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 production of a cytotoxic factor synthesized by human haemic killer cells growing in vitro is described. The factor can be found extra- and intra-cellularly. It is released from the cells by an apocrine form of secretion, illustrated by light and electron micrographs. The culture fluid from 14C-labelled killer cells reveals numerous radioactive bands following SDS-gel electrophoresis. The killing factor is precipitated by 30 to 60% saturation of ammonium sulphate. Cultures of human rhabdomyosarcoma and osteosarcoma cells are more susceptible to the killer cells than normal human dermal or lung fibroblasts. During contact or killer with target cells a higher level of cytotoxic activity can be detected in the culture fluid. The cell-killing activity is completely inactivated by 30 min at 60 degrees C, but it is not absorbed by target cells during 1 h of incubation. The cytotoxic factor is unlikely to be an interferon since it did not prevent the replication of a wide range of viruses and only a low level of interferon could be detected in the culture medium. The introduction of Strep. faecalis into cultures of killer cells caused their transformation into immunoblast-like cells, indicating their lymphoid origin. The cells did not phagocytose the microorganism. When the humoral factor was injected into fibro-sarcoma-bearing mice approximately 50% survived, whereas all control animals died.
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PMID:A humoral cytotoxic substance produced by a human killer cell line. 41 8

Activation of the 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] receptor-hormone complex was studied in-vitro using cytosolic preparations of rat osteogenic sarcoma cell ROS 17/2-8 and a DNA-cellulose assay. We found that salt was required for extraction of the unoccupied receptor indicating its possible nuclear localization. The 1,25(OH)2D3 receptor underwent an activation process similar to other steroid hormones which could be stimulated by heat and salt. At physiological ionic strength 100% of the complexes were, however, activated at 2 degrees C, indicating that the activation process is not absolutely temperature dependent. In contrast to other steroid hormones, 30-50% of the complexes were in an activated state in the absence of heat and salt moreover, alkaline phosphatase and ammonium sulphate had no effect on activation. Activation was also stimulated by ATP and ATP plus 8BrcAMP indicating the possible role of phosphorylation in the activation process; however, further work is required to clarify this point.
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PMID:Activation of the 1,25-dihydroxyvitamin D3 receptor in cultured rat osteogenic sarcoma cells. 299 3

A new cytokine has been recognized in the conditioned media (CM) of freshly isolated acute myelocytic leukemia cells, cultured with 12-0-tetradecanayl phorbol acetate (TPA) 10(-8)M. The fraction with 70,000 MW was separated from CM by ammonium sulfate precipitation, ion-exchange cation and anion chromatography, and Sephadex G-200 gel filtration. It was a fibroblast growth inhibitor (FGI). This substance stopped fetal and skin (MALME 3 line) fibroblast propagation. The cytostatic effect was reversible on removal of FGI. At the same time, FGI did not inhibit macrophage proliferation. The fraction stimulated formation of monocytic and granulocytic colonies altered the phenotype of human U-2 osteosarcoma cells grown from epithelial-like to fibroblast-like cells, and stimulated differentiation of leukemic cells along the macrophage path. Some cells of promyelocytic leukemia line HL-60, grown in the presence of FGI, were stimulated to differentiate and some underwent lysis. The response to FGI of cells from different patients varied.
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PMID:Fibroblast growth inhibitor. 322 59

A conjugate of methotrexate-substituted human serum albumin (HSA) coupled to a monoclonal antibody (791T/36) recognizing osteogenic sarcoma cell lines has been reported previously to have good cytotoxicity and specificity in vitro (Garnett et al., 1983). Cytotoxicity was assessed by the median inhibition (IC50) of [75Se]selenomethionine uptake resulting from a 24-h incubation of conjugate with antigen-bearing 788T or 791T osteogenic sarcoma cell lines. In the present work, the properties of this conjugate have been investigated to determine whether cytotoxicity is optimal with respect to binding activity, and aspects of the mechanism of action investigated by the effects of specific inhibitors of biochemical processes on conjugate cytotoxicity. Conjugate cytotoxicity was reduced by ammonium chloride suggesting that endocytosis and an acidic internal compartment were involved in the mechanism of action. The specific inhibitors of proteinases leupeptin and E64 also reduced conjugate cytotoxicity, while the inhibitors pepstatin A and chymostatin had no effect, demonstrating that cysteine proteinases were involved. The inhibitor of methotrexate transport, folinic acid, reduced the cytotoxicity of conjugate more than that of free methotrexate whereas folic acid had no effect on either, indicating that the methotrexate transport system may still be involved but in a different manner to the free drug. The cytotoxicity of these conjugates is probably near optimal for maximum selectivity.
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PMID:Studies on the mechanism of action of an antibody-targetted drug-carrier conjugate. 387 60

