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 human myeloid leukemia cell line HL-60 transports the oxidized form of ascorbic acid, dehydroascorbic acid (DHA), and accumulates reduced ascorbic acid. We studied the effect of ascorbic acid loading on apoptosis induced by serum- and glucose-free culture and by oxidative stress induced by H2O2. Uptake accumulation studies indicated that incubation of HL-60 cells with DHA resulted in the accumulation of intracellular ascorbic acid which decreased with time when cells were incubated in DHA-free medium. Exposure of HL-60 cells to increasing concentrations of H2O2 resulted in dose-dependent intracellular accumulation of peroxides, as determined by the use of the oxidation-sensitive fluorescent probe 2',7'-dichlorofluorescin-diacetate (DCFH-DA), which was accompanied by a decrease in intracellular ascorbic acid and an increase in apoptosis. A dramatic decrease in intracellular ascorbic acid was noted when preloaded HL-60 cells were exposed to 150 microM H2O2 (the concentration dropped from 5.2 +/- 0.6 mM to 3.6 +/- 0.1 mM in cells preincubated with 150 microM DHA). A dose-dependent protective effect of DHA was observed. Ascorbic acid loading also provided strong protection from apoptosis associated with serum- and glucose-free culture. Flow cytometry studies showed that exposure of HL-60 cells to 150 microM H2O2 resulted in decreased Bcl-2 expression that was associated with enhanced apoptosis (up to 33.6 +/- 2.6%). No significant variation of Bcl-2 expression was measured following exposure of HL-60 cells, loaded with ascorbic acid, to 150 microM H2O2 and only a slight increase (up to 10.1 +/- 3.1%) in apoptosis. These findings indicate that ascorbic acid can inhibit apoptosis induced by oxidative stress in HL-60 cells.
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PMID:Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. 1007 88

As a result of Myc-dependent transcription of the LDH-A gene, Myc-transformed cells (Rat1-Myc) exhibit increased lactate production rates (LPR) even under aerobic conditions (the Warburg effect). Recently, the increased susceptibility to stress-induced apoptosis associated with Myc transfection has been linked to the overexpression of the LDH-A gene. In this report we demonstrate that the overexpression of the anti-apoptotic protein Bcl-2 in Rat1-Myc cells (Rat1-Myc-Bcl-2) reduces the molar ratio of lactate production to glucose consumption (Y(L/G)). The Bcl-2 induced reduction in Y(L/G) may be associated with reduced expression of the LDH-A gene, or a decrease in LDH-A activity. Stimulation of apoptosis by staurosporine, a protein kinase C inhibitor, reduces the LPR in Rat1-Myc cells in a dose-dependent manner. The staurosporine effect on the LPR is rapid and precedes the execution phase of apoptosis as defined by caspase activation and PARP cleavage. This effect on LPR is completely blocked by Bcl-2 overexpression. Serum starvation alone does not affect the LPR of Rat1-Myc or Rat1-Myc-Bcl-2 cells; however, the effect of staurosporine on the LPR of Rat1-Myc cells is potentiated by serum starvation. These data demonstrate that Bcl-2 overexpression reduces the Y(L/G) in Rat1-Myc cells, perhaps via a reduction in the activity or expression of the LDH-A gene, and this reduction may desensitize cells to some pro-apoptotic stimuli. The reduction in LPR in response to staurosporine may be an early step in the induction of apoptosis in Rat1-Myc cells. By abolishing the reduction in LPR, Bcl-2 may protect Rat1-Myc cells from staurosporine-induced apoptosis. Moreover, the lack of effect by serum starvation on the LPR supports a model in which serum starvation induces apoptosis through a pathway distinct from that of the staurosporine and glucose-dependent apoptotic pathway(s) in Myc-transformed cells.
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PMID:Change in lactate production in Myc-transformed cells precedes apoptosis and can be inhibited by Bcl-2 overexpression. 1010 Aug 70

