Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.56 (caspase-3)
 35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

MCF-7 cells lack caspase-3 but undergo mitochondrial-dependent apoptosis via caspase-7 activation. It is assumed that the Apaf-1-caspase-9 apoptosome processes caspase-7 in an analogous manner to that described for caspase-3. However, this has not been validated experimentally, and we have now characterized the caspase-7 activating apoptosome complex in MCF-7 cell lysates activated with dATP/cytochrome c. Apaf-1 oligomerizes to produce approximately 1.4-MDa and approximately 700-kDa apoptosome complexes, and the latter complex directly cleaves/activates procaspase-7. This approximately 700-kDa apoptosome complex, which is also formed in apoptotic MCF-7 cells, is assembled by rapid oligomerization of Apaf-1 and followed by a slower process of procaspase-9 recruitment and cleavage to form the p35/34 forms. However, procaspase-9 recruitment and processing are accelerated in lysates supplemented with caspase-3. In lysates containing very low levels of Smac and Omi/HtrA2, XIAP (X-linked inhibitor of apoptosis) binds tightly to caspase-9 in the apoptosome complex, and as a result caspase-7 processing is abrogated. In contrast, in MCF-7 lysates containing Smac and Omi/HtrA2, active caspase-7 is released from the apoptosome and forms a stable approximately 200-kDa XIAP-caspase-7 complex, which apparently does not contain cIAP1 or cIAP2. Thus, in comparison to caspase-3-containing cells, XIAP appears to have a more significant antiapoptotic role in MCF-7 cells because it directly inhibits caspase-7 activation by the apoptosome and also forms a stable approximately 200-kDa complex with active caspase-7.
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PMID:Caspase-7 is directly activated by the approximately 700-kDa apoptosome complex and is released as a stable XIAP-caspase-7 approximately 200-kDa complex. 1635 6

During the postnatal development of cerebellum, lack of excitatory innervation from the mossy fibers results in cerebellar granule cell (CGC) apoptosis during the migration of the cells toward the internal granule cell layer. Accordingly, CGCs die by apoptosis when cultured in physiological KCl concentrations (5 mm; K5), and they survive in the presence of depolarizing conditions such as high KCl concentration (25 mm; K25) or N-methyl-D-aspartate (NMDA). We have recently shown that NMDA is able to exert a long lasting neuroprotective effect when added to immature (2 days in vitro) CGC cultures by inhibition of caspase-3 activity. Here we show that NMDA- and K25-mediated neuroprotection is associated with an increase in the levels of Bcl-2, an inhibition of K5-mediated increase in Bax, and the inhibition of the release of apoptogenic factors from mitochondria such as Smac/DIABLO and cytochrome c. Moreover, we have shown that similar effects are observed when c-Jun N-terminal kinases (JNKs) are inhibited and that treatment of CGC cultures with NMDA blocks K5-mediated JNK activation. These results allow us to postulate that the inhibition of JNK-mediated release of apoptogenic factors from mitochondria is involved in the NMDA protection from K5-mediated apoptosis of CGCs.
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PMID:N-methyl-D-aspartate blocks activation of JNK and mitochondrial apoptotic pathway induced by potassium deprivation in cerebellar granule cells. 1638 Mar 82

