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)

In vitro studies indicate that in lymphomas, execution of apoptosis involves activation of effector caspases. To investigate activation of effector caspases in vivo in biopsy specimens of lymphomas, a new assay was developed using antibodies against active caspase 3 and p89, a protein fragment generated by caspase-specific cleavage of poly-ADP ribose polymerase (PARP). Using this assay, it was found that in B-cell lymphomas, levels of active caspase 3/p89-positive cells correlate strongly with morphologically recognizable apoptotic cells. The number of active caspase 3/p89-positive cells was low in follicular lymphomas and usually high in diffuse large cell lymphomas. Highest numbers were found in Burkitt lymphomas and in two biopsies of diffuse large B-cell lymphomas (DLCLs) obtained several days after initiation of therapy. It is concluded that apoptosis in reactive lymphoid tissues and in B-cell lymphomas always involves activation of effector caspase 3 and cleavage of one of the major effector caspase substrates, PARP-1. Moreover, levels of effector caspase activation are constantly low in low-grade follicular lymphomas and vary considerably in DLCL and Burkitt lymphoma.
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PMID:Apoptosis in B-cell lymphomas and reactive lymphoid tissues always involves activation of caspase 3 as determined by a new in situ detection method. 1185 94

The apoptotic pathway activated by chimeric anti-CD20 monoclonal antibodies (rituximab, IDEC.C2B8) was analyzed using the Burkitt lymphoma cell line Ramos. Crosslinking of CD20 (CD20XL) induced apoptosis in Ramos cells, which involved loss of mitochondrial membrane potential (Deltapsi(m)), the release of cytochrome-c (cyt-c), and activation of caspases-9 and -3. Nevertheless, several lines of evidence showed that the apoptotic outcome did not depend on these events. First, under circumstances where Ramos cells display resistance to either CD95- or B cell receptor (BCR)-induced apoptosis, CD20XL-induced apoptosis was not affected, pointing to a distinct pathway. Second, the broad-spectrum caspase inhibitor zVAD-fmk prevented processing of caspase-9, -3 and PARP as well as DNA fragmentation, but did not block apoptosis as measured by annexin V staining, cell size and membrane integrity. Lastly, Bcl-2 overexpression blocked cyt-c release and the decrease in Deltapsi(m), and completely prevented CD95- or BCR-mediated apoptosis; however, it did not affect CD20XL-induced cell death. We conclude that although CD20XL can initiate the mitochondrial apoptosis pathway, CD20-induced apoptosis does not necessarily require active caspases and cannot be blocked by Bcl-2. Since most chemotherapeutic drugs require the activation of caspases to exert their cytotoxicity, these findings provide an important rationale for the use of CD20 mAbs in chemoresistant malignancies.
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PMID:CD20-induced B cell death can bypass mitochondria and caspase activation. 1220 Jun 88

Selective serotonin reuptake inhibitors (SSRIs) are the treatment of choice for clinical depression and a range of anxiety-related disorders. They are well tolerated over extended periods with more than 50 million people worldwide benefiting from their use. Here we show that 3 structurally distinct SSRIs--fluoxetine, paroxetine, and citalopram--act directly on Burkitt lymphoma (BL) cells to trigger rapid and extensive programmed cell death. SSRIs unexpectedly stimulated calcium flux, tyrosine phosphorylation, and down-regulation of the c-myc and nm23 genes in Burkitt lymphoma cells remaining faithful to the biopsy phenotype. Resultant SSRI-induced apoptosis was preceded by caspase activation, poly(ADP-ribose) polymerase-1 (PARP-1) cleavage, DNA fragmentation, a loss of mitochondrial membrane potential, and the externalization of phosphatidylserine, and reversed by the overexpression of bcl-2. Normal peripheral blood mononuclear cells and tonsil B cells, whether resting or stimulated into cycle, were largely resistant to SSRI-induced death as were 5 non-BL lymphoid cell lines tested. We discuss these findings within the context of whether the SSRI class of antidepressants could find future application as potential therapeutics for the highly aggressive and-because of its association with AIDS-increasingly more common Burkitt lymphoma.
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PMID:Selective serotonin reuptake inhibitors directly signal for apoptosis in biopsy-like Burkitt lymphoma cells. 1251 26

