RESUMEN
Se presentó a la Cátedra de Endodoncia de la Facultad de Odontología de la Universidad de Buenos Aires un paciente masculino de 62 años de edad que al examen clínico presentaba una fístula vestibular en la zona de la pieza 1.2 y dolor a la percusión. Al examen radiográ-fico se identificó una lesión apical extensa abarcando las piezas dentarias 1.2 y 1.1 endodónticamente trata-das con alteración severa de la anatomía del espacio endodóntico, así como la presencia de postes metáli-cos que no respetaban el eje del canal radicular. Ante el análisis tomográfico se observó una perforación de la pieza 1.2 y una lesión periapical extensa afectando ambas corticales (vestibular y palatina). Se decidió un abordaje microquirúrgico con técnicas de regenera-ción ósea guiada (ROG) y se realizaron los controles clínico-tomográficos a los 6, 12 y 24 meses. Por otro lado, se evaluó con micromografía de rayos X la ana-tomía de los ápices radiculares resecados. La lesión extirpada fue analizada histológicamente (AU)
A 62-year-old male patient attended the Endodontics department of the Buenos Aires University. He was examined clinically and a vestibular fistula in 1.2 area and pain under percussion were found. Radiographic examination identified an extended periapical lesion compromising teeth 1.2 and 1.1 with endodontic treatment severely altering the root canal anatomy, as well as metallic cast posts that did not preserve root canal axis. Regarding the tomographic analysis, a vestibular root perforation was observed (1.2), and both, vestibular and palatal corticals, were affected. We decided to perform a surgical approach with guided bone regeneration techniques (GBR). Clinical-CBCT controls were done at 6, 12 and 24 months. Furthermore, the anatomy of the resected root apex-es was evaluated with X ray microtomography. The removed lesion was histologically analyzed (AU)
Asunto(s)
Humanos , Masculino , Persona de Mediana Edad , Periodontitis Periapical/cirugía , Argentina , Facultades de Odontología , Tomografía Computarizada de Haz Cónico/métodos , Membranas ArtificialesRESUMEN
We measure the quantum speed of the state evolution of the field in a weakly driven optical cavity QED system. To this end, the mode of the electromagnetic field is considered as a quantum system of interest with a preferential coupling to a tunable environment: the atoms. By controlling the environment, i.e., changing the number of atoms coupled to the optical cavity mode, an environment-assisted speed-up is realized: the quantum speed of the state repopulation in the optical cavity increases with the coupling strength between the optical cavity mode and this non-Markovian environment (the number of atoms).
RESUMEN
BACKGROUND: Cancer cell killing might be achieved by the combined use of available drugs. Statins are major anti-hypercholesterolemia drugs, which also trigger apoptosis of many cancer cell types, while docetaxel is a potent microtubule-stabilising agent. METHODS: Here, we looked at the combined effects of lovastatin and docetaxel in cancer cells. RESULTS: Whole transcriptome microarrays in HGT-1 gastric cancer cells demonstrated that lovastatin strongly suppressed expression of genes involved in cell division, while docetaxel had very little transcriptional effects. Both drugs triggered apoptosis, and their combination was more than additive. A marked rise in the cell-cycle inhibitor p21, together with reduction of aurora kinases A and B, cyclins B1 and D1 proteins was induced by lovastatin alone or in combination with docetaxel. The drug treatments induced the proteolytic cleavage of procaspase-3, a drop of the anti-apoptotic Mcl-1 protein, Poly-ADP-Ribose Polymerase and Bax. Strikingly, docetaxel-resistant HGT-1 cell derivatives overexpressing the MDR-1 gene were much more sensitive to lovastatin than docetaxel-sensitive cells. CONCLUSION: These results suggest that the association of lovastatin and docetaxel, or lovastatin alone, shows promise as plausible anticancer strategies, either as a direct therapeutic approach or following acquired P-glycoprotein-dependent resistance.