Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42574 (caspase-3)
 45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

MLH1 is an integral part of the mismatch repair complex, and the loss of this protein is associated with the acquisition of a mutator phenotype, microsatellite instability, and a predisposition to cancer. Deficiencies in the mismatch repair complex, including the loss of MLH1, result in elevated resistance to specific inducers of DNA damage, yet the mechanisms involved in this DNA-damage resistance are largely unknown. Abnormal cellular responses to DNA damage can lead to the selection of cells with a greater propensity for neoplastic transformation and might also reduce the effectiveness of certain chemotherapeutic drugs. It is therefore important to identify agents that provide selective pressure for growth of MLH1-deficient cells and to characterize further the pathways involved. In this study, we show that both human epithelial and mouse embryo fibroblast cell lines lacking the MLH1 protein are more resistant to two inducers of oxidative stress, hydrogen peroxide and tert-butyl hydroperoxide. Our analyses suggest that the observed differences in cellular viability are mediated primarily through apoptotic pathways and not through deficiencies in cell cycle checkpoint controls. Additional characterization of the signaling pathways for hydrogen peroxide-induced apoptosis in MLH1-proficient cells demonstrates the involvement of increased mitochondrial permeability, the release of cytochrome c, and caspase 3 activation. Together, our data indicate that cells lacking MLH1 may possess a selective growth advantage under oxidatively stressed conditions via the disregulation of apoptosis, possibly involving the mitochondria.
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PMID:Involvement of mammalian MLH1 in the apoptotic response to peroxide-induced oxidative stress. 1124 40

Although it is well known that Bcl-2 can prevent apoptosis, the Bcl-2's anti-apoptotic mechanism is not fully understood. Here, we investigate the mechanism of oxidant-induced cell death and to investigate the role of Bcl-2 in the tert-butyl hydroperoxide (t-BuOOH)-induced oxidant injury in Rat-1 fibroblasts and their bcl-2 transfected counterparts, b5 cells. Treatment with t-BuOOH causes mitochondrial disfunction and induced morphological features consistent with apoptosis more markedly in Rat-1 cells than in b5 cells. The hydroperoxide t-BuOOH at concentrations less than 100 nM for as long as 48 h or with higher concentrations (up to 100 microM) for only 3 h induces death in Rat-1 cells, whereas their bcl-2 transfectants were significantly resistant to cytotoxicity by both time and all concentration other than 100 microM. The similar results were obtained also for DNA strand cleavages as detected by TUNEL stain. The bcl-2 transfectants significantly suppressed t-BuOOH-induced increases in both lipid peroxidation and caspase-3 activation 3 and 1 h after t-BuOOH exposure, respectively, but failed to suppress either caspase-1 activation or an enhanced production of the intracellular reactive oxygen species (ROS). Intracellular uptake of [1-(14)C] ascorbic acid (Asc) into the bcl-2 transfectants was superior to that into the non-transfectants always under examined conditions regardless of serum addition to culture medium and cell density. Upregulation of Bcl-2 proteins was rapidly induced after t-BuOOH exposure in the transfectants, but not in non-transfectants, and restored till 24 h to the normal Bcl-2 level. Thus suppressions of both lipid peroxidation and the subsequent cell death events such as caspase-3 activation and DNA cleavage were concerned with the inhibitory effects of Bcl-2 on the t-BuOOH-induced cytotoxicity. And some of these events may correlate with Bcl-2 expression-induced partial enhanced anti-oxidant cellular ability including enrichment of intracellular Asc and oxidative stress-induced upregulation of Bcl-2 protein. On the other hand, ROS production and caspase-1 activation were not related to cytoprotection by Bcl-2.
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PMID:Anti-apoptotic defense of bcl-2 gene against hydroperoxide-induced cytotoxicity together with suppressed lipid peroxidation, enhanced ascorbate uptake, and upregulated Bcl-2 protein. 1270 95

