Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of reactive oxygen species (ROS) on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in solid cancers have yet to be clearly defined. In this study, we found that the classic uncoupler of oxidative phosphorylation, carbonyl cyanide m-chlorophenylhydrazone (CCCP), induced a reduction in DeltaPsim and generation of ROS. This uncoupling effect enhanced TRAIL-induced apoptosis in TRAIL-resistant human colon carcinoma cell lines (RKO, HT29, and HCT8). Sensitization was inhibited by benzyloxycarbonyl-valine-alanine-aspartate fluoromethylketone, indicating the requirement for caspase activation. CCCP per se did not induce apoptosis or release of proapoptotic factors from mitochondria. Generation of ROS by CCCP was responsible for TRAIL-induced Bax and caspase activation because scavenging ROS completely abrogated apical caspase-8 activation and further downstream events leading to cell death. Overexpression of Bcl-2 did not prevent the initial loss of DeltaPsim and ROS generation following CCCP treatment, but did prevent cell death following TRAIL and CCCP exposure. Uncoupling of mitochondria also facilitated TRAIL-induced release of proapoptotic factors. X-linked inhibitor of apoptosis overexpression abrogated TRAIL-induced apoptosis in the presence of CCCP and decreased initiator procaspase-8 processing, indicating that additional processing of caspase-8 required initiation of a mitochondrial amplification loop via effector caspases. Of interest, depletion of caspase-9 in RKO cells did not protect cells from TRAIL/CCCP-induced apoptosis, indicating that apoptosis occurred via a caspase-9-independent pathway. Data suggest that in the presence of mitochondrial-derived ROS, TRAIL induced mitochondrial release of Smac/DIABLO and inactivation of X-linked inhibitor of apoptosis through caspase-9-independent activation of caspase 3.
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PMID:Reactive oxygen species regulate caspase activation in tumor necrosis factor-related apoptosis-inducing ligand-resistant human colon carcinoma cell lines. 1610 97

Polyamines are involved in the regulation of cellular growth and survival by interacting with processes like translation, transcription or ion transport. The aim of our study was to analyze whether polyamines induce apoptosis in hematopoetic cells and to investigate the molecular mechanisms involved. We found an induction of apoptosis by spermine in primary human cells and malignant tumor cell lines. Spermine-treatment resulted in an intracellular increase of reactive oxygen species. Apoptosis was mediated by a collapse of mitochondrial membrane potential, a decrease in Bcl-2 expression and a release of apoptosis mediating molecules from mitochondrial intermembrane space (cytochrome C, Smac/DIABLO). Spermine-mediated apoptosis was caspase-dependent. To test whether spermine mediates apoptosis through metabolites we analyzed the effects of several molecules that interfere with its catabolism. Aminoguanidine, an inhibitor of serum amine oxidase, aldehyde-dehydrogenase, which degrades aldehydes to less reactive molecules or N-acetyl-cysteine, a glutathion precursor, significantly inhibited spermine-mediated apoptosis. From these data we conclude that spermine-derived aldehydes and intracellular accumulation of reactive oxygen species result in mitochondria mediated apoptosis.
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PMID:Induction of apoptosis by spermine-metabolites in primary human blood cells and various tumor cell lines. 1615 48

Mitochondria play a crucial role in regulating cell death, which is mediated by outer membrane permeabilization in response to death triggers such as DNA damage and growth factor deprivation. Mitochondrial membrane permeabilization induces the release of cytochrome c, Smac/DIABLO, and AIF, which are regulated by proapoptotic and antiapoptotic proteins such as Bax/Bak and Bcl-2/xL in caspase-dependent and caspase-independent apoptosis pathways. Mitochondrial dysfunction is mediated in two ways. The first is by increased calcium in mitochondria derived from endoplasmic reticulum (ER); this calcium increase is regulated by Bcl-2 and Bax through the ER-mitochondria connection and the unfolded protein response in the ER. The second is by the lysosomal enzyme cathepsin, which activates Bid through lysosome-mitochondria cross-signaling. The genomic responses in intracellular organelles after DNA damage are controlled and amplified in the cross-signaling via mitochondria; such signals induce apoptosis, autophagy, and other cell death pathways. This review discusses the recent advancements in understanding the molecular mechanism of mitochondria-mediated cell death.
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PMID:Role of mitochondria as the gardens of cell death. 1617 94

