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)

Resveratrol (RES), a natural plant polyphenol, has gained interest as a nontoxic chemopreventive agent capable of inducing tumor cell death in a variety of cancer types. However, the early molecular mechanisms of RES-induced apoptosis are not well defined. Using the human breast cancer cell lines MDA-MB-231 and MCF-7, we demonstrate that RES is antiproliferative and induces apoptosis in a concentration- and time-dependent manner. Preceding apoptosis, RES instigates a rapid dissipation of mitochondrial membrane potential by directly targeting mitochondria. This is followed by release of cytochrome c and second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) into the cytoplasm and substantial increase in the activities of caspases-9 and -3 in MDA-MB-231 cells. In addition, live cell microscopy demonstrates that RES causes an early biphasic increase in the concentration of free intracellular calcium ([Ca2+]i), probably resulting from depletion of the endoplasmic reticulum stores in breast cancer cells. In caspase-3-deficient MCF-7 cells, apoptosis is mediated by the Ca2+-activated protease, calpain, leading to the degradation of plasma membrane Ca2+-ATPase isoform 1 and fodrin; the degradation is attenuated by buffering [Ca2+]i and blocked by calpain inhibitors. Mitochondrial permeability transition pore antagonists also blocked calpain activation. In vivo mouse xenograft studies demonstrate that RES treatment inhibits breast cancer growth with no systemic toxicities. Together, these results suggest a critical role for mitochondria not only in the intrinsic apoptotic pathway but also in the Ca2+ and calpain-dependent cell death initiated by RES. Thus, RES may prove useful as a nontoxic alternative for breast cancer treatment.
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PMID:Mitochondria, calcium, and calpain are key mediators of resveratrol-induced apoptosis in breast cancer. 1784

The herpes simplex virus type 2 (HSV-2) protein ICP10PK has anti-apoptotic activity in virus-infected hippocampal cultures through activation of the Ras/Raf-1/MEK/ERK pathway. To exclude the possible contribution of other viral proteins to cell fate determination, we examined the survival of primary hippocampal cultures and neuronally differentiated PC12 cells transfected with ICP10PK from apoptosis caused by nerve growth factor (NGF) withdrawal. NGF deprivation caused apoptosis in cultures mock-transfected or transfected with the kinase-negative ICP10 mutant p139(TM), but not in ICP10PK-transfected cultures. In one clone (PC47), ICP10PK inhibited caspase-3 activation through up-regulation/stabilization of adenylate cyclase (AC), activation of PKA and MEK, and the convergence of the two pathways on extracellular signal-regulated kinase activation. The anti-apoptotic proteins Bag-1 and Bcl-2 were stabilized and the pro-apoptotic protein Bad was phosphorylated (inactivated). In another clone (PC70), ICP10PK inhibited apoptosis through MEK-dependent up-regulation of the anti-apoptotic protein XIAP (that inhibits the activity of processed caspase-3) and down-regulation of the apoptogenic protein Smac/DIABLO. This may be cell-type specific, but the baculovirus p35 protein did not potentiate the neuroprotective activity of ICP10PK in PC12 cells, suggesting that ICP10PK inhibits both caspase activation and activity. The data indicate that ICP10PK inhibits apoptosis independent of other viral proteins and is a promising neuronal gene therapy platform.
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PMID:The herpes simplex virus type 2 gene ICP10PK protects from apoptosis caused by nerve growth factor deprivation through inhibition of caspase-3 activation and XIAP up-regulation. 1787 40

The spermine analogue N(1),N(11)-diethylnorspermine (DENSPM) efficiently depletes the polyamine pools in the breast cancer cell line L56Br-C1 and induces apoptotic cell death via the mitochondrial pathway. In this study, we have over-expressed the anti-apoptotic protein Bcl-2 in L56Br-C1 cells and investigated the effect of DENSPM treatment. DENSPM-induced cell death was significantly reduced in Bcl-2 over-expressing cells. Bcl-2 over-expression reduced DENSPM-induced release of the pro-apoptotic proteins AIF, cytochrome c, and Smac/DIABLO from the mitochondria. Bcl-2 over-expression reduced the DENSPM-induced activation of caspase-3. Bcl-2 over-expression also prevented DENSPM-induced Bax cleavage and reduction of Bcl-X(L) and survivin levels. The DENSPM-induced activation of the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase was reduced by Bcl-2 over-expression, partly preventing polyamine depletion. Thus, Bcl-2 over-expression prevented a number of DENSPM-induced apoptotic effects.
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PMID:Novel anti-apoptotic effect of Bcl-2: prevention of polyamine depletion-induced cell death. 1792 Sep 46