Replicative senescence of human endothelial cells was analyzed, using primary endothelial cells from the human umbilical vein endothelial cells (HUVEC) as an experimental model system. We had shown before that senescent HUVEC arrest in the G1 phase of the cell cycle and that a subpopulation of the senescent cells undergoes cell death. We now demonstrate that cell death occurs by apoptosis, characterized by activation of caspase 3. Using the redox-sensitive dye dihydrorhodamine 123, a significant accumulation of reactive oxygen species is detected in senescent but not young endothelial cells. To determine if increased oxidative stress may contribute to the senescent phenotype, cells were treated with tert-butyl hydroperoxide (tBHP), which is known to increase oxidative stress by decreasing the intracellular glutathione levels. We show here that mild tBHP stress induces a phenotype of premature senescence in a subpopulation of the treated cells, which closely resembles the phenotype of naturally senescent HUVEC, including growth arrest, senescence-associated beta-gal activity, and apoptotic cell death. These results establish a model of premature senescence for human endothelial cells, which will be suitable to analyze mechanisms of age-associated cell death.
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PMID:Senescence-associated cell death of human endothelial cells: the role of oxidative stress. 1458 Aug 68

Oxidative stress-induced mitochondrial dysfunction has been shown to play a crucial role in the pathogenesis of a wide range of diseases. Protecting mitochondrial function, therefore, is vital for cells to survive during these disease processes. In this study, we demonstrate that melatonin, a chief secretory product of the pineal gland, readily rescued mitochondria from oxidative stress-induced dysfunction and effectively prevented subsequent apoptotic events and death in rat brain astrocytes (RBA-1). The early protection provided by melatonin in mitochondria of intact living cells was investigated by the application of time-lapse conventional, confocal, and multiphoton fluorescent imaging microscopy coupled with noninvasive mitochondria-targeted fluorescent probes. In particular, we observed that melatonin effectively prevented exogenously applied H2O2-induced mitochondrial swelling in rat brain astrocytes at an early time point (within 10 min) and subsequently reduced apoptotic cell death (150 min later). Other early apoptotic events such as plasma membrane exposure of phosphatidyl serine and the positive YOPRO-1 staining of the early apoptotic nucleus were also prevented by melatonin. A mechanistic study at the mitochondrial level related to the early protection provided by melatonin revealed that the indole molecule significantly reduced mitochondrial reactive oxygen species (ROS) formation induced by H2O2 stress. Melatonin also prevented mitochondrial ROS generation caused by other organic hydroperoxides including tert-butyl hydroperoxide and cumene hydroperoxide. This antioxidative effect of melatonin is more potent than that of vitamin E. Via its ability to reduce mitochondrial ROS generation, melatonin prevented H2O2-induced mitochondrial calcium overload, mitochondrial membrane potential depolarization, and the opening of the mitochondrial permeability transition (MPT) pore. As a result, melatonin blocked MPT-dependent cytochrome c release, the downstream activation of caspase 3, the condensation and karyorrhexis of the nucleus and apoptotic fragmentation of nuclear DNA. Thus, the powerful mitochondrial protection provided by melatonin reinforces its therapeutic potential to combat a variety of oxidative stress-induced mitochondrial dysfunctions as well as mitochondria-mediated apoptosis in various diseases.
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PMID:Visualization of the antioxidative effects of melatonin at the mitochondrial level during oxidative stress-induced apoptosis of rat brain astrocytes. 1523 Aug 69

Increased levels of Mcl-1 (myeloid cell factor-1) have been reported in several cancers, suggesting an important role played by Mcl-1 in cancer cell survival. Mcl-1 is an anti-apoptotic protein shown to delay or block apoptosis. In this work, using semiquantitative immunofluorescence, real-time PCR, and RNase protection assay, an increase in Mcl-1 expression was detected in hepatoma HepG2 cells incubated under hypoxia or in the presence of cobalt chloride. Through analysis of the Mcl-1 promoter sequence, a putative HIF-1 (hypoxiainducible factor-1) binding site was identified. A Mcl-1 promoter fragment containing this hypoxia-responsive element was able to bind HIF-1 in vitro. It also induced hypoxia-dependent transcription of a luciferase reporter gene, which was suppressed by anti-HIF-1alpha short interfering RNA. Finally, overexpression of Mcl-1 protected HepG2 cells against apoptosis induced by tert-butyl hydroperoxide as shown by inhibition of caspase-3 activation and DNA fragmentation. All these data suggest a potential anti-apoptotic role of HIF-1 that could protect cells against apoptosis under hypoxia by overexpression of the Mcl-1 protein.
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PMID:Hypoxia-inducible factor-1-dependent overexpression of myeloid cell factor-1 protects hypoxic cells against tert-butyl hydroperoxide-induced apoptosis. 1561 Oct 89

