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: EC:2.4.2.30 (PARP)
13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Type I cells have been defined to be independent of mitochondria for the induction of Fas death receptor-mediated apoptosis, whereas Type II cells are mitochondria-dependent. Knock-out studies in mice show that thymocytes are Type I and liver cells are Type II. We have previously shown that primary human hepatocytes and HCT116 human colon carcinoma cells behave like Type II cells because TRAIL-induced apoptosis can be blocked by the caspase 9 inhibitor, Z-LEHD-FMK. On the other hand, caspase 9 inhibition does not allow survival of TRAIL-treated SW480 colon cancer cells, which is predicted for Type I cells. Investigating the differences in TRAIL-induced apoptotic pathways in HCT116 and SW480 cells revealed that although FADD, BID, and procaspase 3 protein levels are higher in SW480 cells, and although procaspase 8 and FLIP processing is more efficient at the TRAIL-DISC of SW480 cells, BID, procaspase 3, XIAP, and PARP cleavages occur more rapidly in HCT116, despite the higher levels of BCL-2 and HSP70. Cytochrome c release from the mitochondria to the cytoplasm is more efficient in HCT116 cells. These results suggest BID cleavage as a possible limiting factor in the involvement of mitochondria in TRAIL-induced cell death. Thus, regulation of BID cleavage may define if a cell is mitochondria-dependent or -independent in response to TRAIL death receptor-induced apoptosis.
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PMID:Defining characteristics of Types I and II apoptotic cells in response to TRAIL. 1240 50

Bacterial endotoxin (lipopolysaccharide [LPS]) is a potent inducer of human dendritic cell (DC) maturation and survival. Here we show that immature DCs exposed to LPS trigger an early and sustained caspase-like activity, which can be blocked by zVAD (z-Val-Ala-Asp), in the absence of detectable caspase 8 and caspase 10 activation, or poly(ADP-ribose) polymerase (PARP)-cleaving activity. Preventing LPS-induced caspase-like activation in DC results in massive cell death. Importantly, triggering of the caspase-like activity is required for LPS-induced activation of extracellular signal-regulated kinases (ERKs) and for LPS-induced up-regulation of cFLIP (Fas-associating protein with death domain-like interleukin-1 beta-converting enzyme [FLICE]-like inhibitory protein). Therefore, a caspase-dependent pathway initiated by LPS controls survival of human DCs.
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PMID:A caspaselike activity is triggered by LPS and is required for survival of human dendritic cells. 1282 89

Interactions between the cyclin-dependent kinase inhibitor flavopiridol (FP) and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL/Apo2L), were examined in human leukemia cells (U937 and Jurkat). Coexposure of cells to marginally toxic concentrations of TRAIL and FP (24 h) synergistically increased mitochondrial injury (eg, cytochrome c, AIF, Smac/DIABLO release), cytoplasmic depletion of Bax, activation of Bid as well as caspase-8 and -3, PARP cleavage, and apoptosis. Coadministration of TRAIL markedly increased FP-induced apoptosis in leukemic cells ectopically expressing Bcl-2, Bcl-x(L), or a phosphorylation loop-deleted form of Bcl-2 (DeltaBcl-2), whereas lethality was substantially attenuated in cells ectopically expressing CrmA, dominant-negative-FADD, or dominant-negative-caspase-8. TRAIL/FP induced no discernible changes in FLIP, DR4, DR5, Mcl-1, or survivin expression, modest declines in levels of DcR2 and c-IAP, but resulted in the marked transcriptional downregulation of XIAP. Moreover, cells stably expressing an XIAP-antisense construct exhibited a pronounced increase in TRAIL sensitivity comparable to degrees of apoptosis achieved with TRAIL/FP. Conversely, enforced XIAP expression significantly attenuated caspase activation and TRAIL/FP lethality. Together, these findings suggest that simultaneous activation of the intrinsic and extrinsic apoptotic pathways by TRAIL and FP synergistically induces apoptosis in human leukemia cells through a mechanism that involves FP-mediated XIAP downregulation.
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PMID:Potent antileukemic interactions between flavopiridol and TRAIL/Apo2L involve flavopiridol-mediated XIAP downregulation. 1538 34