Smac/DIABLO is a recently identified protein released from mitochondria in response to apoptotic stimuli and promotes apoptosis by antagonizing inhibitor of apoptosis proteins (IAPs). In this study, we observed depressed Smac/DIABLO and increased XIAP expression in ovarian epithelial tissues ordered by normal, benign and malignant epithelia. In epithelial ovarian cancer (EOC), the expression of Smac/DIABLO decreased with the malignancy. Smac/DIABLO expression showed no correlation with TRAIL sensitivity, while lower Smac/DIABLO expression and decreased release of Smac/DIABLO from mitochondria upon apoptosis stimuli were observed in paclitaxel-resistant A2780/pac cells as compared to the sensitive controls. Ectopic Smac/DIABLO alone inhibited cell growth, arrested cells in G0/G1 phase, and sensitized drug-resistant EOC cells to TRAIL or paclitaxel-induced apoptosis. Increased apoptosis was associated with the down-regulation of XIAP, FLIP, and up-regulation of Smac/DIABLO, cytochrome c, p53, along with increased activity of caspase-3. Thus, over-expression of Smac/DIABLO is a promising strategy for drug-resistant ovarian cancer treatment.
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PMID:Transfection of Smac/DIABLO sensitizes drug-resistant tumor cells to TRAIL or paclitaxel-induced apoptosis in vitro. 1802 93

The second messenger cAMP acts via protein kinase A (PKA) to induce apoptosis by mechanisms that are poorly understood. Here, we assessed a role for mitochondria and analyzed gene expression in cAMP/PKA-promoted apoptosis by comparing wild-type (WT) S49 lymphoma cells and the S49 variant, D(-) (cAMP-deathless), which lacks cAMP-promoted apoptosis but has wild-type levels of PKA activity and cAMP-promoted G(1) growth arrest. Treatment of WT, but not D(-), S49 cells with 8-CPT-cAMP (8-(4-chlorophenylthio)-adenosine-3':5'-cyclic monophosphate) for 24 h induced loss of mitochondrial membrane potential, mitochondrial release of cytochrome c and SMAC, and increase in caspase-3 activity. Gene expression analysis (using Affymetrix 430 2.0 arrays) revealed that WT and D(-) cells incubated with 8-CPT-cAMP have similar, but non-identical, extents of cAMP-regulated gene expression at 2 h (approximately 800 transcripts) and 6 h (approximately 1000 transcripts) (|Fold| > 2, p < 0.06); by contrast, at 24 h, approximately 2500 and approximately 1100 transcripts were changed in WT and D(-) cells, respectively. Using an approach that combined regression analysis, clustering, and functional annotation to identify transcripts that showed differential expression between WT and D(-) cells, we found differences in cAMP-mediated regulation of mRNAs involved in transcriptional repression, apoptosis, the cell cycle, RNA splicing, Golgi, and lysosomes. The two cell lines differed in cAMP-response element-binding protein (CREB) phosphorylation and expression of the transcriptional inhibitor ICER (inducible cAMP early repressor) and in cAMP-regulated expression of genes in the inhibitor of apoptosis (IAP) and Bcl families. The findings indicate that cAMP/PKA-promoted apoptosis of lymphoid cells occurs via mitochondrial-mediated events and imply that such apoptosis involves gene networks in multiple biochemical pathways.
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PMID:Gene expression signatures of cAMP/protein kinase A (PKA)-promoted, mitochondrial-dependent apoptosis. Comparative analysis of wild-type and cAMP-deathless S49 lymphoma cells. 1804 52

