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:3.4.22.62 (caspase-9)
7,507 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies from our laboratory had indicated that cytochrome c-independent processing and activation of caspase-9 by caspase-8 contributed to early amplification of the caspase cascade in tumor necrosis factor (TNF)-alpha-treated murine cells. Here we show that murine caspase-9 is phosphorylated by casein kinase 2 (CK2) on a serine near the site of caspase-8 cleavage. CK2 has been shown to regulate cleavage of the pro-apoptotic Bid protein by phosphorylating serine residues near its caspase-8 cleavage site. Similarly, CK2 modification of Ser(348) on caspase-9 appears to render the protease refractory to cleavage by active caspase-8. This phosphorylation did not affect the ability of caspase-9 to autoprocess. Substitution of Ser(348) abolished phosphorylation but not cleavage, and a phospho-site mutant promoted apoptosis in TNF-alpha-treated caspase-9 knock-out mouse embryo fibroblasts. Furthermore, inhibition of CK2 activity and RNA interference-mediated knockdown of the kinase accelerated caspase-9 activation, whereas phosphatase inhibition delayed both caspase-9 activation and death in response to TNF receptor occupation. Taken together, these studies show that TNF receptor cross-linking promotes dephosphorylation of caspase-9, rendering it susceptible to processing by activated caspase-8 protein. Thus, our data suggest that modification of procaspase-9 to protect it from inappropriate cleavage and activation is yet another mechanism by which the oncogenic kinase CK2 promotes survival.
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PMID:Phosphorylation of murine caspase-9 by the protein kinase casein kinase 2 regulates its cleavage by caspase-8. 1846 26

Gynostemma pentaphyllum Makino is known in Asia for its effect on the treatment of hepatitis and cardiovascular diseases. Gypenosides (Gyp) are the major components extracted from Gynostemma pentaphyllum Makino. However, the molecular mechanism underlying the Gyp-induced cell cycle arrest and apoptotic process is unclear. In this study, the chemopreventive role of Gyp in human lung cancer (A549) cells in vitro was evaluated by studying the regulation of the cell cycle and apoptosis. Gyp induced GO/G1 arrest and apoptosis in the human lung cancer A549 cells. Investigation of the cyclin-dependent protein kinase inhibitors by Western blotting showed that p16, p21, p27 and p53 proteins were increased with the increasing time of incubation with Gyp in the A549 cells. This increase may be the major factor by which Gyp caused GO/G1 arrest in the examined cells. Flow cytometric assay and gel electrophoresis of DNA fragmentation also confirmed that Gyp induced apoptosis in the A549 cells. Our data demonstrated that Gyp-induced apoptotic cell death was accompanied by up-regulation of Bax, caspase-3 and caspase-9, but down-regulation of the Bcl-2 levels. Taken together, Gyp appears to exert its anticancer properties by inducing GO/GI-phase arrest and apoptosis via activation of caspase-3 in human lung A549 cancer cells.
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PMID:Gypenosides induced G0/G1 arrest via inhibition of cyclin E and induction of apoptosis via activation of caspases-3 and -9 in human lung cancer A-549 cells. 1846 6

