Assuntos
Neuroblastoma/etiologia , Biomarcadores Tumorais , Sistemas CRISPR-Cas , Gerenciamento Clínico , Suscetibilidade a Doenças , Marcação de Genes , Humanos , Terapia de Alvo Molecular , Mutação , Neuroblastoma/diagnóstico , Neuroblastoma/terapia , Proteína Nuclear Ligada ao X/antagonistas & inibidoresRESUMO
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.
Assuntos
Antineoplásicos Alquilantes/farmacologia , Neoplasias Encefálicas/tratamento farmacológico , Metilação de DNA , Resistencia a Medicamentos Antineoplásicos/genética , Proteína Potenciadora do Homólogo 2 de Zeste/fisiologia , Proteína de Domínio de Morte Associada a Fas/fisiologia , Regulação Neoplásica da Expressão Gênica/genética , Glioma/tratamento farmacológico , Proteínas de Neoplasias/fisiologia , Poli(ADP-Ribose) Polimerase-1/fisiologia , Temozolomida/farmacologia , Proteína Nuclear Ligada ao X/fisiologia , Animais , Antineoplásicos Alquilantes/uso terapêutico , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Sistemas CRISPR-Cas , Dano ao DNA , Reparo do DNA , DNA de Neoplasias/genética , Proteínas de Ligação a DNA/fisiologia , Dioxigenases , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Edição de Genes , Técnicas de Inativação de Genes , Glioma/genética , Glioma/metabolismo , Código das Histonas , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas/fisiologia , Fator de Transcrição STAT5/fisiologia , Temozolomida/uso terapêutico , Ensaio Tumoral de Célula-Tronco , Regulação para Cima , Proteína Nuclear Ligada ao X/antagonistas & inibidores , Proteína Nuclear Ligada ao X/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
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.
Assuntos
Neoplasias/genética , Homeostase do Telômero , Cromatina/ultraestrutura , Evolução Clonal , Proteínas Correpressoras/antagonistas & inibidores , Proteínas Correpressoras/fisiologia , Dano ao DNA , Reparo do DNA , Replicação do DNA , DNA de Neoplasias/metabolismo , DNA de Neoplasias/ultraestrutura , Histonas/fisiologia , Recombinação Homóloga , Humanos , Modelos Genéticos , Chaperonas Moleculares/antagonistas & inibidores , Chaperonas Moleculares/fisiologia , Mutação , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/fisiologia , Neoplasias/ultraestrutura , Conformação de Ácido Nucleico , Telomerase/genética , Telomerase/fisiologia , Proteína Nuclear Ligada ao X/antagonistas & inibidores , Proteína Nuclear Ligada ao X/fisiologiaRESUMO
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.