tert-Butylhydroperoxide has been reported to inhibit growth and induce apoptosis in number of cell types, but little is known about the molecular mechanism mediating these effects. In the present study, we determined the molecular pathways that lead to apoptosis after treatment of cells with t-BOOH. The cells were exposed to different concentrations of t-BOOH (100-750 microM) for 1-4 h and various parameters such as cytotoxicity, ROS (reactive oxygen species) generation, MMP (mitochondrial membrane potential), intracellular Ca++ levels and expression of various proteins involved in apoptosis were determined. Exposure of U-937 cells to t-BOOH induced cytotoxicity in a time dependent manner with about 50% toxicity at 400 microM t-BOOH in 4h. t-BOOH treatment resulted in a time dependent increase in reactive oxygen species levels, Ca++ influx and annexin V positive cells. There was a significant fall in MMP following exposure to t-BOOH with time. t-BOOH treatment of U-937 cells leads to apoptosis, which is accompanied by activation of caspase-3. The caspase-3 inhibitor (Ac-DEVD-CHO) inhibits the cytotoxicity induced by t-BOOH, indicating a direct link between caspase-3 activation and cell death. This activation of apoptosis is accompanied by release of cytochrome c, down regulation of anti-apoptotic protein Bcl-2 levels with concurrent increase in pro-apoptotic proteins Bax and Bad levels. These observations indicate that t-BOOH induces cell death in U-937 macrophages by apoptosis, which is mediated through mitochondrial pathway.
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PMID:Mechanism of tert-butylhydroperoxide induced cytotoxicity in U-937 macrophages by alteration of mitochondrial function and generation of ROS. 1741

Reactive oxygen species can be important mediators of damage to cell molecules and structures. Besides the endogen antioxidant defences, the antioxidant intake in the diet has an important role in the protection against the development of diseases produced by oxidative damage. Resveratrol is a naturally occurring compound present in many plants some of which are part of the human diet. This molecule has been thoroughly investigated because of its antioxidant and anticarcinogenic properties among others. We investigated whether resveratrol could provide protective antioxidant action in primary rat hepatocyte cultures. Primary rat hepatocytes cultures were exposed to 300 microM tert-butyl hydroperoxide; 25, 50 or 75 microM resveratrol or to 300 microM tert-butyl hydroperoxide plus 25, 50 or 75 microM resveratrol for different time periods. Necrosis was evaluated by lactate dehydrogenase liberation to the medium. Apoptosis was evaluated by caspase 3 activity measurement. Changes in cellular morphology after the different treatments were recorded using bright field microscopy. Inhibition of the reactive oxygen species by resveratrol was studied by confocal microscopy and spectrofluorimetrically. Resveratrol inhibited necrosis induced by tert-butyl hydroperoxide. No apoptosis was observed in any treatment. It also was effective in eliminating reactive oxygen species. At 75 microM, the highest concentration tested, resveratrol became slightly cytotoxic. Our results show that resveratrol protects primary rat hepatocytes in culture from oxidative stress induced cell death. These results suggest that resveratrol could enhance the antioxidant status of hepatic cells.
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PMID:Resveratrol protects primary rat hepatocytes against necrosis induced by reactive oxygen species. 1867 78

In the present work, we investigated the protective effects of the ethanol extract of Aralia continentalis roots (AC) on tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity in a cultured Hepa1c1c7 cell line and in mouse liver. Pretreatment with AC prior to the administration of t-BHP significantly prevented the increase in serum levels of hepatic enzyme markers (ALT, AST) and lipid peroxidation and reduced oxidative stress, as measured by glutathione content, in the liver. Histopathological evaluation of the livers also revealed that AC reduced the incidence of liver lesions. The in vitro study showed that AC significantly reduced t-BHP-induced oxidative injury in Hepa1c1c7 cells, as determined by cell cytotoxicity, intracellular glutathione content, lipid peroxidation, reactive oxygen species (ROS) levels, and caspase-3 activation. Also, AC up-regulated phase II genes including heme oxygenase-1 (HO-1), NAD(P)H:quinone reductase, and glutathione S-transferase. Moreover, AC induced Nrf2 nuclear translocation and ERK1/2 and p38 activation, pathways that are involved in inducing Nrf2 nuclear translocation. Taken together, these results suggest that the protective effects of AC against t-BHP-induced hepatotoxicity may, at least in part, be due to its ability to scavenge ROS and to regulate the antioxidant enzyme HO-1 via the ERK1/2 and p38/Nrf2 signaling pathways.
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PMID:Protective mechanisms of Aralia continentalis extract against tert-butyl hydroperoxide-induced hepatotoxicity: in vivo and in vitro studies. 1882 57