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Apoptosis/efectos de los fármacos , Lovastatina/administración & dosificación , Taxoides/administración & dosificación , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Ciclo Celular/efectos de los fármacos , Línea Celular , Línea Celular Tumoral , Docetaxel , Resistencia a Medicamentos/efectos de los fármacos , Resistencia a Medicamentos/inmunología , Sinergismo Farmacológico , Humanos , Lovastatina/farmacología , Análisis por Micromatrices , Proteolisis , Taxoides/farmacologíaRESUMEN
Supplies of marine fish oils are limited, and continued growth in aquaculture production dictates that lipid substitutes in fish diets must be used without compromising fish health and product quality. In this study, the total substitution of a fish meal and fish oil by a blend of vegetable meals (corn, soybean, wheat and lupin) and linseed oil in the diet of European sea bass (Dicentrachus labrax) was investigated. Two groups of European sea bass were fed with fish diet (FD) or vegetable diet (VD) for 9months. VD, totally deprived of eicosapentaenoate (EPA; 20:5n-3) and docosahexaenoate (DHA; 22:6n-3), revealed a nutritional deficiency and affected growth performance. Whilst VD induced a significant increase in fatty acid desaturase 2 (FADS2) and sterol binding regulatory element-binding protein 1 (SREBP-1) mRNA levels, the desaturation rate of [1-(14)C]18:3n-3 into [1-(14)C]18:4n-3, analysed in microsomal preparations using HPLC method, did not show an upregulation of FADS2 activities in liver and intestine of fish fed VD. Moreover Western-blot analysis did not revealed any significant difference of FADS2 protein amount between the two dietary groups. These data demonstrate that sea bass exhibits a desaturase (FADS2) activity whatever their diet, but a post-transcriptional regulation of fads2 RNA prevents an increase of enzyme in fish fed a HUFA-free diet. This led to a lower fish growth and poor muscle HUFA content.
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Lubina/metabolismo , Dieta , Ácido Graso Desaturasas/metabolismo , Proteínas de Peces/metabolismo , Alimentación Animal , Animales , Acuicultura , Lubina/genética , Lubina/crecimiento & desarrollo , Ácido Graso Desaturasas/genética , Ácidos Grasos/análisis , Proteínas de Peces/genética , Regulación de la Expresión Génica , Intestinos/enzimología , Hígado/enzimología , PPAR alfa/genética , PPAR alfa/metabolismo , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/genética , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/metabolismo , VerdurasRESUMEN
The transcription factor E2F1 has a key function during S phase progression and apoptosis. It has been well-demonstrated that the apoptotic function of E2F1 involves its ability to transactivate pro-apoptotic target genes. Alternative splicing of pre-mRNAs also has an important function in the regulation of apoptosis. In this study, we identify the splicing factor SC35, a member of the Ser-Rich Arg (SR) proteins family, as a new transcriptional target of E2F1. We demonstrate that E2F1 requires SC35 to switch the alternative splicing profile of various apoptotic genes such as c-flip, caspases-8 and -9 and Bcl-x, towards the expression of pro-apoptotic splice variants. Finally, we provide evidence that E2F1 upregulates SC35 in response to DNA-damaging agents and show that SC35 is required for apoptosis in response to these drugs. Taken together, these results demonstrate that E2F1 controls pre-mRNA processing events to induce apoptosis and identify the SC35 SR protein as a key direct E2F1-target in this setting.