Nonsteroidal anti-inflammatory drugs (NSAID) are effective in suppressing the formation of colorectal tumors. However, the mechanisms underlying the antineoplastic effects of NSAIDs remain unclear. The effects of NSAIDs are incomplete, and resistance to NSAIDs is often developed. Growing evidence has indicated that the chemopreventive activity of NSAIDs is mediated by induction of apoptosis. Our previous studies showed that second mitochondria-derived activator of caspase (SMAC)/Diablo, a mitochondrial apoptogenic protein, plays an essential role in NSAID-induced apoptosis in colon cancer cells. In this study, we found that SMAC mediates NSAID-induced apoptosis through a feedback amplification mechanism involving interactions with inhibitor of apoptosis proteins, activation of caspase-3, and induction of cytosolic release of cytochrome c. Small-molecule SMAC mimetics at nanomolar concentrations significantly sensitize colon cancer cells to NSAID-induced apoptosis by promoting caspase-3 activation and cytochrome c release. Furthermore, SMAC mimetics overcome NSAID resistance in Bax-deficient or SMAC-deficient colon cancer cells by restoring caspase-3 activation and cytochrome c release. Together, these results suggest that SMAC is useful as a target for the development of more effective chemopreventive strategies and agents.
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PMID:SMAC mimetics sensitize nonsteroidal anti-inflammatory drug-induced apoptosis by promoting caspase-3-mediated cytochrome c release. 1817 20

Caspases are essential mediators of cytokine release and apoptosis. Additionally, caspase activity is required for the proliferation of naive T lymphocytes. It remained unclear how proliferating cells are able to cope with the pro-apoptotic activity especially of effector caspases-3 and -7. Possible reasons might include limited subcellular localization of active caspases or inhibition by endogenous caspase inhibitors. Here, we compared the activation of various caspases in proliferating human T cells with that in apoptotic cells. We show that cleaved caspases-3/-7 appear to be widely distributed in apoptotic cells while they are largely confined to the cytoplasm in proliferating cells. Additionally, in proliferating T cells caspase-3 remains incompletely cleaved, while in apoptotic cells fully mature caspase-3 is generated. We provide evidence that during T cell proliferation the intracellular caspase inhibitor X-linked inhibitor-of-apoptosis protein (XIAP) interacts with caspases-3/-7, thereby blocking their full activation, substrate cleavage, and cell death. The lack of substrate cleavage might also lead to the observed limited subcellular distribution of caspases-3/-7. After induction of apoptosis, second mitochondria-derived activator of caspases/direct inhibitor of apoptosis-binding protein with low isoelectric point (Smac/DIABLO) is released from mitochondria, resulting in the abrogation of the inhibitory effect of XIAP, full activation of caspases-3/-7, and apoptosis.
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PMID:Interaction with XIAP prevents full caspase-3/-7 activation in proliferating human T lymphocytes. 1852 60

A pair of isogenic colon carcinoma cells, SW480 and 620, was used to investigate the mechanisms of acquired tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-resistance during tumour progression. Whereas primary tumour SW480 cells are sensitive to TRAIL-induced apoptosis, metastatic SW620 cells are resistant. The apoptotic signalling activated by TRAIL in SW480 cells is a type II pathway. We show that in SW620 cells, although caspase-8 is recruited and activated at the death-inducing-signalling complex and Bid is cleaved, this does not lead to caspase-9 activation. Comparison of Bcl-2, Bcl-xL and Mcl-1 levels in both cell lines showed no difference. In SW620 cells transfected with a tBid-GFP construct, tBid-GFP was correctly localized to the mitochondria. Thus, the resistance of SW620 cells is at the level of the mitochondria that can withstand large amounts of tBid. Although caspase-3 was directly cleaved by caspase-8 in SW620 cells to yield the p20 fragment, no further autocatalytic maturation into the p17 fragment was observed. We show that, in contrast to SW480 cells, the SW620 cell line expresses high amounts of X-linked inhibitor of apoptosis (XIAP). Downregulation of XIAP with bortezomib or small-interfering RNA was sufficient to restore the sensitivity of SW620 cells to TRAIL-induced apoptosis in the absence of SMAC/Diablo or cytochrome c release from the mitochondria. Thus, SW620 cells have developed a dual resistance to TRAIL-induced apoptosis: a block at the level of the mitochondria and, after a conversion to a type I pathway, an increased expression of XIAP which inhibits this pathway.
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PMID:A mitochondrial block and expression of XIAP lead to resistance to TRAIL-induced apoptosis during progression to metastasis of a colon carcinoma. 1856 Mar 53

