Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006826 (cancer)
 1,092,456 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously reported on cloning of the human gene encoding Bcl-2/adenovirus E1B 19 kDa-interacting protein 3-like protein (Bnip3L) and its growth inhibitory effect on cancer cells. Here we show that Bnip3L contains a motif similar to the BH3 domain which is conserved in Bcl-2 family proteins as well as containing a membrane-anchoring domain, and that Bnip3L interacts with Bcl-2 and Bcl-xL. Immunofluorescence microscopy revealed that Bnip3L was localized in the mitochondria, when in the presence of the membrane-anchoring domain. Transient expression of Bnip3L induced apoptosis of Rat-1 and HeLa cells and mutational analysis revealed that the BH3 domain and the membrane-anchoring domain were required for Bnip3L to induce cell death. Addition of recombinant Bnip3L to isolated mitochondria induced membrane potential loss and cytochrome c release both of which have been suggested to be prerequisite for apoptotic cell death. These results suggest that Bnip3L is one of the BH3-containing pro-apoptotic proteins and that it targets the mitochondria when inducing apoptosis.
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PMID:Bcl-2/E1B 19 kDa-interacting protein 3-like protein (Bnip3L) interacts with bcl-2/Bcl-xL and induces apoptosis by altering mitochondrial membrane permeability. 1046 96

Proapoptotic members of the Bcl-2 family, including Bax, Bak, and Bid, directly trigger the mitochondrial release of apoptogenic cytochrome c and apoptosis-inducing factor into the cytoplasm. One of the crucial steps before Bax can exert its proapoptotic activity is translocation from the cytoplasm to the mitochondria, but the molecular mechanism of this translocation is not understood. To investigate the mechanism of apoptosis-associated Bax translocation, we used an in vitro system comprising isolated mitochondria and cytosol. We found that both endogenous and exogenous added recombinant Bax translocated to the mitochondria more efficiently in the presence of cytosol from cells with VP16-induced apoptosis than with cytoplasm from normal cells. This apoptosis-dependent promotion of Bax translocation was not seen with cytosol that was prepared from VP16-treated cells expressing Bcl-2. Cytosol from cells with VP16-induced apoptosis, but not that from normal cells or Bcl-2-expressing cells, induced cytochrome c release from isolated mitochondria, which, as assessed by immunodepletion experiments, was mainly mediated by Bax. These results suggest that Bcl-2 exerts its antiapoptotic activity partly by inhibiting the translocation of Bax through the modification of cytosolic factors that are involved in such translocation during apoptosis.
Cancer Res 1999 Nov 01
PMID:Apoptotic cytosol facilitates Bax translocation to mitochondria that involves cytosolic factor regulated by Bcl-2. 1055 32

This study deals with the apoptotic effect exerted on human retinoblastoma Y79 cells by both sodium butyrate and an inhibitor of 26S proteasome [z-Leu-Leu-Leu-CHO (MG132)] and their synergistic effect. Exposure to sodium butyrate (1-4 mM) induced an accumulation of cells in the G2-M phase that was already visible after 24 h of treatment, when morphological and biochemical signs of apoptosis appeared only in a small number of cells (5-10%). Thereafter, the apoptotic effects increased progressively with slow kinetics, reaching a maximum after 72 h of exposure, when they concerned a large fraction of cells (>75% with 4 mM sodium butyrate). Sodium butyrate stimulated the conversion of procaspase-3 into caspase-3 and also induced the cleavage of poly-(ADP-ribose) polymerase and lamin B, two hallmarks of apoptosis. All of the apoptotic signals were suppressed by benzyloxy carbonyl-Val-Ala-Asp-fluoromethylketone (a general inhibitor of caspase activities), whereas acetyl-Asp-Glu-Val-Asp aldehyde, a specific inhibitor of caspase-3 activity, only induced a partial reversion of the apoptotic effects. Sodium butyrate also decreased the Bcl-2 level, whereas it increased the Bax level and stimulated the release of cytochrome c from the mitochondria, an event that was most likely responsible for the activation of caspase-3. Finally, sodium butyrate activated 26S proteasome, the major extralysosomal degradative machinery, which is responsible for the degradation of short-lived proteins. Consequently, the levels of p53, N-myc, and IkappaBalpha (factors that play regulatory roles in apoptosis) diminished, whereas the nuclear level of nuclear factor kappaB concomitantly increased. Treatment of Y79 cells with MG132 induced apoptosis with more rapid kinetics than with sodium butyrate. The effects appeared after 8 h of incubation, reaching a maximum at 24 h, and they were accompanied by increased levels of N-myc, p53, and IkappaBalpha. MG132 also favored the release of cytochrome c from the mitochondria and increased the activity of caspase-3. When Y79 cells were exposed to combinations of sodium butyrate and MG132, the latter compound suppressed the decreasing effect induced by sodium butyrate on the levels of p53, N-myc, and IkappaBalpha and the increasing effect on the nuclear level of nuclear factor kappaB. Moreover, an increase in the level of Bax and an enhancement in the release of cytochrome c from the mitochondria were observed. Clear synergistic effects concerning the activation of both caspase-3 and apoptosis were induced by a combination of suboptimal doses of sodium butyrate and MG132. The results support the conclusion that MG132 potentiates the apoptotic effect of sodium butyrate by suppressing its stimulatory effect on 26S proteasome activity. Synergistic interactions between butyrate and inhibitors of proteasome could represent a new important tool in tumor therapy and, in particular, the treatment of retinoblastoma.
Cancer Res 1999 Nov 01
PMID:The apoptotic effects and synergistic interaction of sodium butyrate and MG132 in human retinoblastoma Y79 cells. 1055 39