The ability of cancers to evade immune surveillance and resist immunotherapy raises a fundamental question of how tumor cells survive in the presence of a competent immune system. Studies to address this question have primarily focused on mechanisms by which tumor cells avoid recognition by or induce tolerance in the immune system. However, little is known about whether cancer cells also acquire an intrinsic ability to resist killing by immune effectors. We find that cancer cells enhance their ability to withstand an attack by cytotoxic immune effector cells via acquisition of specific genetic alterations that interfere with the shared mitochondrial death signaling pathway entrained by granzyme B, IFN-gamma, and Apo2 ligand/tumor necrosis factor-related apoptosis inducing ligand (Apo2L/TRAIL), three key mediators of immunologic cell-mediated cytotoxicity. We show that the coexistence of specific mitochondrial signaling defects (either deletion of Bax, overexpression of Bcl-x(L), or deletion of Smac) with expression of X-linked inhibitor of apoptosis protein decreases the sensitivity of cancer cells to IFN-gamma/Apo2L/TRAIL- or granzyme B-induced apoptosis, lymphocyte-mediated cytotoxicity in vitro, and adoptive cellular immunotherapy in vivo. Conversely, negating X-linked inhibitor of apoptosis protein expression or function in tumor cells with defective mitochondrial signaling enables direct activation of caspase-3/-7 by granzyme B or Apo2L/TRAIL, and restores their susceptibility to immunologic cytotoxicity. These findings identify an important mechanism by which cancers evade elimination by immune effector cells and suggest that cancer immunotherapy might be improved by concurrent strategies to alleviate or circumvent the intrinsic mitochondrial death signaling defects that help cancer cells resist immunologic cytotoxicity.
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PMID:Resistance of cancers to immunologic cytotoxicity and adoptive immunotherapy via X-linked inhibitor of apoptosis protein expression and coexisting defects in mitochondrial death signaling. 1645 33

The current study demonstrates a novel cross-talk mechanism between the TRAIL receptor death signaling pathway and the mitochondria. This newly identified pathway is regulated at the mitochondrial outer membrane by a complex between the prosurvival Bcl-2 member, Mcl-1 and the BH3-only protein, Bim. Under non-apoptotic conditions, Bim is sequestered by Mcl-1. Direct degradation of Mcl-1 by TRAIL-activated caspase-8 or caspase-3 produces Mcl-1-free Bim that mediates a Bax-dependent apoptotic cascade. Using Mcl-1 or Bim RNAi, we demonstrate that a loss in Mcl-1 expression significantly enhances the mitochondrial apoptotic response to TRAIL that is now mediated by freed Bim. Whereas overexpression of Mcl-1 contributes to the preservation of the mitochondrial membrane potential, Mcl-1 knockdown facilitates the Bim-mediated dissipation of this potential. Loss of Mcl-1 contributes to an increased level of caspase activity downstream of the mitochondrial response to TRAIL. Furthermore, the Mcl-1 expression level at the mitochondrial outer membrane determines the release efficiency for the apoptogenic proteins cytochrome c, Smac, and HtrA2 in response to Bim. These are the first findings to demonstrate the involvement of Bim in the TRAIL-mediated mitochondrial cascade. They also suggest that Mcl-1 may serve as a direct substrate for TRAIL-activated caspases implying the existence of a novel TRAIL/caspase-8/Mcl-1/Bim communication mechanism between the extrinsic and the intrinsic apoptotic pathways.
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PMID:Interrelated roles for Mcl-1 and BIM in regulation of TRAIL-mediated mitochondrial apoptosis. 1647 25

Isoliquiritigenin (ISL), a simple chalcone derivative, 4,2',4'-trihydroxychalcone, found in licorice, shallot and bean sprouts, has been reported to have chemoprotective effects. To examine the effects of ISL on the growth of prostate cancer cells, we cultured MAT-LyLu (MLL) rat and DU145 human prostate cancer cells with various concentrations (0-20 micromol/L) of ISL. Treatment of the cells with increasing concentrations of ISL led to dose-dependent decreases in the viable cell numbers in both DU145 and MLL cells (P<.05). Hoechst 33258 dye staining of condensed nuclei and annexin V binding to surface phosphatidylserine revealed increased numbers of apoptotic cells after ISL treatment. Western blot analysis revealed that ISL increased the levels of membrane-bound Fas ligand (FasL), Fas, cleaved casapse-8, truncated Bid (tBid), Bax and Bad in DU145 cells (P<.05). Isoliquiritigenin increased the percentage of cells with depolarized mitochondrial membranes, in a concentration-dependent manner (P<.05). Isoliquiritigenin induced the release of cytochrome c and Smac/Diablo from the mitochondria into the cytoplasm (P<.05). Isoliquiritigenin dose-dependently increased the levels of cleaved caspase-9, caspase-7, caspase-3 and poly(ADP-ribose) polymerase (P<.05). The present results indicate that ISL inhibits prostate cancer cell growth by the induction of apoptosis, which is mediated through mitochondrial events, which are associated with an evident disruption of the mitochondrial membrane potential, and the release of cytochrome c and Smac/Diablo, and the activation of caspase-9.
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PMID:Isoliquiritigenin induces apoptosis by depolarizing mitochondrial membranes in prostate cancer cells. 1651 40