The oncoprotein Bcl-2 protects cells against apoptosis, but the exact molecular mechanism that underlies this function has not yet been identified. Studying H2O2-induced cell injury in Rat-1 fibroblast cells, we observed that Bcl-2 had a protective effect against the increase in cytosolic calcium concentration and subsequent cell death. Furthermore, overexpression of Bcl-2 resulted in an alteration of cellular glutathione status: the total amount of cellular glutathione was increased by about 60% and the redox potential of the cellular glutathione pool was maintained in a more reduced state during H2O2 exposure compared with non-Bcl-2-expressing controls. In our cytotoxicity model, disruption of cellular glutathione homoeostasis closely correlated with the pathological elevation of cytosolic calcium concentration. Stabilization of the glutathione pool by Bcl-2, N-acetylcysteine or glucose delayed the cytosolic calcium increase and subsequent cell death, whereas depletion of glutathione by dl-buthionine-(S, R)-sulphoximine, sensitized Bcl-2-transfected cells towards cytosolic calcium increase and cell death. We therefore suggest that the protection exerted by Bcl-2 against H2O2-induced cytosolic calcium elevation and subsequent cell death is secondary to its effect on the cellular glutathione metabolism.
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PMID:Protection against hydrogen peroxide cytotoxicity in rat-1 fibroblasts provided by the oncoprotein Bcl-2: maintenance of calcium homoeostasis is secondary to the effect of Bcl-2 on cellular glutathione. 1022 85

The dihydrochalcone phloretin induced apoptosis in B16 mouse melanoma 4A5 cells and HL60 human leukemia cells. Phloretin was suggested to induce apoptosis in B16 cells mainly through the inhibition of glucose transmembrane transport. The phloretin-induced apoptosis in B16 cells was inhibited by actinomycin D, Ac-YVAD-CHO caspase-1-like inhibitor, and Ac-DEVD-CHO caspase-3-like inhibitor. During the induction of apoptosis by phloretin, the expression of Bax protein in B16 cells increased and the levels of p53, Bcl-2, and Bcl-XL proteins did not change. Our results suggested that phloretin induced apoptosis through the promotion of Bax protein expression and caspases activation. On the other hand, phloretin may induce apoptosis in HL60 cells through the inhibition of protein kinase C activity because phloretin inhibited protein kinase C activity in HL60 cells more than that in B16 cells. The phloretin induced-apoptosis in HL60 cells was not inhibited by actinomycin D and the caspase-1-like inhibitor, but slightly inhibited by the caspase-3-like inhibitor. Phloretin reduced the level of caspase 3 protein in HL60 cells, but not the level of the Bcl-2 protein. Phloretin did not increase the level of Bax protein. Phloretin was suggested to induce apoptosis in HL60 cells through the inhibition of protein kinase C activity, followed by the pathway, which is different from that in B16 cells.
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PMID:Phloretin-induced apoptosis in B16 melanoma 4A5 cells and HL60 human leukemia cells. 1036 85

Food restriction can extend life span in rodents and was recently reported to increase the resistance of neurons in the brain to excitotoxic and metabolic insults. In principle, administration to ad libitum fed rodents of an agent that reduces glucose availability to cells should mimick certain aspects of food restriction. We now report that administration of 2-deoxy-D-glucose (2DG), a non-metabolizable analog of glucose, to adult rats results in a highly significant reduction in seizure-induced spatial memory deficits and hippocampal neuron loss. Pretreatment of rat hippocampal cell cultures with 2DG decreases the vulnerability of neurons to excitotoxic (glutamate) and oxidative (Fe2+) insults. The protective action of 2DG is associated with decreased levels of cellular oxidative stress and enhanced calcium homeostasis. 2DG treatment increased levels of the stress-responsive proteins GRP78 and HSP70 in hippocampal neurons, without affecting levels of Bcl-2 or GRP75, suggesting that mild reductions in glucose availability can increase neuronal resistance to oxidative and metabolic insults by a mechanism involving induction of stress proteins. Our findings establish cell culture and in vivo models of "chemical food restriction" which may prove useful in elucidating mechanisms of neuroprotection and in developing preventive approaches for neurodegenerative disorders that involve oxidative stress and excitotoxicity.
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PMID:2-Deoxy-D-glucose protects hippocampal neurons against excitotoxic and oxidative injury: evidence for the involvement of stress proteins. 1039 35