Penta-O-galloyl-beta-D-glucose is structurally related to (-)-epigallocatechin gallate and is isolated from hydrolyzed tannin. Penta-O-galloyl-beta-D-glucose can inhibit tumor promotion by teleocidin. We investigated the effects of penta-O-galloyl-beta-D-glucose and various tea polyphenols on cell viability in human leukemia HL-60 cells. In this study, we demonstrated that penta-O-galloyl-beta-D-glucose was able to induce apoptosis in a concentration- and time-dependent manner; however, other polyphenols were less effective. We further investigated the molecular mechanisms of penta-O-galloyl-beta-D-glucose-induced apoptosis. Treatment with penta-O-galloyl-beta-D-glucose caused induction of caspase-3/CPP32 activity in dose- and time-dependent manner, but not caspase-1 activity, and induced the degradation of poly-(ADP-ribose) polymerase. Pretreatment with acetyl-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-CHO) and Z-Val-Ala-Asp-fluoromethyl-ketone (Z-VAD-FMK) inhibited penta-O-galloyl-beta-D-glucose-induced DNA fragmentation. Furthermore, treatment with penta-O-galloyl-beta-D-glucose (50 microM) caused a rapid loss of mitochondrial transmembrane potential, release of mitochondrial cytochrome c into cytosol, and subsequent induction of procaspase-9 processing. Our results indicate that penta-O-galloyl-beta-D-glucose allows caspase-activated deoxyribonuclease to enter the nucleus and degrade chromosomal DNA, and induces DFF-45 (DNA fragmentation factor) degradation. These results lead to a working hypothesis that penta-O-galloyl-beta-D-glucose-induced apoptosis is triggered by the release of cytochrome c into the cytosol, procaspase-9 processing, activation of caspase-3, degradation of poly-(ADP-ribose) polymerase, and DNA fragmentation caused by the caspase-activated deoxyribonuclease through the digestion of DFF-45. The induction of apoptosis by penta-O-galloyl-beta-D-glucose may provide a pivotal mechanism for its cancer chemopreventive action.
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PMID:Induction of apoptosis by penta-O-galloyl-beta-D-glucose through activation of caspase-3 in human leukemia HL-60 cells. 1055 85

N-(4-Hydroxyphenyl)retinamide (4HPR) is currently used in cancer prevention and therapy trials. It is thought that its effects result from induction of apoptosis. 4HPR-induced apoptosis in human cervical carcinoma C33A cells involves enhanced generation of reactive oxygen species (ROS). In this study we explored the mechanism by which 4HPR increases ROS and induces apoptosis in these cells. 4HPR induced cytochrome c release from mitochondria to cytoplasm, activated caspase-3, and caused a membrane permeability transition (MPT). All these 4HPR's effects, as well as the induction of apoptosis, were inhibited by antioxidants, which decrease ROS. Thenoyltrifluoroacetone, a mitochondrial respiratory chain (MRC) complex II inhibitor, and carbonylcyanide m-chlorophenyl hydrazone, which uncouples electron transfer and ATP synthesis and inhibits ROS generation by MRC, inhibited 4HPR-induced ROS generation very effectively. Rotenone, an MRC complex I inhibitor was less effective and azide, an MRC complex IV inhibitor, exhibited a marginal effect. In contrast, antimycin A, an MRC complex III inhibitor, enhanced 4HPR-induced ROS generation. These findings suggest that 4HPR enhances ROS generation by affecting a target between complex II and complex III, presumably coenzyme Q. This effect is followed by release of cytochrome c, increased caspase-3 activity, induction of MPT and eventual DNA fragmentation and cell death.
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PMID:Implication of mitochondria-derived reactive oxygen species, cytochrome C and caspase-3 in N-(4-hydroxyphenyl)retinamide-induced apoptosis in cervical carcinoma cells. 1059 38

