Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.61 (caspase-8)
 6,833 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Humans and mice with systemic lupus erythematosus (SLE) and related autoimmune diseases have reduced numbers of NK T cells. An association between NK T cell deficiency and autoimmune disease has been identified. However, the mechanisms for reduction of NK T cell number in patients with SLE are unknown. In the present study we report that NK T cells from active SLE patients are highly sensitive to anti-CD95-induced apoptosis compared with those from normal subjects and inactive SLE patients. CD226 expression is deficient on NK T cells from active SLE patients. The expression of one antiapoptotic member protein, survivin, is found to be selectively deficient in freshly isolated NK T cells from active SLE patients. CD226 preactivation significantly up-regulates survivin expression and activation, which can rescue active SLE NK T cells from anti-CD95-induced apoptosis. In transfected COS7 cells, we confirm that anti-CD95-mediated death signals are inhibited by activation of the CD226 pathway through stabilization of caspase-8 and caspase-3 and through activation of survivin. We therefore conclude that deficient expression of CD226 and survivin in NK T cells from active SLE is a molecular base of high sensitivity of the cells to anti-CD95-induced apoptosis. These observations offer a potential explanation for high apoptotic sensitivity of NK T cells from active SLE, and provide a new insight into the mechanism of reduction of NK T cell number in SLE and understanding the association between NK T cell deficiency and autoimmune diseases.
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PMID:CD226 expression deficiency causes high sensitivity to apoptosis in NK T cells from patients with systemic lupus erythematosus. 2261 Dec 49

Flavopiridol and UCN-01 are two novel protein kinase inhibitors with diverse cellular effects that may complement each other with regards to induction of apoptosis. HeLa cells engineered to overexpress human survivin (HeLa-S) were at least approximately 4.8-fold resistant to UCN-01 relative to proliferation observed in control HeLa cells (HeLa-V). Flavopiridol cytotoxicity as measured using the MTT assay was unaffected in HeLa-S cells when compared with HeLa-V cells. Similarly, simultaneous treatment of HeLa-V cells with flavopiridol and UCN-01 for 72 hours did not result in synergistic inhibition of proliferation; however, in HeLa-S cells, this combination resulted in synergistic inhibition of cell proliferation. Flavopiridol and UCN-01 augmented apoptosis in HeLa-S cells (as compared with HeLa-V cells) as measured by caspase-3 cellular activity assay, DNA fragmentation and PARP cleavage by western blot. In HeLa-V and -S cells, combination treatment resulted in caspase-8 cleavage. Caspase-9 was expressed in HeLa-V cells; however, there was a marked reduction of caspase-9 content in HeLa-S cells only. Combination treatment resulted in a significant reduction in survivin abundance in HeLa-S and SKBR3-UR cells, but not in their respective parental lines. The synergy of Flavopiridol and UCN-01 are selectively toxic to survivin-overexpressing cell lines and the mechanism of toxicity involves caspase-dependent cell death.
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PMID:A study of cytotoxic synergy of UCN-01 and flavopiridol in syngeneic pair of cell lines. 1601 89

The effects of the nuclear factor (NF)-kappaB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), combined with tumor necrosis factor (TNF)-alpha were evaluated in PK-8 pancreatic cancer cells. NF-kappaB was activated by TNF-alpha; however, the administration of DHMEQ abrogated its transcriptional activity. The addition of DHMEQ to TNF-alpha markedly induced apoptosis in PK-8 cells with down-regulation of anti-apoptotic c-FLIP and survivin. Combined treatment significantly suppressed cell viability in vitro, and the anti-tumor effect of DHMEQ was also significant in vivo. We investigated the apoptosis signaling pathway involved in these cell killing effects. Truncated Bid was produced by activated caspase-8, and the subsequent depolarization of the mitochondrial membrane potential (Delta Psi m) peaked at 6 h. Then, the activity of caspase-3 was up-regulated 8-fold. Z-VAD-fmk (a pan-caspase inhibitor) perfectly inhibited the up-regulation of caspase-3 but failed to reverse the cell viability. The above findings indicated that the growth inhibitory effect of combined treatment largely depended on mitochondria-associated caspase-independent apoptosis. The intracellular behavior of apoptosis-inducing factor (AIF) following depolarization of Delta Psi m suggested that AIF executed such a caspase-independent apoptosis. Interestingly, caspase-dependent apoptosis appeared within 6 h, whereas the caspase-independent apoptosis lagged. Thus, the addition of DHMEQ to TNF-alpha was capable of inducing caspase-independent apoptosis in pancreatic cancer cells. Once caspase-independent apoptosis was induced, the apoptosis demonstrated powerful cytotoxicity. Therefore, DHMEQ in combination with TNF-alpha may be a promising treatment for pancreatic cancer.
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PMID:Enhancement of the caspase-independent apoptotic sensitivity of pancreatic cancer cells by DHMEQ, an NF-kappaB inhibitor. 1621 Dec 19

