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)

Cocaine induces apoptosis in coronary artery endothelial cells. Yet the cellular and molecular mechanisms are not clear. Given that cocaine has profound toxic effects on the mitochondria, the present study examined the role of mitochondrial cytochrome c in cocaine-mediated apoptosis. Using cultured bovine coronary artery endothelial cells, we found that cocaine-induced apoptosis was dose dependently inhibited by cyclosporin A with IC(50) of 0.2 microM. The maximum of 65% inhibition was obtained with 3 microM cyclosporin A. Cocaine induced a translocation of cytochrome c from the mitochondria to the cytosol with a 1.8-fold increase in cytosolic cytochrome c levels, and a corresponding decrease in mitochondrial cytochrome c. In accordance with its inhibition of cocaine-induced apoptosis, cyclosporin A blocked cocaine-induced cytochrome c translocation. Correspondingly, cocaine-induced activation of caspase-9 preceded that of caspase-3. Caspase-8 was not activated. Cocaine also produced a dose-dependent decrease in Bcl-2 protein levels, but had no effect on Bax protein levels. The cocaine-induced decrease in the Bcl-2 protein was not affected by cyclosporin A but was partially blocked by caspase-3 inhibitor Ac-DEVD-CHO. Collectively, these data indicate that the release of cytochrome c from the mitochondria and the subsequent activation of caspase-9 and caspase-3 play a key role in cocaine-induced apoptosis in these cells. Furthermore, the down-regulation of the Bcl-2 protein may play an important role in cocaine-induced release of cytochrome c.
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PMID:Role of mitochondrial cytochrome c in cocaine-induced apoptosis in coronary artery endothelial cells. 1108 22

The essential upstream steps in granzyme B-mediated apoptosis remain undefined. Herein, we show that granzyme B triggers the mitochondrial apoptotic pathway through direct cleavage of Bid; however, cleavage of procaspases was stalled when mitochondrial disruption was blocked by Bcl-2. The sensitivity of granzyme B-resistant Bcl-2-overexpressing FDC-P1 cells was restored by coexpression of wild-type Bid, or Bid with a mutation of its caspase-8 cleavage site, and both types of Bid were cleaved. However, Bid with a mutated granzyme B cleavage site remained intact and did not restore apoptosis. Bid with a mutation preventing its interaction with Bcl-2 was cleaved but also failed to restore apoptosis. Rapid Bid cleavage by granzyme B (<2 min) was not delayed by Bcl-2 overexpression. These results clearly placed Bid cleavage upstream of mitochondrial Bcl-2. In granzyme B-treated Jurkat cells, endogenous Bid cleavage and loss of mitochondrial membrane depolarization occurred despite caspase inactivation with z-Val-Ala-Asp-fluoromethylketone or Asp-Glu-Val-Asp-fluoromethylketone. Initial partial processing of procaspase-3 and -8 was observed irrespective of Bcl-2 overexpression; however, later processing was completely abolished by Bcl-2. Overall, our results indicate that mitochondrial perturbation by Bid is necessary to achieve a lethal threshold of caspase activity and cell death due to granzyme B.
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PMID:Initiation of apoptosis by granzyme B requires direct cleavage of bid, but not direct granzyme B-mediated caspase activation. 1108 43