Cells of solid tumours tend to rely on glycolysis for energy. On the other hand, increased glycolysis in solid tumour cells expressing the multidrug resistance protein MDR-1 has been associated with increased malignancy in tumours. We have previously shown that cells of the MDR-1-positive CEM/VLB100 leukaemic cell line have increased mitochondrial electron transport chain (mtETC) activity compared with parental CEM cells. In the present study we used infrared (IR) spectroscopy to demonstrate that the mitochondrial DNA (mtDNA) content in the CEM/VLB100 cell line was significantly increased compared to that in the parental CEM cells. The increase in mtDNA was not accompanied by an increase in mitochondrial protein as both lipid and protein levels were decreased in CEM/VLB100 mitochondria. The ATP content was similar in these two cell lines. However, the ATP-dependent membrane efflux pump function in CEM/VLB100 cells was significantly reduced when mitochondrial ATP synthesis was inhibited by oligomycin, a specific inhibitor of mitochondrial F0F1-ATPase. Proliferation of CEM/VLB100 cells was significantly decreased compared to parental CEM cells, and was independent of p53 expression. Thus, we conclude that: (1) IR spectroscopy is a potential powerful technique for detecting mtDNA, protein and lipid contents simultaneously; (2) leukaemic cells mainly rely on mtDNA for energy; (3) increased expression of an ATP-dependent membrane efflux pump such as Pgp may up-regulate ATP generation and mtDNA content. These metabolic perturbations may exist merely to serve the efflux pump and do not result in an increase in leukaemic cell proliferation. In addition, the associated reduction in mitochondrial lipid and protein may contribute to sensitize the cells to cytochrome c release.
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PMID:Pgp-positive leukaemic cells have increased mtDNA but no increased rate of proliferation. 1060 95

Mitochondrial encephalomyopathies caused by mitochondrial DNA (mtDNA) defects are a genetically and phenotypically heterogeneous group of disorders. The site, percentage and distribution of mutations do not explain the overall clinical heterogeneity that is found. Apoptosis (programmed cell death) is an evolutionarily conserved mechanism that is essential for tissue development and homeostasis. Dysregulation of apoptosis has been implicated in the pathogenesis of various human diseases, such as cancer and autoimmune and neurodegenerative disorders. Recent in vitro evidence has indicated the central role of mitochondria in the apoptotic process. We investigated the occurrence of apoptosis in muscle biopsies of 36 patients carrying different mtDNA mutations and four patients with inclusion body myositis and mitochondrial abnormalities. Apoptotic features, mainly localized in cytochrome c oxidase-negative fibres, were observed in muscle fibres of patients carrying a high percentage of single mtDNA deletions (>40%) and of tRNA point mutations (>70%). By contrast, no apoptotic changes were observed in inclusion body myositis and in patients carrying mutations of mtDNA structural genes. Our study suggests that apoptosis is not simply a means whereby cells with dysfunctional mitochondria are eliminated, but that it seems to play a role in the pathogenesis of mitochondrial disorders associated with mtDNA defects affecting mitochondrial protein synthesis. The imbalance and relative abundances of nuclear-encoded and mtDNA-encoded subunits may favour cytochrome c inactivation and release. Cytochrome c, together with respiratory chain dysfunction, could activate apoptotic pathways that, in turn, inhibit the rate of mitochondrial translation and the importation of nuclear-encoded mitochondrial protein precursors. This vicious circle may amplify the biochemical defects and tissue damage and contribute to the modulation of clinical features.
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PMID:Apoptosis in mitochondrial encephalomyopathies with mitochondrial DNA mutations: a potential pathogenic mechanism. 1061 Nov 24

Flavoprotein reductases play a key role in electron transfer in many physiological processes. We have isolated a cDNA with strong sequence similarities to cytochrome P-450 reductase and nitric-oxide synthase. The cDNA encodes a protein of 597 amino acid residues with a predicted molecular mass of 67 kDa. Northern blot analysis identified a predicted transcript of 3.0 kilobase pairs as well as a larger transcript at 6.0 kilobase pairs, and the gene was mapped to chromosome 9q34.3 by fluorescence in situ hybridization analysis. The amino acid sequence of the protein contained distinct FMN-, FAD-, and NADPH-binding domains, and in order to establish whether the protein contained these cofactors, the coding sequence was expressed in insect cells and purified. Recombinant protein bound FMN, FAD, and NADPH cofactors and exhibited a UV-visible spectrum with absorbance maxima at 380, 460, and 626 nm. The purified enzyme reduced cytochrome c, with apparent K(m) and k(cat) values of 21 microM and 1.3 s(-1), respectively, and metabolized the one-electron acceptors doxorubicin, menadione, and potassium ferricyanide. Immunoblot analysis of fractionated MCF7 cells with antibodies to recombinant NR1 showed that the enzyme is cytoplasmic and highly expressed in a panel of human cancer cell lines, thus indicating that this novel reductase may play a role in the metabolic activation of bioreductive anticancer drugs and other chemicals activated by one-electron reduction.
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PMID:Cloning and characterization of a novel human dual flavin reductase. 1062

