Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Fas/APO-1, a member of the NGF/TNF receptor superfamily expressed on the cell-surface of normal and malignant cells, is known to induce cell death by apoptosis. In the present study, we have investigated Fas/APO-1 gene defects in a human osteosarcoma cell line resistant to the apoptosis-inducing effects of anti-Fas. cDNA cloning and sequencing revealed that these cells contained both 'authentic' and mutant Fas/APO-1 containing a 63 base pair in-frame deletion spanning the transmembrane domain, designated DFas/APO-1. Direct evidence for the existence of a soluble Fas/APO-1 protein was obtained by immunoprecipitation and Western blotting. Taken together with prior studies demonstrating a role for Fas/APO-1 and Fas ligand, respectively, in tumor target cell killing by cytotoxic T-lymphocytes, production of soluble Fas/APO-1 might have significant implications in malignant disease pathogenesis.
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PMID:Soluble Fas/APO-1 in tumor cells: a potential regulator of apoptosis? 754 59

The CD95/APO-1 Fas receptor/ligand system plays a crucial role in growth control by mediating apoptosis in lymphoid and non-lymphoid cells. To investigate the role of CD95-mediated apoptosis in osteosarcoma, we studied 3 human osteosarcoma cell lines (HOS/TE 85, MG 63 and Saos-2) and osteoblasts derived from bone biopsies. In contrast to osteoblast-like cells, all cell lines were resistant to anti-APO-1-induced apoptosis despite constitutive CD95 expression at intermediate levels. Blocking of macromolecular synthesis by cycloheximide or actinomycin D or modulation of CD95 expression by cytokines (TNF-alpha and/or gamma-interferon) restored sensitivity to anti-APO-1-induced cell death. PCR analysis of the CD95 transcripts revealed the production of a truncated splice variant that codes for a soluble form of the CD95 receptor. Synthesis and secretion of soluble CD95 protein into the culture supernatant was demonstrated by Western blot analysis. Treatment with sensitizing cytokines led to up-regulation of full-length CD95 transcripts and the encoded membrane-bound CD95 protein but not the truncated mRNA splice variant and the corresponding soluble receptor, as shown by PCR and Western blot analysis. The biological activity of soluble CD95 secreted by osteosarcoma cells was demonstrated by the ability of osteosarcoma supernatants to protect the sensitive T-cell line Jurkat from anti-APO-1-mediated apoptosis. Our results suggest that the production of soluble CD95 by osteosarcoma cell lines that may block physiological death signals and the production of membrane-bound CD95 are differently regulated by cytokines via modulation of RNA splicing.
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PMID:Modulation of resistance to anti-APO-1-induced apoptosis in osteosarcoma cells by cytokines. 924 1

A transient burst of poly(ADP-ribosyl)ation of nuclear proteins occurs early, prior to commitment to death, in human osteosarcoma cells undergoing apoptosis, followed by caspase-3-mediated cleavage of poly(ADP-ribose) polymerase (PARP). The generality of this early burst of poly(ADP-ribosyl)ation has now been investigated with human HL-60 cells, mouse 3T3-L1, and immortalized fibroblasts derived from wild-type mice. The effects of eliminating this early transient modification of nuclear proteins by depletion of PARP protein either by antisense RNA expression or by gene disruption on various morphological and biochemical markers of apoptosis were then examined. Marked caspase-3-like PARP cleavage activity, proteolytic processing of CPP32 to its active form, internucleosomal DNA fragmentation, and nuclear morphological changes associated with apoptosis were induced in control 3T3-L1 cells treated for 24 h with anti-Fas and cycloheximide but not in PARP-depleted 3T3-L1 antisense cells exposed to these inducers. Similar results were obtained with control and PARP-depleted human Jurkat T cells. Whereas immortalized PARP +/+ fibroblasts showed the early burst of poly(ADP-ribosyl)ation and a rapid apoptotic response when exposed to anti-Fas and cycloheximide, PARP -/- fibroblasts exhibited neither the early poly (ADP-ribosyl)ation nor any of the biochemical or morphological changes characteristic of apoptosis when similarly treated. Stable transfection of PARP -/- fibroblasts with wild-type PARP rendered the cells sensitive to Fas-mediated apoptosis. These results suggest that PARP and poly(ADP-ribosyl)ation may trigger key steps in the apoptotic program. Subsequent degradation of PARP by caspase-3-like proteases may prevent depletion of NAD and ATP or release certain nuclear proteins from poly(ADP-ribosyl)ation-induced inhibition, both of which might be required for late stages of apoptosis.
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PMID:Transient poly(ADP-ribosyl)ation of nuclear proteins and role of poly(ADP-ribose) polymerase in the early stages of apoptosis. 959 11

