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)

Recent studies have indicated that the development of cyclin-dependent kinase (cdk)2 inhibitors that deregulate E2F are a plausible pharmacological strategy for novel antineoplastic agents. We show here that 3-[1-(3H-Imidazol-4-yl)-meth-(Z)-ylidene]-5-methoxy-1,3-dihydro-indol-2-one (SU9516), a novel 3-substituted indolinone compound, binds to and selectively inhibits the activity of cdk2. This inhibition results in a time-dependent decrease (4-64%) in the phosphorylation of the retinoblastoma protein pRb, an increase in caspase-3 activation (5-84%), and alterations in cell cycle resulting in either a G(0)-G(1) or a G(2)-M block. We also report here cell line differences in the cdk-dependent phosphorylation of pRb. These findings demonstrate that SU9516 is a selective cdk2 inhibitor and support the theory that compounds that inhibit cdk2 are viable resources in the development of new antineoplastic agents.
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PMID:A novel cdk2-selective inhibitor, SU9516, induces apoptosis in colon carcinoma cells. 1150 69

Protein phosphatase 1 (PP1) plays important roles in many different aspects of cellular activities including cell cycle control. One important function of PP1 is to activate the retinoblastoma protein pRB. Here we show that pRB is one of PP1's downstream targets during apoptosis. When HL-60 cells synchronized at the G1/S boundary were treated with pro-apoptotic cytosine arabinoside (araC), PP1alpha protein increased twofold and PP1 activity about 30% within 1 h. This was followed by pRB dephosphorylation, pRB cleavage by caspases, DNA fragmentation, the appearance of cells with <2n DNA content and finally, dying and dead cells. In vitro, pRB was protected from caspase-3 digestion by prior Cdk-mediated phosphorylation, whereas PP1alpha converted phospho-pRB into an efficient substrate for caspase-3. Introduction of active PP1alpha into HL-60 cells by electroporation was sufficient to induce characteristics of apoptosis. Similarly, araC-resistant cells, normally unable to die in response to araC, initiated apoptosis when electroporated with active PP1alpha. This was also accompanied by pRB cleavage. In contrast, introduction of inhibitor-2 delayed the onset of araC-induced apoptosis, whereas concomitant introduction of PP1alpha and inhibitor-2 completely prevented PP1alpha-induced apoptosis. These results suggest that dephosphorylation of key proteins by PP1alpha may be crucial for the initiation of apoptosis and further support the concept of PP1 serving as a potential target for anti-cancer therapy.
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PMID:Protein phosphatase 1alpha-mediated stimulation of apoptosis is associated with dephosphorylation of the retinoblastoma protein. 1159 19

Vitamin E-succinate (VES) induced HL-60 human leukemia cells to undergo apoptosis. Treatment with VES induced membrane translocation of Fas; cleavages of caspase-3, PARP, and lamin B; hypophosphorylation of retinoblastoma protein; and increase of p21(WAF1) protein level. During the induction of apoptosis, activity of PKC was gradually increased with downregulation of VES-induced ERK activity and accompanied by activation of caspase-3. Inhibition of PKC by GF109203X blocked VES-mediated membrane translocation of PKC-alpha and cleavage of caspase-3 cascade, resulting in prevention of VES-induced apoptosis. On the contrary, PKC activation by cotreatment with LPC or thapsigargin and VES synergistically increased VES-mediated apoptosis. However, inhibition of ERK activity by PD98059 showed no significant effect on VES-induced PKC activity and apoptosis. Taken together, our data suggest that VES induces activation of PKC and PKC-dependent hypophosphorylation of retinoblastoma protein, which results in induction of apoptosis, and that VES-induced early activation of ERK and ERK-dependent induction of p21(WAF1) are not required for apoptosis.
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PMID:Activation of PKC but not of ERK is required for vitamin E-succinate-induced apoptosis of HL-60 cells. 1168 77

Prior studies have shown that cyclooxygenase (COX)-2, an enzyme involved in inflammatory mechanisms as well as neuronal activities, is up-regulated in the Alzheimer's disease (AD) brain and may represent a therapeutic target for anti-inflammatory treatments. We report the effect of neuronal overexpression of human (h)COX-2 in a murine model of AD neuropathology. Transgenic mice expressing both the human amyloid precursor protein mutation (APPswe) and the human presenilin (PS1-A246E) mutation, with resultant AD plaque pathology, were crossed with transgenic mice expressing human (h)COX-2 in neurons. At 12 months of age, the APPswe/PS1-A246E/hCOX-2 triple-transgenic mice showed an elevation in the number of phosphorylated retinoblastoma (pRb) tumor suppressor protein and active caspase-3 immunopositive neurons, compared to double APPswe/PS1-A246E or single hCOX-2 transgenic controls. No detectable influence of neuronal hCOX-2 on AD neuropathology was found in the brain of APPswe/PS1-A246E/hCOX-2 triple-transgenic mice, compared to double APPswe/PS1-A246E. In vitro studies revealed that hCOX-2 overexpression in primary cortico-hippocampal neurons derived from the hCOX-2 transgenics accelerates beta-amyloid (Abeta)(1-42)-mediated apoptotic damage which was prevented by the cell cycle dependent (CDK) inhibitor, flavoperidol. The data indicates that COX-2 overexpression causes alteration of neuronal cell cycle in a murine model of AD neuropathology, and provides a rational basis for targeting neuronal COX-2 in therapeutic research aimed at slowing the clinical progression of AD.
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PMID:Cyclooxygenase (COX)-2 and cell cycle activity in a transgenic mouse model of Alzheimer's disease neuropathology. 1195 94

