalcemia of malignancy (HHM), but to date no firm cause-and-effect relationship has been established. We attempted to establish such a relationship by determining whether the presence or absence of adenylate cyclase-stimulating activity (ACSA) in the media of cultured tumor cells predicted the occurrence of the syndrome of HHM when these cell lines were grown in nude mice in vivo. Conditioned media from 35 human renal carcinoma cell lines were surveyed for ACSA in the PTH-sensitive rat osteosarcoma 17/2.8 cell assay. 12 lines were positive (mean, 13.7-fold stimulation, range, 3.0 to 44.0), and 23 lines were negative (mean, 1.2-fold stimulation, range, 0.9 to 1.5). We were successful in establishing five of the positive and six of the negative lines in three to five nude mice per line. Mice implanted with the positive lines uniformly became hypercalcemic (mean serum calcium, 15.8 mg/dl), whereas mice implanted with the negative lines uniformly remained normocalcemic (mean serum calcium, 9.5 mg/dl), in spite of comparable mean tumor size. Acid-urea tumor extracts from each of four hypercalcemic animals contained potent in vitro ACSA (mean, 15.9-fold stimulation), while 5/5 extracts from normocalcemic animals did not (mean, 1.4-fold stimulation). Our study demonstrates that in this model system in vitro ACSA is a reliable predictive marker for HHM in vivo. Whether the protein responsible for this activity is also the mediator of the bone resorption seen in HHM remains to be demonstrated.
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PMID:In vitro adenylate cyclase-stimulating activity predicts the occurrence of humoral hypercalcemia of malignancy in nude mice. 334 41

Parathyroid hormone (PTH)-like bioactivity, assayed as adenylate cyclase response in UMR 106-01 osteogenic sarcoma cells, was present in extracts of sheep fetal and maternal parathyroid glands and placenta. Preincubation of extracts with PTH(1-34) antiserum inhibited approximately 40% of the bioactivity in fetal parathyroid extracts, 50% in maternal parathyroid extracts, but only 10% of the bioactivity in the placental extract. Partial purification of placental extracts by chromatography yielded fractions containing PTH-like bioactivity which were similar in behaviour to that of PTH-related protein (PTHrP) from a human lung cancer cell line (BEN). An antiserum against synthetic PTHrP(1-16) partially inhibited the bioactivity of the placental extract and synthetic PTHrP(1-34), but had no effect on the bioactivity of bovine PTH(1-34) or bovine PTH(1-84). The placental PTH-like bioactivity was higher in mid- than in late gestation. Fetal parathyroid glands contained the highest PTH-like bioactivity. Thyroparathyroidectomy of one fetal twin lamb in each of 16 ewes between 110 and 125 days of gestation resulted in decreases of the plasma calcium concentration and reversal of the placental calcium gradient that existed between the ewe and the intact fetus. Perfusion of the placenta of each twin in anaesthetized ewes was carried out sequentially with autologous fetal blood in the absence of the exsanguinated fetus. The plasma calcium concentration in the blood perfusing the placenta of each twin increased, but reached a plateau at a lower concentration in the perfusing blood of thyroparathyroidectomized fetuses than in that of the intact fetuses. Addition of extracts of fetal parathyroid glands or of partially purified PTHrP resulted in further increases in plasma calcium in the autologous blood perfusing the placentae of thyroparathyroidectomized fetuses, but addition of bovine PTH(1-84) or rat PTH(1-34) had no effect. The presence of this PTH-like protein in the fetal parathyroid gland and placenta may contribute to the relative hypercalcaemia of the fetal lamb. This protein, which is similar to PTHrP associated with humoral hypercalcaemia of malignancy, stimulates the placental calcium pump responsible for maintaining a relative fetal hypercalcaemia during gestation.
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PMID:Evidence for a novel parathyroid hormone-related protein in fetal lamb parathyroid glands and sheep placenta: comparisons with a similar protein implicated in humoral hypercalcaemia of malignancy. 337 58

