Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.22.61 (caspase-8)
 6,833 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The anti-cancer effects and possible mechanisms of the freshwater clam (Corbicula fluminea Muller) and its active compounds (FME) on cell viability in human leukemia HL-60 cells were investigated. This study demonstrated that FME was able to inhibit cell proliferation in a concentration- and time-dependent manner. Treatment with FME caused induction of caspase-2, caspase-3, caspase-6, caspase-8, and caspase-9 activity in a time-dependent manner, but not affect caspase-1 activity; it induced the proteolysis of DNA fragmentation factor (DFF-45) and poly(ADP-ribose) polymerase (PARP). Induction of cell death by FME was completely prevented by a pan-caspase inhibitor, Z-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK) and a caspase-2 inhibitor, Z-Val-Asp-Val-Ala-Asp-FMK (Z-VDVAD-FMK). Furthermore, treatment with FME caused a rapid loss of mitochondrial transmembrane potential, stimulation of generation of reactive oxygen species (ROS), release of mitochondrial cytochrome c into cytosol, and GSH depletion. Anti-oxidants such as N-acetylcysteine, catalase, superoxide dismutase, allopurinol, and pyrrolidine dithiocarbamate, but not diphenylene iodonium, significantly inhibited FME-induced cell death. In addition, the results showed that FME-induced apoptosis was accompanied by up-regulation of Bax and Bad, and down-regulation of Bcl-2 and Bcl-XL. Taken together, induction of apoptosis on HL-60 cells by FME was mainly associated with ROS production, GSH depletion, mitochondrial dysfunction, and caspase activation.
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PMID:Apoptosis-inducing active components from Corbicula fluminea through activation of caspase-2 and production of reactive oxygen species in human leukemia HL-60 cells. 1654 98

Development of chemotherapy resistance and evasion from apoptosis in osteosarcoma, a primary malignant bone tumor, is often correlated with constitutive nuclear factor-kappaB (NF-kappaB) activation. Here, we investigated the ability of a polyphenolic fraction of green tea (GTP) that has been shown to have antitumor effects on various malignant cell lines to inhibit growth and induce apoptosis in human osteosarcoma SAOS-2 cells. Treatment of SAOS-2 cells with GTP (20-60 microg/ml) resulted in reduced cell proliferation and induction of apoptosis, which correlated with decreased nuclear DNA binding of NF-kappaB/p65 and lowering of NF-kappaB/p65 and p50 levels in the cytoplasm and nucleus. GTP treatment of cells reduced IkappaB-alpha phosphorylation but had no effect on its protein expression. Furthermore, GTP treatment resulted in the inhibition of IKK-alpha and IKK-beta, the upstream kinases that phosphorylate IkappaB-alpha. The increase in apoptosis in SAOS-2 cells was accompanied with decrease in the protein expression of Bcl-2 and concomitant increase in the levels of Bax. GTP treatment of SAOS-2 cells also resulted in significant activation of caspases as was evident by increased levels of cleaved caspase-3 and caspase-8 in these cells. Treatment of SAOS-2 cells with a specific caspase-3 inhibitor Ac-Asp-Glu-Val-Asp-CHO (Ac-DEVD-CHO) and general caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp (OMe)-fluoromethyl ketone (Z-VAD-FMK) rescued SAOS-2 cells from GTP-induced apoptosis. Taken together, these results indicate that GTP is a candidate therapeutic for osteosarcoma that mediates its antiproliferative and apoptotic effects via activation of caspases and inhibition of NF-kappaB.
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PMID:Green tea polyphenols-induced apoptosis in human osteosarcoma SAOS-2 cells involves a caspase-dependent mechanism with downregulation of nuclear factor-kappaB. 1679 29

Myxoma virus (MYX) prevents apoptosis in RK-13 cells and forms thick dermal lesions with 100% mortality in rabbits. MYX encodes the virulence factor SERP2, a serine proteinase inhibitor (serpin). SERP2 was mutated to evaluate SERP2 function during MYX infection. MYXDeltaSERP2::lacZ (deleted for SERP2) did not inhibit apoptosis in RK-13 cells; infected rabbits had thin dermal lesions and <10% mortality. MYX-SERP2-D294A, a P1-site aspartate to alanine mutant, inactivated the serpin; infection was indistinguishable from MYXDeltaSERP2::lacZ. SERP2-D294E prevented inhibition of caspase-8, caspase-10 and granzyme-B; and MYX-SERP2-D294E failed to block apoptosis in RK-13 cells, but was fully virulent in rabbits. MYXDeltaSERP2::crmA expressed crmA instead of SERP2 and inhibited apoptosis in cell culture, but caused thin lesions and only 70% mortality in rabbits, hence crmA cannot fully substitute for SERP2. Control of apoptosis in culture does not correlate with virulence in rabbits. Virulence may instead depend on inhibition of proinflammatory proteinases by SERP2.
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PMID:Mutation of the Myxoma virus SERP2 P1-site to prevent proteinase inhibition causes apoptosis in cultured RK-13 cells and attenuates disease in rabbits, but mutation to alter specificity causes apoptosis without reducing virulence. 1695 85

Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK, TNFSF12) is a member of the TNF superfamily. TWEAK activates the Fn14 receptor, and may regulate apoptosis, proliferation, and inflammation, processes that play a significant role in pathological conditions. However, there is little information on the function and regulation of this system in the kidney. Therefore, TWEAK and Fn14 expression were studied in cultured murine tubular epithelial MCT cells and in mice in vivo. The effect of TWEAK on cell death was determined. We found that TWEAK and Fn14 expression was increased in experimental acute renal failure induced by folic acid. Cultured tubular cells express both TWEAK and the Fn14 receptor. TWEAK did not induce cell death in non-stimulated tubular cells. However, in cells costimulated with TNFalpha/interferon-gamma, TWEAK induced apoptosis through the activation of the Fn14 receptor. Apoptosis was associated with activation of caspase-8, caspase-9, and caspase-3, Bid cleavage, and evidence of mitochondrial injury. There was no evidence of endoplasmic reticulum stress. A pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-DL-Asp prevented TWEAK-induced apoptosis, but it sensitized cells to necrosis via generation of reactive oxygen species. In conclusion, cooperation between inflammatory cytokines results in tubular cell death. TWEAK and Fn14 may play a role in renal tubular cell injury.
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PMID:Cytokine cooperation in renal tubular cell injury: the role of TWEAK. 1700 19

In order to know how caspases contribute to the intracellular fate of Mycobacterium tuberculosis and host cell death in the infected macrophages, we examined the effect of benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethane (z-VAD-fmk), a broad-spectrum caspase inhibitor, on the growth of M. tuberculosis H37Rv in RAW 264 cells. In the cells treated with z-VAD-fmk, activation of caspase-8, caspase-3/7, and caspase-9 was clearly suppressed, and DNA fragmentation of the infected cells was also reduced. Under this experimental condition, it was found that the treatment markedly inhibited bacterial growth inside macrophages. The infected cells appeared to undergo cell death of the necrosis type in the presence of z-VAD-fmk. We further found that z-VAD-fmk treatment resulted in the generation of intracellular reactive oxygen species (ROS) in the infected cells. By addition of a scavenger of ROS, the host cell necrosis was inhibited and the intracellular growth of H37Rv was significantly restored. Among inhibitors specific for each caspase, only the caspase-9-specific inhibitor enhanced the generation of ROS and induced necrosis of the infected cells. Furthermore, we found that severe necrosis was induced by infection with H37Rv but not H37Ra in the presence of z-VAD-fmk. Caspase-9 activation was also detected in H37Rv-infected cells, but H37Ra never induced such caspase-9 activation. These results indicated that caspase-9, which was activated by infection with virulent M. tuberculosis, contributed to the inhibition of necrosis of the infected host cells, presumably through suppression of intracellular ROS generation.
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PMID:Involvement of caspase-9 in the inhibition of necrosis of RAW 264 cells infected with Mycobacterium tuberculosis. 1740 66

Programmed cell death (PCD) plays critical roles during development and in disease states. One form of programmed cell death utilizes autophagy--a cellular mechanism of degrading bulk cytosolic components--to destroy cells. Previously, the broad-spectrum caspase inhibitor z-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD) was shown to induce autophagic cell death. The mechanism of Zvad-induced cell death was proposed to require caspase-8 inhibition. In our report, we extend these findings to show that--as is the case for apoptosis--induction of autophagic cell death in response to zVAD results in phosphatidylserine exposure prior to loss of membrane integrity. Additionally, we show that caspase-8 inhibition is insufficient to cause autophagic cell death. Rather, the activity of a calpain-like protease must also be blocked. These results reveal the existence of an autophagic PCD-inhibiting calpain-like cysteine protease.
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PMID:A calpain-like protease inhibits autophagic cell death. 1740 99

Primary effusion lymphoma (PEL) is an incurable, aggressive B-cell malignancy that develops rapid resistance to conventional chemotherapy. In efforts to identify novel approaches to block proliferation of PEL cells, we found that sanguinarine, a natural compound isolated from the root plant Sanguinaria canadendid, inhibits cell proliferation and induces apoptosis in a dose-dependent manner in several PEL cell lines. Our data show that sanguinarine treatment of PEL cells results in up-regulation of death receptor 5 (DR5) expression via generation of reactive oxygen species (ROS) and causes activation of caspase-8 and truncation of Bid (tBid). Subsequently, tBid translocates to the mitochondria causing conformational changes in Bax, leading to loss of mitochondrial membrane potential and release of cytochrome c to the cytosol. Sanguinarine-induced release of cytochrome c results in activation of caspase-9 and caspase-3 and poly(ADP-ribose) polymerase (PARP) cleavage, leading to induction of caspase-dependent apoptosis. In addition, we show that pretreatment of PEL cells with carbobenzoxy-Val-Ala-Asp-fluoromethylketone, a universal inhibitor of caspases, abrogates caspase and PARP activation and prevents cell death induced by sanguinarine. Moreover, treatment of PEL cells with sanguinarine down-regulates expression of inhibitor of apoptosis proteins (IAP). Finally, N-acetylcysteine, an inhibitor of ROS, inhibits sanguinarine-induced generation of ROS, up-regulation of DR5, Bax conformational changes, activation of caspase-3, and down-regulation of IAPs. Taken together, our findings suggest that sanguinarine is a potent inducer of apoptosis of PEL cells via up-regulation of DR5 and raise the possibility that this agent may be of value in the development of novel therapeutic approaches for the treatment of PEL.
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PMID:Sanguinarine-dependent induction of apoptosis in primary effusion lymphoma cells. 1744 Jan 3