We examined the effect of (-)-syringaresinol, a furofuran-type lignan isolated from Daphne genkwa, on cell cycle regulation in HL-60 human promyelocytic leukemia cells in vitro. (-)-Syringaresinol decreased the viability of HL-60 cells by inducing G(1) arrest followed by apoptosis in a dose- and time-dependent manner. The G(0)/G(1) phase of the cell cycle is regulated by cyclin-dependent kinases (Cdk), cyclins and cyclin-dependent kinase inhibitors (Cdki). We show by western blot analysis, that the (-)-syringaresinol-induced G(1) arrest was mediated through the increased expression of Cdki proteins (p21(cip1/waf1) and p27(kip1)) with a simultaneous decrease in cdk2, cdk4, cdk6, cyclin D(1), cyclin D(2), and cyclin E expression. The induction of apoptosis after treatment with (-)-syringaresinol for 24 h was demonstrated by morphological changes, DNA fragmentation, altered ratio of Bax/Bcl-2, cleavage of poly(ADP-ribose) polymerase and flow cytometry analysis. (-)-Syringaresinol also induced cytochrome c release and activation of caspase-3 and caspase-9. To our knowledge, this is the first time that (-)-syringaresinol has been reported to potently inhibit the proliferation of human promyelocytic HL-60 cells through G(1) arrest and induction of apoptosis. These findings suggest that (-)-syringaresinol may be a potential chemotherapeutic agent for the treatment of cancer.
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PMID:(-)-Syringaresinol inhibits proliferation of human promyelocytic HL-60 leukemia cells via G1 arrest and apoptosis. 1848 7

2-Methoxyestradiol (2ME2) is an endogenous metabolite of 17beta-estradiol (E(2)). This study aims to examine the anti-tumour activities of 2ME2 on the poorly differentiated HONE-1 NPC cell line. At the concentration of 1 microM, 2ME2 was found to induce a short-term reversible G2/M cell-cycle arrest. Further 10-fold increase to 10 microM, 2ME2 induced both irreversible G2/M phase cell-cycle arrest and apoptosis. Induction of apoptosis and G2/M cell-cycle arrest was due to oxidative stress as both apoptosis and the proportion of cells arresting at G2/M phase could be reduced by the superoxide dismutase (SOD) mimetic, TEMPO. Induction of apoptosis was accompanied with proteolytic cleavage of caspase-9 and -3, but not caspase-8. Kinetics studies revealed that 2ME2 induced a time-dependent inhibition of extracellular signal-regulated protein kinase (ERK) and an activation of c-jun N-terminal kinases (JNKs). The chemical inhibitor of JNKs, SP600125, was found to reduce 2ME2-induced apoptosis of the HONE-1 cells. Confocal microscopy revealed that the induction of G2/M cell-cycle arrest was associated with the presence of immunoreactivity of p-cdc2 (Tyr15) in the nucleus. The G2/M cell-cycle arrest is also correlated with an increased level of inactive p-cdc25C (Ser216) in 2ME2-treated HONE-1 cells. Results from this study indicate that production of superoxide anions might be involved in 2ME2-induced apoptosis and G2/M cell-cycle arrest of the HONE-1 cells.
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PMID:Mechanisms of 2-methoxyestradiol-induced apoptosis and G2/M cell-cycle arrest of nasopharyngeal carcinoma cells. 1849 2

Resistance toward cytotoxic drugs is one of the primary causes for therapeutic failure in cancer therapy. DNA repair mechanisms as well as deficient caspases activation play a critical role in apoptosis resistance of tumor cells toward anticancer drug treatment. Here, we discovered that deficient caspases activation in apoptosis-resistant cancer cells depends on DNA-ligase IV and DNA-protein kinase (DNA-PK), playing crucial roles in the nonhomologous end joining (NHEJ) pathway, which is the predominant pathway for DNA double-strand break repair (DNA-DSB-repair) in mammalian cells. DNA-PK(+/+) as well as DNA-ligase IV (+/+) cancer cells were apoptosis resistant and deficient in activation of caspase-3, caspase-9, and caspase-8 and in cleavage of poly(ADP-ribose) polymerase after doxorubicin treatment. Inhibition of NHEJ by knocking out DNA-PK or DNA-ligase IV restored caspases activation and apoptosis sensitivity after doxorubicin treatment. In addition, inhibition of caspases activation prevented doxorubicin-induced apoptosis but could not prevent doxorubicin-induced DNA damage, indicating that induction of DNA damage is independent of caspases activation. However, caspases activation depends on induction of DNA damage left unrepaired by NHEJ-DNA-DSB-repair. We conclude that DNA damage left unrepaired by DNA-ligase IV or DNA-PK might be the initiator for caspases activation by doxorubicin in cancer cells. Failure in caspases activation using doxorubicin depends on loss of DNA damage and is due to higher rates of NHEJ-DNA-DBS-repair.
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PMID:DNA-ligase IV and DNA-protein kinase play a critical role in deficient caspases activation in apoptosis-resistant cancer cells by using doxorubicin. 1850 26

