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1.
Microbes Environ ; 25(2): 95-102, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21576859

RESUMO

Tetraheme cytochrome c-554 is a physiological electron acceptor of hydroxylamine oxidoreductase (HAO), a core enzyme of ammonia oxidation in chemoautotrophic nitrifiers. Here we report the purification of cytochrome c-554 from Nitrosococcus oceani strain NS58, a marine gammaproteobacterial ammonia-oxidizing bacterium. The NS58 cytochrome is a 25 kDa-protein having four hemes c. The absorption spectrum of the cytochrome showed peaks at 420 nm, 523 nm, and 554 nm, with shoulders at around 430 nm and 580 nm in the reduced state. In contrast to the highly basic counterpart from the betaproteobacterium Nitrosomonas europaea, the NS58 cytochrome c-554 was an acidic protein whose isoelectric point was 4.6. HAO was also purified, and the reaction with the NS58 cytochrome was found to be salt-tolerant. Compared with the activity observed in a non-salt solution, 60% of the activity remained in a saline concentration comparable to that of seawater.


Assuntos
Chromatiaceae/efeitos dos fármacos , Chromatiaceae/enzimologia , Grupo dos Citocromos c/metabolismo , Oxirredutases/metabolismo , Cloreto de Sódio/farmacologia , Sequência de Aminoácidos , Amônia/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/efeitos dos fármacos , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Catálise , Chromatiaceae/genética , Chromatiaceae/metabolismo , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/genética , Grupo dos Citocromos c/isolamento & purificação , DNA Bacteriano/isolamento & purificação , DNA Ribossômico/química , DNA Ribossômico/genética , Transporte de Elétrons , Heme/química , Cinética , Microscopia Eletrônica de Transmissão , Modelos Moleculares , Dados de Sequência Molecular , Oxirredução , Oxirredutases/efeitos dos fármacos , Oxirredutases/genética , Oxirredutases/isolamento & purificação , Filogenia , RNA Ribossômico 16S/genética , Tolerância ao Sal , Água do Mar/microbiologia , Alinhamento de Sequência , Análise de Sequência de DNA , Espectrofotometria
2.
Arch Biochem Biophys ; 436(1): 154-60, 2005 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-15752720

RESUMO

Despite extensive investigations on the acid-unfolded and acid/salt-induced molten globule(-like) states of cytochrome c using variety of techniques, structural features of the acid-unfolded state in terms of residual secondary structures and the structural transition between the acid-unfolded and acid/salt-refolded states have not been fully characterized beyond the circular dichroism (CD) spectroscopy. It is unusual that secondary structure(s) of the unfolded state leading to the molten globule state, an important protein folding intermediate, as determined by CD was not fully corroborated by independent experimental method(s). In this study, we carried out an equilibrium titration of acid-induced unfolding and subsequent acid- and salt-induced refolding of cytochrome c using Fourier transform infrared spectroscopy. The spectral profiles of the equilibrium titration reveal new structural details about the acid-unfolded state and the structural transition associated with the acid/salt-refolded molten globule(-like) states of cytochrome c.


Assuntos
Grupo dos Citocromos c/química , Ácido Clorídrico/farmacologia , Dobramento de Proteína , Sais/farmacologia , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Relação Dose-Resposta a Droga , Concentração de Íons de Hidrogênio , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Titulometria
3.
Am J Pathol ; 163(5): 2053-63, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-14578204

RESUMO

Calmodulin (CaM) antagonists have been shown to inhibit tumor cell invasion and metastasis and to induce apoptosis in various tumor models, but the molecular mechanism of CaM antagonist-mediated apoptosis is poorly understood. Here, we demonstrate that interferon (IFN)-gamma induces susceptibility to CaM antagonist-mediated apoptosis in human cholangiocarcinoma cells weakly expressing Fas (Fas-low cells). During CaM antagonist-mediated apoptosis in IFN-gamma-pretreated Fas-low cells, cleavage of caspases-8, -9, and -3 and Bid, release of cytochrome c from the mitochondria and an increase in the free cytosolic calcium concentration were observed. CaM antagonists also caused depolarization of the mitochondrial membrane independent of caspase activation. Although a broad-range caspase inhibitor partially blocked CaM antagonist-mediated apoptosis, the neutralizing Fas antibody had no effect, suggesting that CaM antagonist-mediated apoptosis does not require interaction between CaM antagonists and surface Fas. CaM antagonists induce apoptosis via mechanisms other than inhibition of CaM-dependent protein kinase II and calcineurin, as their inhibitors, KN93 and cyclosporine A, had no effect on apoptosis. Taken together, these results indicate that CaM antagonists induce apoptosis in both caspase-dependent and -independent manners, and that susceptibility to CaM antagonists is modulated by IFN-gamma. The combination of IFN-gamma and CaM antagonists, including tamoxifen, may be a potential therapeutic modality for cholangiocarcinoma and possibly other malignancies.