In present studies, treatment with tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL, also known as Apo-2 ligand [Apo-2L]) is shown to induce apoptosis of the human acute leukemia HL-60, U937, and Jurkat cells in a dose-dependent manner, with the maximum effect seen following treatment of Jurkat cells with 0.25 microg/mL of Apo-2L (95.0% +/- 3.5% of apoptotic cells). Susceptibility of these acute leukemia cell types, which are known to lack p53(wt) function, did not appear to correlate with the levels of the apoptosis-signaling death receptors (DRs) of Apo-2L, ie, DR4 and DR5; decoy receptors (DcR1 and 2); FLAME-1 (cFLIP); or proteins in the inhibitors of apoptosis proteins (IAP) family. Apo-2L-induced apoptosis was associated with the processing of caspase-8, Bid, and the cytosolic accumulation of cytochrome c as well as the processing of caspase-9 and caspase-3. Apo-2L-induced apoptosis was significantly inhibited in HL-60 cells that overexpressed Bcl-2 or Bcl-x(L). Cotreatment with either a caspase-8 or a caspase-9 inhibitor suppressed Apo-2L-induced apoptosis. Treatment of human leukemic cells with etoposide, Ara-C, or doxorubicin increased DR5 but not DR4, Fas, DcR1, DcR2, Fas ligand, or Apo-2L levels. Importantly, sequential treatment of HL-60 cells with etoposide, Ara-C, or doxorubicin followed by Apo-2L induced significantly more apoptosis than treatment with Apo-2L, etoposide, doxorubicin, or Ara-C alone, or cotreatment with Apo-2L and the antileukemic drugs, or treatment with the reverse sequence of Apo-2L followed by one of the antileukemic drugs. These findings indicate that treatment with etoposide, Ara-C, or doxorubicin up-regulates DR5 levels in a p53-independent manner and sensitizes human acute leukemia cells to Apo-2L-induced apoptosis. (Blood. 2000;96:3900-3906)
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PMID:Antileukemic drugs increase death receptor 5 levels and enhance Apo-2L-induced apoptosis of human acute leukemia cells. 1109 76

In this study we sought to clarify the role of the proapoptotic potential of mitochondria in the death pathway emanating from the TRAIL (APO-2L) and CD95 receptors in pancreatic carcinoma cells. We focused on the role of the Bcl-2 family member Bcl-XL, using three pancreatic carcinoma cell lines as a model system, two of which have high (Panc-1, PancTuI) and one has low (Colo357) Bcl-XL expression. In these cell lines, the expression of Bcl-XL correlated with sensitivity to apoptosis induced by TRAIL or anti-CD95. Flow cytometric analysis revealed cell surface expression of TRAIL-R1 and TRAIL-R2 on PancTuI and Colo357, and TRAIL-R2 on Panc-1 cells. In Colo357 cells retrovirally transduced with Bcl-XL, caspase-8 activation in response to treatment with TRAIL or anti-CD95 antibody was not different from parental cells and EGFP-transfected controls, however, apoptosis was completely suppressed as measured by the mitochondrial transmembrane potential deltapsim, caspase-3 activity (PARP cleavage) and DNA-fragmentation. Inhibition of Bcl-XL function by overexpression of Bax or administration of antisense oligonucleotides against Bcl-XL mRNA resulted in sensitization of Panc-1 cells to TRAIL and PancTuI cells to anti-CD95 antibody-induced cell death. The results show that Bcl-XL can protect pancreatic cancer cells from CD95- and TRAIL-mediated apoptosis. Thus, in these epithelial tumour cells the mitochondrially mediated 'type II' pathway of apoptosis induction is not only operative regarding the CD95 system but also regarding the TRAIL system.
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PMID:Bcl-XL protects pancreatic adenocarcinoma cells against CD95- and TRAIL-receptor-mediated apoptosis. 1111 25

Tumor necrosis (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family of cytokines that promotes apoptosis. TRAIL induces apoptosis in a wide variety of tumor cells but not in normal cells. Oncogene Bcl-2 can protect cells from apoptosis induced by various stress stimuli. However, it is not clear whether Bcl-2 can regulate TRAIL-induced apoptosis. The objective of this study was to investigate whether Bcl-2 can regulate apoptosis induced by TRAIL. TRAIL initiates the activation of caspases, the loss of mitochondrial transmembrane potential (Delta psi(m)), and the redistribution of mitochondrial cytochrome c. TRAIL has no effect on Delta psi(m) and apoptosis in Jurkat cells deficient in either FADD or caspase-8, suggesting both FADD and caspase-8 are required for TRAIL signaling. Overexpression of Bcl-2 delays, but does not inhibit, TRAIL-induced Delta psi(m), cytochrome c release from mitochondria and apoptosis, whereas etoposide-induced apoptosis is blocked by Bcl-2. XIAP, cowpox virus CrmA and baculovirus p35 inhibits TRAIL-induced apoptosis. These data suggest that TRAIL can be used to kill Bcl-2 positive cells that can not be killed by other class of chemotherapeutic drugs.
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PMID:Failure of Bcl-2 to block mitochondrial dysfunction during TRAIL-induced apoptosis. Tumor necrosis-related apoptosis-inducing ligand. 1111 58