The p16 tumor suppressor gene is frequently inactivated in human cancer tissues and cell lines. We previously reported that wild-type p16 expression from an adenovirus vector (Adv/p16) induced p53-dependent apoptotic cell death in non-small cell lung cancer (NSCLC) cell lines. Here we show the potential mechanism of apoptosis induced by Adv/p16 infection. Infection of human NSCLC cell line A549, which carries the wild-type p53 gene, with Adv/p16 resulted in activation of caspase-3, accompanied by the cleavage of its substrate poly (ADP-ribose) polymerase (PARP), on day 3 of infection. The retinoblastoma (Rb) cell cycle regulator protein was also cleaved after activation of caspase-3; when the levels of Rb significantly diminished, apoptosis began. When A549 cells were pretreated with the caspase-inhibitory peptide N-acetyl-asp-Glu-Val-Asp-CHO (aldehyde) (Ac-DEVD-CHO), Adv/p16-mediated apoptosis and Rb cleavage were greatly inhibited. Furthermore, MDM2, a negative regulator of p53 expression was upregulated 3 days after Adv/p16 infection, and MDM2 was subsequently cleaved by caspase-3; MDM2 cleavage was inhibited by Ac-DEVD-CHO treatment. These data implied that cleavage of Rb, in addition to activation of caspase-3, represented a mechanism by which Adv/p16 induced apoptotic cell death in human NSCLC cells. Our results support the clinical relevance of Adv/p16 as a treatment for p16-null human NSCLC that express wild-type p53.
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PMID:Activation of caspase-3 and cleavage of Rb are associated with p16-mediated apoptosis in human non-small cell lung cancer cells. 1196 Mar 84

Extensive studies have implicated the role of dietary fatty acids in prostatecancer progression. Platelet-type 12-Lipoxygenase (12-LOX) has beenshown to regulate growth, metastasis, and angiogenesis of prostate cancer. The effect of two 12-LOX inhibitors, Baicalein and N-benzyl-N-hydroxy-5-phenylpentamide (BHPP), on the mechanisms controlling cell cycle progression and apoptosis were examined in two prostate cancer cell lines, PC3 and DU-145. Treatment with Baicalein or BHPP resulted in a dose-dependent decrease in cell proliferation, as measured by BrdUrd incorporation. This growth arrest was shown to be because of cell cycle inhibition at G0/G1, and was associated with suppression of cyclin D1 and D3 protein levels. PC3 cells also showed a strong decrease in phosphorylated retinoblastoma (pRB) protein, whereas the other retinoblastoma-associated proteins, p107 and p130, were inhibited in DU-145 cells. Treatment with 12-hydroxyeicosatetraenoic acid in the presence of Baicalein blocked loss of pRB, whereas 12(S)-HETE alone induced pRB expression. Treatment with either Baicalein or BHPP resulted in significant apoptosis in both cell lines as measured by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling. DU-145 cells underwent apoptosis more rapidly than PC-3 cells. The mechanisms involved were decreased phosphorylation of Akt, loss of survivin and subsequent activation of caspase-3 and caspase-7 in each cell line, decreased Bcl-2 and Bcl-X(L) expression in DU-145, and a shift in Bcl-2/Bax levels favoring apoptosis in PC-3 cells. Addition of 12(S)-HETE protected both cell lines from Baicalein-induced apoptosis, whereas other LOX metabolites, 5(S)-HETE, or 15(S)-HETE did not. These results show that the 12-LOX pathway is a critical regulator of prostate cancer progression and apoptosis, by affecting various proteins regulating these processes. Therefore, inhibition of 12-LOX is a potential therapeutic agent in the treatment of prostate cancer.
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PMID:Mechanisms controlling cell cycle arrest and induction of apoptosis after 12-lipoxygenase inhibition in prostate cancer cells. 1198 Jun 74