Assuntos
Apoptose/efeitos dos fármacos , Calmodulina/antagonistas & inibidores , Caspases/metabolismo , Interferon gama/farmacologia , Proteína Agonista de Morte Celular de Domínio Interatuante com BH3 , Western Blotting , Proteínas de Transporte/efeitos dos fármacos , Proteínas de Transporte/metabolismo , Inibidores de Caspase , Linhagem Celular Tumoral , Colangiocarcinoma/metabolismo , Colangiocarcinoma/patologia , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Inibidores Enzimáticos/farmacologia , Humanos , Potenciais da Membrana/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Receptor fas/genética
4.
Oncogene ; 22(40): 6220-30, 2003 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-13679861

RESUMO

N-(4-hydroxyphenyl)retinamide (4-HPR, fenretinide) is a potent chemopreventive agent whose effect has been suggested to involve apoptosis induction. 4-HPR induces a loss of the mitochondrial transmembrane potential and the mitochondrial release of cytochrome c before caspase activation. Inhibition of mitochondrial membrane permeabilization (MMP) by transfection with Bcl-2 or the Cytomegalovirus UL37 gene product vMIA prevented caspase activation and cell death. In contrast to other retinoid derivatives, 4-HPR has no direct MMP-inducing effects when added to isolated mitochondria or when added to proteoliposomes containing the MMP-regulatory permeability transition pore complex (PTPC). Moreover, although reactive oxygen species (ROS) overproduction appears to be instrumental for 4-HPR-induced MMP and apoptosis, inhibition of the NF-kappaB or p53-mediated signal transduction pathways failed to modulate 4-HPR-induced apoptosis. 4-HPR was found to cause an antioxidant-inhibitable conformational change of both Bax and Bak, leading to the exposure of their N-termini and to the mitochondrial relocalization of Bax. Cells with a Bax(-/-) Bak(-/-) genotype were resistant against the 4-HPR-induced MMP, overproduction of ROS and cell death. Altogether, these data indicate that 4-HPR induces MMP through an ROS-mediated pathway that involves the obligatory contribution of the proapopotic Bcl-2 family members Bax and/or Bak.


Assuntos
Anticarcinógenos/farmacologia , Apoptose/efeitos dos fármacos , Fenretinida/farmacologia , Mitocôndrias/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Inibidores de Caspase , Caspases/metabolismo , Grupo dos Citocromos c/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Células HeLa , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Mitocôndrias/efeitos dos fármacos , Permeabilidade/efeitos dos fármacos , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Transdução de Sinais , Células Tumorais Cultivadas , Proteína Killer-Antagonista Homóloga a bcl-2 , Proteína X Associada a bcl-2
5.
Oncogene ; 22(40): 6231-42, 2003 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-13679862

RESUMO

Effects of the PI-3 kinase inhibitor LY294002 (LY) have been examined in relation to responses of human leukemia cells to histone deacetylase inhibitors (HDIs). Coexposure of U937 cells for 24 h to marginally toxic concentrations of LY294002 (e.g., 30 microM) and sodium butyrate (SB; 1 mM) resulted in a marked increase in mitochondrial damage (e.g., cytochrome c and Smac/DIABLO release, loss of DeltaPsi(m)), caspase activation, and apoptosis. Similar results were observed in Jurkat, HL-60, and K562 leukemic cells and with other HDIs (e.g., SAHA, MS-275). Exposure of cells to SB/LY was associated with Bcl-2 and Bid cleavage, XIAP and Mcl-1 downregulation, and diminished CD11b expression. While LY blocked SB-mediated Akt activation, enforced expression of a constitutively active (myristolated) Akt failed to attenuate SB/LY-mediated lethality. Unexpectedly, treatment of cells with SB+/-LY resulted in a marked reduction in phosphorylation (activation) of p44/42 mitogen-activated protein (MAP) kinase. Moreover, enforced expression of a constitutively active MEK1 construct partially but significantly attenuated SB/LY-induced apoptosis. Lastly, cotreatment with LY blocked SB-mediated induction of p21(CIP1/WAF1); moreover, enforced expression of p21(CIP1/WAF1) significantly reduced SB/LY-mediated apoptosis. Together, these findings indicate that LY promotes SB-mediated apoptosis through an AKT-independent process that involves MEK/MAP kinase inactivation and interference with p21(CIP1/WAF1) induction.


Assuntos
Apoptose/efeitos dos fármacos , Ciclinas/metabolismo , Inibidores de Histona Desacetilases , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Inibidores de Fosfoinositídeo-3 Quinase , Benzamidas/farmacologia , Butiratos/farmacologia , Cromonas/farmacologia , Complexo de Ataque à Membrana do Sistema Complemento , Proteínas do Sistema Complemento , Inibidor de Quinase Dependente de Ciclina p21 , Grupo dos Citocromos c/efeitos dos fármacos , Sinergismo Farmacológico , Inibidores Enzimáticos/farmacologia , Glicoproteínas/efeitos dos fármacos , Células HL-60 , Humanos , Células Jurkat , Células K562 , Leucemia Mielogênica Crônica BCR-ABL Positiva/enzimologia , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Mitocôndrias/efeitos dos fármacos , Morfolinas/farmacologia , Proteínas de Plantas , Piridinas/farmacologia , Células U937
6.
J Cell Biol ; 162(6): 1031-43, 2003 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-12975347

RESUMO

We examined the temporal and causal relationship between Smac/DIABLO release, cytochrome c (cyt-c) release, and caspase activation at the single cell level during apoptosis. Cells treated with the broad-spectrum caspase inhibitor z-VAD-fmk, caspase-3 (Casp-3)-deficient MCF-7 cells, as well as Bax-deficient DU-145 cells released Smac/DIABLO and cyt-c in response to proapoptotic agents. Real-time confocal imaging of MCF-7 cells stably expressing Smac/DIABLO-yellow fluorescent protein (YFP) revealed that the average duration of Smac/DIABLO-YFP release was greater than that of cyt-c-green fluorescent protein (GFP). However, there was no significant difference in the time to the onset of release, and both cyt-c-GFP and Smac/DIABLO-YFP release coincided with mitochondrial membrane potential depolarization. We also observed no significant differences in the Smac/DIABLO-YFP release kinetics when z-VAD-fmk-sensitive caspases were inhibited or Casp-3 was reintroduced. Simultaneous measurement of DEVDase activation and Smac/DIABLO-YFP release demonstrated that DEVDase activation occurred within 10 min of release, even in the absence of Casp-3.