Effective treatments for advanced prostate cancer are much needed. Toward this goal, we show apoptosis and impaired long-term survival of androgen-independent prostate cancer cells (PC3 and PC3 derivatives) co-treated with the cyclin-dependent kinase (CDK) inhibitor roscovitine and an AKT inhibitor (LY294002 or API-2). Apoptosis of PC3 cells by the drug combination required caspase-9 but not caspase-8 activity and thus is mitochondria-dependent. Roscovitine reduced amounts of the caspase inhibitor XIAP, and API-2 increased amounts of the BH3-only protein Bim. PC3 cells apoptosed when co-treated with API-2 and either cdk9 siRNA, dominant-negative cdk9, or the cdk9 inhibitor DRB; they did not apoptose when co-treated with API-2 and XIAP siRNA. Bax accumulated in mitochondria in response to API-2, whereas release of cytochrome c from mitochondria required both API-2 and roscovitine. We suggest that roscovitine elicits events that activate Bax once it translocates to mitochondria and that inactivation of cdk9 signals these events and the down-regulation of XIAP. Collectively, our data show apoptosis of prostate cancer cells by a drug combination and identify Bax activation as a basis of cooperation.
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PMID:Apoptosis of metastatic prostate cancer cells by a combination of cyclin-dependent kinase and AKT inhibitors. 1870 58

Inappropriate activation of phosphatidylinositol 3-kinase-Akt signaling contributes to the development of several human malignancies. Modulation of Akt activity is a strategy that may be valuable in chemopreventive and chemotherapeutic regimens. We have previously demonstrated that apigenin, a plant flavone, causes decreased survival in human prostate cancer cells. However, the molecular mechanism underlying this observation remains elusive. In the present study, we investigated the mechanisms of apigenin action on human prostate cancer PC-3 cells, which possess constitutively active Akt. Treatment of PC-3 cells with apigenin (5-40 microM) resulted in significant dose- and time-dependent decrease in Akt phosphorylation at Serine473. Apigenin-mediated dephosphorylation of Akt resulted in inhibition of its kinase activity, which was confirmed by reduced phosphorylation of proapoptotic proteins BAD and glycogen synthase kinase-3, essential downstream targets of Akt. Hypophosphorylation of BAD resulted in reduced interaction with 14-3-3beta protein after 20 microM apigenin exposure to PC-3 cells for 24 h. Inactivation of Akt seems to be associated with downregulation of insulin-like growth factor receptor 1 protein level and inhibition of its autophosphorylation upon apigenin treatment. Exposure to apigenin significantly induced caspase-9 activity and decreased the survival of PC-3 cells in a dose-dependent manner. Furthermore, Serine473 phosphorylation of ectopically expressed Akt in DU145 cells was significantly reduced upon 20 microM apigenin treatment. In vivo, apigenin intake through gavage resulted in inactivation of Akt and induction of apoptosis in PC-3 tumors. These results suggest that Akt inactivation and dephosphorylation of BAD is a critical event, at least in part, in apigenin-induced decreased cell survival and apoptosis.
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PMID:Plant flavonoid apigenin inactivates Akt to trigger apoptosis in human prostate cancer: an in vitro and in vivo study. 1872 86

