Asunto(s)
Antibacterianos/farmacología , Enterobacteriaceae Resistentes a los Carbapenémicos/aislamiento & purificación , Carbapenémicos/farmacología , Farmacorresistencia Bacteriana Múltiple , Enterobacter cloacae/efectos de los fármacos , Infecciones por Enterobacteriaceae/microbiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Enterobacteriaceae Resistentes a los Carbapenémicos/genética , Enterobacter cloacae/enzimología , Enterobacter cloacae/genética , Enterobacter cloacae/aislamiento & purificación , Humanos , Pruebas de Sensibilidad Microbiana , Reacción en Cadena de la Polimerasa , Centros de Atención Terciaria , beta-Lactamasas/biosíntesis , beta-Lactamasas/efectos de los fármacos , beta-Lactamasas/genética , beta-Lactamasas/metabolismoRESUMEN
Tumor necrosis factor-related apoptosis-inducing ligand-TNFSF10 (TRAIL), a member of the TNF-α family and a death receptor ligand, was shown to selectively kill tumor cells. Not surprisingly, TRAIL is downregulated in a variety of tumor cells, including BCR-ABL-positive leukemia. Although we know much about the molecular basis of TRAIL-mediated cell killing, the mechanism responsible for TRAIL inhibition in tumors remains elusive because (a) TRAIL can be regulated by retinoic acid (RA); (b) the tumor antigen preferentially expressed antigen of melanoma (PRAME) was shown to inhibit transcription of RA receptor target genes through the polycomb protein, enhancer of zeste homolog 2 (EZH2); and (c) we have found that TRAIL is inversely correlated with BCR-ABL in chronic myeloid leukemia (CML) patients. Thus, we decided to investigate the association of PRAME, EZH2 and TRAIL in BCR-ABL-positive leukemia. Here, we demonstrate that PRAME, but not EZH2, is upregulated in BCR-ABL cells and is associated with the progression of disease in CML patients. There is a positive correlation between PRAME and BCR-ABL and an inverse correlation between PRAME and TRAIL in these patients. Importantly, knocking down PRAME or EZH2 by RNA interference in a BCR-ABL-positive cell line restores TRAIL expression. Moreover, there is an enrichment of EZH2 binding on the promoter region of TRAIL in a CML cell line. This binding is lost after PRAME knockdown. Finally, knocking down PRAME or EZH2, and consequently induction of TRAIL expression, enhances Imatinib sensibility. Taken together, our data reveal a novel regulatory mechanism responsible for lowering TRAIL expression and provide the basis of alternative targets for combined therapeutic strategies for CML.
Asunto(s)
Antígenos de Neoplasias/metabolismo , Proteínas de Unión al ADN/metabolismo , Leucemia Mielógena Crónica BCR-ABL Positiva/metabolismo , Ligando Inductor de Apoptosis Relacionado con TNF/metabolismo , Factores de Transcripción/metabolismo , Adenocarcinoma/tratamiento farmacológico , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Antígenos de Neoplasias/análisis , Antineoplásicos/uso terapéutico , Benzamidas , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Carcinoma/tratamiento farmacológico , Carcinoma/genética , Carcinoma/metabolismo , Línea Celular , Proteínas de Unión al ADN/análisis , Progresión de la Enfermedad , Proteína Potenciadora del Homólogo Zeste 2 , Proteínas de Fusión bcr-abl/análisis , Proteínas de Fusión bcr-abl/metabolismo , Humanos , Mesilato de Imatinib , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Melanoma/tratamiento farmacológico , Melanoma/genética , Melanoma/metabolismo , Piperazinas/uso terapéutico , Complejo Represivo Polycomb 2 , Regiones Promotoras Genéticas , Pirimidinas/uso terapéutico , Interferencia de ARN , Ligando Inductor de Apoptosis Relacionado con TNF/análisis , Ligando Inductor de Apoptosis Relacionado con TNF/genética , Factores de Transcripción/análisis , Células Tumorales Cultivadas , Regulación hacia ArribaRESUMEN
CD95 (Fas/Apo-1)-mediated apoptosis was shown to occur through two distinct pathways. One involves a direct activation of caspase-3 by large amounts of caspase-8 generated at the DISC (Type I cells). The other is related to the cleavage of Bid by low concentration of caspase-8, leading to the release of cytochrome c from mitochondria and the activation of caspase-3 by the cytochrome c/APAF-1/caspase-9 apoptosome (Type II cells). It is also known that the protein synthesis inhibitor cycloheximide (CHX) sensitizes Type I cells to CD95-mediated apoptosis, but it remains contradictory whether this effect also occurs in Type II cells. Here, we show that sub-lethal doses of CHX render both Type I and Type II cells sensitive to the apoptogenic effect of anti-CD95 antibodies but not to chemotherapeutic drugs. Moreover, Bcl-2-positive Type II cells become strongly sensitive to CD95-mediated apoptosis by the addition of CHX to the cell culture. This is not the result of a restraint of the anti-apoptotic effect of Bcl-2 at the mitochondrial level since CHX-treated Type II cells still retain their resistance to chemotherapeutic drugs. Therefore, CHX treatment is granting the CD95-mediated pathway the ability to bypass the mitochondria requirement to apoptosis, much alike to what is observed in Type I cells.