X-linked inhibitor of apoptosis protein (XIAP) inhibits apoptosis mainly through inhibition of caspase-9 and executioner caspases of -3 and -7. The inhibition of the former protease is implemented through the bacculoviral inhibitory repeat-3 (Bir3) domain, while the inhibition of the latter is accomplished by the interaction of the linker region located between the Bir1 and the Bir2 domains with their active sites. Both modes of inhibition are antagonized by SMAC, which is released from mitochondria during the initiation of the intrinsic apoptosis pathway. Although the mechanism of SMAC interference in Bir3 inhibition of caspase-9 is clearly established, the mechanism by which SMAC interferes with the inhibition of the executioner caspases by XIAP remains largely unknown. To address this issue, we performed a limited proteolysis of glutathione S-transferase (GST)-tagged XIAP-Bir2 by trypsin in the presence and in the absence of SMAC peptide. Under these conditions, the proteolysis of the linker region was diminished considerably. Furthermore, the rate of association of caspase-3 and -7 with XIAP in the presence of the SMAC peptide was reduced drastically, suggesting that SMAC peptide restricts the exposure of the linker region. A limited proteolysis of caspase-7 in the presence of GST-Bir2 and GST-NBir3 (the Bir3 domain of human NAIP) as negative controls was also performed. Matrix-assisted laser desorption/ionization time-of-flight analysis of the fragments revealed the identity of protected sites, suggesting that the Bir2 domain makes numerous contacts with the large subunit of caspase-7. These, combined with the results from Far-Western experiments, strongly suggest that the groove for the inhibitor(s)-of-apoptosis-protein-binding motif on the Bir2 favors binding to the N-terminus of the large subunit rather than to the small subunit of caspase-7. Our results further show that the active-site pocket of caspase-7 is first occupied by the linker region, followed by the interaction of the N-terminus of the enzyme with the SMAC-binding site of the Bir2 domain.
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PMID:A mechanistic insight into SMAC peptide interference with XIAP-Bir2 inhibition of executioner caspases. 1861 10

Tumor hypoxia, which is caused by the rapid proliferation of tumor cells and aberrant vasculature in tumors, results in inadequate supplies of oxygen and nutrients to tumor cells. Paradoxically, these unfavorable growth conditions benefit tumor cell survival, although the mechanism is poorly understood. We have demonstrated for the first time that hypoxia inhibits TRAIL-induced apoptosis by blocking translocation of Bax from cytosol to the mitochondria in tumor cells. However, it is largely unknown how hypoxia-inhibited Bax translocation attenuates TRAIL-induced apoptosis. Here, we demonstrate that despite its inhibitory activity in TRAIL-induced apoptosis, hypoxia does not affect TRAIL-triggered proximal apoptotic signaling events, including caspase-8 activation and Bid cleavage. Instead, hypoxia inhibited processing of caspase-3, leading to incomplete activation of the caspase. Importantly, hypoxia-blocked translocation of Bax to the mitochondria significantly inhibited releasing the mitochondrial factors, such as cytochrome c and Smac/DIABLO, to the cytosol in response to TRAIL. It is well-known that complete processing/activation of caspase-3 requires Smac/DIABLO released from mitochondria. Therefore, our data indicate that an engagement of the apoptotic mitochondrial events leading to caspase-3 activation is blocked by hypoxia. Our data shed new light on understanding of the apoptotic signal transduction and targets regulated by tumor hypoxia.
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PMID:Blockade of processing/activation of caspase-3 by hypoxia. 1876 22


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