We demonstrate here that selective activation of endogenous members of the caspase family and cleavage of substrates responsible for the maintenance of nuclear functional and structural integrity are major effectors of antigen receptor (AgR)- and ionomycin-triggered apoptosis in Ramos-Burkitt lymphoma (Ramos-BL) B cells. Ramos-BL B cells express significant proenzyme levels of caspase-2, -3, -7 and -8, low levels of caspase-6 and are caspase-1-negative. However, while anti-IgM and ionomycin trigger for significant activation of caspase-3, -7 and -8 at 12-16 h and at 4 h post-stimulation respectively, both anti-IgM and ionomycin fail to activate caspase-2 indicating that AgR- and ionomycin-triggered Ramos-BL B cell apoptosis is mediated by the selective activation of, at least, caspase-3, -7 and -8. Anti-IgM triggers for cleavage of the resident nuclear proteins poly(ADP-ribose) polymerase (PARP) at 8 h, lamins B1 and B2 from 12 to 16 h; likewise, ionomycin triggers for degradation of PARP at 2 h, lamins B1 and B2 at 4 h. Signal transduction through CD40 rescues Ramos-BL B cells from AgR- and ionomycin-triggered apoptosis at a very early stage of the apoptotic process by inhibiting both the early cleavage of PARP as well as the activation of caspase-3, -7 and -8 and cleavage of lamin B1; CD40-mediated rescue occurs upstream of CD40-induced expression of Bcl-2 and increased expression of Bcl-xL. In such cellular populations subject to regulation through apoptosis, dysregulation of the apoptotic mechanisms can have devastating consequences by contributing to the pathogenesis of malignancy as well as to lymphoproliferative and autoantibody disorders. An understanding of the role played by caspases in the execution of apoptosis may provide insight into the pathogenesis of these disease states and thereby provide targets for novel therapeutic strategy.
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PMID:Temporal ordering of caspase activation and substrate cleavage during antigen receptor-triggered apoptosis in Ramos-Burkitt lymphoma B cells. 1285 74

Ramos-Burkitt lymphoma (Ramos-BL) B cell line is a neoplastic model of normal B cell selection by apoptosis at the germinal center site during maturation of the humoral immune response and can be triggered into apoptosis by cross-linking their surface antigen receptor with antibodies directed against immunoglobulin (Ig)M (anti-IgM) or by treating with the calcium ionophore ionomycin. We have recently demonstrated that anti-IgM and ionomycin trigger significant activation of caspase-3, -7 and -8 and for cleavage of the resident nuclear proteins poly(ADP-ribose) polymerase (PARP) and lamin B1 in Ramos-BL B cells, suggesting that these caspases may be localized to the nucleus as well as to the cytoplasm of Ramos-BL B cells. In order to examine this hypothesis further, we fractionated Ramos-BL B cells into their cytosolic and nuclear components and examined for expression of the endogenous proform and active large subunit of caspase-3; procaspase-3 and its active p17 large subunit were identified in both the cytosolic and nuclear fractions of Ramos-BL B cells. Immunofluorescence staining together with ordinary and confocal microscopy confirmed the observations that procaspase-3 immunoreactivity was clearly identified in the cytoplasm and nucleus while Fas ligand staining was localized to the cell surface and PARP immunoactivity to the nucleus, which were used as controls; procaspase-3 exhibited granular nuclear immunoreactivity whereas PARP displayed diffuse nuclear immunoreactivity; both of which was more intense in the internucleolar regions. Taken together, we now present evidence that procaspases and their active large subunits are found in both the cytoplasm and the nucleus and that procaspases localized not only in the cytoplasm but also in the nucleus are activated following application of apoptotic stimulus in Ramos-BL B cells.
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PMID:Procaspase-3 and its active large subunit localized in both cytoplasm and nucleus are activated following application of apoptotic stimulus in Ramos-Burkitt lymphoma B cells. 1288 46

Latent membrane protein 2A (LMP2A) blocks B-cell receptor signal transduction in vitro by binding the Syk and Lyn protein tyrosine kinases. As well as blocking B-cell signal transduction, LMP2A has been shown to activate the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway, which acts as a survival signal in both B cells and epithelial cells. Transforming growth factor beta 1 (TGF-beta 1) is a multifunctional cytokine that plays important roles in regulating cell growth and differentiation in many biological systems. The loss of the growth-inhibitory response to the TGF-beta 1 signal is found in many cancers and is widely thought to promote tumor development. In this study, we found that LMP2A induced the phosphorylation of Akt (serine 473) in Burkitt's lymphoma cell line Ramos and in gastric carcinoma cell line HSC-39 and partially enhanced cell viability following TGF-beta 1 treatment. In addition, LMP2A partially inhibited TGF-beta 1-induced DNA fragmentation and cleavage of poly(ADP-ribose) polymerase (PARP). In the presence of LY294002, an inhibitor of PI3-K, the LMP2A-mediated inhibitory effects on TGF-beta 1-induced DNA fragmentation and cleavage of PARP were alleviated. Furthermore, LMP2A did not alter the levels of expression of type I and type II TGF-beta 1 receptors. Taken together, these results suggest that LMP2A may inhibit TGF-beta 1-mediated apoptosis through activation of the PI3-K/Akt pathway.
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PMID:Latent membrane protein 2A inhibits transforming growth factor-beta 1-induced apoptosis through the phosphatidylinositol 3-kinase/Akt pathway. 1474 35