The tumor necrosis factor receptor, p60 (TNF-R1), transduces death signals via the association of its cytoplasmic domain with several intracellular proteins. By screening a mammalian cDNA library using the yeast two-hybrid cloning technique, we isolated a ubiquitin-homology protein, DAP-1, which specifically interacts with the cytoplasmic death domain of TNF-R1. Sequence analysis reveals that DAP-1 shares striking sequence homology with the yeast SMT3 protein that is essential for the maintenance of chromosome integrity during mitosis (Meluh, P. B., and Koshland, D. (1995) Mol. Biol. Cell 6, 793-807). DAP-1 is nearly identical to PIC1, a protein that interacts with the PML tumor suppressor implicated in acute promyelocytic leukemia (Boddy, M. N., Howe, K., Etkin, L. D., Solomon, E., and Freemont, P. S. (1996) Oncogene 13, 971-982), and the sentrin protein, which associates with the Fas death receptor (Okura, T., Gong, L., Kamitani, T., Wada, T., Okura, I., Wei, C. F., Chang, H. M., and Yeh, E. T. (1996) J. Immunol. 157, 4277-4281). The in vivo interaction between DAP-1 and TNF-R1 was further confirmed in mammalian cells. In transient transfection assays, overexpression of DAP-1 suppresses NF-kappaB/Rel activity in 293T cells, a human kidney embryonic carcinoma cell line. Overexpression of either DAP-1 or sentrin causes apoptosis of TNF-sensitive L929 fibroblast cell line, as well as TNF-resistant osteosarcoma cell line, U2OS. Furthermore, the dominant negative Fas-associated death domain protein (FADD) protein blocks the cell death induced by either DAP-1 or FADD. Collectively, these observations highly suggest a role for DAP-1 in mediating TNF-induced cell death signaling pathways, presumably through the recruitment of FADD death effector.
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PMID:The ubiquitin-homology protein, DAP-1, associates with tumor necrosis factor receptor (p60) death domain and induces apoptosis. 1018 98

Spontaneous apoptosis in human osteosarcoma cells was observed to be associated with a marked increase in the intracellular abundance of p53. Immunoprecipitation and immunoblot analysis revealed that, together with a variety of other nuclear proteins, p53 undergoes extensive poly(ADP-ribosyl)ation early during the apoptotic program in these cells. Subsequent degradation of poly(ADP-ribose) (PAR), attached to p53 presumably by PAR glycohydrolase, the only reported enzyme to degrade PAR, was apparent concomitant with the onset of proteolytic processing and activation of caspase-3, caspase-3-mediated cleavage of poly(ADP-ribose) polymerase (PARP), and internucleosomal DNA fragmentation during the later stages of cell death. The decrease in PAR covalently bound to p53 also coincided with the marked induction of expression of the p53-responsive genes bax and Fas. These results suggest that poly(ADP-ribosyl)ation may play a role in the regulation of p53 function and implies a regulatory role for PARP and/or PAR early in apoptosis.
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PMID:Poly(ADP-ribosyl)ation of p53 during apoptosis in human osteosarcoma cells. 1023 7