Assuntos
Apoptose/fisiologia , Proteínas de Transporte/metabolismo , Células Eucarióticas/metabolismo , Proteínas Mitocondriais/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2 , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose , Proteínas de Bactérias , Proteínas de Transporte/efeitos dos fármacos , Caspase 3 , Inibidores de Caspase , Caspases/deficiência , Caspases/genética , Caspases/metabolismo , Linhagem Celular , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Inibidores Enzimáticos/farmacologia , Células Eucarióticas/citologia , Células Eucarióticas/efeitos dos fármacos , Proteínas de Fluorescência Verde , Células HeLa , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas Luminescentes , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Proteínas Mitocondriais/efeitos dos fármacos , Peptídeo Hidrolases/efeitos dos fármacos , Peptídeo Hidrolases/metabolismo , Proteínas Proto-Oncogênicas/deficiência , Proteínas Proto-Oncogênicas/genética , Fatores de Tempo , Proteína X Associada a bcl-2
7.
Biochim Biophys Acta ; 1642(1-2): 79-85, 2003 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-12972296

RESUMO

Glucocorticoids are widely used as anti-inflammatory and chemotherapeutic agents. However, prolonged use of glucocorticoids leads to osteoporosis. This study was designed to examine the mechanism of dexamethasone (DEX)-induced apoptosis in murine osteoblastic MC3T3-E1 cells. Total RNA was extracted from MC3T3-E1 cells treated with 10(-7) M DEX for 6 h. DEX exerted a variety of effects on apoptotic gene expression in osteoblasts. Ribonuclease protection assays (RPA) revealed that DEX upregulated mRNA levels of caspases-1, -3, -6, -8, -11, -12, and bcl-XL. Western blot analysis showed enhanced processing of these caspases, with the appearance of their activated enzymes 8 h after DEX treatment. In addition, DEX also induced the activation of caspase-9. DEX elevated the levels of cleaved poly(ADP-ribose) polymerase and lamin A, a caspase-3 and a caspase-6 substrate, respectively. Expression of bcl-XL protein level was upregulated by DEX. Cytochrome c release was detected in the cytosol of DEX-treated cells. Furthermore, caspase-3 enzyme activity was elevated by 2-fold after DEX treatment for 7 h. Finally, early apoptotic cells were detected in cells treated with DEX for 3 h. Our results demonstrate that DEX-induced apoptosis involves gene activation of a number of caspases.


Assuntos
Apoptose/efeitos dos fármacos , Caspases/genética , Dexametasona/farmacologia , Indução Enzimática/efeitos dos fármacos , Osteoblastos/efeitos dos fármacos , Animais , Apoptose/fisiologia , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/genética , Lamina Tipo A/efeitos dos fármacos , Lamina Tipo A/metabolismo , Camundongos , Osteoblastos/enzimologia , Osteoporose/induzido quimicamente , Osteoporose/enzimologia , Osteoporose/genética , Poli(ADP-Ribose) Polimerase-1 , Poli(ADP-Ribose) Polimerases , Proteínas/efeitos dos fármacos , Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/metabolismo , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologia , Ativação Transcricional , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/genética , Proteína bcl-X
8.
J Dent Res ; 82(10): 802-6, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14514760

RESUMO

15-deoxy-Delta(12,14)-prostaglandin J(2) (15-d-PGJ(2)) and troglitazone have been shown to induce apoptosis in several carcinoma cell lines. However, apoptotic signaling pathways of these agents are poorly understood. We tested the hypothesis that peroxisome proliferator-activated receptor-gamma ligands such as these two agents will induce caspase-mediated apoptosis in human oral squamous cell carcinomas (SCC). Treatment of these cell lines with 15-d-PGJ(2) or troglitazone decreased cell viability in a time- and dose-dependent manner. 15-d-PGJ(2), but not troglitazone, induced apoptosis, and this effect was time-dependent. Exposure of cells to 20 micro M of 15-d-PGJ(2) initiated early cytochrome c release, followed by late caspase activation. Furthermore, co-treatment with caspase inhibitors such as Z-VAD-FMK or Z-DEVD-FMK of oral SCC cells that had been treated with 20 micro M of 15-d-PGJ(2) blocked apoptosis. Our study demonstrates that treatment with 15-d-PGJ(2), but not troglitazone, induces apoptosis in human SCC cell lines, and 15-d-PGJ(2) appears to work through cytochrome c release and caspase activation.


Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Carcinoma de Células Escamosas/patologia , Cromanos/farmacologia , Fatores Imunológicos/farmacologia , Neoplasias Bucais/patologia , Prostaglandina D2/farmacologia , Tiazóis/farmacologia , Tiazolidinedionas , Clorometilcetonas de Aminoácidos/farmacologia , Análise de Variância , Antineoplásicos/administração & dosagem , Inibidores de Caspase , Caspases/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cromanos/administração & dosagem , Inibidores de Cisteína Proteinase/farmacologia , Grupo dos Citocromos c/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Humanos , Fatores Imunológicos/administração & dosagem , Oligopeptídeos/farmacologia , Prostaglandina D2/administração & dosagem , Prostaglandina D2/análogos & derivados , Transdução de Sinais/efeitos dos fármacos , Tiazóis/administração & dosagem , Fatores de Tempo , Troglitazona , Células Tumorais Cultivadas
9.
Stroke ; 34(10): 2489-94, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14500933

RESUMO

BACKGROUND AND PURPOSE: Ischemic injury and reperfusion increases superoxide (O2-) production and reduces the ability of neurons to scavenge free radicals, leading to the release of cytochrome c and apoptosis. Here we test whether overexpression with the use of gene therapy of the antioxidant glutathione peroxidase (Gpx), delivered before or after experimental stroke, is protective against ischemic injury. METHODS: Sixty-two rats underwent middle cerebral artery occlusion for 1 hour. Defective herpes simplex viral vectors expressing Gpx/lacZ or lacZ alone (control) were delivered into each striatum 12 hours before or 2 or 5 hours after ischemia onset. RESULTS: Striatal neuron survival at 2 days was improved by 36% when Gpx was delivered 12 hours before ischemia onset, 26% with a 2-hour delay, and 25% when delayed 5 hours. After ischemia, Gpx overexpression significantly reduced cytosolic translocation of cytochrome c and increased the proportion of Bcl-2-positive cells compared with cells transfected with control vector. Bax and activated caspase-3, while present in control-transfected neurons after ischemia, were rarely noted in Gpx-transfected cells. CONCLUSIONS: Expression from these herpes simplex viral vectors begins 4 to 6 hours after injection, which suggests a 9- to 11-hour temporal therapeutic window for Gpx. This is the first study to show that overexpression of Gpx with the use of gene therapy protects against experimental stroke, even with postischemic transfection, and the neuroprotective mechanism involves attenuation of apoptosis-related events.


Assuntos
Apoptose/fisiologia , Grupo dos Citocromos c/metabolismo , Glutationa Peroxidase/biossíntese , Neurônios/metabolismo , Acidente Vascular Cerebral/metabolismo , Animais , Apoptose/efeitos dos fármacos , Caspase 3 , Caspases/efeitos dos fármacos , Caspases/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Corpo Estriado/patologia , Grupo dos Citocromos c/efeitos dos fármacos , Citoproteção/genética , Modelos Animais de Doenças , Esquema de Medicação , Terapia Genética/métodos , Vetores Genéticos/administração & dosagem , Vetores Genéticos/genética , Glutationa Peroxidase/administração & dosagem , Glutationa Peroxidase/genética , Masculino , Neurônios/efeitos dos fármacos , Neurônios/patologia , Fármacos Neuroprotetores/administração & dosagem , Proteínas Proto-Oncogênicas/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Ratos Sprague-Dawley , Simplexvirus/genética , Acidente Vascular Cerebral/patologia , Acidente Vascular Cerebral/terapia , Fatores de Tempo , Proteína X Associada a bcl-2
10.
J Natl Cancer Inst ; 95(15): 1138-49, 2003 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-12902443

RESUMO

BACKGROUND: The incidence of nonmelanoma skin cancer, basal cell carcinomas (BCCs), and squamous cell carcinomas (SCCs) is increasing, representing a major medical and economic problem. Imiquimod, a topical small-molecule immune response modifier, has shown efficacy toward BCC and actinic keratoses in clinical trials. Imiquimod acts both indirectly, via cytokine-mediated stimulation of cellular immune responses, and directly, through unknown mechanisms against tumor cells. We examined the mechanism by which imiquimod induces apoptosis in cancer cells. METHODS: Apoptosis was assessed by enzyme-linked immunosorbent assay, western blot analysis, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays in five SCC cell lines, HaCaT cells (a spontaneously immortalized human keratinocyte cell line), and normal keratinocytes treated with imiquimod, with its analog resiquimod, or with neither. Expression of death receptors, caspases, and cytochrome c in the apoptotic signaling cascade was analyzed using western blot and flow cytometric analyses. The functional relevance of imiquimod-induced cytochrome c release was assessed by transfection of HaCaT cells with Bcl-2. Apoptosis in BCCs in vivo was assessed by TUNEL assays of imiquimod-treated and untreated tumors from three patients. Differences between treated and untreated cells and tumors were determined using a two-tailed Student's t test. RESULTS: Imiquimod, but not resiquimod, induced apoptosis in all SCC cell lines and HaCaT cells. This induction involved activation of several caspases and Bcl-2-dependent cytosolic translocation of cytochrome c but was independent of the membrane-bound death receptors Fas, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-R1-R4 receptors, and tumor necrosis factor-R1 and -R2 receptors. Topical application of imiquimod to BCC tumors in vivo induced apoptosis. CONCLUSION: Imiquimod has the potential to induce apoptosis in skin cancer cells, possibly by circumventing mechanisms developed by malignant tumors to resist apoptotic signals.