Asunto(s)
Proteínas Reguladoras de la Apoptosis/metabolismo , Apoptosis/fisiología , Mitocondrias/metabolismo , Transducción de Señal/fisiología , Receptor fas/metabolismo , Anticuerpos/farmacología , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Proteínas Reguladoras de la Apoptosis/antagonistas & inhibidores , Proteína Proapoptótica que Interacciona Mediante Dominios BH3/efectos de los fármacos , Proteína Proapoptótica que Interacciona Mediante Dominios BH3/metabolismo , Caspasas/efectos de los fármacos , Caspasas/metabolismo , Cicloheximida/farmacología , Citocromos c/efectos de los fármacos , Citocromos c/metabolismo , Relación Dosis-Respuesta a Droga , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/fisiología , Sinergismo Farmacológico , Células HL-60 , Humanos , Mitocondrias/efectos de los fármacos , Inhibidores de la Síntesis de la Proteína/farmacología , Proteínas Proto-Oncogénicas c-bcl-2/efectos de los fármacos , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Transducción de Señal/efectos de los fármacos , Receptor fas/antagonistas & inhibidoresRESUMEN
A growing body of evidence suggests that the pineal hormone, melatonin, has immunomodulatory properties, although very little is known about its effect on leukocytes. Therefore, we aimed to investigate the effect of melatonin and its oxidation product N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) on cytokine production by neutrophils and peripheral blood mononuclear cells (PBMCs). AFMK (0.001-1 mM) inhibits the lipopolysaccharide (LPS)-mediated production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8) more efficiently in neutrophils than PBMCs. Moreover, the inhibitory activity of AFMK is stronger than that of melatonin. Interestingly, monocytes efficiently oxidize melatonin to AFMK. We conclude that neutrophils are one of the main targets for melatonin and that at least part of the effects described for melatonin on immune cells may be due to its oxidation product, AFMK. We also consider that the oxidation of melatonin may be an important event in the cross-talking between neutrophils and monocytes.
Asunto(s)
Citocinas/metabolismo , Kinuramina/análogos & derivados , Kinuramina/farmacología , Melatonina/farmacología , Neutrófilos/efectos de los fármacos , Neutrófilos/metabolismo , Análisis de Varianza , Células Cultivadas , Humanos , Kinuramina/metabolismo , Melatonina/metabolismo , Oxidación-Reducción/efectos de los fármacosRESUMEN
Bcr-Abl is one of the most potent antiapoptotic molecules and is the tyrosine-kinase implicated in Philadelphia (Ph) chromosome-positive leukemia. It is still obscure how Bcr-Abl provides the leukemic cell a strong resistance to chemotherapeutic drugs. A rational drug development produced a specific inhibitor of the catalytic activity of Bcr-Abl called STI571. This drug was shown to eliminate Bcr-Abl-positive cells both in vitro and in vivo, although resistant cells may appear in culture and relapse occurs in some patients. In the study described here, Bcr-Abl-positive cells treated with tyrosine-kinase inhibitors such as herbimycin A, genistein or STI571 lost their phosphotyrosine-containing proteins, but were still extremely resistant to apoptosis. Therefore, in the absence of tyrosine-kinase activity, Bcr-Abl-positive cells continue to signal biochemically to prevent apoptosis induced by chemotherapeutic drugs. We propose that secondary antiapoptotic signals are entirely responsible for the resistance of Bcr-Abl-positive cells. Precise determination of such signals and rational drug development against them should improve the means to combat Ph chromosome-positive leukemia.