We have focused on the roles of PARP and poly(ADP-ribosyl)ation early in apoptosis, as well as during the early stages of differentiation-linked DNA replication. In both nuclear processes, a transient burst of PAR synthesis and PARP expression occurs early, prior to internucleosomal DNA cleavage before commitment to apoptosis as well as at the round of DNA replication prior to the onset of terminal differentiation. In intact human osteosarcoma cells undergoing spontaneous apoptosis, both PARP and PAR decreased after this early peak, concomitant with the inactivation and cleavage of PARP by caspase-3 and the onset of substantial DNA and nuclear fragmentation. Whereas 3T3-L1, osteosarcoma cells, and immortalized PARP +/+ fibroblasts exhibited this early burst of PAR synthesis during Fas-mediated apoptosis, neither PARP-depleted 3T3-L1 PARP-antisense cells nor PARP -/- fibroblasts showed this response. Consequently, whereas control cells progressed into apoptosis, as indicated by induction of caspase-3-like PARP-cleavage activity, PARP-antisense cells and PARP -/- fibroblasts did not, indicating a requirement for PARP and poly(ADP-ribosyl)ation of nuclear proteins at an early reversible stage of apoptosis. In parallel experiments, a transient increase in PARP expression and activity were also noted in 3T3-L1 preadipocytes 24 h after induction of differentiation, a stage at which approximately 95% of the cells were in S-phase, but not in PARP-depleted antisense cells, which were consequently unable to complete the round of DNA replication required for differentiation. PARP, a component of the multiprotein DNA replication complex (MRC) that catalyzes viral DNA replication in vitro, poly(ADP-ribosyl)ates 15 of approximately 40 MRC proteins, including DNA pol alpha, DNA topo I, and PCNA. Depletion of endogenous PARP by antisense RNA expression in 3T3-L1 cells results in MRCs devoid of any DNA pol alpha and DNA pol delta activities. Surprisingly, there was no new expression of PCNA and DNA pol alpha, as well as the transcription factor E2F-1 in PARP-antisense cells during entry into S-phase, suggesting that PARP may play a role in the expression of these proteins, perhaps by interacting with a site in the promoters for these genes.
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PMID:Involvement of PARP and poly(ADP-ribosyl)ation in the early stages of apoptosis and DNA replication. 1033 50

Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) has been implicated in the etiology of localized juvenile periodontitis (LJP), and produces a multiplicity of tissue-damaging products. Among those products, the capsular-like polysaccharide antigen (CPA) from A. actinomycetemcomitans is a potent mediator of bone resorption. In fact, this CPA (serotype b) is known to promote osteoclast-like cell formation via interleukin (IL)-1alpha production in mouse marrow cultures. Although osteoblasts complete bone formation, there are few reports focusing on the effect of CPA in bone-forming activity of osteoblasts in inflammatory disease sites. We hypothesized that CPA plays a mediating role in osteoblastic cells. Therefore, the purpose of this study was to examine the effect of CPA from A. actinomycetemcomitans on the mouse osteoblastic cell line MC3T3-E1 and human osteosarcoma SaOS-2 cells. A. actinomycetemcomitans serotype c resulted in a potent dose-dependent inhibition of cell proliferation of both cell lines. Characterization of the antiproliferative activity in the CPA demonstrated that it was not cytotoxic for MC3T3-E1. A 20-hour incubation with CPA-c resulted in a significant increase in apoptotic cell death in the cells, as evaluated by both cellular DNA fragmentation ELISA and FACS analysis. In contrast to the results obtained with a cytokine mixture (tumor necrosis factor-alpha, IL-1beta, and interferon-gamma), no inducible nitric oxide (NO) synthase gene expression or NO release could be detected in MC3T3-E1 after incubation with CPA-c. Further, both CPA-b and -c caused potent induction of apoptosis-related modifiers, e.g., Fas mRNA, whereas bcl-2 mRNA levels were unchanged. Therefore, this study has shown that CPA from A. actinomycetemcomitans contains a potent antiproliferative polysaccharide whose activity is associated with apoptotic cell death in MC3T3-E1, and that CPA per se is an inducer of apoptosis mediated by the Fas system but not by NO.
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PMID:Anti-proliferative capsular-like polysaccharide antigen from Actinobacillus actinomycetemcomitans induces apoptotic cell death in mouse osteoblastic MC3T3-E1 cells. 1037 Dec 46