Assuntos
Aminoquinolinas/farmacologia , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/imunologia , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/imunologia , Imidazóis/farmacologia , Fatores Imunológicos/farmacologia , Western Blotting , Carcinoma Basocelular/tratamento farmacológico , Carcinoma Basocelular/imunologia , Carcinoma de Células Escamosas/metabolismo , Caspase 3 , Caspases/efeitos dos fármacos , Grupo dos Citocromos c/efeitos dos fármacos , Fragmentação do DNA/efeitos dos fármacos , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Imiquimode , Marcação In Situ das Extremidades Cortadas , Queratinócitos/efeitos dos fármacos , Queratinócitos/imunologia , Proteínas Proto-Oncogênicas c-bcl-2/efeitos dos fármacos , Receptores do Fator de Necrose Tumoral/efeitos dos fármacos , Células Tumorais Cultivadas , Regulação para Cima/efeitos dos fármacos
11.
Eur J Pharmacol ; 473(1): 1-7, 2003 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-12877931

RESUMO

In Parkinson's disease, neuroprotective therapy to rescue dopamine neurons has been proposed. Ginsenoside Rg1, one of the biologically active ingredients of ginseng, may be a candidate neuroprotective drug. In the present study, the mechanism underlying the neuroprotection provided by ginsenosde Rg1 was studied against apoptosis induced by exogenous dopamine in PC12 cells. Pretreatment with ginsenoside Rg1 markedly reduced the generation of dopamine-induced reactive oxygen species and the release of mitochondrial cytochrome c into the cytosol, and subsequently inhibited the activation of caspase-3. In addition, Rg1 pretreatment also reduced inducible nitric oxide (NO) synthase protein level and NO production. These results suggested that ginsenoside Rg1 may attenuate dopamine-induced apoptotic cell death through suppression of intracellular oxidative stress, and that it may rescue or protect dopamine neurons in Parkinson's disease.


Assuntos
Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Dopamina/metabolismo , Ginsenosídeos/farmacologia , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Animais , Western Blotting , Caspase 3 , Inibidores de Caspase , Caspases/metabolismo , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Fragmentação do DNA , Dopamina/farmacologia , Citometria de Fluxo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo II , Células PC12 , Panax/química , Ratos
12.
Oncogene ; 22(29): 4543-56, 2003 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-12881711

RESUMO

We have recently reported that the cytokine interferon-alpha (IFNalpha), commonly used in the treatment of cancer, induced a caspase-dependent apoptosis in tumor cell lines. The signaling mechanisms involved have not been defined. Here, we show that both proapoptotic Bcl-2 family members Bak and Bax were activated by IFNalpha, strictly in correlation with the induction of apoptosis. Using double stainings, we demonstrated that Bak was activated prior to cytochrome c (cyt c) release and caspase-3 activation, whereas activated Bax was only found in cells with released cyt c, mitochondrial depolarization, as well as activated caspase-3. Furthermore, IFNalpha-induced activation of Bak, and to a large extent also of Bax, was dependent on caspase activity. With the use of a panel of specific caspase inhibitors we found, however, that none of caspases-1 to -10 were responsible for this activation. Neither was the Ca(2+)-dependent protease calpain nor the stress-activated p38 SAPK pathway significantly involved. Overexpression of Bcl-2 blocked apoptosis induced by IFNalpha totally abolished Bak activation, as well as decreased the amount of activated Bax. We conclude that IFNalpha induces Bak and Bax activation via distinct mechanisms involving an unknown protease, and that their activation is regulated by Bcl-2.


Assuntos
Apoptose/efeitos dos fármacos , Linfoma de Burkitt/metabolismo , Interferon-alfa/farmacologia , Proteínas de Membrana/metabolismo , Mieloma Múltiplo/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Apoptose/fisiologia , Proteína Agonista de Morte Celular de Domínio Interatuante com BH3 , Linfoma de Burkitt/tratamento farmacológico , Linfoma de Burkitt/patologia , Calpaína/antagonistas & inibidores , Calpaína/metabolismo , Proteínas de Transporte/efeitos dos fármacos , Proteínas de Transporte/metabolismo , Inibidores de Caspase , Caspases/metabolismo , Inibidores de Cisteína Proteinase/farmacologia , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Inibidores Enzimáticos/farmacologia , Humanos , Potenciais da Membrana/efeitos dos fármacos , Proteínas de Membrana/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Mieloma Múltiplo/tratamento farmacológico , Mieloma Múltiplo/patologia , Proteínas Proto-Oncogênicas/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2/genética , Células Tumorais Cultivadas , Proteína Killer-Antagonista Homóloga a bcl-2 , Proteína X Associada a bcl-2 , Proteínas Quinases p38 Ativadas por Mitógeno
13.
Int J Mol Med ; 12(2): 247-52, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12851726

RESUMO

Various stimuli including anticancer drugs are capable of initiating the apoptotic death program in human tumor cells via activation of caspases. Mitochondria play an essential role for cell apoptotic commitment. Previous studies have shown a potential role of calpain activation in apoptosis, however, the involved molecular mechanisms remain to be defined. In the current study, we have examined the expression and activation of mitochondrial calpain in Jurkat T leukemia cells, MCF-7 breast carcinoma and LNCaP prostate cancer cells during apoptosis induced by an anticancer drug (VP-16, tamoxifen) or the specific p38 kinase inhibitor PD-169316. Our results suggest that increased expression and autolysis of the mitochondrial calpain small subunit are tightly associated with calpain activation in an early stage of apoptosis. In contrast, there were no correlations observed between the early calpain activation and changes in levels of mitochondrial calpain large subunit and the endogenous calpain inhibitor calpastatin. Furthermore, pretreatment with the specific pharmacological calpain inhibitor calpeptin blocked the drug-induced calpain small subunit autolysis and calpain activation in mitochondria and inhibited apoptosis-associated caspase-3 activation, demonstrating that mitochondrial calpain activation through small subunit cleavage is an essential step for inducing tumor cell apoptosis by various anticancer drugs.