The majority of high-risk neuroblastomas lack the expression of caspase-8 due to gene silencing which suggest a mechanism for the selection of tumour cells that are refractory to multiple cytotoxic drugs including tumour necrosis factor-related apoptosis-inducing ligand (TRAIL). Inhibitors of DNA methyltransferases and IFN-gamma induce expression of caspase-8, and sensitise some neuroblastoma cells to TRAIL-mediated apoptosis. Here we demonstrate that a combination of cytostatic drugs with IFN-gamma and TRAIL synergistically induces neuroblastoma cell death, which may have implications for future therapy of children with neuroblastoma. Treatment of neuroblastoma cells with IFN-gamma induced caspase-8 expression in all cell lines investigated. In five of the neuroblastoma cell lines (SHEP-1, SK-N-AS, SK-N-FI, SH-SY-5Y and Kelly), IFN-gamma promoted TRAIL-mediated cleavage of caspase-8, initiating a caspase cascade involving caspase-7 and PARP followed by apoptosis. IFN-gamma-mediated facilitation of apoptosis was inhibited by the pan-caspase inhibitor zVAD-fmk and the caspase-8 specific inhibitor zIEDT-fmk, indicating an important role of caspase-8 in mediating sensitation by IFN-gamma in neuroblastoma cells. In three of the cell lines [SK-N-BE(2), SK-N-DZ and IMR-32] caspase-8 expression was induced by IFN-gamma, but the cells were still resistant to TRAIL-mediated apoptosis. The pattern of basal TRAIL receptor expression, decoy receptors, FLIP and FADD could not be correlated with resistance or sensitivity to TRAIL-induced apoptosis. Importantly, treatment of neuroblastoma cell lines with cytostatic drugs increased apoptosis in the TRAIL-sensitive cell lines whereas the resistant cell lines were susceptible to TRAIL-mediated apoptosis in the presence of the anticancer drugs. The mechanism of the increased susceptibility to apoptosis might results from drug-mediated up-regulation of the death receptors DR4 and DR5.
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PMID:Synergistic induction of apoptosis in neuroblastoma cells using a combination of cytostatic drugs with interferon-gamma and TRAIL. 1554 26

Neonatal rat ventricular myocytes (NRVM) grown in normoxic environment are not susceptible to Fas-induced apoptosis. In the present work, we tested the hypothesis that free radical injury represented by transient exposure to H2O2 sensitizes NRVM to Fas-mediated apoptosis. NRVM were treated with H2O2 (0.5 mM) for 2-4 h and thereafter exposed for 7 h to recombinant Fas ligand (rFasL, 10 ng/ml) plus an enhancing antibody (1 microg/ml). Apoptotic cardiomyocytes were counted and apoptosis-related proteins were measured by Western blot. H2O2 alone induced apoptosis (9.4+/-1.0%) that was preceded by activation of caspases-8 and -3, and PARP degradation. Incubation of NRVM with H2O2, followed by exposure to rFasL, increased the apoptotic index to 13.8+/-2.0%, but did not change caspase-8 or PARP activation. To investigate the mechanism underlying the sensitizing affect of H2O2 towards Fas-induced apoptosis, we studied the effects of H2O2 on the expression of key apoptosis signaling proteins. Incubation with H2O2 for 2-4 h decreased Fas expression and the expression of the Fas-related antiapoptotic proteins FLIP(L) and ARC, and increased the expression of the antiapoptotic proteins bcl-2 and xIAP. FADD expression was unchanged. Next, we tested the effect of H2O2 on the apoptosis-inducing, Fas-dependent Daxx-ASK-1-JUN kinase pathway. H2O2 dramatically increased ASK-1 expression and JUN kinase activation, but did not effect Daxx expression. Based on these findings we concluded that H2O2 sensitizes NRVM to Fas-mediated apoptosis by activating the Daxx-ASK-1-JUN kinase pathway, and by shifting the balance between proapoptotic and antiapoptotic proteins towards the former.
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PMID:Hydrogen peroxide predisposes neonatal rat ventricular myocytes to Fas-mediated apoptosis. 1615 98