The human Burkitt lymphoma Daudi cell line expresses constitutively active nuclear factor kappaB (NF-kappaB) in the nucleus in spite of high levels of inhibitor kappaB-alpha (IkappaB-alpha) in the cytoplasm. The antiproliferative response of these cells to interferon-alpha (IFN-alpha) correlated with the inhibition of the constitutive NF-kappaB activity by the cytokine. The present study shows that IFN-alpha caused an increase in p53 level, inhibited cell proliferation by [(3)H]thymidine incorporation, and stimulated cytotoxicity and apoptosis by PARP-cleavage in the Daudi cells. In order to study the relationship between the constitutively active NF-kappaB and IkappaB-alpha, a dominant negative mutant IkappaB-alpha (IkappaB-alphaDN), lacking the N-terminal 36 amino acids required for the activation of NF-kappaB by tumor necrosis factor-alpha (TNF-alpha), was expressed in the Daudi cells. The expression of IkappaB-alphaDN protein did not inhibit the constitutive NF-kappaB activity, but it inhibited cell proliferation, antiproliferative response to IFN-alpha, and phosphorylated mitogen activated protein kinase (p-MAPK) level. Thus, our results suggest that constitutive NF-kappaB activity in the human Burkitt lymphoma Daudi cells is maintained by a mechanism independent of IkappaB-alpha degradation, and that the IkappaB-alpha is involved in the proliferation of these cells, possibly through the MAP kinase pathway. Therefore, in addition to IFN-alpha treatment, both NF-kappaB and IkappaB-alpha may be used as drug targets for inhibiting cell proliferation in the lymphomas.
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PMID:Relationship between constitutive nuclear factor-kappaB (NF-kappaB) and inhibitor kappaB-alpha (IkappaB-alpha) in an interferon-alpha-sensitive human Burkitt lymphoma cell line. 1597 56

Epstein-Barr virus (EBV) infects more than 90% of the human population and has a potential oncogenic nature. Trichostatin A (TSA) has potent antitumor activity, but its exact mechanism on EBV-infected cells is unclear. This study examined the effects of TSA on proliferation and apoptosis of the Burkitt's lymphoma cell line, Akata. TSA treatment inhibited cell growth and induced cytotoxicity in both the EBV-negative and -positive Akata cells. TSA sensitively induced apoptosis in both cells, as demonstrated by the increased number of positively stained cells in the TUNEL assay, the migration of many cells to sub-G1 phase by flow cytometric analysis, and the formation of DNA ladders. This suggests that EBV has no effect on the sensitivity to TSA. Western blot analysis showed that the cleavage of PARP and Bid and the activation of caspases are closely related to the TSA-induced apoptosis of the cells. The reduction in mitochondrial transition potential and the release of apoptosis-inducing factor from mitochondria to cytosol was also observed after the TSA treatment, but was suppressed by treating the cells with a cathepsin B inhibitor. Overall, these findings suggest that besides the caspase-dependent pathway, mitochondrial events are also associated with the TSA-induced apoptosis of Akata cells.
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PMID:Involvement of caspase activation and mitochondrial stress in trichostatin A-induced apoptosis of Burkitt's lymphoma cell line, Akata. 1681 25

Gamma-irradiation leads to apoptosis and cell cycle arrest in eukaryotic cells. Olomoucine is a novel purine analog acting as a cyclin-dependent kinase inhibitor. The effects of olomoucine in gamma-irradiation mediated cell growth inhibition and apoptosis were studied in the Raji cell line (Burkitt's lymphoma). Gamma-irradiation caused a G2 arrest, increasing the G2/M fragment of the cells. Apoptosis by gamma-irradiation was apparent both by DNA-electrophoresis and PARP-1 cleavage. The combination of olomoucine with irradiation caused an increased G2 arrest and decreased cell survival and DNA synthesis in the non-apoptotic fraction of the remaining cells. Irradiation, as well as olomoucine and the combination of both, induced apoptosis. It seems that olomoucine delays the apoptotic process and inhibits DNA fragmentation, but it decreased survival, cell cycle progression and proliferation of irradiated cells.
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PMID:Cyclin-dependent kinase (CDK) inhibitor olomoucine enhances gamma-irradiation-induced apoptosis and cell cycle arrest in Raji cells. 1709 72

A new NF-kappaB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), inhibited proliferation and induced apoptosis in human Burkitt lymphoma, HS-Sultan and Daudi cell lines. The activation of caspase-3 and the cleavage of caspase substrate PARP were observed after treatment with DHMEQ. The induction of apoptosis by DHMEQ was prevented by the pretreatment of Burkitt lymphoma cells with pan-caspase inhibitor, z-VAD-FMK. The expression of anti-apoptotic factors such as IAP-1 and XIAP was suppressed by DHMEQ. Phosphorylation of ERK and JNK was induced by DHMEQ. In conclusion, these results demonstrate that NF-kappaB might be an ideal target to develop for new anti-cancer drugs for Burkitt lymphoma.
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PMID:Targeting NF-kappaB and induction of apoptosis by novel NF-kappaB inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) in Burkitt lymphoma cells. 1746 73


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