Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42574 (caspase-3)
 45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fumonisin B1 (FB1), the most potent of the fumonisin mycotoxins, is a carcinogen and causes a wide range of species-specific toxicoses. FB1 modulates the activity of protein kinase C (PKC), a family of phospholipid-dependent serine/threonine kinases that play important role in modulating a variety of biologic responses ranging from regulation of cell growth to cell death. Although it has been demonstrated that FB1 induces apoptosis in many cell lines, the precise mechanism of apoptosis is not fully understood. In this study, we investigated the membrane localization of various PKC isoforms, PKC enzyme activity, and its downstream targets, namely nuclear factor-kappa B (NF-kappaB), tumor necrosis factor alpha (TNFalpha), and caspase 3, in porcine renal epithelial (LLC-PK1) cells. FB1 repressed cytosol to membrane translocation of PKC-alpha, -delta, -epsilon, and -zeta isoforms over 24-72 h. The FB1-induced membrane PKC repression was corroborated by a concentration-dependent decrease in total PKC activity. Exposure of cells to phorbol 12-myristate 13-acetate (PMA) for this duration also resulted in repressed PKC membrane localization and activity comparable to FB1. Exposure of cells to FB1 (10 microM) was associated with inhibition of cytosol to nuclear translocation of NF-kappaB and NF-kappaB-DNA binding at 72 h. The expression of TNFalpha was significantly inhibited at 24 and 48 h in response to 1 and 10 microM FB1. Increased caspase 3 activity was observed in LLC-PK1 cells exposed to > or =1 microM FB1 at 48 h. PMA also increased the caspase 3 activity at 24 and 48 h. Results suggest that FB1-induced apoptosis involves the activation of caspase 3, which is associated with the repression of PKC and possibly its down-stream effectors, NF-kappaB and TNFalpha.
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PMID:Fumonisin B1-induced apoptosis is associated with delayed inhibition of protein kinase C, nuclear factor-kappaB and tumor necrosis factor alpha in LLC-PK1 cells. 1459 27

During apoptosis, cells are fragmented into sealed packages for safe disposal by phagocytosis, a process requiring major reorganisation of the cytoskeleton. The small p21 GTPase-activated kinases (PAKs) have been implicated in regulating cytoskeletal dynamics and a subset are activated by caspase 3/7 cleavage. However, the functional importance of this activation in apoptosis remains unknown. Using early Xenopus embryos, we have dissected xPAK1 activation from other causative events in apoptosis. An apoptotic-like cell fragmentation was observed 30 min after expression of the xPAK1 catalytic domain and occurred in the absence of other markers of apoptosis. In vitro, activated xPAK1 phosphorylated the regulatory light chain (xMLC) of myosin II at threonine 18 and serine 19, events known to activate the actin-dependent ATPase of cytoskeletal myosin. In vivo, activated xPAK1 induced hyperphosphorylation of xMLC. BDM, a myosin inhibitor, and ML-7, a MLCK inhibitor, both abrogated cell fragmentation induced by activated xPAK1, and ML-7 also inhibited xPAK1 activity. Endogenous xPAK1 was cleaved during normal apoptosis and this was associated with xPAK1 activation and increased serine 19 phosphorylation of xMLC. The data show that PAK activation is sufficient for apoptotic body formation in vivo and strongly suggest that activation of myosin II is essential for this process.
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PMID:The catalytic domain of xPAK1 is sufficient to induce myosin II dependent in vivo cell fragmentation independently of other apoptotic events. 1459 1

Focal adhesion kinase (FAK) prevents apoptosis in many cell types. We have reported that tyrosine residues in FAK are dephosphorylated and FAK is degraded during mannitol-induced apoptosis in human neuroblastoma cells. Several studies suggest that FAK dephosphorylation and degradation are separate events. The current study defines the relationship between FAK dephosphorylation and degradation in neuroblastoma cells using okadaic acid (OA). OA, a serine phosphatase inhibitor, promotes serine/threonine phosphorylation, which in turn blocks tyrosine phosphorylation. OA induced focal adhesion loss, actin cytoskeleton disorganization, and cellular detachment, which corresponded to a loss of FAK Tyr397 phosphorylation. These changes preceded caspase-3 activation, Akt and MAP kinase activity loss, protein ubiquitination, and cellular apoptosis. Insulin-like growth factor-I prevented mannitol-induced, but not OA-induced, substrate detachment and FAK Tyr397 dephosphorylation, and the effects of OA on FAK Tyr397 phosphorylation were irreversible. The proteolytic degradation of FAK is temporally distinct from its tyrosine dephosphorylation, occurring when apoptotic pathways are already initiated and during a generalized destruction of signaling proteins. Therefore, agents resulting in the dephosphorylation of FAK may be beneficial for therapeutic treatment, irrespective of FAK protein levels, as this may result in apoptosis, which cannot be prevented by growth factor signaling.
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PMID:Degradation and dephosphorylation of focal adhesion kinase during okadaic acid-induced apoptosis in human neuroblastoma cells. 1467 Jan 78

