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)

Studies of the biochemical mechanisms evoked by conventional treatments for neoplastic diseases point to apoptosis as a key process for elimination of unwanted cells. Although the pathways through which chemotherapeutics promote cell death remain largely unknown, caspase proteases play a central role in the induction of apoptosis in response to a variety of stimuli including tumor necrosis factor, fas ligand, and growth factor deprivation. In this article, we demonstrate the induction of caspase protease activity in MCF7 human breast carcinoma cells exposed to the topoisomerase inhibitor, etoposide. Caspase protease activity was assessed by incubating cell lysates with the known caspase substrates, acetyl-L-aspartic-L-glutamic-L-valyl-L-aspartic acid 4-methyl-7-aminocoumarin or acetyl-L-tyrosyl-L-valyl-L-aspartic acid 4-methyl-7-aminocoumarin. We observed maximal cleavage of acetyl-L-aspartic-L-glutamic-L-valyl-L-aspartic acid 4-methyl-7-aminocoumarin within 6 hr following etoposide addition, a time that precedes cell death. In contrast, acetyl-L-tyrosyl-L-valyl-L-aspartic acid 4-methyl-7-aminocoumarin was resistant to cleavage activity. This substrate cleavage specificity implies that a caspase-3-like protease is activated in response to DNA damage. Consistent with the lysate protease activity, an intracellular marker of caspase activation, poly-ADP ribose polymerase (PARP), was cleaved in a concentration- and time-dependent manner after etoposide-treatment. PARP cleavage followed caspase activation and reached maximum cleavage between 12 and 16 hr. Incubation of the cells with the peptidic caspase inhibitor z-valine-alanine-asparagine-CH2F prevented caspase activation, inhibited PARP cleavage, and inhibited cell death. Thus, etoposide killing of MCF7 cells requires a caspase-3-like protease.
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PMID:Caspase activation in MCF7 cells responding to etoposide treatment. 949 10

CD95 ligand (CD95L)-induced apoptosis is a novel immunotherapeutic approach to malignant glioma. Here, we report that interferon-alpha (IFN-alpha) sensitizes LN-229 and T98G human malignant glioma cells to CD95L-induced apoptosis. In contrast to the effects of IFN-gamma and TNF-alpha which sensitize glioma cells to CD95 antibody-induced apoptosis in part by enhancing CD95 expression, IFN-alpha has no effect on CD95 expression at the cell surface of LN-229 and T98G cells. To confirm that changes in CD95 expression are not required for the effects of IFN-alpha, we show that IFN-alpha enhances CD95L-induced apoptosis even in CD95-transfected LN-308 glioma cells. These LN-308 cells have little endogenous CD95 expression but express high levels of CD95 from a stably integrated CD95 expression plasmid. The sensitizing effects of IFN-alpha appear to be independent of cell cycle effects of IFN-alpha and are unaffected by ectopic expression of the bcl-2 proto-oncogene. IFN-alpha enhances CD95L-induced activation of caspase-3, a critical mediator of CD95L-induced cell death. IFN-alpha also increases the cytotoxic effects of BCNU, teniposide and cytarabine in both cell lines, and of vincristine in LN-229 cells. Doxorubicin and 5-fluorouracil toxicity are unaffected by IFN-alpha. IFN-alpha may be a useful adjunct to novel strategies of immunochemotherapy for malignant gliomas that target CD95-mediated apoptosis.
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PMID:Interferon-alpha enhances CD95L-induced apoptosis of human malignant glioma cells. 967 Aug 53

The cytotoxic cytokine, CD95 ligand, is an experimental anti-cancer agent. Here, we describe a novel pathway of drug-mediated augmentation of CD95 ligand-induced apoptosis. We report that prolonged pre-exposure of human malignant glioma cells to different cytotoxic agents, VM26, cytarabine and cisplatin, induces strong sensitization to CD95 ligand-induced apoptosis. CD95 gene transfer does not prevent sensitization, suggesting that sensitization is not mediated by drug-induced CD95 expression. Priming with cytotoxic drugs greatly increases CD95 ligand-induced caspase 3 activity, indicating that the cytotoxic drugs positively modulate the CD95-dependent signalling cascade up-stream of caspase 3 activation.
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PMID:Chemotherapy primes malignant glioma cells for CD95 ligand-induced apoptosis up-stream of caspase 3 activation. 971 75