Fas/APO-1 (or CD95) is a 45-kDa cell surface glycoprotein that transduces cellular death signals for apoptosis upon cross-linking with the Fas ligand, which is experimentally replaced by anti-Fas antibodies. We examined the Fas expression at the protein and mRNA levels, and susceptibility to anti-Fas-mediated apoptosis, in 14 osteosarcoma cell lines. Ten of 14 ostesarcoma cell lines constitutively expressed detectable levels of Fas on the cell surface with positive cell rates ranging from 10.2 to 72.4%. Four other cell lines expressed Fas almost exclusively in the cytoplasm. An antibody against Fas was able to induce Fas-mediated cell death only in two cell lines with high levels of surface Fas. In the presence of the protein synthesis inhibitor cyclohexamide, antibody to Fas led to an induction of apoptosis in ten of the osteosarcoma cell lines antibody-concentration dependently. These data suggest that Fas is a potential protein related to apoptosis in osteosarcomas when the sensitizing activity of cyclohexamide on anti-Fas-mediated cytotoxicity was exerted.
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PMID:Modulation of fas-mediated apoptosis in osteosarcoma cell lines. 1056 18

Osteosarcoma is one of the most common primary malignant tumors of bone. Treatment of this tumor with systemic chemotherapy dramatically improves the prognosis, although the molecular mechanisms involved in the drug action are poorly understood. In chemosensitive leukaemic T cells and certain solid tumors, cytotoxic drugs mediate the induction of apoptosis by activation of the CD95/APO-1/Fas system. Triggering of the corresponding signaling pathway may involve CD95-receptor/ligand interaction, activation of caspases, or alterations in mitochondrial function. The purpose of our study was to determine if similar mechanisms are involved in the chemosensitivity of osteosarcomas. We found that cytotoxic drugs induce characteristic biochemical and morphological alterations related to apoptosis in osteosarcoma cell lines, including activation of caspases and disturbance of mitochondrial function. However, drug treatment did not result in activation of CD95-receptor or CD95-ligand mRNA. In addition, drug-induced apoptosis was blocked by caspase inhibitors but not by inhibition of CD95-ligand action, indicating a CD95-receptor/ligand-independent mechanism in osteosarcoma cell lines.
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PMID:Drug-induced apoptosis in osteosarcoma cell lines is mediated by caspase activation independent of CD95-receptor/ligand interaction. 1071 73

The mechanisms of escape from Fas/CD95-mediated apoptosis induced by immunosurveillance(NK cells and T cells) in tumor cells are correlated to tumorigenicity. Human osteosarcoma cell MG-63 constitutively expressed cell surface Fas antigen but was resistant to apoptosis by Fas stimulation. However, suboptimal dose of cisplatin(CDDP) could sensitize MG-63 cells to Fas-mediated apoptosis without up-regulation of cell-surface Fas antigen. Western blotting analysis showed that MG-63 cells constitutively expressed FLICE inhibitory protein long form(FLIP-L), which was a novel anti-apoptotic protein and had a potency of tumorigenicity. CDDP down-regulated FLIP-L in a time-dependent manner in MG-63 cells but did not influence expression of other anti-apoptotic molecules such as XIAP, c-IAP-1, c-IAP-2, FADD or pro-caspase-8. Moreover, antisense oligonucleotide to FLIP-L confirmed that down-regulation of FLIP-L induced sensitization to Fas-mediated apoptosis. These findings suggest that FLIP-L contributes to resistance to Fas-mediated apoptosis in MG-63 cells, and sensitization to Fas-mediated apoptosis by CDDP can be a new application of immune therapy.
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PMID:Cisplatin (CDDP) sensitizes human osteosarcoma cell to Fas/CD95-mediated apoptosis by down-regulating FLIP-L expression. 1109 25


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