A major concern in clinical treatment of cancers is resistance of tumors such as hepatocellular carcinoma (HCC) and osteosarcoma to current chemotherapy protocols. Here, we reported that overexpression of second mitochondria-derived activator of caspase (Smac) sensitized osteosarcoma cells and HCC cells in vitro to chemotherapeutic drugs-induced apoptosis. Constitutive expression of Smac resulted in enhanced Bax accumulation on mitochondria upon etoposide stimulation and inhibited Bcl-2-induced antiapoptosis activity. Thus, Smac would sensitize tumor cells to chemotherapeutic drugs in part through promoting Bax translocation to mitochondria and bypassing Bcl-2 block. Moreover, we demonstrated that blockade of Smac expression by antisense smac did not impair etoposide-induced apoptosis; however, p53-induced apoptosis was impaired in smac deficient Saos-2 cell. This suggested Smac might be required in p53-induced apoptosis. Most importantly, complete eradication of HepG2 xenografts in vivo was achieved upon combined therapy with Ad-Smac and 5-Fu. Thus, overexpression of Smac in tumor cells might be a potent strategy for cancer treatment by sensitization of tumor cells to chemotherapeutic drugs.
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PMID:Transfection of Smac sensitizes tumor cells to etoposide-induced apoptosis and eradicates established human hepatoma in vivo. 1621 Oct 87

Sulindac is a nonsteroidal anti-inflammatory drug (NSAID) that induces apoptosis in cultured colon cancer cells and in intestinal epithelia in association with its chemopreventive efficacy. Resistance to sulindac is well documented in patients with familial adenomatous polyposis; however, the molecular mechanisms underlying such resistance remain unknown. We determined the effect of ectopic Bcl-2 expression upon sulindac-induced apoptotic signaling in SW480 human colon cancer cells. Sulindac sulfide activated both the caspase-8-dependent and mitochondrial apoptotic pathways. Ectopic Bcl-2 attenuated cytochrome c release and apoptosis induction compared with SW480/neo cells. Coadministration of sulindac sulfide and the small-molecule Bcl-2 inhibitor HA14-1 increased apoptosis induction and enhanced caspase-8 and caspase-9 cleavage, Bax redistribution, and cytochrome c and second mitochondria-derived activator of caspase release. Given that sulindac sulfide activated caspase-8 and increased membrane death receptor (DR4 and DR5) protein levels, we evaluated its combination with the endogenous death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Coadministration of sulindac sulfide and TRAIL cooperatively enhanced apoptotic signaling as effectively as did HA14-1. Together, these data indicate that HA14-1 or TRAIL can enhance sulindac sulfide-induced apoptosis and represent novel strategies for circumventing Bcl-2-mediated apoptosis resistance in human colon cancer cells.
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PMID:Sulindac sulfide-induced apoptosis is enhanced by a small-molecule Bcl-2 inhibitor and by TRAIL in human colon cancer cells overexpressing Bcl-2. 1622 96

