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)

Nonsteroidal anti-inflammatory drugs (NSAID) reduce the risk for cancer, due to their antiproliferative and apoptosis-inducing effects. A critical pathway for apoptosis involves the release of cytochrome c from mitochondria, which then interacts with Apaf-1 to activate caspase proteases that orchestrate cell death. In this study we found that treatment of a human cancer cell line with aspirin induced caspase activation and the apoptotic cell morphology, which was blocked by the caspase inhibitor zVAD-fmk. Further analysis of the mechanism underlying this apoptotic event showed that aspirin induces translocation of Bax to the mitochondria and mitochondrial release of cytochrome into the cytosol. The release of cytochrome c from mitochondria was inhibited by overexpression of the antiapoptotic protein Bcl-2 and cells that lack Apaf-1 were resistant to aspirin-induced apoptosis. These data provide evidence that the release of cytochrome c is an important part of the apoptotic mechanism of aspirin.
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PMID:Aspirin induces apoptosis through release of cytochrome c from mitochondria. 1122 43

Bcl-XL, a member of the Bcl-2-related anti-apoptosis protein family, antagonizes a diverse range of apoptosis-inducing stimuli by preventing mitochondrial permeability transition, release of apoptogenic factors including cytochrome C, and caspase activation. We have tested the hypothesis that the susceptibility of Bcl-XL-expressing leukaemic cells to apoptosis induced by VP16 (etoposide) can be enhanced by pharmacological downregulation of Bcl-XL in vivo. Two subcutaneous xenograft models of B-cell leukaemia-employing SEMK-2 and BV173 cell lines were established in severe combined immunodeficient/non-obese diabetic mice followed by 14 d of continuous subcutaneous administration of Bcl-XL-specific second generation oligonucleotides ISIS 16009 or ISIS 15999. Tumours were disaggregated, enabling investigation of Bcl-XL expression and apoptosis susceptibility at single-cell resolution using cytofluorimetry. Marked sequence-specific reduction of Bcl-XL was associated with sequence-specific enhancement of VP16-induced mitochondrial permeability transition, caspase-3 activation and loss of membrane asymmetry. A negative correlation between Bcl-XL expression and apoptosis susceptibility was observed, together with a positive correlation with respect to a reduced redox state. Bcl-XL downregulation reduces the threshold for VP16-induced apoptosis by potentiating mitochondrial dysfunction and its sequelae, and therefore presents a novel therapeutic strategy for reversing chemoresistance.
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PMID:In vivo suppression of Bcl-XL expression facilitates chemotherapy-induced leukaemia cell death in a SCID/NOD-Hu model. 1126 76

Regional levels of anti-apoptotic Bcl-2 mRNA and the cytosolic cytochrome c protein were measured after lateral fluid percussion (FP) brain injury in rats. Levels of Bcl-2 mRNA were significantly decreased in the injured left cortex (IC) and ipsilateral hippocampus (IH), but not in the contralateral right cortex (CC) and hippocampus (CH) after brain injury. Levels of Bcl-2 mRNA were significantly decreased as early as 2 h and stayed decreased as long as 48 h in the IC and IH after injury. Levels of the cytosolic cytochrome c protein were significantly increased in the IC and IH, but not in the CC and CH after brain injury. Levels of cytosolic cytochrome c were significantly increased in the IC at 30 min, 48 and 72 h, and in the IH at 2 h and as long as 72 h after injury. The increase of cytosolic cytochrome c suggests that the mitochondrial release of cytochrome is increased in the IC and IH after lateral FP brain injury. These data show that the reduction of anti-apoptotic Bcl-2 and increases of mitochondrial release of cytochrome c protein occur only in the IC and IH, regions which have been observed to undergo apoptosis and neuronal cell loss after lateral FP brain injury. Therefore, it is likely that the reduction of Bcl-2 and the increased cytochrome c protein in the cytosol contribute to the observed apoptosis and neuronal cell death in the IC and IH after lateral FP brain injury in rats.
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PMID:Regional expression of Bcl-2 mRNA and mitochondrial cytochrome c release after experimental brain injury in the rat. 1138 86