Three bioassays are widely employed for the measurement of PTH-like adenylate cyclase-stimulating factors (ACSFs) derived from tumors associated with humoral hypercalcemia of malignancy. These include renal cortical adenylate cyclase (RAC) assays, rat osteosarcoma (ROS) adenylate cyclase assays, and fetal bone resorption (FBR) assays. A previous study has suggested that the potency of one human tumor-derived ACSF, expressed in PTH equivalents, was 30-fold higher in the ROS assay than in the RAC assay, but no study has directly compared all three bioassays using a single PTH standard and a single ACSF preparation. We compared one partially purified ACSF preparation to a single lot of bPTH 1-34 in all three bioassays. The results indicate that the relative potency of this ACSF as compared to the PTH standard varied with the assay employed, with the ROS assay yielding a specific activity estimate 47.5-fold higher than the RAC, and the FBR 6.7-fold higher than the RAC but 7.1-fold lower than the ROS. These findings support the possibility that distinct subpopulations of PTH receptors exist on different PTH target tissues. Further, they underscore the importance of bioassay choice when estimating the specific activity of tumor-derived ACSF preparations.
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PMID:The relative potency of a human tumor-derived PTH-like adenylate cyclase-stimulating preparation in three bioassays. 345 55

The tumor line CAC-8, is a serially transplantable adenocarcinoma maintained in nude mice which originated from a hypercalcemic dog. Nude mice with CAC-8 developed a syndrome of humoral hypercalcemia of malignancy. CAC-8 contained a protein factor which stimulated adenylate cyclase of bone and kidney cells in vitro. The adenylate cyclase (AC) of rat osteosarcoma cell lines, ROS 17/2.8 (ROS) and UMR-106, was stimulated by the tumor extract and potentiated by forskolin (0.1 microM). The ROS cells responded to the lowest concentration of CAC-8 extract, but UMR cells responded with a greater increase in AC activity compared to controls following exposure to CAC-8 extract. Pretreatment of ROS 17/2.8 cells with dexamethasone enhanced the response to CAC-8 extract. The opossum kidney cell line (OK) was less sensitive to the AC-stimulating activity of CAC-8 extract, but AC stimulation was increased in the presence of forskolin. Bovine (1-34) parathyroid hormone (BPTH) (10 nM) stimulated AC equally in ROS, UMR, and OK cells. Isoproterenol (1.0 microM) stimulated AC activity in ROS and UMR cells but not in OK cells. The AC-stimulating activity of CAC-8 appeared to bind to the parathyroid hormone receptor of ROS, UMR, and OK cells since addition of the parathyroid hormone receptor antagonist, [8,18norleucine, 34tyrosine]BPTH (3-34) amide, inhibited CAC-8-mediated cyclic adenosine 5'-monophosphate production and alone did not stimulate AC activity. The AC-stimulating activity of CAC-8 was acid and heat stable. Trypsin digestion reduced BPTH and CAC-8 stimulation of AC to near basal levels and treatment of CAC-8 extract with dithiothreitol reduced AC stimulation in UMR cells by approximately 50%. Extracts of the hypercalcemic tumor line (CAC-8) contained bone and kidney AC-stimulating activity which was enhanced by forskolin and dexamethasone, inhibited by [8,18Nle, 34Tyr]BPTH (3-34) amide, heat stable, trypsin sensitive, inactivated by reduction, and had a relative molecular weight of 34,000 by gel exclusion chromatography. Isolation and characterization of the factor(s) produced by CAC-8 that stimulate AC activity will be useful in further understanding the pathogenesis of humoral hypercalemia of malignancy in animal and human patients.
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PMID:Bone and kidney adenylate cyclase-stimulating activity produced by a hypercalcemic canine adenocarcinoma line (CAC-8) maintained in nude mice. 346 38

Parathyroid hormone (PTH, less than 10(-8) M) stimulated adenylate cyclase in fibroblasts, but not epithelial cells, isolated from fetal rat lung. In contrast to osteosarcoma cells (UMR 106), the response of fibroblasts to PTH was increased by pretreatment with cortisol (less than 10(-8)-10(-7) M).
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PMID:The adenylate cyclase response to parathyroid hormone in fetal lung fibroblasts is enhanced by cortisol. 348 Jul 62