Assuntos
Apoptose/fisiologia , Calpaína/metabolismo , Mitocôndrias/metabolismo , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Autólise , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Ativação Enzimática , Inibidores Enzimáticos/farmacologia , Etoposídeo/farmacologia , Feminino , Humanos , Imidazóis/farmacologia , Células Jurkat/efeitos dos fármacos , Masculino , Mitocôndrias/enzimologia , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Subunidades Proteicas , Tamoxifeno/farmacologia , Células Tumorais Cultivadas , Proteínas Quinases p38 Ativadas por Mitógeno
14.
Nat Cell Biol ; 5(7): 647-54, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12792650

RESUMO

Many pro-apoptotic signals activate caspase-9, an initiator protease that activates caspase-3 and downstream caspases to initiate cellular destruction. However, survival signals can impinge on this pathway and suppress apoptosis. Activation of the Ras-Raf-MEK-ERK mitogen-activated protein kinase (MAPK) pathway is associated with protection of cells from apoptosis and inhibition of caspase-3 activation, although the targets are unknown. Here, we show that the ERK MAPK pathway inhibits caspase-9 activity by direct phosphorylation. In mammalian cell extracts, cytochrome c-induced activation of caspases-9 and -3 requires okadaic-acid-sensitive protein phosphatase activity. The opposing protein kinase activity is overcome by treatment with the broad-specificity kinase inhibitor staurosporine or with inhibitors of MEK1/2. Caspase-9 is phosphorylated at Thr 125, a conserved MAPK consensus site targeted by ERK2 in vitro, in a MEK-dependent manner in cells stimulated with epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol-13-acetate (TPA). Phosphorylation at Thr 125 is sufficient to block caspase-9 processing and subsequent caspase-3 activation. We suggest that phosphorylation and inhibition of caspase-9 by ERK promotes cell survival during development and tissue homeostasis. This mechanism may also contribute to tumorigenesis when the ERK MAPK pathway is constitutively activated.


Assuntos
Apoptose/fisiologia , Caspases/metabolismo , Sobrevivência Celular/fisiologia , Transformação Celular Neoplásica/metabolismo , Células Eucarióticas/enzimologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Células 3T3 , Animais , Apoptose/efeitos dos fármacos , Sequência de Bases/genética , Caspase 3 , Caspase 9 , Sobrevivência Celular/efeitos dos fármacos , Transformação Celular Neoplásica/genética , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Inibidores Enzimáticos/farmacologia , Fator de Crescimento Epidérmico/farmacologia , Células Eucarióticas/efeitos dos fármacos , Células HeLa , Humanos , MAP Quinase Quinase 1 , Camundongos , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Dados de Sequência Molecular , Fosforilação/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Piridinas/farmacologia , Proteínas Recombinantes de Fusão , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Treonina/metabolismo
15.
Eur J Neurosci ; 17(6): 1189-96, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12670307

RESUMO

It is usually accepted that prion and amyloid-beta (A beta) peptides induce apoptotic cell death. However, the mechanisms that trigger neuronal death, induced by these amyloidogenic peptides, remain to be clarified. In the present study we analysed the neurotoxic effects of the synthetic prion and A beta peptides, PrP106-126 and A beta 25-35, in primary cultures of rat brain cortical cells. PrP106-126 and A beta 25-35 incubated at a concentration of 25 micro m for 24 h, did not affect cell membrane integrity, but decreased the metabolic capacity of the cells. The intracellular free Ca2+ concentration and reactive oxygen species levels increased significantly after 24 h treatment with PrP106-126 and A beta 25-35. Furthermore, these peptides (after 24 h exposure) also induced cytochrome c release from mitochondria and increased caspase-3-like activity. FK506, an inhibitor of the Ca2+/calmodulin-dependent phosphatase, calcineurin, was able to prevent cytochrome c release, caspase-3 activation and cell death induced by A beta 25-35 or PrP106-126 peptides. Taken together these data suggest that calcineurin is involved in A beta 25-35 and PrP106-126 neurotoxicity.


Assuntos
Peptídeos beta-Amiloides/toxicidade , Apoptose/efeitos dos fármacos , Encéfalo/metabolismo , Calcineurina/metabolismo , Neurônios/metabolismo , Neurotoxinas/toxicidade , Fragmentos de Peptídeos/toxicidade , Príons/toxicidade , Animais , Western Blotting , Encéfalo/efeitos dos fármacos , Inibidores de Calcineurina , Cálcio/metabolismo , Caspase 3 , Caspases/efeitos dos fármacos , Caspases/metabolismo , Técnicas de Cultura de Células , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Inibidores Enzimáticos/farmacologia , Imuno-Histoquímica , Peroxidação de Lipídeos/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neurônios/efeitos dos fármacos , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Tacrolimo/farmacologia
16.
Am J Physiol Cell Physiol ; 285(2): C353-69, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12686516