The combination of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and cisplatin resulted in a greater cytotoxicity than could be accounted for by the addition of the cytotoxic effects of the agents alone. In this study, we hypothesized that the synergistic interaction between the two modalities can be changed when both the sequence and the time interval between the two treatments are varied. To test the hypothesis, human head-and-neck squamous-cell carcinoma (HNSCC)-6 cells were either pretreated with 0.01-0.5 microg/ml TRAIL for various times (0-24 h) followed by treatment with 5 microg/ml cisplatin or pretreated with 5 microg/ml cisplatin for various times (0-24 h) followed by treatment with 0.5 microg/ml TRAIL. In latter case, the synergistic effect was gradually increased when the time interval between the two treatments was increased. In former case, a maximal synergy occurred within 0-4 h of pretreatment with TRAIL. However, the synergistic effect was gradually decreased when the time interval between the two treatments was increased. Data from immunoblotting analysis reveal that a similar pattern emerged for the PARP cleavage and caspase activation. The synergistic effect is not associated with DR4, DR5, FADD, and FLIP(L). Interestingly, a complex pattern of synergistic interaction between TRAIL and cisplatin is related to the cleavage of FLIP(S). Although overexpression of FLIP(S) protected cells from FLIP(S) cleavage and apoptotic death, blockage of FLIP(S) cleavage by replacing Asp(39) and Asp(42) residues with alanine did not further enhance FLIP(S)-mediated protection. Taken together, FLIP(S) cleavage reflects apoptotic damage, but it does not cause apoptosis.
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PMID:Time sequence of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and cisplatin treatment is responsible for a complex pattern of synergistic cytotoxicity. 1651 44

Prolonged ERK/MAPK activation has been implicated in neuronal cell death in vitro and in vivo. We found that HEK293 cells, recently reported to express neuronal markers, are exquisitely sensitive to long term ERK stimulation. Activation of an inducible form of Raf-1 (Raf-1:ER) in HEK293 cells induced massive apoptosis characterized by DNA degradation, loss of plasma membrane integrity and PARP cleavage. Cell death required MEK activity and protein synthesis and occurred via the death receptor pathway independently of the mitochondrial pathway. Accordingly, prolonged ERK stimulation activated caspase 8 and strongly potentiated Fas signaling. The death receptor adaptator FADD was found to be rapidly induced upon ERK activation. However using RNA interference and ectopic expression, we demonstrated that neither FADD nor Fas were necessary for caspase 8 activation and cell death. These findings reveal that prolonged ERK/MAPK stimulation results in caspase 8 activation and cell death.
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PMID:Prolonged activation of ERK1,2 induces FADD-independent caspase 8 activation and cell death. 1653 83

Silymarin is a polyphenolic flavonoid from milk thistle (Silybum marianum), which has anti-inflammatory, cytoprotective, and anticarcinogenic effects. In this study, we assessed the effect of silibinin (Fig. 1), the major active compound in silymarin, on ultraviolet light (UV)-induced cell apoptosis in HaCaT cells, a human keratinocyte cell line. Pretreatment with silibinin 500 microM significantly inhibited UV-induced apoptosis in HaCaT cells after 9 h incubation. The expression of Fas-associating protein with death domain (FADD), a downstream molecule of the death receptor pathway, was completely eliminated by silibinin treatment in UV-irradiated HaCaT cells, followed by inhibition of cleavage of procaspase-8, whose activation induced cell apoptosis and decreased the release of cytochrome c from mitochondria. The caspase-8 inhibitor z-IETD-fmk at 10 microM increased the ratio of UV-irradiated HaCaT cell viability, suggesting that UV-induced HaCaT cell apoptosis was partially due to activation of the caspase-8 pathway. Moreover, UV-induced cleavage of procaspase-3 and digestion of its substrates, the inhibitor of caspase-activated DNase (ICAD) and poly-(ADP-ribose) polymerase (PARP), were also reduced by silibinin pretreatment. While unexpectedly, it was found in our study that pretreatment with silibinin increased HaCaT cell death by CD95 agonistic antibody CH11. Consequently, the protective effect of silibinin against UV irradiation in HaCaT cells is exerted by inactivation of caspase-8 after direct down-regulation of FADD expression, resulting in blockage of UV-induced apoptosis.
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PMID:Silibinin prevents UV-induced HaCaT cell apoptosis partly through inhibition of caspase-8 pathway. 1675

