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)

We used the osteogenic sarcoma cell line, UMR-106-01, to determine whether the rise in free cytosolic Ca2+ concentration ([Ca2+]i) and cellular cAMP following PTH stimulation are able to be regulated independently. For this purpose, we compared the effect of a PTH antagonist, stimulation of protein kinase C, augmentation by prostaglandins, and the time course of desensitization of the two cellular responses. Two x 10(-7) M of the PTH antagonist 8,18Nle 34Tyr-bPTH(3-34) amide ([Nle,Tyr]bPTH(3-34)A) was required to inhibit 10(-9) M bPTH(1-34)-stimulated cAMP generation by 50%. 10(-7) M bPTH(1-34) completely overcame the inhibition induced by 10(-6) M [Nle,Tyr]bPTH(3-34)A. Only 7 x 10(-8) M and 2.7 x 10(-7) M [Nle,Tyr]bPTH(3-34)A were required to half maximally inhibit the [Ca2+]i increase evoked by 3 x 10(-8) and 10(-7) M bPTH(1-34), respectively. In addition, dissociation between [Ca2+]i and cAMP signals was observed when modulation by protein kinase C and prostaglandins was tested. Preincubation of the cells with 10 nM TPA for 5 minutes markedly inhibited the PTH-evoked [Ca2+]i increase. Short incubation with PGF2 alpha augmented the PTH-evoked [Ca2+]i increase. Similar pretreatments had no effect on the PTH-stimulated cAMP increase. Finally, preincubation with 1.5 x 10(-9) M bPTH(1-34) for 20 minutes almost completely blocked the effect of 10(-7) M bPTH(1-34) on [Ca2+]i, while preincubation with 5 x 10(-9) M bPTH(1-34) for 4 hours was required to inhibit the effect of 10(-8) M bPTH(1-34) on cAMP production by 50%. The differences in the regulation of the two PTH-stimulated cellular signaling systems, in particular, the response to antagonists and the time course of desensitization, could be at the level of the PTH receptor(s) or at a postreceptor domain.
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PMID:Dissociation between parathyroid hormone-stimulated cAMP and calcium increase in UMR-106-01 cells. 132 47

An 125I-labeled synthetic analog of bovine parathyroid hormone, [8-norleucine,18-norleucine,34-tyrosine]PTH-(1-34) amide ([Nle]PTH-(1-34)-NH2), purified by high-pressure liquid chromatography (HPLC), was employed to label the parathyroid hormone (PTH) receptor in cell lines derived from PTH target tissues: the ROS 17/2.8 rat osteosarcoma of bone and the CV1 and COS monkey kidney lines. After incubation of the radioligand with intact cultured cells, the hormone was covalently attached to receptors by using either a photoaffinity technique or chemical (affinity) cross-linking. In each case, covalent labeling was specific, as evidenced by a reduction of labeling when excess competing nonradioactive ligand was present. After covalent attachment of radioligand, membranes were prepared from the cells and solubilized in the nonionic detergent Nonidet P-40 or octyl glucoside. The soluble membrane fraction present in the supernatant of a 100,000 X g centrifugation was incubated with IgG prepared from anti-PTH antiserum generated to the amino-terminal region, residues 1-34, of PTH. The IgG-PTH-receptor complex was precipitated with staphylococcal protein A-Sepharose. Analysis of the immunoprecipitate on NaDod-SO4/polyacrylamide gel electrophoresis followed by autoradiography revealed the presence of a doublet of apparent molecular mass 69-70 kDa. Specifically labeled bands of approximate molecular mass 95 and 28 kDa were also observed. The anti-PTH IgG was affinity purified by passage over a PTH-Sepharose column and used to make an immunoaffinity column. The 70- and 28-kDa bands were also observed after labeled solubilized membrane preparations were allowed to bind to this column and then were eluted by using a [Nle]PTH-(1-34)-NH2-containing buffer or acetic acid. These studies suggest that the use of an anti-PTH antiserum that binds receptor-bound hormone is likely to be a useful step in the further physiochemical characterization and purification of the PTH receptor.
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PMID:Immunoprecipitation of the parathyroid hormone receptor. 302 60