RESUMO

Reactive oxygen species (ROS) appear to play an important role in regulating growth and survival of prostate cancer. However, the sources for ROS production in prostate cancer cells have not been determined. We report that ROS are generated by intact American Type Culture Collection DU 145 cells and by their membranes through a mechanism blocked by NAD(P)H oxidase inhibitors. ROS are critical for growth in these cells, because NAD(P)H oxidase inhibitors and antioxidants blocked proliferation. Components of the human phagocyte NAD(P)H oxidase, p22phox and gp91phox, as well as the Ca2+ concentration-responsive gp91phox homolog NOX5 were demonstrated in DU 145 cells by RT-PCR and sequencing. Although the protein product for p22phox was not detectable, both gp91phox and NOX5 were identified throughout the cell by immunostaining and confocal microscopy and NOX5 immunostaining was enhanced in a perinuclear location, corresponding to enhanced ROS production adjacent to the nuclear membrane imaged by 2',7'-dichlorofluorescin diacetate oxidation. The calcium ionophore ionomycin dramatically stimulated ferricytochrome c reduction in cell media, further supporting the importance of NOX5 for ROS production. Antisense oligonucleotides for NOX5 inhibited ROS production and cell proliferation in DU 145 cells. In contrast, antisense oligonucleotides to p22phox or gp91phox did not impair cell growth. Inhibition of ROS generation with antioxidants or NAD(P)H oxidase inhibitors increased apoptosis in cells. These results indicate that ROS generated by the newly described NOX5 oxidase are essential for prostate cancer growth, possibly by providing trophic intracellular oxidant tone that retards programmed cell death.


Assuntos
Apoptose/genética , Carcinoma/enzimologia , Divisão Celular/genética , Proteínas de Membrana/metabolismo , NADPH Oxidases/metabolismo , Neoplasias da Próstata/enzimologia , Espécies Reativas de Oxigênio/metabolismo , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Transformação Celular Neoplásica/efeitos dos fármacos , Transformação Celular Neoplásica/metabolismo , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Inibidores Enzimáticos/farmacologia , Humanos , Ionóforos/farmacologia , Masculino , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/genética , NADPH Oxidase 2 , NADPH Oxidase 5 , NADPH Oxidases/antagonistas & inibidores , NADPH Oxidases/genética , Membrana Nuclear/metabolismo , Oligorribonucleotídeos Antissenso/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/fisiologia , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/metabolismo , Células Tumorais Cultivadas
17.
J Biol Chem ; 278(29): 26458-65, 2003 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-12702728

RESUMO

Trehalose, a naturally occurring osmolyte, is known to be an exceptional stabilizer of proteins and helps retain the activity of enzymes in solution as well as in the freeze-dried state. To understand the mechanism of action of trehalose in detail, we have conducted a thorough investigation of its effect on the thermal stability in aqueous solutions of five well characterized proteins differing in their various physico-chemical properties. Among them, RNase A has been used as a model enzyme to investigate the effect of trehalose on the retention of enzymatic activity upon incubation at high temperatures. 2 m trehalose was observed to raise the transition temperature, Tm of RNase A by as much as 18 degrees C and Gibbs free energy by 4.8 kcal mol-1 at pH 2.5. There is a decrease in the heat capacity of protein denaturation (DeltaCp) in trehalose solutions for all the studied proteins. An increase in the DeltaG and a decrease in the DeltaCp values for all the proteins points toward a general mechanism of stabilization due to the elevation and broadening of the stability curve (DeltaG versus T). A direct correlation of the surface tension of trehalose solutions and the thermal stability of various proteins has been observed. Wyman linkage analysis indicates that at 1.5 m concentration 4-7 molecules of trehalose are excluded from the vicinity of protein molecules upon denaturation. We further show that an increase in the stability of proteins in the presence of trehalose depends upon the length of the polypeptide chain. The pH dependence data suggest that even though the charge status of a protein contributes significantly, trehalose can be expected to work as a universal stabilizer of protein conformation due to its exceptional effect on the structure and properties of solvent water compared with other sugars and polyols.


Assuntos
Excipientes/farmacologia , Proteínas/química , Proteínas/efeitos dos fármacos , Trealose/farmacologia , Animais , Bovinos , Fenômenos Químicos , Físico-Química , Quimotripsinogênio/química , Quimotripsinogênio/efeitos dos fármacos , Quimotripsinogênio/metabolismo , Grupo dos Citocromos c/química , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Estabilidade de Medicamentos , Estabilidade Enzimática/efeitos dos fármacos , Técnicas In Vitro , Cinética , Muramidase/química , Muramidase/efeitos dos fármacos , Muramidase/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Desnaturação Proteica/efeitos dos fármacos , Proteínas/metabolismo , Ribonuclease Pancreático/química , Ribonuclease Pancreático/efeitos dos fármacos , Ribonuclease Pancreático/metabolismo , Soluções , Tensão Superficial , Temperatura , Termodinâmica , Inibidores da Tripsina , alfa-Amilases/antagonistas & inibidores
18.
Proc Natl Acad Sci U S A ; 100(7): 3838-40, 2003 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-12646702

RESUMO

The kinetics of electron transfer from the triplet-excited Zn-porphyrin to a Ru(NH(3))(5)(His-33)(3+) complex have been measured in Zn-substituted ruthenium-modified cytochrome c under denaturing conditions. In the folded protein, the electron-tunneling rate constant is 7.5 x 10(5) s(-1). As the protein is denatured with guanidine hydrochloride, a faster adiabatic electron-transfer reaction appears (4.0 x 10(6) s(-1), [guanidine hydrochloride] = 5.4 M) that is limited by the rate of intrachain diffusion to bring the Zn-porphyrin and Ru complex into contact. The 250-ns contact time for formation of a 15-residue loop in denatured cytochrome c is in accord with a statistical model developed by Camacho and Thirumalai [Camacho, C. J. & Thirumalai, D. (1995) Proc. Natl. Acad. Sci. USA 92, 1277-1281] that predicts that the most probable transient loops formed in denatured proteins are comprised of 10 amino acids. Extrapolation of the cytochrome c contact time to a 10-residue loop sets the folding speed limit at approximately 10(7) s(-1).