Asunto(s)
Empalme Alternativo/genética , Apoptosis/genética , Factor de Transcripción E2F1/metabolismo , Proteínas Nucleares/genética , Ribonucleoproteínas/genética , Regulación hacia Arriba/genética , Empalme Alternativo/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Proteína Reguladora de Apoptosis Similar a CASP8 y FADD/metabolismo , Caspasa 8/metabolismo , Caspasa 9/metabolismo , Línea Celular Tumoral , Ciclofosfamida/farmacología , Daño del ADN , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Ratones , Proteínas Nucleares/metabolismo , Unión Proteica/efectos de los fármacos , Precursores del ARN/metabolismo , Ribonucleoproteínas/metabolismo , Factores de Empalme Serina-Arginina , Transcripción Genética/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacos , Proteína bcl-X/genética , Proteína bcl-X/metabolismoRESUMEN
AIM: Various surgical procedures, extravenous (VPE) AND intravenous (VPI) valvuloplasties were described for the treatment of superficial (IVCS) and deep (IVCP) chronic venous insufficiency. METHODS: In 18 years: 153 VPE in limbs affected with IVCS. 9 VPE, 26 VPI (10 typical, 8 atypical, 8 autologous) and 38 other procedures in 74 limbs with IVCP selected and controlled by US (hemodynamic improvement or normalization = MNE) and X-ray (5 VPI). RESULTS: IVCS: 153 VPE=8,2% of the general casuistry. ;: MNE) 90,2% ( mean follow-up. 5 y,4 m.); stable at 10 y 68%; best results in IVCS <20 y. (Chi-sq.P=0.05). IVCP: VPE=12,3% and VPI=35,6% of the interventions; 9 VPE: MNE 88,8%; 26 VPI: MNE 81,4%; hemodynamic normalization by VPE-VPI(n.7/27=25,9%) (mean follow-up.7 y.,8 m.). CONCLUSIONS: VPE: Indicated in selected cases with IVCS and IVCP. In IVCP VPE-VPI are preferable than other procedures. Atypical and autologous VPI represents a technical progress in valveless syndromes.
Asunto(s)
Extremidad Inferior/irrigación sanguínea , Procedimientos Quirúrgicos Vasculares/métodos , Insuficiencia Venosa/cirugía , Enfermedad Crónica , Humanos , Estudios RetrospectivosRESUMEN
Caspases play important roles in apoptotic cell death and in some other functions, such as cytokine maturation, inflammation, or differentiation. We show here that the 5'-flanking region of the human CASP-2 gene contains three functional response elements for sterol regulatory element binding proteins (SREBPs), proteins that mediate the transcriptional activation of genes involved in cholesterol, triacylglycerol, and fatty acid synthesis. Exposure of several human cell lines to statins, lipid-lowering drugs that drive SREBP proteolytic activation, induced the CASP-2 gene to an extent similar to that for known targets of SREBP proteins. Adenoviral vector-mediated transfer of active SREBP-2 also induced expression of the CASP-2 gene and the caspase-2 protein and increased the cholesterol and triacylglycerol cellular content. These rises in lipids were strongly impaired following small interfering RNA-mediated silencing of the CASP-2 gene. Taken together, our results identify the human CASP-2 gene as a member of the SREBP-responsive gene battery that senses lipid levels in cells and raise the possibility that caspase-2 participates in the control of cholesterol and triacylglycerol levels.
Asunto(s)
Cisteína Endopeptidasas/fisiología , Proteína 2 de Unión a Elementos Reguladores de Esteroles/fisiología , Región de Flanqueo 5' , Sitios de Unión , Caspasa 2 , Línea Celular Tumoral , Colesterol/biosíntesis , Cisteína Endopeptidasas/biosíntesis , Cisteína Endopeptidasas/genética , Regulación de la Expresión Génica , Humanos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , ARN Interferente Pequeño/genética , Elementos de Respuesta , Proteína 2 de Unión a Elementos Reguladores de Esteroles/genética , Triglicéridos/biosíntesisRESUMEN
Oxidized low-density lipoproteins play important roles in the development of atherosclerosis and contain several lipid-derived, bioactive molecules which are believed to contribute to atherogenesis. Of these, some cholesterol oxidation products, referred to as oxysterols, are suspected to favor the formation of atherosclerotic plaques involving cytotoxic, pro-oxidant and pro-inflammatory processes. Ten commonly occurring oxysterols (7alpha-, 7beta-hydroxycholesterol, 7-ketocholesterol, 19-hydroxycholesterol, cholesterol-5alpha,6alpha-epoxide, cholesterol-5beta,6beta-epoxide, 22R-, 22S-, 25-, and 27-hydroxycholesterol) were studied for both their cytotoxicity and their ability to induce superoxide anion