The capacity of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) to preferentially induce apoptosis in malignant cells while sparing normal tissues renders it an attractive therapeutic agent. Nevertheless, the molecular determinants governing sensitivity towards TRAIL remain to be defined. Acknowledging the previously demonstrated deregulation of prostate-apoptosis-response-gene-4 (par-4) in ex vivo cells of patients suffering from acute and chronic lymphatic leukemia, we here tested the hypothesis that expression of par-4 influences sensitivity to TRAIL. Evaluating this hypothesis we show, that par-4-transfected T-lymphoblastic Jurkat cells exhibit a considerably increased rate of apoptosis upon incubation with an agonistic TRAIL-antibody as compared to their mock-transfected counterparts. Defining the underlying molecular mechanisms we provide evidence, that par-4 enhances sensitivity towards TRAIL by employing crucial members of the extrinsic pathway. Thus, par-4-overexpressing Jurkat clones show an enforced cleavage of c-Flip(L) together with an increased activation of the initiator caspases-8 and -10. In addition, expression of par-4 enables cells to down-regulate the inhibitor-of-apoptosis proteins cIAP-1, cIAP-2, XIAP and survivin with a concomitantly enhanced activation of the executioner caspases-6 and -7. Supporting the crucial role of caspase-8 in par-4-promoted apoptosis we demonstrate that inhibition of caspase-8 considerably reduces TRAIL-induced apoptosis in par-4 and mock-transfected Jurkat clones and reverses the described molecular changes. In conclusion, we here provide first evidence that expression of par-4 in neoplastic lymphocytes augments sensitivity to TRAIL-induced cell death and outline the responsible molecular mechanisms, in particular the crucial role of caspase-8 activation.
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PMID:Prostate-apoptosis-response-gene-4 increases sensitivity to TRAIL-induced apoptosis. 1628 45

Ponicidin, an ent-kaurane diterpenoid derived from a constituent of the herbal supplement PC-SPES, Rabdosia rubescens, is recently reported to have anti-tumor effects on a large variety of cancers. In this study, we demonstrate that ponicidin exhibits cytotoxicity, induces apoptosis, disrupts the mitochondrial membrane potential, and triggers the activation of caspase-3, -8 and -9 in lung cancer A549 and GLC-82 cells. Ponicidin treatment of lung cancer cells caused downregulation of anti-apoptotic protein Bcl-2 and survivin as well as upregulaton of pro-apoptotic protein Bax in a time dependent manner when apoptosis ocurred. Ponicidin induced activation of caspase-3 can be blocked by a caspase-3-specific inhibitor z-DEVD-FMK Furthermore, the caspase-8-specific inhibitor z-IETD-FMK could block the ponicidin-induced activation of caspase-3, PARP cleavage, and prevented the release of cytochrome c from mitochondria into the cytoplasm. This indicate that activated caspase-8 initiates the release of cytochrome c during ponicidin-induced apoptosis. We therefore conclude that ponicidin has significant apoptosis-inducing effects by activation of caspase-3 -8, and -9 as well as downregulation of anti-apoptotic protein Bcl-2, survivin and upregulation of pro-apoptotic protein Bax, with caspase-8 acting as an upstream activator. The data offer a potential mechanism for ponicidin-induced apoptosis in lung cancer cells, suggesting that ponicidin may severve as an effective reagent for the treatment of lung cancer, and that in vivo anti-cancer effects as well as its potential clinical effectiveness need further investigation.
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PMID:Ponicidin, an ent-kaurane diterpenoid derived from a constituent of the herbal supplement PC-SPES, Rabdosia rubescens, induces apoptosis by activation of caspase-3 and mitochondrial events in lung cancer cells in vitro. 1653 82