A rat osteosarcoma cell clone (ROS 17/2), and osteoblast-enriched populations from rat calvaria cultured in the presence of concanavalin A, have been shown to produce latent collagenase and collagenase inhibitors. The enzymes and inhibitor activities from the ROS 17/2 cells were concentrated by ammonium sulphate precipitation and separated by gel filtration on AcA 54 resin. The size of the latent collagenase (Mr approximately equal to 58000) was reduced on conversion to active enzyme (Mr approximately equal to 48000) by p-aminophenylmercuric acetate. Latent and active forms of gelatinase activity, similar in size to the corresponding forms of collagenase, were also resolved. The collagenase inhibitor activity, which was sensitive to organomercurials, was recovered in two peaks (Mr approximately equal to 68000 and 30000). The active collagenase cleaved interstitial collagens (type I = III greater than II) producing typical 3/4 and 1/4 fragments. This activity was inhibited by the metal ion chelators ethylenediaminetetraacetic acid and o-phenanthroline. Additional specific cleavages of native collagen were also observed which, from the susceptibility of this activity to phenylmethylsulphonyl fluoride, leupeptin and antipain, suggested the presence of a second collagenolytic enzyme. This synthesis of collagenolytic enzymes by these osteoblast-like cells suggests that individual osteoblasts, like fibroblasts, are capable of both synthesizing and degrading their respective organic matrices in vivo.
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PMID:Synthesis of collagenase and collagenase inhibitors by osteoblast-like cells in culture. 609 78

High-pressure liquid chromatography in combination with field desorption mass spectrometry as techniques of high specificity and sensitivity have been applied to the identification and quantitation of the anticancer drug methotrexate and its metabolites which occur in clinical high-dose therapy. Field desorption mass spectra of methotrexate and several methotrexate and folic acid derivatives, when investigated as free acids or ammonium salts, yield abundant protonated molecular ions and a consistent pattern of structurally significant fragments. High-pressure liquid chromatographic separation of methotrexate metabolites was performed on reverse-phase, C-18 columns using a volatile, ammonium bicarbonate/acetate containing mobile phase that was especially suited for the field desorption mass spectral analysis of isolated metabolites, and provided the definite identification of 7-hydroxymethotrexate and 4-[[2,4-diamino-6-pteridinyl]methyl]methylamino]-benzoic acid in serum and urine of patients treated with high-dose methotrexate. The high intensity and stability of the [MH]+ ions was found suitable for the quantitation of methotrexate and related folate analogues by field desorption mass spectrometry. A synthetic methotrexate derivative, methotrexate-gamma-(2-hydroxy)ethyl-amide was used as internal standard for the quantitative determination of methotrexate in serum and urine. In a study to comparatively assess the potential of specific quantitation methods, serum and urine levels of methotrexate and its major metabolite, 7-hydroxymethotrexate were determined by (i) an enzyme immunoassay, (ii) reverse phase high-pressure liquid chromatography and (iii) field desorption mass spectrometry. Results obtained from four patients with osteogenic sarcoma receiving high-dose methotrexate/leucovorin rescue therapy consistently show the sustained elimination of 7-hydroxymethotrexate over several days, thus indicating the utility of specifically monitoring this nephrotoxic metabolite, at massive methotrexate doses.
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PMID:Identification and quantitation of methotrexate and methotrexate metabolites in clinical high-dose therapy by high pressure liquid chromatography and field desorption mass spectrometry. 703 62

We have previously described a specific, saturable receptor for rat collagenase-3 in the rat osteosarcoma cell line, UMR 106-01. Binding of rat collagenase-3 to this receptor is coupled to the internalization and eventual degradation of the enzyme and correlates with observed extracellular levels of the enzyme. In this study we have shown that decreased binding, internalization, and degradation of 125I-rat collagenase-3 were observed in cells after 24 h of parathyroid hormone treatment; these activities returned to control values after 48 h and were increased substantially (twice control levels) after 96 h of treatment with the hormone. Subcellular fractionation studies to identify the route of uptake and degradation of collagenase-3 localized intracellular accumulation of 125I-rat collagenase-3 initially in Golgi-associated lysosomes and later in secondary lysosomes. Maximal lysosomal accumulation of the radiolabel and stimulation of general lysosomal activity occurred after 72 h of parathyroid hormone treatment. Preventing fusion of endosomes with lysosomes (by temperature shift, colchicine, or monensin) resulted in no internalized 125I-collagenase-3 in either lysosomal fraction. Treatment of UMR cells with the above agents or ammonium chloride decreased excretion of 125I-labeled degradation products of collagenase-3. These experiments demonstrated that degradation of collagenase-3 required receptor-mediated endocytosis and sequential processing by endosomes and lysosomes. Thus, parathyroid hormone regulates the expression and synthesis of collagenase-3 as well as the abundance and functioning of the collagenase-3 receptor and the intracellular degradation of its ligand. The coordinate changes in the secretion of collagenase-3 and expression of the receptor determine the net abundance of the enzyme in the extracellular space.
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PMID:Regulation of the collagenase-3 receptor and its role in intracellular ligand processing in rat osteoblastic cells. 1009 9