betaTC-tet cells are conditionally immortalized pancreatic beta cells which can confer long-term correction of hyperglycemia when transplanted in syngeneic streptozocin diabetic mice. The use of these cells for control of type I diabetes in humans will require their encapsulation and transplantation in non-native sites where relative hypoxia and cytokines may threaten their survival. In this study we genetically engineered betaTC-tet cells with the anti-apoptotic gene Bcl-2 using new lentiviral vectors and showed that it protected this cell line against apoptosis induced by hypoxia, staurosporine and a mixture of cytokines (IL-1beta, IFN-gamma and TNF-alpha). We further demonstrated that Bcl-2 expression permitted growth at higher cell density and with shorter doubling time. Expression of Bcl-2, however, did not inter- fere either with the intrinsic mechanism of growth arrest present in the betaTC-tet cells or with their normal glucose dose-dependent insulin secretory activity. Furthermore, Bcl-2 expressing betaTC-tet cells retained their capacity to secrete insulin under mild hypoxia. Finally, transplantation of these cells under the kidney capsule of streptozocin diabetic C3H mice corrected hyperglycemia for several months. These results demonstrate that the murine betaTC-tet cell line can be genetically modified to improve its resistance against different stress-induced apoptosis while preserving its normal physiological function. These modified cells represent an improved source for cell transplantation therapy of type I diabetes.
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PMID:Lentivirus-mediated Bcl-2 expression in betaTC-tet cells improves resistance to hypoxia and cytokine-induced apoptosis while preserving in vitro and in vivo control of insulin secretion. 1045 20

The effects of a transient exposure to hydrogen peroxide (10 min at 200 microM H(2)O(2)) on pancreatic beta cell signal transduction and insulin secretion have been evaluated. In rat islets, insulin secretion evoked by glucose (16.7 mM) or by the mitochondrial substrate methyl succinate (5 mM) was markedly blunted following exposure to H(2)O(2). In contrast, the secretory response induced by plasma membrane depolarization (20 mM KCl) was not significantly affected. Similar results were obtained in insulinoma INS-1 cells using glucose (12.8 mM) as secretagogue. After H(2)O(2) treatment, glucose no longer depolarized the membrane potential (DeltaPsi) of INS-1 cells or increased cytosolic Ca(2+). Both DeltaPsi and Ca(2+) responses were still observed with 30 mM KCl despite an elevated baseline of cytosolic Ca(2+) appearing approximately 10 min after exposure to H(2)O(2). The mitochondrial DeltaPsi of INS-1 cells was depolarized by H(2)O(2) abolishing the hyperpolarizing action of glucose. These DeltaPsi changes correlated with altered mitochondrial morphology; the latter was not preserved by the overexpression of the antiapoptotic protein Bcl-2. Mitochondrial Ca(2+) was increased following exposure to H(2)O(2) up to the micromolar range. No further augmentation occurred after glucose addition, which normally raises this parameter. Nevertheless, KCl was still efficient in enhancing mitochondrial Ca(2+). Cytosolic ATP was markedly reduced by H(2)O(2) treatment, probably explaining the decreased endoplasmic reticulum Ca(2+). Taken together, these data point to the mitochondria as primary targets for H(2)O(2) damage, which will eventually interrupt the transduction of signals normally coupling glucose metabolism to insulin secretion.
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PMID:Hydrogen peroxide alters mitochondrial activation and insulin secretion in pancreatic beta cells. 1048 38

The toxicity of tributyltin chloride (TBT) involves Ca(2+) overload, cytoskeletal damage, and mitochondrial failure leading to cell death by apoptosis or necrosis. Here, we examined whether the intracellular ATP level modulates the mode of cell death after exposure to TBT. When Jurkat cells were energized by the mitochondrial substrate, pyruvate, low concentrations of TBT (1-2 microM) triggered an immediate depletion of intracellular ATP followed by necrotic death. When ATP levels were maintained by the addition of glucose, the mode of cell death was typically apoptotic. Glycolytic ATP production was required for apoptosis at two distinct steps. First, maintenance of adequate ATP levels accelerated the decrease of mitochondrial membrane potential, and the release of the intermembrane proteins adenylate kinase and cytochrome c from mitochondria. A possible role of the adenine nucleotide exchanger in this first ATP-dependent step is suggested by experiments performed with the specific inhibitor, bongkrekic acid. This substance delayed cytochrome c release in a manner similar to that caused by ATP depletion. Second, caspase activation following cytochrome c release was only observed in ATP-containing cells. Bcl-2 had only a minor effect on TBT-triggered caspase activation or cell death. We conclude that intracellular ATP concentrations control the mode of cell death in TBT-treated Jurkat cells at both the mitochondrial and caspase activation levels.
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PMID:Tributyltin-induced apoptosis requires glycolytic adenosine trisphosphate production. 1052 61