Apoptosis mediated by anticancer drugs may involve activation of death-inducing ligand/receptor systems such as CD95 (APO-1/Fas), cleavage of caspases, and perturbance of mitochondrial functions. We investigated the sequence of these events in SHEP neuroblastoma cells transfected with Bcl-2 or Bcl-X(L) using two different drugs, namely, doxorubicin (Doxo), which activates the CD95/CD95 ligand (CD95-L) system, and betulinic acid (Bet A), which does not enhance the expression of CD95 or CD95-L and which, as shown here, directly targets mitochondria. Apoptosis induced by both drugs was inhibited by Bcl-2 or Bcl-X(L) overexpression or by bongkrekic acid, an agent that stabilizes mitochondrial membrane barrier function, suggesting a critical role for mitochondria. After Doxo treatment, enhanced CD95/CD95-L expression and caspase-8 activation were not blocked by Bcl-2 or Bcl-X(L) and were found in cells with a mitochondrial transmembrane potential (delta psi(m)) that was still normal (delta psi(m)high cells). In marked contrast, after Bet A treatment, caspase-8 activation occurred in a Bcl-2- or Bcl-X(L)-inhibitable fashion and was confined to cells that had lost their delta psi(m) (delta psi(m)low cells). Mitochondria from cells treated with either Doxo or Bet A induced cleavage of both caspase-8 and caspase-3 in cytosolic extracts. Thus, caspase-8 activation may occur upstream or downstream of mitochondria, depending on the apoptosis-initiating stimulus. In contrast to caspase-8, cleavage of caspase-3 or poly(ADP-ribose)polymerase was always restricted to delta psi(m)low cells, downstream of the Bcl-2- or Bcl-X(L)-controlled checkpoint of apoptosis. Cytochrome c, released from mitochondria undergoing permeability transition, activated caspase-3 but not caspase-8 in a cell-free system. However, both caspases were activated by apoptosis-inducing factor, indicating that the mechanism of caspase-8 activation differed from that of caspase-3 activation. Taken together, our findings demonstrate that perturbance of mitochondrial function constitutes a central coordinating event in drug-induced cell death.
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PMID:Molecular ordering of apoptosis induced by anticancer drugs in neuroblastoma cells. 976 78

Sendai virus (SV) infection and replication lead to a strong cytopathic effect with subsequent death of host cells. We now show that SV infection triggers an apoptotic program in target cells. Incubation of infected cells with the peptide inhibitor z-VAD-fmk abrogated SV-induced apoptosis, indicating that proteases of the caspase family were involved. Moreover, proteolytic activation of two distinct caspases, CPP32/caspase-3 and, as shown for the first time in virus-infected cells, FLICE/caspase-8, could be detected. So far, activation of FLICE/caspase-8 has been described in apoptosis triggered by death receptors, including CD95 and tumor necrosis factor (TNF)-R1. In contrast, we could show that SV-induced apoptosis did not require TNF or CD95 ligand. We further found that apoptosis of infected cells did not influence the maturation and budding of SV progeny. In conclusion, SV-induced cell injury is mediated by CD95- and TNF-R1-independent activation of caspases, leading to the death of host cells without impairment of the viral life cycle.
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PMID:Sendai virus infection induces apoptosis through activation of caspase-8 (FLICE) and caspase-3 (CPP32). 984 76