Assuntos
Grupo dos Citocromos c/química , Grupo dos Citocromos c/metabolismo , Citocromos c , Compostos Organometálicos/química , Compostos Organometálicos/metabolismo , Grupo dos Citocromos c/efeitos dos fármacos , Transporte de Elétrons , Guanidina , Histidina , Cinética , Substâncias Macromoleculares , Metaloporfirinas/química , Metaloporfirinas/metabolismo , Modelos Moleculares , Conformação Proteica , Desnaturação Proteica , Dobramento de Proteína , Estrutura Terciária de Proteína , Rutênio , Sacarose/farmacologia , Fatores de Tempo , Zinco
19.
Urology ; 61(3): 646-50, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12639677

RESUMO

OBJECTIVES: We have previously demonstrated that cocaine exposure leads to apoptosis in rat testes. To understand further the mechanism of cocaine-induced testicular damage, we studied the effect of cocaine on cytochrome c release from the mitochondria. We also determined the caspase 3, caspase 8, and caspase 9 activities in rat testes after chronic cocaine exposure. METHODS: Thirty-day-old male Sprague-Dawley rats received cocaine hydrochloride or equal volumes of normal saline subcutaneously daily for 90 days. The testes were removed at 15, 30, and 90 days of cocaine or saline administration. Mitochondria and cytosolic fractions from testes were isolated. Western blotting was performed in both fractions using anti-cytochrome c antibody. Caspase 3, caspase 8, and caspase 9 activities were determined by fluorometric assay. RESULTS: The expression of cytochrome c protein in the cytosolic fraction was increased on day 15 and persisted for up to 90 days after cocaine injection compared with controls. However, the expression of cytochrome c in testes was decreased in the mitochondria fraction on days 15, 30, and 90 after cocaine injections compared with the corresponding controls. The caspase activity study showed caspase 3 and caspase 9 activities increased in cocaine-treated testes at each point of the study compared with the corresponding controls. However, the caspase 8 activity in cocaine-treated testes did not change significantly at each point of the study compared with the corresponding controls. CONCLUSIONS: Our results suggest that the release of cytochrome c from mitochondria and its subsequent activation of caspase 9 and caspase 3 in testes play a key role in cocaine-induced germ cell apoptosis. Our findings also indicate that cocaine-induced testicular germ cell apoptosis in rats is at least initiated through a mitochondria-associated pathway.


Assuntos
Apoptose/efeitos dos fármacos , Cocaína/farmacologia , Grupo dos Citocromos c/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Testículo/efeitos dos fármacos , Testículo/enzimologia , Animais , Western Blotting , Caspase 3 , Caspase 8 , Caspase 9 , Caspases/metabolismo , Grupo dos Citocromos c/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Fluorometria , Masculino , Mitocôndrias/metabolismo , Modelos Animais , Ratos , Ratos Sprague-Dawley , Espermatozoides/efeitos dos fármacos , Espermatozoides/enzimologia , Espermatozoides/metabolismo , Testículo/metabolismo
20.
Blood ; 101(3): 1080-6, 2003 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-12393561

RESUMO

Low-risk myelodysplastic syndromes (MDS), including refractory anemia and sideroblastic anemia, are characterized by increased apoptotic death of erythroid progenitors. The signaling pathways that elicit this pathologic cell death in MDS have, however, remained unclear. Treatment with erythropoietin in combination with granulocyte colony-stimulating factor (G-CSF) may synergistically improve the anemia in patients with MDS, with a concomitant decrease in the number of apoptotic bone marrow precursors. Moreover, we have previously reported that G-CSF inhibits Fas-induced caspase activation in sideroblastic anemia (RARS). The present data demonstrate that almost 50% of erythroid progenitor cells derived from patients with MDS exhibit spontaneous release of cytochrome c from mitochondria with ensuing activation of caspase-9, whereas normal erythroid progenitors display neither of these features. G-CSF significantly inhibited cytochrome c release and suppressed apoptosis, most noticeably in cells from patients with sideroblastic anemia. Furthermore, inhibition of caspase-9 suppressed both spontaneous and Fas-mediated apoptosis of erythroid progenitors in all low-risk MDS cases studied. We propose that the increased sensitivity of MDS progenitor cells to death receptor stimulation is due to a constitutive activation of the mitochondrial axis of the apoptotic signaling pathway in these cells. These studies yield a mechanistic explanation for the beneficial clinical effects of growth factor administration in patients with MDS, and provide a model for the study of growth factor-mediated suppression of apoptosis in other bone marrow disorders.


Assuntos
Apoptose/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Fator Estimulador de Colônias de Granulócitos/farmacologia , Mitocôndrias/fisiologia , Síndromes Mielodisplásicas/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Inibidores de Caspase , Grupo dos Citocromos c/efeitos dos fármacos , Células Precursoras Eritroides/efeitos dos fármacos , Células Precursoras Eritroides/patologia , Células-Tronco Hematopoéticas/efeitos dos fármacos , Células-Tronco Hematopoéticas/patologia , Humanos , Pessoa de Meia-Idade , Mitocôndrias/metabolismo , Transdução de Sinais/efeitos dos fármacos , Receptor fas/farmacologia
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