Histologic criteria defining malignancy in smooth muscle tumors are currently site specific. This study was undertaken to determine whether, in leiomyosarcomas (LMS) occurring in different anatomic locations, there were differences in patterns of expression of molecules that have been demonstrated to be associated with biologically aggressive behavior in malignant neoplasms, and also to determine their diagnostic utility. Formalin-fixed paraffin-embedded tissue blocks were selected from 16 extrauterine leiomyosarcomas (EULMS), 14 cases of uterine leiomyosarcomas (ULMS) and from five cases each of uterine and extrauterine leiomyomas (LM). Utilizing immunohistochemical (ABC) techniques with antigen retrieval, we assessed serial sections of each tumor for immunoreactivity with Glut1, CD44s, bcl2, cyclin D1, and estrogen receptor. Molecular genotyping for detecting k-ras-2 point mutation, p53 gene loss, and mdm2 gene amplification was performed on microdissected tumor samples from the same histologic sections. All of the uterine and extrauterine LM were diffusely positive for CD44s, bcl2, and cyclin D1, and uniformly negative for Glut1. In contrast, 50% of the ULMS and 25% of EULMS were Glutl positive. Moreover, Glut1 positivity closely correlated with aggressive biologic behavior reflected by distant metastatic spread. Eighty-percent of LM and 70% of the ULMS were estrogen receptor positive, whereas only one retroperitoneal tumor had focal weak positivity. Over 80% of the extrauterine and 50% of the uterine sarcomas showed absence of CD44s immunoreactivity. Percentage of cyclin D1 immunoreactivity was independent of tumor grade and inversely proportional to the percent of bcl2 positivity. An LMS of the male breast contained k-ras-2 exon 1 point mutation (codon 12 aspartate substitution of glycine). P53 allelic imbalance was present in 29% of ULMS and 57% EULMS. Mdm2 amplification was present in three of six EULMS but not in ULMS. In addition to clinical staging, Glut1 positivity together with patterns of immunoreactivity of CD44 and bcl2 may be helpful in identifying aggressive smooth muscle tumors of the uterus and some EULMS. The presence of estrogen receptor staining may be helpful in identifying uterine versus nonuterine LMS. Although sample numbers are too small for definite conclusions, this study suggests that there are differences in glucose transport, expression of adhesion molecules, and estrogen receptors in ULMS and EULMS, which in part may be due to the estrogen dependency of the ULMS. P53 mutations and mdm2 amplifications appear to be more frequent in EULMS.
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PMID:Comparative immunohistochemical and molecular analysis of uterine and extrauterine leiomyosarcomas. 1057 96

A number of bioreactor configurations have been developed for the manufacture of products from mammalian cell hosts. Even in the most efficient of these, however, problems such as nutrient exhaustion, growth factor deprivation, and toxin accumulations may arise. Consequently, the current effort focused on the feasibility of overexpressing anti-apoptosis genes in baby hamster kidney (BHK) and Chinese hamster ovary (CHO) cells as a means of limiting cell death upon exposure to three such insults. Extended periods of glucose deprivation, serum withdrawal, and treatment with ammonium chloride each caused significant damage, often apoptotic in nature, to BHK and CHO cells, typically rendering cultures completely nonviable. The overexpression of bcl-2 and bcl-x(L), however, was able to abrogate the cell death in BHK cultures, though to varying degrees. For instance, the presence of Bcl-2, which did little to suppress apoptosis upon glucose deprivation, significantly improved the viabilities of these cells during serum withdrawal. In contrast, bcl-x(L) overexpression provided BHK cells with enhanced protection in the absence of glucose, allowing cultures to remain viable throughout the entire three week study. CHO cultures, on the other hand, displayed similar trends in survival in response to both glucose and serum deprivation. During these studies, Bcl-x(L) was consistently able to afford cells the highest degree of protection, though Bcl-2 also enhanced culture viabilities and viable numbers. Death suppression following exposure to 50 mM ammonium chloride was observed to a limited extent in both BHK and CHO cells overexpressing bcl-2 and bcl-x(L). However, even during such harsh treatment, Bcl-x(L) was able to enhance the survival of both cultures, providing CHO cells with viable numbers that were nearly 20-fold that of the controls after five days of exposure. Furthermore, the extensions in cell survival provided by the anti-apoptosis gene products enabled the recovery of many of the cultures during rescue attempts in which the death-inducing stimulus was removed. Clearly, engineering cells to better withstand and recover from the insults common during the large scale cultivation of mammalian cells has a number of potential applications in the biopharmaceutical industries where cell death can limit culture productivities.
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PMID:Part II. Overexpression of bcl-2 family members enhances survival of mammalian cells in response to various culture insults. 1064 30


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