production (O2*-) and IL-8 secretion in U937 human promonocytic leukemia cells. Cytotoxic effects (phosphatidylserine externalization, loss of mitochondrial potential, increased permeability to propidium iodide, and occurrence of cells with swollen, fragmented and/or condensed nuclei) were only identified with 7beta-hydroxycholesterol, 7-ketocholesterol and cholesterol-5beta,6beta-epoxide, which also induce lysosomal destabilization associated or not associated with the formation of monodansylcadaverine-positive cytoplasmic structures. No relationship between oxysterol-induced cytotoxicity and HMG-CoA reductase activity was found. In addition, the highest O2*- overproduction quantified with hydroethidine was identified with 7beta-hydroxycholesterol, 7-ketocholesterol and cholesterol-5beta,6beta-epoxide, with cholesterol-5alpha, 6alpha-epoxide and 25-hydroxycholesterol. The highest capacity to simultaneously stimulate IL-8 secretion (quantified by ELISA and by using a multiplexed, particle-based flow cytometric assay) and enhance IL-8 mRNA levels (determined by RT-PCR) was observed with 7beta-hydroxycholesterol and 25-hydroxycholesterol. None of the effects observed for the oxysterols were detected for cholesterol. Therefore, oxysterols may have cytotoxic, oxidative, and/or inflammatory effects, or none whatsoever.
Asunto(s)
Colesterol/análogos & derivados , Colesterol/toxicidad , Acilcoenzima A/metabolismo , Permeabilidad de la Membrana Celular/efectos de los fármacos , Colesterol/fisiología , Citoplasma/metabolismo , Humanos , Hidroxicolesteroles/toxicidad , Interleucina-8/biosíntesis , Interleucina-8/genética , Potenciales de la Membrana/efectos de los fármacos , Membranas Mitocondriales/efectos de los fármacos , Oxidación-Reducción , Fosfatidilserinas/metabolismo , ARN Mensajero/biosíntesis , Superóxidos/metabolismo , Células U937RESUMEN
Sterol Regulatory Element Binding Proteins (SREBP) are transcription factors that regulate lipid synthesis. We have shown recently that the human CASP-2 gene, encoding procaspase-2, was under the positive control of SREBP-2 that transactivates several responsive elements in the promoter region. We describe here the function of an additional SREBP-responsive element located in the first intron. Remarkably, this site is uniquely responsive to SREBP-1c that is mainly involved in fatty acids synthesis. This observation, together with our recent findings, strengthens the notion that the CASP-2 gene belongs to the SREBP-responsive gene battery in human cells.
Asunto(s)
Caspasas/genética , Intrones , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/metabolismo , Sitios de Unión , Caspasa 2 , Caspasas/metabolismo , Células Cultivadas , ADN/metabolismo , Humanos , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/genética , Proteína 2 de Unión a Elementos Reguladores de Esteroles/genética , Proteína 2 de Unión a Elementos Reguladores de Esteroles/metabolismo , Activación TranscripcionalRESUMEN
Various surgical techniques have been proposed for the treatment of chronic venous insufficiency of post-thrombotic recanalized deep veins of the lower limbs. The preferable method seems to be represented by intravenous valvuloplasty except for the cases affected by extensive valvular damage. For this reason some experimental autologous, heterologous and prosthetic venous valves have been proposed. Such a problem emerged for 1 patient (male, aged 78 years, right limb, leg dystrophy, multiple ulcerations at the ankle) which was selected by duplex, Doppler venous pressure index, photoplethysmography and ascending phlebography. An iliac-femoral and popliteal post-thrombotic, recanalized, decompensated venous insufficiency and one Cockett's perforator incompetence were diagnosed (CEAP classification: C6s Es As2d14 Pr). A bicuspid apparently repairable popliteal valve was detected by phlebography. A traditional intravenous valvuloplasty was planned but the valve was not found at surgical exploration. A monocuspid valve reconstruction by intimal flap vein was performed. The following results were obtained and controlled after one year: stable ulceration healing, dystrophy reduction, improvement in the quality of life, normalization of the hemodynamic parameters and of the radiological morphology of the new valve. It can be concluded that monocuspid valvular repair by intimal flap can be successfully performed in cases affected by secondary valveless deep venous insufficiency of the lower limbs.