In the present study, we aimed to elucidate the mechanism responsible for the interactive effects of histone deacetylase (HDAC) inhibitors [suberoylanilide hydroxamic acid (SAHA), MS-275, m-carboxycinnamic acid bishydroxamide (CBHA), and trichostatin-A (TSA)] and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) on apoptosis in leukemia cells. HDAC inhibitors enhance the apoptosis-inducing potential of TRAIL in leukemia cells (HL60, Jurkat, K562, and U937) through multiple mechanisms; up-regulation of DR4, DR5, Bak, Bax, Bim, Noxa and PUMA, down-regulation of IAPs, Mcl-1, Bcl-2, Bcl-XL and cFLIP, release of mitochondrial proteins (cytochrome c, Smac/DIABLO and Omi/Htr2) to the cytosol, induction of p21WAF1/CIP1 and p27KIP1, activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase (PARP). The sequential treatment of cells with HDAC inhibitors followed by TRAIL was more effective in inducing apoptosis than the concurrent treatment or single agent alone. The up-regulation of death receptors and inhibition of cFLIP by HDAC inhibitors will increase the ability of TRAIL to induce apoptosis, due to enhance activation of caspase-8, cleavage of Bid, and release of mitochondrial proteins to the cytosol, and subsequent activation of caspase-9 and caspase-3. Thus, the combination of HDAC inhibitors and TRAIL can be used as a new therapeutic approach for the treatment of leukemia.
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PMID:Interactive effects of histone deacetylase inhibitors and TRAIL on apoptosis in human leukemia cells: involvement of both death receptor and mitochondrial pathways. 1627 96

Interactions between the novel histone deacetylase inhibitor LAQ824 and the cyclin-dependent kinase inhibitor roscovitine were examined in human leukemia cells. Pretreatment (24 hours) with a subtoxic concentration of LAQ824 (30 nmol/L) followed by a minimally toxic concentration of roscovitine (10 micromol/L; 24 hours) resulted in greater than additive effects on apoptosis in U937, Jurkat, and HL-60 human leukemia cells and blasts from three patients with acute myelogenous leukemia. These events were associated with enhanced conformational changes in Bax; mitochondrial release of cytochrome c, Smac/DIABLO, and apoptosis-inducing factor; and a marked increase in caspase activation. LAQ824/roscovitine-treated cells displayed caspase-dependent down-regulation of p21(CIP1) and Mcl-1 and a pronounced caspase-independent reduction in X-linked inhibitor of apoptosis (XIAP) expression. The lethality of this regimen was significantly attenuated by ectopic expression of XIAP, a nuclear localization signal-defective p21(CIP1) mutant, Mcl-1, and Bcl-2. Combined exposure to LAQ824 and roscovitine resulted in a significant reduction in XIAP mRNA levels and diminished phosphorylation of the carboxyl-terminal domain of RNA polymerase II. Notably, roscovitine blocked LAQ824-mediated differentiation. Finally, LAQ824 and roscovitine individually and in combination triggered an increase in generation of reactive oxygen species; moreover, coadministration of the free radical scavenger N-acetylcysteine prevented LAQ824/roscovitine-mediated mitochondrial injury and apoptosis. Collectively, these findings suggest that combined treatment of human leukemia cells with LAQ824 and roscovitine disrupts maturation and synergistically induces apoptosis, lending further support for an antileukemic strategy combining novel histone deacetylase and cyclin-dependent kinase inhibitors.
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PMID:Potentiation of the lethality of the histone deacetylase inhibitor LAQ824 by the cyclin-dependent kinase inhibitor roscovitine in human leukemia cells. 1627 99

Panton-Valentine leukocidin (PVL) is a pore-forming toxin secreted by Staphylococcus aureus that has recently been associated with necrotizing pneumonia. In the present study, we report that in vitro, PVL induces polymorphonuclear cell death by necrosis or by apoptosis, depending on the PVL concentration. PVL-induced apoptosis was associated with a rapid disruption of mitochondrial homeostasis and activation of caspase-9 and caspase-3, suggesting that PVL-induced apoptosis is preferentially mediated by the mitochondrial pathway. Polymorphonuclear cell exposure to PVL leads to mitochondrial localization of the toxin, whereas Bax, 1 of the 2 essential proapoptotic members of the Bcl-2 family, was still localized in the cytosol. Addition of PVL to isolated mitochondria induced the release of the apoptogenic proteins cytochrome c and Smac/DIABLO. Therefore, we suggest that PVL, which belongs to the pore-forming toxin family, could act at the mitochondrion level by creating pores in the mitochondrial outer membrane. Furthermore, LukS-PV, 1 of the 2 components of PVL, was detected in lung sections of patients with necrotizing pneumonia together with DNA fragmentation, suggesting that PVL induces apoptosis in vivo and thereby is directly involved in the pathophysiology of necrotizing pneumonia.
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PMID:Staphylococcus aureus Panton-Valentine leukocidin directly targets mitochondria and induces Bax-independent apoptosis of human neutrophils. 1627 17