PDT has been reported to induce cancer cell expression of cytokines, such as IL-6 and TNF-alpha, but it has been unclear whether cytokine expression by cancer cells is directly related to the antitumor effect of PDT. We treated Lewis lung carcinoma (LLC) cells with a new photosensitizer, mono-L-aspartyl chlorin e6 (NPe6) and light from a diode laser and found that expression of the mRNA of IL-2, IL-6, and TNF-alpha was increased by NPe6-mediated-PDT 6 hr later. To elucidate the mechanism of the direct anti-tumor effect of cytokine expression, we examined the photosensitivity of cytokine-gene-transfected cells, namely LLC-IL-2, LLC-IL-6, and LLC-TNF-alpha cells, by MTT assay. The IL-6 gene transfected, LLC-IL-6 cells were significantly more sensitive to cytotoxic effects than the parent LLC cells and other cytokine gene-transfected cells. This finding indicates that IL-6 expression modulates cellular sensitivity to PDT and that IL-2 and TNF-alpha expressions does not. In addition, the apoptosis of LLC-IL-6 cells induced by NPe6-PDT was greater than in the other cells as determined by DNA fragmentation and staining of apoptotic nuclei. Because IL-6 has been reported to induce apoptosis by downregulating expression of Bcl-2, we analyzed the expression of apoptosis-related Bcl-2, Bax, and cytochrome C by Western blot analysis. Decreased expression of Bcl-2 and cytochrome C was observed in both LLC cells and LLC-IL-6 cells. Bax protein increased in a time-dependent manner, and the ratio of Bax to Bcl-2 rose markedly after PDT in LLC-IL-6 cells. These results suggest that the increased sensitivity of LLC-IL-6 cells to PDT-induced cytotoxicity results from the high ratio of Bax to Bcl-2 in the IL-6-dependent apoptotic pathway. In conclusion, IL-6 expression plays a role in cellular sensitivity to PDT, and combination of IL-6 and PDT may provide a new strategy for cancer treatment.
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PMID:Increased cytotoxic effects of photodynamic therapy in IL-6 gene transfected cells via enhanced apoptosis. 1147 50

Tissue factor pathway inhibitor-2 (TFPI-2) is a 32 kDa serine protease inhibitor found at high levels in extracellular matrix. Recombinant human TFPI-2 has recently been shown to be a strong inhibitor of trypsin, plasmin, plasma kallikrein, and factor XIa amidolytic activity. Earlier studies in our laboratory showed that the expression of TFPI-2 is lost during tumor progression in human gliomas. We stably transfected this protease inhibitor in multiform glioblastoma cell line (SNB-19) and in low-grade glioma cell line (Hs683) in sense and antisense orientation respectively. This confirmed that the upregulation/down-regulation of TFPI-2 plays a significant role in the invasive behavior of human gliomas both in vitro and in vivo models. Collectively, these results suggested an idea to determine whether TFPI-2 is necessary for cell survival and inhibition of tumor formation in nude mice, due to apoptosis of intracerebrally injected SNB-19 cells. In the present study we determined p-ERK levels and found that they are decreased in TFPI-2 over-expressed clones (SNB-19) and increased in TFPI-2 down-regulated clones (Hs683). We also checked the levels of BAX/BCl-2, caspases (for e.g., 9, 7, 3, 8), PARP, cytochrome-c and Apaf-1. Moreover, the increase of apoptosis in vitro is associated with increased and decreased expression of apoptotic protein BAX in sense clones (SNB-19) and antisense clones (Hs683) respectively, when compared to controls and vice versa with Bcl-2 the anti-apoptotic protein. Caspases (9, 7 and 3), cytochrome-c, Apaf-1 and PARP levels are increased in SNB-19 and decreased in Hs683. Caspase 8 was not expressed in either cell line. Caspases 9 and 3 activity assay revealed higher activity in sense clones (SNB-19) but lesser in antisense clones (Hs683) compared to controls. This is the first report of TFPI-2 playing a novel role in cell survival in human gliomas.
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PMID:A novel role of tissue factor pathway inhibitor-2 in apoptosis of malignant human gliomas. 1149 41

By GenBank database searches and PCR, we have identified a novel human Bcl2-like gene, Bcl2-L-10, which contains conserved BH4, BH1 and BH2 domains but lacks BH3 domain. The Bcl2-L-10 gene has been assigned to chromosome 15q21.2. Transfection experiments demonstrated that Bcl2-L-10 can block apoptosis induced by interleukin-3 withdrawal and Bax expression, by prevention of cytochrome C release, caspase-3 activation and mitochondrial membrane potential collapse. Bcl2-L-10 cannot block TNFalpha-induced apoptosis. Furthermore, both the BH4 domain and the transmembrane domain of Bcl2-L-10 are necessary for its suppressive action on cell death. Our results demonstrated that Bcl2-L-10 is a newly detected anti-apoptotic member of the Bcl-2 family and that it blocks apoptosis in the mitochondrial death pathway but not in the death receptor pathway.
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PMID:Bcl2-L-10, a novel anti-apoptotic member of the Bcl-2 family, blocks apoptosis in the mitochondria death pathway but not in the death receptor pathway. 1168 80

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent environmental contaminant that can exert developmental toxicity. To investigate the stage-specific effects of TCDD on preimplantation embryos, we exposed mouse embryos to TCDD at different stages (1-, 2-, and 8-cell) and collected them at different stages of development (the 1- or 2-, 8-cell, and blastocyst stage, respectively). Semiquantitative RT-PCR revealed increased constitutive gene expression of the arylhydrocarbon receptor (AhR) and AhR nuclear translocator (Arnt) at the 1-cell stage, decreased expression at the 2- to 8-cell stage, and increased expression again at the blastocyst stage, and addition of TCDD to media did not affect their mRNA levels. Interestingly, no cytochrome P4501A1 (CYP1A1) mRNA was detected in embryos at the 1-, 2-, and 8-cell stages after exposure to 10 nM TCDD for 12 or 24 h, whereas CYP1A1 mRNA was significantly increased at the blastocyst stage in response to TCDD, and its induction was found to be concentration-dependent on TCDD exposure from 0.01 to 10 nM for 24 h. In addition, no significant differences in development rate of preimplantation embryos, cell number of blastocyst embryos, or apoptotic indices, such as TUNEL-positive cell number or Bax/Bcl-2 expression ratios were observed at the blastocyst stage between TCDD-exposed groups and non-exposed group. These results suggest that the sensitivity to TCDD differs with the embryonic stage, which may reflect an ability of embryos to adapt to environmental stressors, such as dioxins.
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PMID:Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on preimplantation mouse embryos. 1198 89