BID is a BH3 domain-only member of the Bcl-2 family that acts as an apoptotic agonist in programmed cell death. After cleavage by caspase-8, the N-terminal of BID (N-BID) stays in the cytosol while the C-terminal of BID (C-BID) translocates to mitochondria, leading to cytochrome c release in vivo and in vitro. We have previously reported that BID or truncated BID (tBID) can induce the release of entrapped trypsin and cytochrome c from large unilamellar vesicles (LUVs). Further studies have been performed and are presented here; the results demonstrate that C-BID, like BID and tBID, induces vesicle leakage, whereas N-BID or the BID mutants BID (D59A) and BID (G94E) fail to have any significant effects. The affinity of the above-mentioned proteins for soybean phospholipid LUVs (SLUVs) decreased in an order similar to their leakage-inducing capability: tBID > BID > BID (D59A), while N-BID and BID (G94E) were unable to bind to the vesicles at all. BID-induced leakage was dependent on the lipid composition of vesicles. Acidic phospholipid (e.g. phosphatidic acid or phosphatidylglycerol) was necessary for BID-induced leakage while the presence of phosphatidylethanolamine or cholesterol reduced the leakage. It was also found C-BID is better able to penetrate the soybean phospholipid monolayer than BID or tBID. A further finding was that tBID, but not full-length BID, could stimulate the aggregation of SLUVs. Finally, Bcl-x(L), an apoptotic antagonist in programmed cell death, can prevent the aggregation of LUVs induced by tBID, but not the release of entrapped trypsin. It is postulated that two separate domains of tBID are responsible for inducing leakage and aggregation of phospholipid vesicles.
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PMID:Leakage and aggregation of phospholipid vesicles induced by the BH3-only Bcl-2 family member, BID. 1112 Nov 1

Fas and its ligand, FasL, are a receptor-ligand pair identified as promoting cell death in several tissues. Vascular smooth muscle cells (VSMCs) are resistant to FasL or anti-Fas antibody (Ab) signal, and a number of in vitro studies show that VSMC death can only be induced by anti-Fas Ab or FasL in the presence of protein inhibitor or additional inflammatory mediators. It remains to be clarified whether known, constitutively expressed cytoprotective molecules are reduced by protein inhibitor, thereby accounting for sensitization to cell death by Fas/FasL signaling. We found that Fas mRNA and protein exist in several primary VSMCs, as previously reported. We also demonstrated (1) that critical death-signaling molecules, such as FADD, caspase-1/ICE, and caspase-3/YAMA, are present in these VSMCs, (2) that human VSMCs contain high concentrations of c-FLIP (3) and that following treatment with the protein inhibitor, CHX, cell extracts showed a decrease in c-FLIP protein that was dose- and time-dependent on the degree of apoptosis and inversely correlated with both caspase-8 and -3 activity. In contrast, there was neither a change nor an even modest upregulation of Bcl-2 family, even after 12 h of treatment with CHX. Taken together, these results may provide a novel insight into atherogenesis and suggest that c-FLIP may contribute to an apoptosis-resistant state of VSMC, and that a downregulation of c-FLIP may render VSMCs susceptible to apoptosis.
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PMID:Transition of apoptotic resistant vascular smooth muscle cells to troptotic sensitive state is correlated with downregulation of c-FLIP. 1114 6