Asunto(s)
Vena Poplítea/cirugía , Colgajos Quirúrgicos , Insuficiencia Venosa/cirugía , Anciano , Humanos , Úlcera de la Pierna/etiología , Masculino , Pletismografía , Vena Poplítea/diagnóstico por imagen , Vena Poplítea/patología , Ultrasonografía , Insuficiencia Venosa/diagnósticoRESUMEN
Platelet transfusion is widely used to prevent bleeding in patients with severe thrombocytopenia. The maximal storage duration of platelet concentrates is usually 5 days, due to the platelet storage lesion that impairs their functions when stored for longer times. Some of the morphological and biochemical changes that characterize this storage lesion are reminiscent of cell death by apoptosis. The present study analyzed whether proteins involved in nucleated cell apoptosis could play a role in the platelet storage lesion. Storage of leukocyte-depleted platelets obtained by apheresis is associated with a late and limited activation of caspases, mainly caspase-3. This event correlates with an increased expression of the pro-apoptotic BH3-only protein Bim in the particulate fraction and a slight and late release of the pro-apoptotic mitochondrial protein Diablo/Smac in the cytosol. Platelets do not express the death receptors Fas, DR4 and DR5 on their plasma membrane, while the expression of the decoy receptor DcR2 increases progressively during platelet storage. Addition of low concentrations of the cryoprotector dimethylsulfoxide accelerates platelet caspase activation during storage, an effect that is partially prevented by the caspase inhibitor z-VAD-fmk. Altogether, DcR2 expression on the plasma membrane is an early event while caspase activation is a late event during platelet storage. These observations suggest that caspases are unlikely to account for the platelet storage lesion. As a consequence, addition of caspase inhibitors may not improve the quality of platelet concentrates stored in standard conditions.
Asunto(s)
Plaquetas/metabolismo , Caspasas/metabolismo , Proteínas de la Membrana , Proteínas Proto-Oncogénicas , Receptores del Factor de Necrosis Tumoral/metabolismo , Apoptosis , Proteínas Reguladoras de la Apoptosis , Proteína 11 Similar a Bcl2 , Plaquetas/enzimología , Conservación de la Sangre , Proteínas Portadoras/metabolismo , Caspasas/efectos de los fármacos , Dimetilsulfóxido/farmacología , Activación Enzimática/efectos de los fármacos , Humanos , Péptidos y Proteínas de Señalización Intracelular , Proteínas Mitocondriales/metabolismo , Transfusión de Plaquetas , Precursores de Proteínas/metabolismo , Manejo de Especímenes , Factores de Tiempo , Receptores Señuelo del Factor de Necrosis TumoralRESUMEN
Phenobarbital has long been used as a sedative and antiepileptic drug. The drug is the representative of a myriad of lipophilic molecules able to evoke a pleiotropic response in the liver and also in prokaryotes and flies. A great deal of novel information has been obtained in recent years regarding the mechanism of cytochrome P450 (CYP) gene induction by phenobarbital. Most importantly, a nuclear orphan receptor, the constitutive androstane receptor has been identified as a primary determinant of the transcriptional activation of CYP genes in response to phenobarbital-like inducers in mammals. Another nuclear receptor, the pregnane X receptor can also mediate some of the phenobarbital response, but the functional overlap of the two inductive pathways is only partial. The response of mammalian CYP2B genes to phenobarbital was abolished in the liver of mice carrying a null allele of the constitutive androstane receptor gene, whereas that of CYP3A genes was lost in pregnane X receptor knock-out mice.
