Asunto(s)
Neuroblastoma/etiología , Biomarcadores de Tumor , Sistemas CRISPR-Cas , Manejo de la Enfermedad , Susceptibilidad a Enfermedades , Marcación de Gen , Humanos , Terapia Molecular Dirigida , Mutación , Neuroblastoma/diagnóstico , Neuroblastoma/terapia , Proteína Nuclear Ligada al Cromosoma X/antagonistas & inhibidoresRESUMEN
Rationale: Glioma is the most common primary malignant brain tumor in adults. Chemoresistance of temozolomide (TMZ), the first-line chemotherapeutic agent, is a major issue in the management of patients with glioma. Alterations of alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene constitute one of the most prevalent genetic abnormalities in gliomas. Therefore, elucidation of the role of ATRX contributing to TMZ resistance in glioma is urgently needed. Methods: We performed the bioinformatics analysis of gene expression, and DNA methylation profiling, as well as RNA and ChIP-seq data sets. CRISPR-Cas9 gene editing system was used to achieve the ATRX knockout in TMZ resistant cells. In vitro and in vivo experiments were carried out to investigate the role of ATRX contributing to TMZ resistance in glioma. Results: We found that ATRX expression was upregulated via DNA demethylation mediated by STAT5b/TET2 complex and strengthened DNA damage repair by stabilizing PARP1 protein in TMZ resistant cells. ATRX elicited PARP1 stabilization by the down-regulating of FADD expression via the H3K27me3 enrichment, which was dependent on ATRX/EZH2 complex in TMZ resistant cells. Magnetic resonance imaging (MRI) revealed that the PARP inhibitor together with TMZ inhibited glioma growth in ATRX wild type TMZ resistant intracranial xenograft models. Conclusions: The present study further illustrated the novel mechanism of the ATRX/PARP1 axis contributing to TMZ resistance. Our results provided substantial new evidence that PARP inhibitor might be a potential adjuvant agent in overcoming ATRX mediated TMZ resistance in glioma.
Asunto(s)
Antineoplásicos Alquilantes/farmacología , Neoplasias Encefálicas/tratamiento farmacológico , Metilación de ADN , Resistencia a Antineoplásicos/genética , Proteína Potenciadora del Homólogo Zeste 2/fisiología , Proteína de Dominio de Muerte Asociada a Fas/fisiología , Regulación Neoplásica de la Expresión Génica/genética , Glioma/tratamiento farmacológico , Proteínas de Neoplasias/fisiología , Poli(ADP-Ribosa) Polimerasa-1/fisiología , Temozolomida/farmacología , Proteína Nuclear Ligada al Cromosoma X/fisiología , Animales , Antineoplásicos Alquilantes/uso terapéutico , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Sistemas CRISPR-Cas , Daño del ADN , Reparación del ADN , ADN de Neoplasias/genética , Proteínas de Unión al ADN/fisiología , Dioxigenasas , Proteína Potenciadora del Homólogo Zeste 2/genética , Edición Génica , Técnicas de Inactivación de Genes , Glioma/genética , Glioma/metabolismo , Código de Histonas , Humanos , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Regiones Promotoras Genéticas , Proteínas Proto-Oncogénicas/fisiología , Factor de Transcripción STAT5/fisiología , Temozolomida/uso terapéutico , Ensayo de Tumor de Célula Madre , Regulación hacia Arriba , Proteína Nuclear Ligada al Cromosoma X/antagonistas & inhibidores , Proteína Nuclear Ligada al Cromosoma X/genética , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Alternative lengthening of telomeres (ALT) is a mechanism of telomere maintenance that is observed in many of the most recalcitrant cancer subtypes. Telomeres in ALT cancer cells exhibit a distinctive nucleoprotein architecture shaped by the mismanagement of chromatin that fosters cycles of DNA damage and replicative stress that activate homology-directed repair (HDR). Mutations in specific chromatin-remodeling factors appear to be key determinants of the emergence and survival of ALT cancer cells. However, these may represent vulnerabilities for the targeted elimination of ALT cancer cells that infiltrate tissues and organs to become devastating tumors. In this review we examine recent findings that provide new insights into the factors and mechanisms that mediate telomere length maintenance and survival of ALT cancer cells.
Asunto(s)
Neoplasias/genética , Homeostasis del Telómero , Cromatina/ultraestructura , Evolución Clonal , Proteínas Co-Represoras/antagonistas & inhibidores , Proteínas Co-Represoras/fisiología , Daño del ADN , Reparación del ADN , Replicación del ADN , ADN de Neoplasias/metabolismo , ADN de Neoplasias/ultraestructura , Histonas/fisiología , Recombinación Homóloga , Humanos , Modelos Genéticos , Chaperonas Moleculares/antagonistas & inhibidores , Chaperonas Moleculares/fisiología , Mutación , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/fisiología , Neoplasias/ultraestructura , Conformación de Ácido Nucleico , Telomerasa/genética , Telomerasa/fisiología , Proteína Nuclear Ligada al Cromosoma X/antagonistas & inhibidores , Proteína Nuclear Ligada al Cromosoma X/fisiologíaRESUMEN
Low-grade astrocytomas (LGAs) carry neomorphic mutations in isocitrate dehydrogenase (IDH) concurrently with P53 and ATRX loss. To model LGA formation, we introduced R132H IDH1, P53 shRNA, and ATRX shRNA into human neural stem cells (NSCs). These oncogenic hits blocked NSC differentiation, increased invasiveness in vivo, and led to a DNA methylation and transcriptional profile resembling IDH1 mutant human LGAs. The differentiation block was caused by transcriptional silencing of the transcription factor SOX2 secondary to disassociation of its promoter from a putative enhancer. This occurred because of reduced binding of the chromatin organizer CTCF to its DNA motifs and disrupted chromatin looping. Our human model of IDH mutant LGA formation implicates impaired NSC differentiation because of repression of SOX2 as an early driver of gliomagenesis.