RESUMEN
Gliomas are the most common primary tumours affecting the adult central nervous system and respond poorly to standard therapy. Myc is causally implicated in most human tumours and the majority of glioblastomas have elevated Myc levels. Using the Myc dominant negative Omomyc, we previously showed that Myc inhibition is a promising strategy for cancer therapy. Here, we preclinically validate Myc inhibition as a therapeutic strategy in mouse and human glioma, using a mouse model of spontaneous multifocal invasive astrocytoma and its derived neuroprogenitors, human glioblastoma cell lines, and patient-derived tumours both in vitro and in orthotopic xenografts. Across all these experimental models we find that Myc inhibition reduces proliferation, increases apoptosis and remarkably, elicits the formation of multinucleated cells that then arrest or die by mitotic catastrophe, revealing a new role for Myc in the proficient division of glioma cells.
Asunto(s)
Astrocitoma/patología , Neoplasias Encefálicas/patología , Glioblastoma/patología , Glioma/patología , Mitosis/fisiología , Proteínas Proto-Oncogénicas c-myc/antagonistas & inhibidores , Animales , Apoptosis/fisiología , Astrocitoma/fisiopatología , Astrocitoma/terapia , Neoplasias Encefálicas/fisiopatología , Neoplasias Encefálicas/terapia , Línea Celular Tumoral , Proliferación Celular/fisiología , Modelos Animales de Enfermedad , Glioblastoma/fisiopatología , Glioblastoma/terapia , Glioma/fisiopatología , Glioma/terapia , Xenoinjertos , Humanos , Ratones , Ratones Transgénicos , Proteína Tirosina Fosfatasa no Receptora Tipo 1/fisiología , Proteínas Proto-Oncogénicas c-myc/fisiología , Enzimas Activadoras de Ubiquitina/fisiologíaRESUMEN
In response to microenvironmental signals, macrophages undergo different activation, including the "classic" proinflammatory phenotype (also called M1), the "alternative" activation induced by the IL-4/IL-13 trigger, and the related but distinct heterogeneous M2 polarization associated with the anti-inflammatory profile. The latter is induced by several stimuli, including IL-10 and TGF-ß. Macrophage-polarized activation has profound effects on immune and inflammatory responses and in tumor biology, but information on the underlying molecular pathways is scarce. In the present study, we report that alternative polarization of macrophages requires the transcription factor c-MYC. In macrophages, IL-4 and different stimuli sustaining M2-like polarization induce c-MYC expression and its translocation to the nucleus. c-MYC controls the induction of a subset (45%) of genes associated with alternative activation. ChIP assays indicate that c-MYC directly regulates some genes associated with alternative activation, including SCARB1, ALOX15, and MRC1, whereas others, including CD209, are indirectly regulated by c-MYC. c-MYC up-regulates the IL-4 signaling mediators signal transducer and activator of transcription-6 and peroxisome proliferator-activated receptorγ, is also expressed in tumor-associated macrophages, and its inhibition blocks the expression of protumoral genes including VEGF, MMP9, HIF-1α, and TGF-ß. We conclude that c-MYC is a key player in alternative macrophage activation, and is therefore a potential therapeutic target in pathologies related to these cells, including tumors.
Asunto(s)
Biomarcadores de Tumor/genética , Neoplasias de la Mama/metabolismo , Neoplasias del Colon/metabolismo , Regulación Neoplásica de la Expresión Génica , Macrófagos/metabolismo , Neoplasias Pancreáticas/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Biomarcadores de Tumor/metabolismo , Western Blotting , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Diferenciación Celular , Células Cultivadas , Inmunoprecipitación de Cromatina , Colon/metabolismo , Colon/patología , Neoplasias del Colon/genética , Neoplasias del Colon/patología , Femenino , Perfilación de la Expresión Génica , Humanos , Interleucina-4/farmacología , Activación de Macrófagos/efectos de los fármacos , Macrófagos/citología , Análisis de Secuencia por Matrices de Oligonucleótidos , PPAR gamma/genética , PPAR gamma/metabolismo , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patología , Proteínas Proto-Oncogénicas c-myc/genética , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factor de Transcripción STAT6/genética , Factor de Transcripción STAT6/metabolismo , Transducción de SeñalRESUMEN
Several studies have shown that the adult pancreas possesses a limited potential for beta-cell regeneration upon tissue injury. One of the difficulties in studying beta-cell regeneration has been the lack of a robust, synchronized animal model system that would allow controlled regulation of beta-cell loss and subsequent proliferation in adult pancreas. Here we present a transgenic mouse regeneration model in which the c-Myc transcription factor/mutant estrogen receptor (cMycER(TAM)) fusion protein can be specifically activated in mature beta-cells. We have studied these transgenic mice by immunohistochemical and biochemical methods to assess the ablation and posterior regeneration of beta-cells. Activation of the cMycER(TAM) fusion protein results in synchronous and selective beta-cell apoptosis followed by the onset of acute diabetes. Inactivation of c-Myc leads to gradual regeneration of insulin-expressing cells and reversal of diabetes. Our results demonstrate that the mature pancreas has the ability to fully recover from almost complete ablation of all existing beta-cells. Our results also suggest the regeneration of beta-cells is mediated by replication of beta-cells rather than neogenesis from pancreatic ducts.