Caspase-independent death mechanisms have been shown to execute apoptosis in many types of neuronal injury. P53 has been identified as a key regulator of neuronal cell death after acute injury such as DNA damage, ischemia, and excitotoxicity. Here, we demonstrate that p53 can induce neuronal cell death via a caspase-mediated process activated by apoptotic activating factor-1 (Apaf1) and via a delayed onset caspase-independent mechanism. In contrast to wild-type cells, Apaf1-deficient neurons exhibit delayed DNA fragmentation and only peripheral chromatin condensation. More importantly, we demonstrate that apoptosis-inducing factor (AIF) is an important factor involved in the regulation of this caspase-independent neuronal cell death. Immunofluorescence studies demonstrate that AIF is released from the mitochondria by a mechanism distinct from that of cytochrome-c in neurons undergoing p53-mediated cell death. The Bcl-2 family regulates this release of AIF and subsequent caspase-independent cell death. In addition, we show that enforced expression of AIF can induce neuronal cell death in a Bax- and caspase-independent manner. Microinjection of neutralizing antibodies against AIF significantly decreased injury-induced neuronal cell death in Apaf1-deficient neurons, indicating its importance in caspase-independent apoptosis. Taken together, our results suggest that AIF may be an important therapeutic target for the treatment of neuronal injury.
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PMID:Apoptosis-inducing factor is involved in the regulation of caspase-independent neuronal cell death. 1214 75

The protein kinase C (PKC) signal transduction pathway negatively regulates receptor-initiated cell death. In HeLa cells, tumor necrosis factor-alpha (TNF)-mediated cell death involved mitochondria and was blocked by the overexpression of Bcl-2. The PKC-specific inhibitor bisindolylmaleimide and the PKCdelta inhibitor rottlerin enhanced TNF-induced cell death. We have investigated if potentiation of TNF-induced cell death by rottlerin involved amplification of the mitochondrial pathway. TNF induced cleavage of the proapoptotic protein Bid and release of mitochondrial cytochrome c. Rottlerin enhanced activation of caspase-8 and cleavage of Bid. It also enhanced activation of caspase-9 but it did not increase cytochrome c in the cytosol. It, however, increased release of mitochondrial apoptosis-inducing factor (AIF) to the cytosol. Overexpression of Bcl-2 prevented release of both cytochrome c and AIF to the cytosol. Prolonged exposure (> or =6 h) of HeLa cells to rottlerin and TNF decreased the level of cytochrome c but not of AIF in the cytosol. These results suggest that rottlerin activates a cytochrome-c-independent cell death pathway to potentiate cell death by TNF.
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PMID:Potentiation of tumor necrosis factor-alpha-induced cell death by rottlerin through a cytochrome-C-independent pathway. 1216 76

The apoptotic pathway activated by chimeric anti-CD20 monoclonal antibodies (rituximab, IDEC.C2B8) was analyzed using the Burkitt lymphoma cell line Ramos. Crosslinking of CD20 (CD20XL) induced apoptosis in Ramos cells, which involved loss of mitochondrial membrane potential (Deltapsi(m)), the release of cytochrome-c (cyt-c), and activation of caspases-9 and -3. Nevertheless, several lines of evidence showed that the apoptotic outcome did not depend on these events. First, under circumstances where Ramos cells display resistance to either CD95- or B cell receptor (BCR)-induced apoptosis, CD20XL-induced apoptosis was not affected, pointing to a distinct pathway. Second, the broad-spectrum caspase inhibitor zVAD-fmk prevented processing of caspase-9, -3 and PARP as well as DNA fragmentation, but did not block apoptosis as measured by annexin V staining, cell size and membrane integrity. Lastly, Bcl-2 overexpression blocked cyt-c release and the decrease in Deltapsi(m), and completely prevented CD95- or BCR-mediated apoptosis; however, it did not affect CD20XL-induced cell death. We conclude that although CD20XL can initiate the mitochondrial apoptosis pathway, CD20-induced apoptosis does not necessarily require active caspases and cannot be blocked by Bcl-2. Since most chemotherapeutic drugs require the activation of caspases to exert their cytotoxicity, these findings provide an important rationale for the use of CD20 mAbs in chemoresistant malignancies.
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PMID:CD20-induced B cell death can bypass mitochondria and caspase activation. 1220 Jun 88


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