Asunto(s)
Hidrocarburo de Aril Hidroxilasas , Sistema Enzimático del Citocromo P-450/genética , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Hipnóticos y Sedantes/farmacología , Fenobarbital/farmacología , Androstanos/metabolismo , Animales , Secuencia de Bases , Citocromo P-450 CYP2B6 , Sistema Enzimático del Citocromo P-450/metabolismo , ADN , Hipnóticos y Sedantes/química , Ratones , Datos de Secuencia Molecular , Oxidorreductasas N-Desmetilantes/genética , Fenobarbital/química , Proteínas Quinasas/metabolismo , Ratas , Receptores Citoplasmáticos y Nucleares/metabolismo , Activación TranscripcionalRESUMEN
La frecuencia de flebopatías latentes en casos aparentemente normales, la no infrecuente asociación de VMI reticulares y TMI con una IVC subclínica de los miembros inferiores, la gravedad de algunos síndromes de IVP y la elevada frecuencia de la asociación con la IVS requieren de soluciones que permiten garantizar lo más posible intervenciones resolutivas, la estabilidad en los resultados y la remisión del inestetismo que siempre acompaña tales cuadros clínicos...Los autores presentan un conciso pero bien documentados informe sobre las variables terpéuticas de las enfermedades varicosas, la insuficiencia venosa crónica, la insuficiencia venosa profunda y las distintas posibilidades quirúrgicas al alcance del especialista
Asunto(s)
Humanos , Insuficiencia Venosa/cirugía , Várices/cirugía , Cirugía Plástica , Sistema LinfáticoRESUMEN
La frecuencia de flebopatías latentes en casos aparentemente normales, la no infrecuente asociación de VMI reticulares y TMI con una IVC subclínica de los miembros inferiores, la gravedad de algunos síndromes de IVP y la elevada frecuencia de la asociación con la IVS requieren de soluciones que permiten garantizar lo más posible intervenciones resolutivas, la estabilidad en los resultados y la remisión del inestetismo que siempre acompaña tales cuadros clínicos...Los autores presentan un conciso pero bien documentados informe sobre las variables terpéuticas de las enfermedades varicosas, la insuficiencia venosa crónica, la insuficiencia venosa profunda y las distintas posibilidades quirúrgicas al alcance del especialista
Asunto(s)
Humanos , Várices/cirugía , Insuficiencia Venosa/cirugía , Cirugía Plástica , Sistema LinfáticoRESUMEN
1. The ability of various in vitro systems for CYP enzymes (computer modelling, human liver microsomes, precision-cut liver slices, hepatocytes in culture, recombinant enzymes) to predict various aspects of in vivo metabolism and kinetics of carbamazepine (CBZ) was investigated. 2. The study was part of the EUROCYP project that aimed to evaluate relevant human in vitro systems to study drug metabolism. 3. CBZ was given to the participating laboratories without disclosing its chemical nature. 4. The most important enzyme (CYP3A4) and metabolic route (10,11-epoxidation) were predicted by all the systems studied. 5. Minor enzymes and routes were predicted to a different extent by various systems. 6. Prediction of a clearance class, i.e. slow clearance, was correctly predicted by microsomes, slices, hepatocytes and recombinant enzymes (CYP3A4). 7. The 10,11-epoxidation of CBZ by the recombinant CYP3A4 was enhanced by the addition of exogenous cytochrome-b5, leading to a considerable over-prediction. 8. Induction potency of CBZ was predicted in cultured hepatocytes in which 7-ethoxycoumarin O-deethylase was used as an index activity. 9. It seems that for a principally CYP-metabolized substance such as CBZ, all liver-derived systems provide useful information for prediction of metabolic routes, rates and interactions.