In human osteosarcoma membranes, gold(III) (Au(III)) inhibits prostaglandin E2- and isoproterenol-mediated stimulation of adenylate cyclase activity without affecting basal enzyme activity. Forskolin activation of adenylate cyclase is also blocked by Au(III) with ID50 of 1-2 microM. The inhibition by Au(III) is preserved in membranes prepared from pertussis toxin-treated cells. The inhibitory effect of Au(III) is additive to inhibition of adenylate cyclase by 2',5'-dideoxyadenosine. These data provide evidence that the action of Au(III) is at or near the catalytic moiety of the cyclase system and that Au(III) does not act via the guanine nucleotide-binding inhibitory component or the adenosine P-site inhibitory pathway.
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PMID:Gold(III) inhibits activated human osteosarcoma adenylate cyclase by an action at or near the catalytic component. 349 71

The effects of transforming growth factor alpha (TGF-alpha) and epidermal growth factor (EGF) on parathyroid hormone (PTH)-responsive adenylate cyclase were examined in clonal rat osteosarcoma cells (UMR-106) with the osteoblast phenotype. Recombinant TFG-alpha and EGF incubated with UMR-106 cells for 48 h each produced concentration-dependent inhibition of PTH-responsive adenylate cyclase, with maximal inhibition of 38-44% at 1-3 ng/ml of either growth factor. TGF-alpha and EGF also inhibited beta-adrenergic agonist (isoproterenol)-stimulated adenylate cyclase by 32%, but neither growth factor affected enzyme response to prostaglandin or basal (unstimulated) activity. Nonreceptor-mediated activation of adenylate cyclase by forskolin and cholera toxin was inhibited 18-20% by TGF-alpha and EGF. Pertussis toxin augmented PTH-stimulated adenylate cyclase, suggesting modulation of PTH response by a functional inhibitory guanine nucleotide-binding regulatory component of the enzyme. However, pertussis toxin had no effect on TGF-alpha inhibition of PTH response. Growth factor inhibition of PTH response was time-dependent, with maximal inhibition by 4-12 h of TGF-alpha exposure, and was reduced by prior treatment of UMR-106 cells with cycloheximide. TGF-alpha was not mitogenic for UMR-106 cells. The results indicate that TGF-alpha and EGF selectively impair PTH- and beta-adrenergic agonist-responsive adenylate cyclase of osteoblast-like cells. Growth factor inhibition of adenylate cyclase may be exerted at the receptor for stimulatory agonist and at nonreceptor components excluding pertussis toxin-sensitive guanine nucleotide-binding regulatory proteins. The inhibitory action of growth factors may also require protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Inhibition of parathyroid hormone-responsive adenylate cyclase in clonal osteoblast-like cells by transforming growth factor alpha and epidermal growth factor. 350 Jan 68

Native bovine parathyroid hormone (bPTH) was found to be readily cleaved with human leukocyte elastase to yield the fragments bPTH(1-41) and bPTH(42-84). These were then isolated by reverse-phase HPLC and characterised by gas-phase sequencing and amino acid analysis. The biological activities of these fragments were assessed in an adenylate cyclase bioassay using the rat osteosarcoma cell line UMR106. bPTH(1-41) was found to have approximately twice the molar potency of the native hormone from which it was derived. bPTH(42-84) had no biological activity and did not modulate the adenylate cyclase response to these cells to the native hormone. The possible physiological significance of these observations is discussed.
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PMID:The biological properties of bovine parathyroid hormone (1-41), a fragment generated from the native hormone by human leukocytes. 365 Jan 10

A variety of solid tumors secrete proteins that are immunochemically distinct from parathyroid hormone (PTH) but activate PTH-responsive adenylate cyclase. Such PTH-like proteins have been proposed as mediators of the hypercalcemia and hypophosphatemia frequently associated with malignancies. We purified to apparent homogeneity a PTH-like protein with a molecular weight of 6,000, that is produced by human renal carcinoma cells. The amino-terminal sequence of the PTH-like protein and that of human PTH were found to display at least five identities in the first 13 positions. The purified protein bound to PTH receptors, activated adenylate cyclase in renal plasma membranes, and stimulated cAMP formation in rat osteosarcoma cells. The PTH-like protein reproduced two additional effects of PTH, stimulation of bone resorption in fetal rat limb bone cultures and inhibition of phosphate uptake in cultured opossum kidney cells. These properties are consistent with a role for PTH-like proteins as mediators of the syndrome of malignancy-associated hypercalcemia.
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PMID:Parathyroid hormonelike protein from human renal carcinoma cells. Structural and functional homology with parathyroid hormone. 368 May 30


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