The novel retinoid 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphtalene carboxylic acid (AHPN/CD437), a retinoic acid receptor (RAR)gamma activator, has been found to inhibit the growth and to induce apoptosis of a wide variety of malignant cell types including solid tumors and various leukemias. Interestingly, CD437 is able to induce apoptosis in some all-trans-retinoic acid (ATRA)-resistant models. In a number of experimental systems, the early apoptotic stage that precedes nuclear chromatinolysis consists in mitochondrial alterations, including a disruption of the inner mitochondrial transmembrane potential (delta(psi)m) mediated by the mitochondrial permeability transition (MPT). Similarly CD437 causes RPMI 8226, a human myeloma cell line, to undergo a rapid delta(psi)m disruption that precedes other apoptotic alterations such as the generation of reactive oxygen species and DNA fragmentation. The same sequence of events is observed during the CD437-induced apoptosis in L363, a RARgamma-negative human myeloma cell line, as well as RPMI 8226 cytoplasts (anucleate cells). Indeed, RPMI 8226 cells and cytoplasts manifest a similar degree in delta(psi)m loss, phosphatidylserine exposure, and caspase activation in response to CD437, which indicates that nuclear effects cannot account for the apoptogenic potential of CD437. The mitochondrial release of cytochrome c, the activation of caspases as well as nuclear signs of CD437-induced apoptosis are fully prevented by the MPT inhibitory compound cyclosporin A. Purified mitochondria can be directly induced to undergo MPT with CD437 but not with ATRA. In a cell-free in vitro system consisting of exposing mitochondrial supernatants to isolated nuclei, only supernatants from CD437-treated mitochondria provoke chromatin condensation, whereas supernatants from mitochondria treated with ATRA, or with the combination of CD437 and cyclosporin A, remain inactive. In conclusion, these results suggest that the rapid execution of CD437-induced apoptosis is a nucleus-independent (and probably RARgamma-independent) phenomenon involving mitochondria and MPT.
Cancer Res 1999 Dec 15
PMID:The novel retinoid 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphtalene carboxylic acid can trigger apoptosis through a mitochondrial pathway independent of the nucleus. 1062 21

The tyrphostin AG957 (NSC 654705) inhibits p210bcr/abl, the transforming kinase responsible for most cases of chronic myelogenous leukemia (CML). The present studies were performed to determine the fate of AG957-treated cells and assess the selectivity of AG957 for CML myeloid progenitors. When K562 cells (derived from a patient with blast crisis CML) were treated with AG957, dose- and time-dependent p210bc/abl down-regulation was followed by mitochondrial release of cytochrome c, activation of caspase-9 and caspase-3, and apoptotic morphological changes. These apoptotic changes were inhibited by transfection with cDNA encoding dominant negative caspase-9 but not dominant-negative FADD or blocking anti-Fas antibodies. In additional experiments, a 24-h AG957 exposure caused dose-dependent inhibition of K562 colony formation in soft agar. To extend these studies to clinical samples of CML, peripheral blood mononuclear cells from 10 chronic phase CML patients and normal controls were assayed for the growth of hematopoietic colonies in vitro in the presence of increasing concentrations of AG957. These assays demonstrated selectivity of AG957 for CML progenitors, with median IC50s (CML versus normal) of 7.3 versus >20 microM AG957 in granulocyte colony-forming cells (P < 0.001), 5.3 versus >20 microM in granulocyte/macrophage colony-forming cells (P < 0.05), and 15.5 versus > 20 microM in erythroid colony-forming cells (P > 0.05). The adamantyl ester of AG957 (NSC 680410) down-regulated p210bcr/abl in K562 cells and inhibited granulocyte colony formation in CML specimens at lower concentrations without enhanced toxicity in normal progenitors. These observations not only demonstrate that AG957-induced p210bcr/abl down-regulation is followed by activation of the cytochrome c/Apaf-1/caspase-9 pathway but also indicate that this class of kinase inhibitor exhibits selectivity worthy of further evaluation.
Clin Cancer Res 2000 Jan
PMID:Effects of the bcr/abl kinase inhibitors AG957 and NSC 680410 on chronic myelogenous leukemia cells in vitro. 1065 55


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