Apoptosis is a highly controlled process, whose triggering is associated with the activation of caspases. Apoptosis can be induced via a subgroup of the tumor necrosis factor (TNF) receptor superfamily, which recruit and activate pro-caspase-8 and -10. Regulation of apoptosis is achieved by several inhibitors, including c-FLICE-inhibitory protein, which prevents apoptosis by inhibiting the pro-apoptotic activation of upstream caspases. Here we show that the human intracellular serine protease inhibitor (serpin), protease inhibitor 9 (PI9), inhibits TNF-, TNF-related apoptosis-inducing ligand- and Fas ligand-mediated apoptosis in certain TNF-sensitive cell lines. The reactive center P1 residue of PI9 was required for this inhibition since PI9 harboring a Glu --> Ala mutation in its reactive center failed to impair death receptor-induced cell death. This suggests a classical serpin-protease interaction. Indeed, PI9 inhibited apoptotic death by directly interacting with the intermediate active forms of caspase-8 and -10. This indicates that PI9 can regulate pro-apoptotic apical caspases.
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PMID:Ectopic expression of the serine protease inhibitor PI9 modulates death receptor-mediated apoptosis. 1747 12

Caspase-8, the proximal enzyme in the death-induction pathway of the TNF/nerve growth factor receptor family, is activated upon juxtaposition of its molecules within the receptor complexes and is then self-processed. Caspase-8 also contributes to the regulation of cell survival and growth, but little is known about the similarities or the differences between the mechanisms of these nonapoptotic functions and of the enzyme's apoptotic activity. In this study, we report that in bacterial artificial chromosome-transgenic mice, in which the aspartate residue upstream of the initial self-processing site in caspase-8 (D387) was replaced by alanine, induction of cell death by Fas is compromised. However, in contrast to caspase-8-deficient mice, which die in utero at mid-gestation, the mice mutated at D387 were born alive and seemed to develop normally. Moreover, mice with the D387A mutation showed normal in vitro growth responses of T lymphocytes to stimulation of their Ag receptor as well as of B lymphocytes to stimulation by LPS, normal differentiation of bone marrow macrophage precursors in response to M-CSF, and normal generation of myeloid colonies by the bone marrow hematopoietic progenitors, all of which are compromised in cells deficient in caspase-8. These finding indicated that self-processing of activated caspase-8 is differentially involved in the different functions of this enzyme: it is needed for the induction of cell death through the extrinsic cell death pathway but not for nonapoptotic functions of caspase-8.
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PMID:Mutation of a self-processing site in caspase-8 compromises its apoptotic but not its nonapoptotic functions in bacterial artificial chromosome-transgenic mice. 1868 43

B7-H1 is a newly identified member of the B7 family with important regulatory functions in cell-mediated immune responses, and it is expressed in human immune cells and several tumors. We first observed that expression of surface B7-H1 on B cells was increased during the immortalization process by EBV, which is strongly related to both inflammation and tumorigenesis. Cross-linking of B7-H1 on EBV-transformed B cells using anti-B7-H1 Ab (clone 130002) induced reactive oxygen species (ROS) generation, mitochondrial disruption, release of apoptotic proteins from mitochondria, and subsequent apoptosis. Inhibition of caspases and ROS generation recovered B7-H1-mediated apoptosis and proteolytic activities of caspase-8, -9, and -3. We observed that B7-H1 stimulation induced both transcription and translation of fasL. ZB4, an antagonistic anti-fas Ab, and NOK-1, an antagonistic anti-fasL Ab, effectively blocked apoptosis without exerting any influence on ROS generation. N-acetylcysteine (NAC) completely blocked the induction of fasL mRNA and protein. We found that B7-H1 stimulation activated the phosphorylation of JNK and c-jun and down-regulated ERK1/2 and p-Akt. NAC blocked the activation of JNK and down-regulation of ERK, but both z-VAD-fmk (N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone) and ZB4 did not inhibit JNK activation of B7-H1 stimulation. SP600125 blocked fasL induction and apoptosis but did not affect ROS generation after B7-H1 stimulation. Taken together, we concluded that B7-H1-mediated apoptosis on EBV-transformed B cells may be involved in the induction of fasL, which is evoked by ROS generation and JNK activation after cross-linking of B7-H1. These results provide a new concept for understanding reverse signaling through B7-H1 and another mechanism of tumor immunotherapy using anti-B7-H1.
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PMID:Cross-linking of B7-H1 on EBV-transformed B cells induces apoptosis through reactive oxygen species production, JNK signaling activation, and fasL expression. 1894 Dec 6


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