In this study, we have investigated the underlying molecular mechanism for the potent proapoptotic effect of luteolin on human hepatoma cells both in vitro and in vivo, focusing on the signal transducer and activator of transcription 3 (STAT3)/Fas signaling. A clear apoptosis was found in the luteolin-treated HLF hepatoma cells in a time- and dosage-dependent manner. In concert with the caspase-8 activation by luteolin, an enhanced expression in functional Fas/CD95 was identified. Consistent with the increased Fas/CD95 expression, a drastic decrease in the Tyr(705) phosphorylation of STAT3, a known negative regulator of Fas/CD95 transcription, was found within 20 minutes in the luteolin-treated cells, leading to down-regulation in the target gene products of STAT3, such as cyclin D1, survivin, Bcl-xL, and vascular endothelial growth factor. Of interest, the rapid down-regulation in STAT3 was consistent with an accelerated ubiquitin-dependent degradation in the Tyr(705)-phosphorylated STAT3, but not the Ser(727)-phosphorylated one, another regulator of STAT3 activity. The expression level of Ser(727)-phosphorylated STAT3 was gradually decreased by the luteolin treatment, followed by a fast and clear down-regulation in the active forms of CDK5, which can phosphorylate STAT3 at Ser(727). An overexpression in STAT3 led to resistance to luteolin, suggesting that STAT3 was a critical target of luteolin. In nude mice with xenografted tumors using HAK-1B hepatoma cells, luteolin significantly inhibited the growth of the tumors in a dosage-dependent manner. These data suggested that luteolin targeted STAT3 through dual pathways-the ubiquitin-dependent degradation in Tyr(705)-phosphorylated STAT3 and the gradual down-regulation in Ser(727)-phosphorylated STAT3 through inactivation of CDK5, thereby triggering apoptosis via up-regulation in Fas/CD95.
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PMID:Luteolin promotes degradation in signal transducer and activator of transcription 3 in human hepatoma cells: an implication for the antitumor potential of flavonoids. 1665 38

Caspase-8 belongs to the cysteine protease family and is known to be activated at the initial step in the cascade of TRAIL-induced apoptosis. The activation of procaspase-8 can be blocked by a relatively large amount of c-FLIP, which renders resistance to death receptor-mediated apoptosis in many types of cancer cells. To ask if extrinsic over-expression of caspase-8 contributes to the induction of apoptosis, we introduced the caspase-8 gene into HCC cells using an adenoviral (Adv) vector (Adv-Casp8). We demonstrated that Adv-Casp8 increased expression of active forms of caspase-8 in MOI-dependent manner. A large amount of Adv-Casp8 (MOI of 50) induced apoptosis significantly in HCC cells and resulted in downregulation of c-FLIP (in SK-Hep1, HLE, and HepG2 cells), XIAP, survivin, and Bcl-xL (in HLE cells) and dynamic release of cytochrome c and Smac from the mitochondria into the cytosol. On the other hand, a small amount of Adv-Casp8 (MOI of 10) causes a slight but detectable increase in the level of apoptosis with only a small effect on anti-apoptotic proteins and mitochondrial activation. However, small amounts of Adv-Casp8 augmented TRAIL- or chemotherapeutic agent-induced cell death (with an MOI of 10 or 20, respectively). These results suggest both that exogenous over-expression of caspase-8 by Adv-Casp8 may be essential for induction of HCC cell death and that the combination of Adv-Casp8 and TRAIL or chemotherapeutic agents could provide a useful strategy for treatment of HCC.
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PMID:Adenovirus-mediated transfection of caspase-8 sensitizes hepatocellular carcinoma to TRAIL- and chemotherapeutic agent-induced cell death. 1675 Feb 75