Astrocytes are a major cellular component of the brain that are capable of intense proliferation and metabolic activity during diverse inflammatory brain diseases (such as multiple sclerosis, Alzheimer's dementia, tumor, HIV encephalitis, or prion disease). In this biological process, called reactive gliosis, astrocyte apoptosis is frequently observed and could be an important mechanism of regulation. However, the factors responsible for apoptosis in human astrocytes are poorly defined. Here, we report that short term cultured astrocytes derived from different brain regions express significant levels of CD95 at their surface. Only late passage astrocytes are sensitive to CD95 ligation using either CD95 mAb or recombinant CD95 ligand. Blocking experiments using caspase inhibitors with different specificities (DEVD-CHO, z-VAD-fmk, and YVAD-cmk), an enzymatic activity assay, and immunoblotting show that CPP32/caspase-3 play a prominent role in CD95-induced astrocyte death. In contrast, early passage astrocytes are totally resistant to death, but a significant increase in astrocytic IL-8 secretion (p < 0.001, by Wilcoxon's test for paired samples) is observed after CD95 triggering. Production of IL-8 contributes to the resistance of astrocytes to CD95 ligation. Furthermore, in the presence of IFN-gamma, resistant astrocytes became sensitive to CD95-mediated death. These data suggest that microenvironmental factors can influence the consequences of CD95 ligation on astrocytes. Therefore, we propose that CD95 expressed by human astrocytes plays a pivotal role in the regulation of astrocyte life and death and may be a key factor in inflammatory processes in the brain, such as reactive gliosis.
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PMID:CD95 (Fas/Apo-1) as a receptor governing astrocyte apoptotic or inflammatory responses: a key role in brain inflammation? 997 11

We have previously shown that nitric oxide (NO) stimulates apoptosis in different human neoplastic lymphoid cell lines through activation of caspases not only via CD95/CD95L interaction, but also independently of such death receptors. Here we investigated mitochondria-dependent mechanisms of NO-induced apoptosis in Jurkat leukemic cells. NO donor glycerol trinitrate (at the concentration, which induces apoptotic cell death) caused (1) a significant decrease in the concentration of cardiolipin, a major mitochondrial lipid; (2) a downregulation in respiratory chain complex activities; (3) a release of the mitochondrial protein cytochrome c into the cytosol; and (4) an activation of caspase-9 and caspase-3. These changes were accompanied by an increase in the number of cells with low mitochondrial transmembrane potential and with a high level of reactive oxygen species production. Higher resistance of the CD95-resistant Jurkat subclone (APO-R) cells to NO-mediated apoptosis correlated with the absence of cytochrome c release and with less alterations in other mitochondrial parameters. An inhibitor of lipid peroxidation, trolox, significantly suppressed NO-mediated apoptosis in APO-S Jurkat cells, whereas bongkrekic acid (BA), which blocks mitochondrial permeability transition, provided only a moderate antiapoptotic effect. Transfection of Jurkat cells with bcl-2 led to a complete block of apoptosis due to the prevention of changes in mitochondrial functions. We suggest that the mitochondrial damage (in particular, cardiolipin degradation and cytochrome c release) induced by NO in human leukemia cells plays a crucial role in the subsequent activation of caspase and apoptosis.
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PMID:Nitric-oxide-induced apoptosis in human leukemic lines requires mitochondrial lipid degradation and cytochrome C release. 1009 Sep 45