We have previously reported that the downregulation of MMP-2 by adenovirus-mediated delivery of MMP-2 siRNA (Ad-MMP-2) reduced spheroid invasion and angiogenesis in vitro, and, metastasis and tumor growth in vivo. In this study, we investigated the mechanism of Ad-MMP-2-mediated growth inhibition in vitro and in vivo. Ad-MMP-2 infection led to the induction of apoptosis as determined by TUNEL assay, Annexin-V staining and PARP-1 cleavage in a dose-dependent manner in A549 cells. Ad-MMP-2 decreased the content of the antiapoptotic members of the Bcl-2 family proteins (Bcl-2 and Bcl-xL) and increased the content of the pro-apoptotic members of the Bcl-2 family (Bax and Bcl-xS) as determined by immunoblotting analysis. Furthermore, Ad-MMP-2-mediated apoptosis was accompanied by increase in truncated Bid, release of cytochrome c and the activation of caspase-8, -9 and -3. Immunoblot analysis showed that Ad-MMP-2 infection caused upregulation of Fas/Fas-L and FADD, and Anti-Fas-L antibody reversed Ad-MMP-2-induced apoptosis. Tissue inhibitor of metalloproteinases (TIMP)-3, an endogenous inhibitor of MMP-2, which cleaves Fas-L and activates the Fas/Fas-L inducing apoptotic pathway, was increased in Ad-MMP-2-treated cells. Adenovirus-mediated expression of MMP-2 siRNA in human lung xenografts in vivo resulted in increased immunostaining of Fas, Fas-L, cleaved Bid and TIMP-3. This is the first report, to our knowledge, showing that MMP-2 inhibition upregulates TIMP-3 levels, which in turn, promotes apoptosis in lung cancer.
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PMID:MMP-2 siRNA induced Fas/CD95-mediated extrinsic II apoptotic pathway in the A549 lung adenocarcinoma cell line. 1759 56

Myrtucommulone (MC) is a unique, nonprenylated acylphloroglucinol contained in the leaves of myrtle (Myrtus communis). Here, we addressed the potential of MC to induce apoptosis of cancer cells. MC potently induced cell death of different cancer cell lines (EC(50) 3-8 microM) with characteristics of apoptosis, visualized by the activation of caspase-3, -8 and -9, cleavage of poly(ADP-ribose)polymerase (PARP), release of nucleosomes into the cytosol, and DNA fragmentation. MC was much less cytotoxic for non-transformed human peripheral blood mononuclear cells (PBMC) or foreskin fibroblasts (EC(50) cell death = 20-50 microM), and MC up to 30 microM hardly caused processing of PARP, caspase-3, -8 and -9 in human PBMC. MC-induced apoptosis was mediated by the intrinsic rather than the extrinsic death pathway. Thus, MC caused loss of the mitochondrial membrane potential in MM6 cells and evoked release of cytochrome c from mitochondria. Interestingly, Jurkat cells deficient in caspase-9 were resistant to MC-induced cell death and no processing of PARP or caspase-8 was evident. In cell lines deficient in either CD95 (Fas, APO-1) signalling, FADD or caspase-8, MC was still able to potently induce cell death and PARP cleavage. Conclusively, MC induces apoptosis in cancer cell lines, with marginal cytotoxicity for non-transformed cells, via the mitochondrial cytochrome c/Apaf-1/caspase-9 pathway.
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PMID:Myrtucommulone from Myrtus communis induces apoptosis in cancer cells via the mitochondrial pathway involving caspase-9. 1795 73


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