Phytoestrogens are polyphenolic non-steroidal plant compounds with estrogen-like biological activity. The phytoestrogen puerarin, the main isoflavone glycoside found in the root of Pueraria lobata, has been used for various medicinal purposes in traditional Chinese medicines for thousands of years. Recent studies have indicated that the estrogen receptor (ER), through interaction with p85, regulates phosphoinositide 3-kinase (PI3K) activity, revealing a physiologic, non-nuclear function of ER that may be relevant in cytoprotection. In this study, we demonstrate that the phytoestrogen puerarin inhibits tert-butyl hydroperoxide (t-BHP)-induced oxidative injury via an ER-dependent Gbeta1/PI3K/Akt and heme oxygenase-1 (HO-1) pathway. Pretreatment of Hepa1c1c7 and HepG2 cells with puerarin significantly reduced t-BHP-induced caspase-3 activation and subsequent cell death. Also, puerarin up-regulated HO-1 expression and this expression conferred cytoprotection against oxidative injury induced by t-BHP. Moreover, puerarin induced Nrf2 nuclear translocation, which is upstream of puerarin-induced HO-1 expression, and PI3K activation, a pathway that is involved in induced Nrf2 nuclear translocation, HO-1 expression and cytoprotection. Puerarin-induced up-regulation of HO-1 and cytoprotection against t-BHP were abolished by silencing Nrf2 expression with specific siRNA. Also, puerarin-mediated increases in PI3K activation and HO-1 induction were reversed by co-treatment with ICI 182,780 and pertussis toxin. Taken together, these results suggest that puerarin augments cellular antioxidant defense capacity through ER-dependent HO-1 induction via the Gbeta1/PI3K/Akt-Nrf2 signaling pathway, thereby protecting cells from oxidative stress.
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PMID:Mechanism of phytoestrogen puerarin-mediated cytoprotection following oxidative injury: estrogen receptor-dependent up-regulation of PI3K/Akt and HO-1. 1884 76

Oxidative stress is widely recognized as an important mediator of apoptosis in liver cells and plays a pivotal role in the pathogenesis of several diseases. Cocoa flavonoids have shown a powerful antioxidant activity providing protection against oxidation and helping prevent oxidative stress-related diseases. However, the molecular mechanisms responsible for this protection are not fully understood. Thus, in this study we investigated the protective effect of a cocoa polyphenolic extract (CPE) against tert-butyl hydroperoxide (t-BOOH)-induced apoptosis and the molecular mechanisms involved in this process. Incubation of HepG2 cells with t-BOOH induced apoptosis as evidenced by caspase-3 activation. This effect was accompanied by increased reactive oxygen species formation and by transient activation of the extracellular regulated kinases (ERKs) as well as sustained activation of the c-Jun N-terminal kinases (JNKs). On the contrary, pretreatment of HepG2 cells with CPE prevented apoptosis through the reduction of reactive oxygen species generation and the modulation of the apoptotic pathways activated by t-BOOH. CPE treatment also activated survival signaling proteins, such as protein kinase B (AKT) and ERKs, and increased the activities of two antioxidant enzymes, glutathione peroxidase (GPx) and glutathione reductase (GR). ERK's implication on GPx and GR induction and the protective effect of CPE against t-BOOH-induced oxidative stress and apoptosis were confirmed through experiments with selective inhibitors. These findings suggest that CPE is an effective inductor of GPx and GR activities via ERK activation and that this up-regulation seems to be required to attenuate t-BOOH-induced injury.
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PMID:Cocoa flavonoids up-regulate antioxidant enzyme activity via the ERK1/2 pathway to protect against oxidative stress-induced apoptosis in HepG2 cells. 1919 69


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