Asunto(s)
Anticonvulsivantes/metabolismo , Carbamazepina/metabolismo , Sistema Enzimático del Citocromo P-450/metabolismo , Hígado/enzimología , Células Cultivadas , Simulación por Computador , Citocromo P-450 CYP3A , Compuestos Epoxi/metabolismo , Hepatocitos/metabolismo , Humanos , Técnicas In Vitro , Cinética , Microsomas Hepáticos/enzimología , Oxigenasas de Función Mixta/metabolismo , Proteínas Recombinantes/metabolismoRESUMEN
Exposure of U937 human leukemic cells to the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) induces their differentiation into monocyte/macrophage-like cells. This terminal differentiation is associated with a resistant phenotype to apoptosis induced by the topoisomerase II inhibitor etoposide. The inhibition occurs upstream of the mitochondrial release of cytochrome c and the activation of procaspase-2, -3, -6, -7, -8, and -9. By using cell-free systems, it was demonstrated that the mitochondrial pathway to cell death that involves mitochondrial membrane depolarization, cytochrome c release and cytosolic activation of procaspases by cytochrome c/dATP remains functional in TPA-differentiated U937 cells. Accordingly, 2 drugs recently shown to target the mitochondria, namely lonidamine and arsenic trioxide, bypass the resistance of TPA-differentiated U937 cells to classical anticancer drugs. Cell death induced by the 2 compounds is associated with mitochondrial membrane depolarization, release of cytochrome c and Smac/Diablo from the mitochondria, activation of caspases, poly(ADP-ribose) polymerase cleavage and internucleosomal DNA fragmentation. Moreover, the decreased glutathione content associated with the differentiation process amplifies the ability of arsenic trioxide to activate the mitochondrial pathway to cell death. Similar results were obtained by comparing undifferentiated and TPA-differentiated human HL60 leukemic cells. These data demonstrate that mitochondria-targeting agents bypass the resistance to classical anticancer drugs induced by TPA-mediated leukemic cell differentiation. (Blood. 2001;97:3931-3940)
Asunto(s)
Apoptosis/efectos de los fármacos , Arsenicales/farmacología , Indazoles/farmacología , Leucemia/patología , Mitocondrias/efectos de los fármacos , Óxidos/farmacología , Acetato de Tetradecanoilforbol/farmacología , Antineoplásicos/farmacología , Trióxido de Arsénico , Caspasas/efectos de los fármacos , Caspasas/fisiología , Diferenciación Celular/efectos de los fármacos , Sistema Libre de Células/efectos de los fármacos , Sistema Libre de Células/enzimología , Resistencia a Medicamentos , Etopósido/farmacología , Humanos , Mitocondrias/enzimología , Proteínas Proto-Oncogénicas c-bcl-2/efectos de los fármacos , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Células U937/efectos de los fármacos , Células U937/enzimología , Células U937/ultraestructuraRESUMEN
The ability of various human derived in vitro systems to predict various aspects of the in vivo metabolism and kinetics of almokalant have been investigated in a multicenter collaborative study. Although almokalant has been withdrawn from further clinical development, its metabolic and pharmacokinetic properties have been well characterized. Studies with precision-cut liver slices, primary hepatocyte cultures, and hepatic microsomal fractions fortified with UDP-glucuronic acid all suggested that almokalant is mainly glucuronidated to the stereoisomers M18a and M18b, which is in good agreement with the results in vivo. Both in vivo and in vitro studies indicate that the formation of M18b dominates over that of M18a, although the difference is more pronounced with the in vitro systems. Molecular modeling, cDNA-expressed enzyme analysis, correlation analysis, and inhibition studies did not clearly indicate which P450 enzymes catalyze the oxidative pathways, which may indicate a problem in identifying responsible enzymes for minor metabolic routes by in vitro methods. All of the in vitro systems underpredicted the metabolic clearance of almokalant, which has previously been reported to be a general problem for drugs that are cleared by P450-dependent metabolism. Although few studies on in vivo prediction of primarily glucuronidated drugs have appeared, in vitro models may consistently underpredict in vivo metabolic clearance. We conclude that in vitro systems, which monitor phase II metabolism, would be beneficial for prediction of the in vivo metabolism, although all of the candidate liver-derived systems studied here, within their intrinsic limitations, provided useful information for predicting metabolic routes and rates.