Integrin-linked kinase (ILK) is one of the signaling moieties that interact with the cytoplasmic domains of integrin beta1 and beta3 subunits. Integrin-mediated outside-in signals cooperate with vascular endothelial growth factor (VEGF) receptor to promote morphological changes, cell proliferation and motility in endothelial cells. In this report we demonstrate that VEGF-induced vessel morphogenesis of human umbilical vein endothelial cells (HUVEC) was inhibited by the transfection of a dominant negative, kinase-deficient ILK (ILK-KD), as well as by treatment with the phosphatidylinositol 3-kinase inhibitor LY294002. VEGF induced phosphorylation of protein kinase B (PKB/Akt), a regulator of cell survival and apoptosis, on serine 473, but not on threonine 308, in an ILK-dependent manner. Furthermore, transfection of antisense ILK (ILK-AS) blocked the survival effect of VEGF in annexin-V binding assays, and a VEGF-mediated decrease in caspase activity was reversed by both ILK-KD and ILK-AS as measured by a homogeneous caspase-3/7 assay. We also demonstrate that both chemotactic migration and cell proliferation of HUVEC induced by VEGF were suppressed by the inhibition of ILK. We conclude that ILK plays an important role in vascular morphogenesis mediated by VEGF.
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PMID:Integrin-linked kinase regulates vascular morphogenesis induced by vascular endothelial growth factor. 1467 8

Grape seed proanthocyanidin extract (GSPE), a polyphenolic compound with antioxidant properties, may protect against cardiac ischemia and reperfusion injury. However, its potential toxicity at higher doses is unknown. The authors tested the effects of GSPE on reactive oxygen species (ROS) generation, cell survival, lactate dehydrogenase (LDH) release, and caspase- 3 activity using chick cardiomyocytes incubated with GSPE at 5, 10, 50, 100, or 500 micrograms/mL in medium for 8 h. Exposure to increasing concentrations of GSPE (100 or 500 micrograms/mL) resulted in an increase in ROS generation and cell death as measured by propidium iodide uptake and LDH release. Caspase-3 activity was significantly increased fourfold in cells exposed to GSPE 500 micrograms/ mL compared to controls; this was abolished by the selective caspase-3 inhibitor Ac-Asp-Gln-Thr-Asp-H (50 microM), which also significantly reduced the cell death resulting from GSPE (500 micrograms/mL). The antioxidant N-acetylcysteine (NAC, 100 microM) reduced cell death induced by GSPE (500 micrograms/mL) but failed to attenuate caspase-3 activation. Collectively, the authors conclude that higher doses of GSPE could cause apoptotic cell injury via effector caspase-3 activation and subsequent induction of ROS generation. Consumers may take higher doses of dietary supplements in the belief that natural herbs have no major side effects. This study demonstrates that dosages of GSPE should be optimized to avoid potential harmful pro-oxidant effects.
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PMID:Grape seed proanthocyanidins induce pro-oxidant toxicity in cardiomyocytes. 1473 30

20-O-(beta-D-glucopyranosyl)-20(S)-protopanaxadiol (IH901), an intestinal bacterial metabolite of ginseng saponin formed from ginsenosides Rb1, Rb2, and Rc, is suggested to be a potential chemopreventive agent. Here, we show that IH901 induces apoptosis in human hepatoblastoma HepG2 cells. IH901 led to an early activation of procaspase-3 (12 h posttreatment), and the activation of caspase-8 became evident only later (18 h posttreatment). Caspase activation was a necessary requirement for apoptosis because caspase inhibitors significantly inhibited cell death by IH901. Treatment of HepG2 cells with IH901 also induced the cleavage of cytosolic factors such as Bid and Bax and translocation of truncated Bid (tBid) to mitochondria. A time-dependent release of cytochrome c from mitochondria was observed, which was accompanied by activation of caspase-9. A broad-spectrum caspase inhibitor, N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD-fmk), and a specific inhibitor for caspase-8, N-benzyloxycarbonyl-Ile-Glu-Thr-Asp-fluoromethylketone (zIETD-fmk), abrogated Bid processing and translocation, and caspase-3 activation. Cytochrome c release was inhibited by zVAD-fmk, however, the inhibition by zIETD-fmk was not complete. The activation of caspase-8 was inhibited not only by zIETD-fmk but also by zVAD-fmk. The results, together with the kinetic change of caspase activation, indicate that activation of caspase-8 occurred downstream of caspase-3 and -9. Our data suggest that the activation of caspase-8 after early caspase-3 activation might act as an amplification loop necessary for successful apoptosis. Primary hepatocytes isolated from normal Sprague-Dawley rats were not affected by IH901 (0-60 microM). The very low toxicity in normal hepatocytes and high activity in hepatoblastoma HepG2 cells suggest that IH901 is a promising experimental cancer chemopreventive agent.
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PMID:A ginseng saponin metabolite-induced apoptosis in HepG2 cells involves a mitochondria-mediated pathway and its downstream caspase-8 activation and Bid cleavage. 1476 78