Islet transplantation is a treatment option for type I diabetic patients. Preservation of human pancreata prior to islet isolation using two-layer method with perfluorocarbon (PFC) and University of Wisconsin solution (UW) results in twofold increase in islet yields. The objective of this study was to determine the mechanism by which islets undergo apoptosis and determine PFC's effects on this process. Gene array analysis was used to analyze the expression of pro- and anti-apoptotic genes in islets isolated from pancreata preserved under varying conditions. A 12-fold increase in the expression of inhibitor of apoptosis (IAP) and survivin was observed in islets isolated from pancreata preserved in PFC. This was accompanied by decreased expression of BAD (3.7-fold), BAX (2.7-fold) and caspases (5.2-fold). Levels of activated caspase-9 (77.98%), caspase-2 (61.5%), caspase-3 (68.3%) and caspase-8 (37.2%) were also reduced. 'Rescue' of pancreata after storage (12 h) in UW by preservation using PFC also resulted in a down-regulation of pro-apoptotic genes and inhibition of caspase activation. Apoptosis observed in islets from all groups was mainly mitochondria-dependent, mediated by change in redox potential initiated by hypoxia. We demonstrate that reduction in hypoxia of pancreata preserved using PFC leads to significant up-regulation of anti-apoptotic and inhibition of pro-apoptotic genes.
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PMID:Improved islet yields from pancreas preserved in perflurocarbon is via inhibition of apoptosis mediated by mitochondrial pathway. 1682 73

The synergistic interaction between proteasome inhibitors and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a promising approach to induce cell death in tumor cells. However, the molecular and biochemical mechanisms of this synergism have been proven to be cell type specific. We therefore focused our investigation on TRAIL-resistant colon carcinoma cells in this study. DNA fragmentation, mitochondrial membrane depolarization and increased caspase-3-like enzyme activity was exclusively induced only by combined treatment with proteasome inhibitors (epoxomicin, MG132, bortezomib/PS-341) and TRAIL. The expression level of anti-apoptotic proteins (XIAP, survivin, Bcl-2, Bcl-XL), regulated by NF-kappaB transcription factor, was not effected by any of these treatments. TRAIL alone induced only partial activation of caspase-3 (p20), while the combination of TRAIL and proteasome inhibition led to the full proteolytic activation of caspase-3 (p17). Only the combination treatment induced marked membrane depolarization and the release of cytochrome c, HtrA2/Omi and Smac/DIABLO. Apoptosis-inducing factor (AIF) was not released in any of these conditions. These results are consistent with a model where the full activation of caspase-3 by caspase-8 is dependent on the release of Smac/DIABLO in response to the combined treatment. This molecular mechanism, independent of the inhibition NF-kappaB activity, may provide rationale for the combination treatment of colon carcinomas with proteasome inhibitors and recombinant TRAIL or agonistic antibody of TRAIL receptors.
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PMID:Proteasome inhibitors sensitize colon carcinoma cells to TRAIL-induced apoptosis via enhanced release of Smac/DIABLO from the mitochondria. 1699 92

We have reported previously that R-enantiomer of etodolac (R-etodolac), which is under investigation in phase 2 clinical trials in chronic lymphocytic leukemia, induces potent cytotoxicity at clinically relevant concentrations in multiple myeloma (MM) cells. In this study, we demonstrated that SDX-308 (CEP-18082), a novel analog of etodolac, has more potent cytotoxicity than R-etodolac against both MM cell lines and patient MM cells, including tumor cells resistant to conventional (dexamethasone, doxorubicine, melphalan) and novel (bortezomib) therapies. SDX-308-induced cytotoxicity is triggered by caspase-8/9/3 activation and poly (ADP-ribose) polymerase cleavage, followed by apoptosis. SDX-308 significantly inhibits beta-catenin/T-cell factor pathway by inhibiting nuclear translocation of beta-catenin, thereby downregulating transcription and expression of downstream target proteins including myc and survivin. Neither interleukin-6 nor insulin-like growth factor-1 protect against growth inhibition triggered by SDX-308. Importantly, growth of MM cells adherent to bone marrow (BM) stromal cells is also significantly inhibited by SDX-308. Our data therefore indicate that the novel etodolac analog SDX-308 can target MM cells in the BM milieu.
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PMID:Novel etodolac analog SDX-308 (CEP-18082) induces cytotoxicity in multiple myeloma cells associated with inhibition of beta-catenin/TCF pathway. 1726 21


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