The possibility that some combinations of mtDNA polymorphisms, previously associated with Leber's hereditary optic neuropathy (LHON), may affect mitochondrial respiratory function was tested in osteosarcoma-derived transmitochondrial cytoplasmic hybrids (cybrids). In this cellular system, in the presence of the same nuclear background, different exogenous mtDNAs are used to repopulate a parental cell line previously devoid of its original mtDNA. No detectable differences in multiple parameters exploring respiratory function were observed when mtDNAs belonging to European haplogroups X, H, T and J were used. Different possible explanations for the previously established association between haplogroup J and LHON 11778/ND4 and 14484/ND6 pathogenic mutations are discussed, including the unconventional proposal that mtDNA haplogroup J may exert a protective rather than detrimental effect.
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PMID:Respiratory function in cybrid cell lines carrying European mtDNA haplogroups: implications for Leber's hereditary optic neuropathy. 1237 8

Leber's hereditary optic neuropathy (LHON), a maternally inherited form of central vision loss, is associated with mitochondrial DNA pathogenic point mutations affecting different subunits of complex I. We here report that osteosarcoma-derived cytoplasmic hybrids (cybrid) cell lines harboring one of the three most frequent LHON pathogenic mutations, at positions 11778/ND4, 3460/ND1, and 14484/ND6, undergo cell death when galactose replaces glucose in the medium, contrary to control cybrids that maintain some growth capabilities. This is a well known way to produce a metabolic stress, forcing the cells to rely on the mitochondrial respiratory chain to produce ATP. We demonstrate that LHON cybrid cell death is apoptotic, showing chromatin condensation and nuclear DNA laddering. Moreover, we also document the mitochondrial involvement in the activation of the apoptotic cascade, as shown by the increased release of cytochrome c into the cytosol in LHON cybrid cells as compared with controls. Cybrids bearing the 3460/ND1 and 14484/ND6 mutations seemed more readily prone to undergo apoptosis as compared with the 11778/ND4 mutation. In conclusion, LHON cybrid cells forced by the reduced rate of glycolytic flux to utilize oxidative metabolism are sensitized to an apoptotic death through a mechanism involving mitochondria.
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PMID:Leber's hereditary optic neuropathy (LHON) pathogenic mutations induce mitochondrial-dependent apoptotic death in transmitochondrial cells incubated with galactose medium. 1244 13

Leber hereditary optic neuropathy (LHON) is a maternally inherited form of retinal ganglion cell degeneration leading to optic atrophy which is caused by point mutations in the mitochondrial genome (mtDNA). Three pathogenic mutations (positions 11778/ND4, 3460/ND1 and 14484/ND6) account for the majority of LHON cases and they affect genes that encode for different subunits of mitochondrial complex I. Excitotoxic injury to retinal ganglion cells and the optic nerve has been previously hypothesized, especially given the high susceptibility of this neural cell type to glutamate toxicity. Osteosarcoma-derived cytoplasmic hybrids (cybrids) generated from six unrelated LHON patients, two cell lines for each pathogenic mutation, were compared with cybrids obtained from three healthy controls. Molecular and biochemical analyses showed that excitatory amino acid transporter 1 (EAAT1)/GLAST is the most active glutamate transporter in this cellular model. The glutamate uptake maximal velocity was significantly reduced in all LHON cybrids compared with control cybrids. This reduction was correlated in a mutation-specific fashion with the degree of mitochondrial production of reactive oxygen species, which is enhanced in LHON cybrids. Our findings support the hypothesis that the genetically determined mitochondrial dysfunction in LHON patients leads to impaired activity of the EAAT1 glutamate transporter. This observation is particularly relevant since EAAT1 is the major means of glutamate removal in the inner retina and this prevents retinal ganglion cells being damaged as a result of excitotoxicity.
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PMID:Leber hereditary optic neuropathy mtDNA mutations disrupt glutamate transport in cybrid cell lines. 1534 61


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