A potent inhibitor of serine/threonine kinases, staurosporine exerts antiproliferative and apoptotic effects in many cancer cells, although the exact mechanism of its action is still unclear. This study examines the effects of staurosporine on Chang liver cells, an immortalized non-tumor cell line, in comparison with those caused in HuH-6 and HepG2 cells, two human hepatoma cell lines. Our results provide evidence that staurosporine promotes apoptosis in Chang liver cells as observed by flow cytometric analysis and acridine orange/ethidium bromide staining. The effect appeared already after 8 h of treatment and increased with treatment time and dose. After 48 h of exposure to 200 nM staurosporine clear apoptotic signs were observed in about 50% of the cells. Western blotting analysis showed that in Chang liver cells staurosporine induced a marked decrease in the levels of the antiapoptotic factors Bcl-2 (-75%) and Bcl-XL (-50%). Staurosporine also caused loss of mitochondrial transmembrane potential, release of cytochrome c from mitochondria and activation of caspase-3. The involvement of caspases in staurosporine-induced cell death was also suggested by the observation that the addition of z-VAD-fmk, a general inhibitor of caspases, suppressed apoptosis. In HuH-6 and HepG2 cells treatment with staurosporine induced the arrest of cells in G2/M phase of cell cycle. This effect was not modified by z-VAD-fmk and was not accompanied by the appearance of biochemical signs of apoptosis. We conclude that staurosporine induced apoptosis in Chang liver cells by a mitochondria-caspase-dependent pathway which was closely correlated with a decrease in Bcl-2 and Bcl-XL levels, while in HuH-6 and HepG2 hepatoma cells the drug caused only an antiproliferative effect.
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PMID:Staurosporine-induced apoptosis in Chang liver cells is associated with down-regulation of Bcl-2 and Bcl-XL. 1501 Aug 57

The expression of cyclooxygenase (COX)-2 is increased in human cancers including cholangiocarcinoma. This study was designed to evaluate the effect and mechanisms of the selective COX-2 inhibitor celecoxib in the growth control of human cholangiocarcinoma cells. Immunohistochemical analysis using human cholangiocarcinoma tissues showed increased levels of COX-2 as well as phospho-Akt (Thr (308)), a protein kinase activated by COX-2-mediated prostaglandins, in human cholangiocarcinoma cells. Treatment of cultured human cholangiocarcinoma cells (HuCCT1, SG231, and CCLP1) with celecoxib resulted in a dose- and time-dependent reduction of cell viability. Fluorescence microscopy, Western blot, and caspase activity assays demonstrated that celecoxib induced morphological features of apoptosis, activation of caspase-9 and caspase-3, and release of cytochrome c. The celecoxib-induced cell death was significantly blocked by N-benzyloxy-carbonyl-Val-Ala-Asp-fluoromethylketone, a wide-spectrum caspase inhibitor. Furthermore, cholangiocarcinoma cells treated with celecoxib showed significant reduction of Akt phosphorylation, whereas the levels of Bcl-2 and Bax were not altered. Inhibition of Akt activation by LY294002 significantly decreased the viability of human cholangiocarcinoma cells. These findings suggest that celecoxib inhibits cholangiocarcinoma growth partly through induction of apoptosis and inhibition of Akt phosphorylation.
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PMID:The cyclooxygenase-2 inhibitor celecoxib blocks phosphorylation of Akt and induces apoptosis in human cholangiocarcinoma cells. 1502 50