Many anticancer drugs are able to induce apoptosis in tumor cells but the mechanisms underlying this phenomenon are poorly understood. Some authors reported that the p53 tumor suppressor gene may be responsible for drug-induced apoptosis; however, chemotherapy-induced apoptosis can also be observed in p53 negative cells. Recently, doxorubicin (DXR) was reported to induce CD95L expression to mediate apoptosis through the CD95/CD95L system. Thus, an impairment of such a system may be involved in drug resistance. We evaluated the in vitro antitumor activity of several cytotoxic drugs on two human p53-negative T-cell lymphoma cell lines, the HUT78-B1 CD95L-resistant cell line and the HUT78 parental CD95L-sensitive cell line. We demostrated by Western blotting assay that DXR and etoposide (VP-16) were able to induce CD95L expression after 4 h of treatment. In contrast, they were unable to induce the expression of p53. DXR, at concentrations ranging from 0.001 - 1 microg/ml, and VP16, at concentrations ranging from 0.05 - 1 microg/ml, were equally cytotoxic and induced apoptosis in both cell lines as assessed by fluorescence microscopy and flow cytometry analyses. Although we observed a slightly reduced percentage of apoptotic cells in HUT78B1 when compared with the parental HUT78 cells after few hours of drug exposure, this difference was no longer evident at 48 or 72 h. Similarly, the exposure of HUT78 cells to a CD95-blocking antibody partially reduced early apoptosis (24 h) without affecting the long-term effects of the drugs including cytotoxicity. Furthermore, as observed with DXR and VP-16, both the CD95L-sensitive and the CD95L-resistant cell lines resulted equally sensitive to the cytotoxic effects of a number of different cytotoxic drugs (vincristine, camptothecin, 5-fluorouracil and methotrexate). The treatment with the Caspase-3 tetrapeptide aldehyde inhibitor, Ac-DEVD-CHO, did not affect the DXR-induced apoptosis whereas it only modestly inhibited apoptosis and cytotoxicity of VP-16, while Z-VAD.FMK, a Caspase inhibitor that prevents the processing of Caspase-3 to its active form, was able to block DXR-induced apoptosis at 24 h but not at 48 h. Thus, our results do not confirm a crucial role for the CD95/CD95L system in drug-induced apoptosis and suggest the involvement of alternative p53-independent pathways at least in this experimental model system.
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PMID:The CD95/CD95 ligand system is not the major effector in anticancer drug-mediated apoptosis. 1020 May 32

Chemotherapeutic agents and gamma-irradiation used in the treatment of brain tumors, the most common solid tumors of childhood, have been shown to act primarily by inducing apoptosis. Here, we report that activation of the CD95 pathway was involved in drug- and gamma-irradiation-induced apoptosis of medulloblastoma and glioblastoma cells. Upon treatment CD95 ligand (CD95-L) was induced that stimulated the CD95 pathway by crosslinking CD95 via an autocrine/paracrine loop. Blocking CD95-L/receptor interaction using F(ab')2 anti-CD95 antibody fragments strongly reduced apoptosis. Apoptosis depended on activation of caspases (interleukin 1beta-converting enzyme/Ced-3 like proteases) as it was almost completely abrograted by the broad range caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone. Apoptosis was mediated by cleavage of the receptor proximal caspase FLICE/MACH (caspase-8) and the downstream caspase CPP32 (caspase-3, Apopain) resulting in cleavage of the prototype caspase substrate PARP. Moreover, CD95 was upregulated in wild-type p53 cells thereby increasing responsiveness towards CD95 triggering. Since activation of the CD95 system upon treatment was also found in primary medulloblastoma cells ex vivo, these findings may have implications to define chemosensitivity and to develop novel therapeutic strategies in the management of malignant brain tumors.
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PMID:Activation of the CD95 (APO-1/Fas) pathway in drug- and gamma-irradiation-induced apoptosis of brain tumor cells. 1020 87

Susceptibility to CD95 (Fas/APO-1)-mediated apoptosis in human glioma cells depends on CD95 expression and unknown factors that regulate signal transduction. Thus, LN-18 cells are highly sensitive to CD95 ligand (CD95L) whereas LN-229 cells require coexposure to inhibitors of RNA or protein synthesis for induction of apoptosis. Here, we report that caspase 8 and 3 activation, poly(ADP-ribose)polymerase cleavage and apoptosis are inhibited by the lipoxygenase inhibitor, nordihydroguaretic acid (NDGA), or ectopic expression of crm-A or bcl-2. CD95L-induced glioma cell apoptosis does not involve ceramide generation. Apoptosis induced by exogenous ceramide resembles CD95-mediated apoptosis in that bcl-2 is protective but differs in that NDGA and crm-A have no effect and in that cycloheximide (CHX) inhibits rather than potentiates ceramide-induced cell death. We conclude that caspase 8 and caspase 3 activation, but not ceramide generation, are required for CD95 ligand-induced apoptosis of glioma cells and that bcl-2, crm-A and NDGA all act upstream of caspases to inhibit apoptosis.
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PMID:Crm-A, bcl-2 and NDGA inhibit CD95L-induced apoptosis of malignant glioma cells at the level of caspase 8 processing. 1020 95


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