Smac/DIABLO is a mitochondrial protein released into cytosol during the progression of apoptosis. Smac/DIABLO promotes apoptosis by neutralizing the inhibitory effect of the inhibitor of apoptosis proteins (IAPs) on the processing and activity of the effecter of caspase. Here, we generated synthetic Smac peptide which possesses an IAP-binding domain and Drosophila antennapaedia penetration sequence, and examined whether it enhances the effect of the chemotherapeutic agent etoposide in the human glioblastoma cell line. Cellular uptake of Smac peptide in several glioma cell lines was most prominent at 6-12 h after addition. Caspase activity assay showed that our peptide successfully increased the activity of caspase-3 and caspase-9 in etoposide-induced apoptosis. In addition, Smac peptide increased the amount of cleaved PARP (poly ADP-ribose polymerase), but control peptides did not. Moreover, the addition of z-VAD-fmk, a caspase inhibitor, counterbalanced the effect of Smac peptide. Finally, we demonstrated that Smac peptide could enhance the growth inhibition effect of etoposide compared with control peptides. These results suggest that synthetic Smac peptide may be a new molecular targeting anti-tumor therapy for human glioblastoma.
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PMID:Synthetic Smac peptide enhances the effect of etoposide-induced apoptosis in human glioblastoma cell lines. 1657 41

Doxycycline (Dc) has been demonstrated to inhibit cell growth and induce apoptosis in tumor cells, although its mechanism of action is not fully understood. The present study demonstrates that apoptosis can be induced in HeLa cells. Western blot data demonstrated that cytochrome c (Cyt c), Smac (the second mitochondria-derived activator of caspase), calpain I, caspase-9, -3 and -8 were involved in the apoptotic process, while the pan caspase inhibitor zVAD-fmk almost completely inhibited Dc-induced apoptosis. We further demonstrated that the release of mitochondrial proteins and the activation of calpains occurred upstream of the caspase cascade, in which caspase-9 was activated in response to the release of Cyt c, that caspase-8 activation was caspase and calpain dependent, and that caspase-3 was activated mainly by caspase-8 and -9. Caspase-8 played important roles in the activation of caspase-3 and induction of apoptosis, whereas the role of the caspase-9 was limited.
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PMID:Mitochondria and calpains mediate caspase-dependent apoptosis induced by doxycycline in HeLa cells. 1659 38

We investigated the effects of 1-methoxy-canthin-6-one, isolated from the medicinal plant Ailanthus altissima Swingle, on apoptosis in human leukemia (Jurkat), thyroid carcinoma (ARO and NPA), and hepatocellular carcinoma (HuH7) cell lines. Cultures incubated with the compound showed >50% of sub-G1 (hypodiploid) elements in flow cytometry analysis; the apoptosis-inducing activity was evident at <10 micromol/L and half-maximal at about 40 micromol/L 1-methoxy-canthin-6-one. The appearance of hypodiploid elements was preceded by mitochondrial membrane depolarization, mitochondrial release of cytochrome c, and Smac/DIABLO and procaspase-3 cleavage. We subsequently investigated the effect of 1-methoxy-canthin-6-one in combination with human recombinant tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in the four cell lines. Suboptimal concentrations (10 micromol/L 1-methoxy-canthin-6-one and 0.25 ng/mL TRAIL, respectively) of the two agents, unable to elicit apoptosis when used alone, induced mitochondrial depolarization, activation of caspase-3, and 45% to 85% of sub-G1 elements when added together to the cells. The synergism seemed to rely partly on the enhanced expression of TRAIL receptor 1 (TRAIL-R1; DR4), analyzed by immunofluorescence, by 1-methoxy-canthin-6-one. Cell incubation with 1-methoxy-canthin-6-one resulted in activating c-Jun NH2-terminal kinase (JNK), as revealed by Western blotting; induction of apoptosis and TRAIL-R1 up-regulation by 1-methoxy-canthin-6-one were >80% prevented by the addition of the JNK inhibitor (JNKI) SP600125JNKI, indicating that both effects were almost completely mediated by JNK activity. On the other hand, synergism with TRAIL was reduced by about 50%, suggesting that besides up-regulating TRAIL-R1, 1-methoxy-canthin-6-one could influence other factor(s) that participated in TRAIL-induced apoptosis. These findings indicate that 1-methoxy-canthin-6-one can represent a candidate for in vivo studies of monotherapies or combined antineoplastic therapies.
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PMID:1-Methoxy-canthin-6-one induces c-Jun NH2-terminal kinase-dependent apoptosis and synergizes with tumor necrosis factor-related apoptosis-inducing ligand activity in human neoplastic cells of hematopoietic or endodermal origin. 1661 64