During the postnatal development of cerebellum, lack of excitatory innervation from the mossy fibers results in cerebellar granule cell (CGC) apoptosis during the migration of the cells toward the internal granule cell layer. Accordingly, CGCs die by apoptosis when cultured in physiological KCl concentrations (5 mm; K5), and they survive in the presence of depolarizing conditions such as high KCl concentration (25 mm; K25) or N-methyl-D-aspartate (NMDA). We have recently shown that NMDA is able to exert a long lasting neuroprotective effect when added to immature (2 days in vitro) CGC cultures by inhibition of caspase-3 activity. Here we show that NMDA- and K25-mediated neuroprotection is associated with an increase in the levels of Bcl-2, an inhibition of K5-mediated increase in Bax, and the inhibition of the release of apoptogenic factors from mitochondria such as Smac/DIABLO and cytochrome c. Moreover, we have shown that similar effects are observed when c-Jun N-terminal kinases (JNKs) are inhibited and that treatment of CGC cultures with NMDA blocks K5-mediated JNK activation. These results allow us to postulate that the inhibition of JNK-mediated release of apoptogenic factors from mitochondria is involved in the NMDA protection from K5-mediated apoptosis of CGCs.
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PMID:N-methyl-D-aspartate blocks activation of JNK and mitochondrial apoptotic pathway induced by potassium deprivation in cerebellar granule cells. 1638 Mar 82

Mitogen-activated protein kinase (MAPK) is activated in the majority of melanomas, and its activity is essential for cell survival. In this report, we examined the effects of a novel raf inhibitor BAY 43-9006 on melanoma cell viability and intracellular signaling and found that it induces apoptosis through a caspase-independent mechanism. At concentrations that suppress extracellular signal-regulated kinase (ERK) phosphorylation, BAY 43-9006 dephosphorylates Bad on Ser(75) and Ser(99), activates Bak and Bax, and reduces the mitochondrial transmembrane potential. BAY 43-9006 (sorafenib) down-modulates the levels of Bcl-2 and Bcl-X(L) in a MAPK-independent manner in A2058 and SKMEL5 melanoma cells but not in the more resistant A375 cells. Of the three lines tested, only A375 cells were rescued from BAY 43-9006-induced apoptosis by knocking down Bad. BAY 43-9006 induced poly(ADP-ribose) polymerase cleavage and the mitochondrial release of cytochrome c and SMAC. However, the pan-caspase inhibitor Z-VAD-fmk had only a modest protective effect against the drug, suggesting that BAY 43-9006-induced apoptosis is largely caspase independent. BAY 43-9006 but not the MAP/ERK kinase inhibitors PD98059 or U0126 induced the nuclear translocation of apoptosis-inducing factor (AIF) in A2058 and SKMEL5 cells, and the introduction of a small interfering RNA (siRNA) for AIF partially protected these cells from BAY 43-9006-induced apoptosis. The AIF siRNA had little effect in A375 cells, in which drug-induced AIF release was negligible. These data indicate that in sensitive cell lines, BAY 43-9006-induced apoptosis is independent of Bad dephosphorylation and caspase activation and largely mediated through the nuclear translocation of AIF.
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PMID:The Raf inhibitor BAY 43-9006 (Sorafenib) induces caspase-independent apoptosis in melanoma cells. 3161 13


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