Even if the carboxyl-terminal (C-) fragments/intact (I-) PTH ratio is tightly regulated by the ionized calcium (Ca(2+)) concentration in humans and animals, in health and in disease, the physiological roles of C-PTH fragments and of the C-PTH receptor remain elusive. To explore these issues, we studied the influence of synthetic C-PTH peptides of various lengths on Ca(2+) concentration and on the calcemic response to human (h) PTH-(1-34) and hPTH-(1-84) in anesthetized thyroparathyroidectomized (TPTX) rats. We also looked at the capacity of these PTH preparations to react with the PTH/PTHrP receptor and with a receptor for the carboxyl (C)-terminal portion of PTH (C-PTH receptor) in rat osteosarcoma cells, ROS 17/2.8. The Ca(2+) concentration was reduced by 0.19 +/- 0.03 mmol/liter over 2 h in all TPTX groups. Infusion of solvent over 2 more h had no further effect on the Ca(2+) concentration (-0.01 +/- 0.01 mmol/liter), whereas infusion of hPTH-(7-84) or a fragment mixture [10% hPTH-(7-84) and 45% each of hPTH-(39-84) and hPTH-(53-84)] 10 nmol/h further decreased the Ca(2+) concentration by 0.18 +/- 0.02 (P<0.001) and 0.07+/-0.04 mmol/liter (P< 0.001), respectively. Infusion of hPTH-(1-84) or hPTH-(1-34) (1 nmol/h) increased the Ca(2+) concentration by 0.16 +/- 0.03 (P < 0.001) and 0.19 +/- 0.03 mmol/liter (P < 0.001), respectively. Adding hPTH-(7-84) (10 nmol/h) to these preparations prevented the calcemic response and maintained Ca(2+) concentrations equal to or below levels observed in TPTX animals infused with solvent alone. Adding the fragment mixture (10 nmol/h) to hPTH-(1-84) did not prevent a normal calcemic response, but partially blocked the response to hPTH-(1-34), and more than 3 nmol/h hPTH-(7-84) prevented it. Both hPTH-(1-84) and hPTH-(1-34) stimulated cAMP production in ROS 17/2.8 clonal cells, whereas hPTH-(7-84) was ineffective in this respect. Both hPTH-(1-84) and hPTH-(1-34) displaced (125)I-[Nle(8,18),Tyr(34)]hPTH-(1-34) amide from the PTH/PTHrP receptor, whereas hPTH-(7-84) had no such influence. Both hPTH-(1-84) and hPTH-(7-84) displaced (125)I-[Tyr(34)]hPTH-(19-84) from the C-PTH receptor, the former preparation being more potent on a molar basis, whereas hPTH-(1-34) had no effect. These results suggest that C-PTH fragments, particularly hPTH-(7-84), can influence the Ca(2+) concentration negatively in vivo and limit in such a way the calcemic responses to hPTH-(1-84) and hPTH-(1-34) by interacting with a receptor different from the PTH/PTHrP receptor, possibly a C-PTH receptor.
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PMID:Synthetic carboxyl-terminal fragments of parathyroid hormone (PTH) decrease ionized calcium concentration in rats by acting on a receptor different from the PTH/PTH-related peptide receptor. 1125 Sep 17

A series of conformationally-restricted analogues of hPTH was prepared, based on the parent peptide agonist, cyclo(Lys(18)-Asp(22))[Ala(1),Nle(8),Lys(18),Asp(22),Leu(27)]hPTH(1-31)NH(2) (2, EC(50)=0.29nM). Truncation of 2 at either the N- or C-termini resulted in peptides with reduced agonist activity as measured by stimulation of adenylate cyclase activity in the rat osteosarcoma cell line (ROS 17/2.8). Alanine- and glycine-scanning at the N-terminus of 2 was consistent with data previously obtained on linear hPTH(1-34). Other locations within the primary sequence of hPTH(1-31)NH(2) were evaluated by the placement of the [i, i+4] lactam constraining element. Ring size and lactam orientations at the 18-22 positions were also examined.
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PMID:Analogues of human parathyroid hormone (1-31)NH(2): further evaluation of the effect of conformational constraint on biological activity. 1181 62

Separase, an endopeptidase, plays a pivotal role in the separation of sister chromatids at anaphase by cleaving its substrate cohesin Rad21. Recent study suggests that separase is an oncogene. Overexpression of separase induces aneuploidy and mammary tumorigenesis in mice. Separase is also overexpressed and mislocalized in a wide range of human cancers, including breast, prostate, and osteosarcoma. Currently, there is no quantitative assay to measure separase enzymatic activity. To quantify separase enzymatic activity, we have designed a fluorogenic assay in which 7-amido-4-methyl coumaric acid (AMC)-conjugated Rad21 mitotic cleavage site peptide (Ac-Asp-Arg-Glu-Ile-Nle-Arg-MCA) is used as the substrate of separase. We used this assay to quantify separase activity during cell cycle progression and in a panel of human tumor cell lines as well as leukemia patient samples.
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PMID:Development and validation of a fluorogenic assay to measure separase enzyme activity. 1949 91