Asunto(s)
Antiarrítmicos/metabolismo , Microsomas Hepáticos/metabolismo , Propanolaminas/metabolismo , Antiarrítmicos/farmacocinética , Inhibidores Enzimáticos del Citocromo P-450 , Sistema Enzimático del Citocromo P-450/metabolismo , Hepatocitos/metabolismo , Humanos , Técnicas In Vitro , Microsomas Hepáticos/enzimología , Propanolaminas/farmacocinéticaRESUMEN
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a new cytokine that was proposed to specifically induce apoptosis of cancer cells. In tumor cells that are resistant to the cytokine, subtoxic concentrations of chemotherapeutic drugs can restore the response to TRAIL. The present study further explores the mechanisms that determine tumor cell sensitivity to TRAIL by comparing four human colon carcinoma cell lines We show that colon cancer cell sensitivity to TRAIL-induced apoptosis and cytotoxicity correlates with the expression of the death receptors TRAIL-R1 and TRAIL-R2 at the cell surface, as determined by now cytometry, whereas the two decoy receptors TRAIL-R3 and TRAIL-R4 can be detected only in permeabilized cells. Clinically relevant concentrations of cisplatin and doxorubicin sensitize the most resistant colon cancer cell lines to TRAIL-induced cell death without modifying the expression nor the localization of TRAIL receptors in these cells. TRAIL induces the activation of procaspase-8 and triggers caspase-dependent apoptosis off colon cancer cells. Cytotoxic drugs lower the signaling threshold required for TRAIL-induced procaspase-8 activation. In turn, caspase-8 cleaves Bid, a BH3 domain-containing proapoptotic molecule of the Bcl-2 family and activates effector caspases. Together, these data indicate that chemotherapeutic drugs sensitize colon tumor cells to TRAIL-mediated caspase-8 activation and apoptosis.
Asunto(s)
Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Caspasas/metabolismo , Neoplasias del Colon/patología , Glicoproteínas de Membrana/farmacología , Factor de Necrosis Tumoral alfa/farmacología , Antibióticos Antineoplásicos/farmacología , Apoptosis/fisiología , Proteínas Reguladoras de la Apoptosis , Caspasa 3 , Caspasa 8 , Caspasa 9 , Membrana Celular/metabolismo , Cisplatino/farmacología , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/metabolismo , Doxorrubicina/farmacología , Sinergismo Farmacológico , Activación Enzimática/efectos de los fármacos , Humanos , Receptores del Ligando Inductor de Apoptosis Relacionado con TNF , Receptores del Factor de Necrosis Tumoral/biosíntesis , Solubilidad , Ligando Inductor de Apoptosis Relacionado con TNF , Células Tumorales CultivadasRESUMEN
Anticancer drugs can induce tumour cell death by apoptosis. The main pathway from specific damage induced by the drug to apoptosis involves activation of caspases in the cytosol by pro-apoptotic molecules such as cytochrome c released from the mitochondria. At least in some cell types, anticancer drugs also upregulate the expression of death receptors and sensitize tumour cells to their cognate ligands, which could be used to amplify the response to cytotoxic drugs. The Bcl-2 family of proteins, which includes anti- and pro-apoptotic molecules, regulates cell sensitivity at the mitochondrial level. Chemotherapeutic drugs modulate their expression (e.g. through p53-dependent gene transcription), their activity (e.g. by phosphorylation) and their subcellular localization (e.g. by translocation of pro-apoptotic proteins from the cytosol to the mitochondria). When interacting with tumour cells, anticancer drugs also activate lipid- and kinase-dependent signalling pathways that modulate the death response to specific damage. Protective pathways include activation of NF kappa B transcription factor, accumulation of heat shock proteins and activation of proteins involved in cell cycle regulation. The recent identification on these pathways to cell death has suggested several new strategies to improve the therapeutic efficacy of currently used anticancer drug regimens.