Chemotherapy-induced apoptosis is generally thought to be dependent on a pathway headed by caspase-9. This model is primarily based on studies performed in leukemia cells; however, little is known about caspase cascades in relatively resistant solid tumor cells, including non-small cell lung cancer (NSCLC) cells. Using the NSCLC cell line NCI-H460 (H460), here, we studied the effect of stable expression of various caspase inhibitors on apoptosis induced by the anticancer drugs cisplatin, topotecan, and gemcitabine. Interestingly, overexpression of caspase-9S and X-linked inhibitor of apoptosis (XIAP), both able to inhibit caspase-9 activity, failed to block apoptosis. In contrast, stable expression of caspase-8 inhibitors, such as cytokine response modifier A (CrmA) and dominant-negative caspase-8, almost completely abrogated apoptosis and also enhanced clonogenic survival. Caspase-8 activation in H460 cells was not mediated by death receptors, inasmuch as overexpression of dominant-negative Fas-associated death domain (FADD-DN) did not prevent procaspase-8 cleavage and subsequent apoptosis. However, stable expression of Bcl-2 and Bcl-xL did suppress these apoptotic events, including the release of cytochrome c from mitochondria, which was observed in drug-treated H460 cells. In the NSCLC cell line H460, we, thus, provide evidence for the existence of a novel drug-inducible apoptotic pathway in which activation of caspase-8, and not of caspase-9, forms the apical and mitochondria-dependent step that subsequently activates the downstream caspases.
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PMID:Chemotherapy triggers apoptosis in a caspase-8-dependent and mitochondria-controlled manner in the non-small cell lung cancer cell line NCI-H460. 1115 22

Dimethylammonium salt of 2,4-dichlorophenoxyacetic acid (DMA-2,4-D) is a widely used herbicide that is considered moderately toxic. In the present study we found that DMA-2,4-D is able to cause apoptosis in peripheral blood lymphocytes of healthy individuals and Jurkat T cells. Apoptosis induced by DMA-2,4-D was dose and time dependent, independent of Fas, TNF receptor 1 or the aromatic hydrocarbon receptor, and involved disruption of the mitochondrial transmembrane potential and activation of caspase-9. ZVAD-FMK, a broad-spectrum inhibitor of caspases, blocked DMA-2,4-D-induced apoptosis completely. While an inhibitor of caspase-9, as well as caspase-9 and caspase-3 inhibitors in combination, strongly blocked DMA-2,4-D-induced apoptosis, an inhibitor of caspase-3 had a moderate inhibitory effect. Unlike Fas-mediated apoptosis, the initiator caspase, caspase-8, was not involved in DMA-2,4-D-induced apoptosis. Transfection of Jurkat cells with Bcl-2 prevented DMA-2,4-D-induced disruption of the mitochondrial transmembrane potential and led to a complete blockage of apoptosis. Our data indicate that DMA-2,4-D kills human lymphocytes by initiating apoptosis via a direct effect on mitochondria. The activation of caspases occurs downstream of mitochondrial damage, and the dysfunction of mitochondria appears to be sufficient for triggering all downstream events leading to apoptosis.
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PMID:Induction of apoptosis in human lymphocytes by the herbicide 2,4-dichlorophenoxyacetic acid. 1116 16

It was investigated whether proteasome activity was implicated in susceptibility of human vascular smooth muscle cells (VSMCs) to Fas-mediated death. Human fetal aorta smooth muscle cells were treated with agonistic anti-Fas antibody (CH11) and proteasome inhibitors (MG115 or MG132) and then cell death was determined by morphology, viability, and DNA fragmentation. The present study reports that: (a) crosslinking of Fas receptor with anti-Fas antibody in the presence of proteasome inhibitor-induced death and DNA degradation in human VSMCs that were blocked by caspases inhibitor z-DEVD.fmk; (b) cotreatment with anti-Fas antibody and proteasome inhibitor activated caspase-3; (c) proteasome inhibitors did not influence expression of procaspase-8, procaspase-3, c-FLIP, and Bcl-2; and (d) proteasome inhibitors up-regulated Fas and FADD. The data indicate that proteasome activity is important in survival of VSMCs and provide the first evidence that proteasome is involved in Fas signal transduction. The present study proposes novel mechanism(s) by which VSMCs become susceptible to FasL.
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PMID:Proteasome inhibitors sensitize human vascular smooth muscle cells to Fas (CD95)-mediated death. 1118 Oct 46


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