Synthetic analogs of 1,4-anthraquinone (AQ code number), a compound that mimics the antiproliferative effects of daunorubicin (daunomycin) in the nanomolar range in vitro but has the advantage of blocking nucleoside transport and retaining its efficacy in multidrug-resistant tumor cells, were tested for their ability to induce apoptosis in the HL-60 cell system. AQ10 and, especially, the new lead antiproliferative compounds AQ8 and AQ9 reduce the growth and integrity of wild-type, drug-sensitive, HL-60-S cells more effectively than AQ1, suggesting that various methyl group substituents at C6 may enhance the bioactivity of the parent compound. Internucleosomal DNA fragmentation, a late marker of apoptosis, is similarly induced in a biphasic manner by increasing concentrations of AQ8 and AQ9 at 24 hr. Poly(ADP-ribose) polymerase-1 (PARP-1) cleavage, an early event required for cells committed to apoptosis, is detected within 3-6 hr in HL-60-S cells treated with AQ9. In accord with the fact that the caspases 9 and 3 cascade is responsible for PARP-1 cleavage, the activities of initiator caspase-9 and effector caspase-3 are induced by AQ9 in the same time- and concentration-dependent manners and to the same maximal degrees in both the HL-60-S and multidrug-resistant HL-60-RV cell lines. Interestingly, a 1-hr pulse treatment is sufficient for AQ8 and AQ9 to maximally induce caspase-9 and -3 activities at 6 hr. The release of mitochondrial cytochrome c (Cyt c) is also detected within 3-6hr in HL-60-S cells treated with AQ9, a finding consistent with the fact that Cyt c is the apoptotic trigger that activates caspase-9. Moreover, AQ analogs induce Cyt c release, caspase-9 and -3 activities and PARP-1 cleavage in relation with their abilities to decrease tumor cell growth and integrity, AQ8 and AQ9 being consistently the most effective. Since apical caspases 2 and 8 may both act upstream of mitochondria to promote Cyt c release, it is significant to show that AQ9 maximally induces caspase-2 and -8 activities at 6 and 9 hr, respectively. During AQ8 treatment, the caspase-2 inhibitor benzyloxycarbonyl (z)-Val-Asp-Val-Ala-Asp (VDVAD)-fluoromethyl ketone (fmk) totally blocks caspase-9, -3, and -8 activations, whereas the caspase-8 inhibitor z-Ile-Glu-Thr-Asp-(IETD)-fmk does not prevent caspase-2, -9, and -3 activations, suggesting that AQ-induced caspase-2 activity is an upstream event critical for the activation of the downstream caspases 9 and 3 cascade, including the mitochondrial amplification loop through caspase-8. However, these caspase-2 and -8 inhibitors fail to alter AQ8-induced Cyt c release, suggesting that AQs might also target mitochondria independently from caspase activation. Furthermore, the antagonistic anti-Fas DX2 and ZB4 monoclonal antibodies (mAbs), which block the induction of Cyt c release and caspase-2, -8, and -9 activities by the agonistic anti-Fas CH11 mAb, and the neutralizing anti-Fas ligand (FasL) NOK-1 mAb all fail to inhibit AQ9-induced Cyt c release and caspase-2, -8, and -9 activities, suggesting that the FasL/Fas signaling pathway is not involved in the mechanism by which antiproliferative AQ analogs trigger apoptosis in HL-60 cells.
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PMID:Synthetic 1,4-anthracenedione analogs induce cytochrome c release, caspase-9, -3, and -8 activities, poly(ADP-ribose) polymerase-1 cleavage and internucleosomal DNA fragmentation in HL-60 cells by a mechanism which involves caspase-2 activation but not Fas signaling. 1503 4

Fusion between nonsynchronized cells leads to the formation of heterokarya which transiently activate Cyclin-dependent kinase 1 (Cdk1)/cyclin B1 and enter the prophase of the cell cycle, where they arrest due to a loss of Cdk1/cyclin B1 activity, activate p53, disorganize centrosomes, and undergo apoptosis. Here, we show that the down regulation of Cdk1/cyclin B is secondary to the activation of the DNA structure checkpoint kinase Chk2. Thus, syncytia generated by the fusion of asynchronous HeLa cells contain elevated levels of active Chk2 but not Chk1. Chk2 bearing the activating phosphorylation on threonine-68 accumulates in BRCA1 nuclear bodies when the cells arrest at the G2/M boundary. Inhibition of Chk2 by transfection of a dominant-negative Chk2 mutant or a chemical inhibitor, debromohymenialdesine, stabilizes centrosomes, maintains high cyclin B1 levels, and allows for a prolonged activation of Cdk1. Under these conditions, multinuclear HeLa syncytia do not arrest at the G2/M boundary and rather enter mitotis and subsequently die during the metaphase of the cell cycle. This mitotic catastrophe is associated with the activation of the pro-apoptotic caspase-3. Inhibition of caspases allows the cells to go beyond the metaphase arrest, indicating that apoptosis is responsible for cell death by mitotic catastrophe. In another, completely different model of mitotic catastrophe, namely 14.3.3 sigma-deficient HCT116 colon carcinoma cells treated with doxorubicin, Chk2 activation was also found to be deficient as compared to 14.3.3 sigma-sufficient controls. Inhibition of Chk2 again facilitated the induction of mitotic catastrophe in HCT116 wild-type cells. In conclusion, a conflict in cell cycle progression or DNA damage can lead to mitotic catastrophe, provided that the checkpoint kinase Chk2 is inhibited. Inhibition of Chk2 thus can sensitize proliferating cells to chemotherapy-induced apoptosis.
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PMID:The cell cycle checkpoint kinase Chk2 is a negative regulator of mitotic catastrophe. 1504 74


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