Necdin is expressed predominantly in postmitotic neurons and serves as a growth suppressor that is functionally similar to the retinoblastoma tumor suppressor protein. Using primary cultures of dorsal root ganglion (DRG) of mouse embryos, we investigated the involvement of necdin in the terminal differentiation of neurons. DRG cells were prepared from mouse embryos at 12.5 days of gestation and cultured in the presence of nerve growth factor (NGF). Immunocytochemistry revealed that necdin accumulated in the nucleus of differentiated neurons that showed neurite extension and expressed the neuronal markers microtubule-associated protein 2 and synaptophysin. Suppression of necdin expression in DRG cultures treated with antisense oligonucleotides led to a marked reduction in the number of terminally differentiated neurons. The antisense oligonucleotide-treated cells did not attempt to reenter the cell cycle, but underwent death with characteristics of apoptosis such as caspase-3 activation, nuclear condensation, and chromosomal DNA fragmentation. Furthermore, a caspase-3 inhibitor rescued antisense oligonucleotide-treated cells from apoptosis and significantly increased the population of terminally differentiated neurons. These results suggest that necdin mediates the terminal differentiation and survival of NGF-dependent DRG neurons and that necdin-deficient nascent neurons are destined to caspase-3-dependent apoptosis.
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PMID:Necdin is required for terminal differentiation and survival of primary dorsal root ganglion neurons. 1208 4

Cross-linking of the B cell antigen receptor (BCR) on germinal center B cells can induce growth arrest and apoptosis, thereby eliminating potentially autoreactive B cells. Using the Burkitt lymphoma cell line Ramos as a model, we studied the commitment to apoptosis following growth arrest, as well as how triggering of CD40 or addition of tumor necrosis factor (TNF)-alpha can interfere to block cell death. Both BCR triggering and direct induction of growth arrest by sodium butyrate (n-But) caused hypophosphorylation of the retinoblastoma protein (pRb), followed by apoptosis. Interestingly, although CD40 ligation or TNF-alpha efficiently prevented BCR-induced and n-But-induced apoptosis, these co-stimuli did not inhibit, but rather augmented, growth arrest. Analysis of cell cycle regulators showed that each apoptotic and T(h) stimulus distinctly affected cyclins or cyclin-dependent kinase inhibitors, indicating that growth arrest can be uncoupled from apoptosis. BCR ligation and growth arrest activated the intrinsic or mitochondrial route of apoptosis. CD40 ligation and TNF-alpha prevented release of cytochrome c and activation of caspase-3, which could not be explained by effects on the expression of Bcl-2, Bcl-x(L) or Bax. Finally, the onset of BCR-induced apoptosis occurred after 10-12 h and addition of CD40 mAb or TNF-alpha at that point still prevented further execution of apoptosis. We conclude that in mature B cells apoptosis is not an obligatory event following growth arrest. Instead, commitment to apoptosis can be rapidly controlled by T cells via CD40 ligand and TNF-alpha, downstream of the pRb-regulated restriction point of the cell cycle, but prior to mitochondrial cytochrome c release.
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PMID:Prevention of B cell antigen receptor-induced apoptosis by ligation of CD40 occurs downstream of cell cycle regulation. 1220 95

The retinoblastoma tumour suppressor protein RB is cleaved by caspases during apoptosis. Here we have mutated the caspase cleavage site in the carboxy terminus of the murine Rb protein in the mouse germ line to create the Rb-MI allele. After endotoxic shock, expression of Rb-MI inhibits apoptosis in the intestines, but not in the spleen, and promotes the survival of male mice. Fibroblasts expressing Rb-MI protein are protected from apoptosis induced by the tumour-necrosis factor-alpha type I receptor (TNFRI) but remain sensitive to cell death induced by DNA damage. Correspondingly, the release of cytochrome c and the activation of caspase-3 induced by TNFRI, but not by DNA damage, are defective in cells expressing Rb-MI. Our results highlight the importance of Rb cleavage in TNFRI-induced apoptosis.
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PMID:Signal-dependent protection from apoptosis in mice expressing caspase-resistant Rb. 1236 Feb 86

Recently we demonstrated the induction of apoptosis by the addition of recombinant lipocalin-type prostaglandin D(2) synthase (L-PGDS) to the culture medium of LLC-PK(1) cells. Because protein kinase C (PKC) has been shown to be involved in the apoptotic process of various cell types, we examined the potential role of L-PGDS in phorbol 12-myristate 13-acetate (PMA)-induced apoptosis. We report here the enzymatic activation and phosphorylation of L-PGDS in response to phorbol ester in cell culture and the direct phosphorylation of recombinant L-PGDS by PKC in vitro. Treatment of cells with PMA or L-PGDS decreased phosphatidylinositol 3-kinase (PI3-K) activity and concomitantly inhibited protein kinase B (PKB/Akt) phosphorylation, which led to the hypophosphorylation and activation of Bad. In addition, hypophosphorylation of retinoblastoma protein was also observed in response to L-PGDS-induced apoptosis. Cellular depletion of L-PGDS levels by using an antisense RNA strategy prevented PI3-K inactivation by phorbol ester and inhibited caspase-3 activation and apoptosis. We conclude that phorbol ester-induced apoptosis is mediated by L-PGDS phosphorylation and activation by PKC and is accompanied by inhibition of the PI3-K/PKB anti-apoptotic signaling pathways.
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PMID:Elevated L-PGDS activity contributes to PMA-induced apoptosis concomitant with downregulation of PI3-K. 1238 64


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