The role of caspases and calpain in cisplatin-induced endothelial cell death is unknown. Thus we investigated whether caspases and calpain are mediators of cisplatin-induced apoptosis and necrosis in endothelial cells. Cultured pancreatic microvascular endothelial (MS1) cells were exposed to 10 and 50 microM cisplatin. Apoptosis or necrosis was determined by Hoechst 33342 and propidium iodide (PI) nuclear staining. Cells treated with 10 microM cisplatin had normal ATP levels, increased caspase-3-like activity, excluded PI and demonstrated morphological characteristics of apoptosis at 24 h. Cells treated with 50 microM cisplatin had severe ATP depletion, increased caspase-3-like activity, and displayed extensive PI staining indicative of necrosis at 24 h. There was a dose-dependent increase in caspase-2-like activity and Smac/DIABLO protein. Calpain activity increased significantly with 50 microM, but not 10 microM cisplatin at 24 h. With 50 microM cisplatin, ATP levels were significantly reduced starting at 18 h, caspase-2- and caspase-3-like activities were significantly increased starting at 18 h, and LDH release started at 8 h with maximum increase at 18-24 h. Calpain activity was not increased before 24 h. The increase in LDH release and the nuclear PI staining with 50 microM cisplatin at 24 h was reduced by either the pancaspase inhibitor, Q-VD-OPH, or the calpain inhibitor, PD-150606. Calpain inhibitor had no effect on caspase-3-like activity. In conclusion, in cisplatin-treated endothelial cells, caspases, the major mediators of apoptosis, can also cause necrosis. A calpain inhibitor protects against necrosis without affecting caspase-3-like activity suggesting that calpain-mediated necrosis is independent of caspase-3.
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PMID:Caspases and calpain are independent mediators of cisplatin-induced endothelial cell necrosis. 1662 72

Livin, a member of the inhibitor of apoptosis protein (IAP) family, encodes a protein containing a single baculoviral IAP repeat (BIR) domain and a COOH-terminal RING finger domain. It has been reported that Livin directly interacts with caspase-3 and -7 in vitro and caspase-9 in vivo via its BIR domain and is negatively regulated by Smac/DIABLO. Nonetheless, the detailed mechanism underlying its antiapoptotic function has not yet been fully characterized. In this report, we provide, for the first time, the evidence that Livin can act as an E3 ubiquitin ligase for targeting the degradation of Smac/DIABLO. Both BIR domain and RING finger domain of Livin are required for this degradation in vitro and in vivo. We also demonstrate that Livin is an unstable protein with a half-life of less than 4 h in living cells. The RING domain of Livin promotes its auto-ubiquitination, whereas the BIR domain is likely to display degradation-inhibitory activity. Mutation in the Livin BIR domain greatly enhances its instability and nullifies its binding to Smac/DIABLO, resulting in a reduced antiapoptosis inhibition. Our findings provide a novel function of Livin: it exhibits E3 ubiquitin ligase activity to degrade the pivotal apoptotic regulator Smac/DIABLO through the ubiquitin-proteasome pathway.
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PMID:Livin promotes Smac/DIABLO degradation by ubiquitin-proteasome pathway. 1672 33


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