The induction of programmed cell death in premalignant or malignant cancer cells by chemopreventive agents could be a valuable tool to control prostate cancer initiation and progression. In this work, we present evidence that the C-28 methyl ester of the synthetic oleanane triterpenoid 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO-Me) induces cell death in androgen-responsive and unresponsive human prostate cancer cell lines at nanomolar and low micromolar concentrations. CDDO-Me induced caspase-3, caspase-8, and caspase-9 activation; poly(ADP-ribose) polymerase cleavage; internucleosomal DNA fragmentation; and loss of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction in PC3 and DU145 cells. However, caspase-3 and caspase-8 inhibition by Z-DEVD-fmk and Z-IETD-fmk, respectively, or general caspase inhibition by BOC-D-fmk or Z-VAD-fmk did not rescue loss of cell viability induced by CDDO-Me, suggesting the activation of additional caspase-independent mechanisms. Interestingly, CDDO-Me induced inactivating phosphorylation at Ser(9) of glycogen synthase kinase 3beta (GSK3beta), a multifunctional kinase that mediates essential events promoting prostate cancer development and acquisition of androgen independence. The GSK3 inhibitor lithium chloride and, more effectively, GSK3 gene silencing sensitized PC3 and DU145 prostate cancer cells to CDDO-Me cytotoxicity. These data suggest that modulation of GSK3beta activation is involved in the cell death pathway engaged by CDDO-Me in prostate cancer cells.
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PMID:Glycogen synthase kinase 3beta regulates cell death induced by synthetic triterpenoids. 1875 13

Coumarin (1,2-benzopyrone) is a naturally occurring fragrant compound found in a variety of plants and spices. Coumarins have attracted intense interest in recent years because of their diverse pharmacological activities. This study examines the antioxidant coumarin 7,8-diacetoxy-4-methylcoumarin (DAMC) and its thiocoumarin derivative 7,8-diacetoxy-4-methylthiocoumarin (DAMTC) for their effect on human non-small cell lung cancer A549 cells. Here we show that both DAMC and DAMTC not only inhibited cell proliferation, but also induced apoptosis with an IC(50) of 160 microg/ml as confirmed by morphological examination, annexin-V assay and flow cytometric analysis. Interestingly, it was observed that these two coumarin compounds exhibited little cytotoxicity towards peripheral blood mononuclear cells but induced apoptosis in malignant cells. DAMC/DAMTC treatment also resulted in pronounced release of apoptogenic cytochrome c from mitochondria to cytosol, alteration of mitochondrial membrane potential (DeltaPsi(m)), and activation of caspase-9 and caspase-3. Although an increase in the levels of reactive oxygen species (ROS) was observed, pre-treatment with antioxidant showed no protective effect against DAMC/DAMTC-induced apoptosis. Results of present study suggest that downregulation of Bcl-xl, Cox-2 and mitogen activated protein kinase pathway and upregulation of p53, Akt and NF-kappaB pathway are involved in the underlying molecular mechanism of apoptosis induction by DAMC and DAMTC in A549 cells.
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PMID:Apoptogenic effect of 7,8-diacetoxy-4-methylcoumarin and 7,8-diacetoxy-4-methylthiocoumarin in human lung adenocarcinoma cell line: role of NF-kappaB, Akt, ROS and MAP kinase pathway. 1906 72

The precise regulation of programmed cell death is critical for the normal development of the nervous system. We show here that DYRK1A (minibrain), a protein kinase essential for normal growth, is a negative regulator of the intrinsic apoptotic pathway in the developing retina. We provide evidence that changes in Dyrk1A gene dosage in the mouse strongly alter the cellularity of inner retina layers and result in severe functional alterations. We show that DYRK1A does not affect the proliferation or specification of retina progenitor cells, but rather regulates the number of cells that die by apoptosis. We demonstrate that DYRK1A phosphorylates caspase-9 on threonine residue 125, and that this phosphorylation event is crucial to protect retina cells from apoptotic cell death. Our data suggest a model in which dysregulation of the apoptotic response in differentiating neurons participates in the neuropathology of diseases that display DYRK1A gene-dosage imbalance effects, such as Down's syndrome.
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PMID:The protein kinase DYRK1A regulates caspase-9-mediated apoptosis during retina development. 1908 Oct 73


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