Similar Datasets
Project description:The net transcriptome of a cancer cell is defined by relative levels of transcription factors, activators, suppressors and co-factors. These in turn are controlled by epigenetic, genetic and metabolic restraints. Here we used RNA-Seq, ChIP-qPCR, and ChIP-Seq to determine the impact of MYCN protein levels on p53 and MYCN mediated transcription in neuroblastoma, a p53 wild-type neural crest derived pediatric malignancy. Of note, about 25% of neuroblastoma is MYCN amplified and expresses 10-100 fold higher levels of MYCN protein than non-amplified tumors. We hypothesized that p53 functions would be globally altered by extreme MYCN levels and this could help to explain aggressive biology and poor long term survival which distinguishes MYCN-amplified neuroblastoma. In fact, we found that in the context of high MYCN levels, activation of p53 results in marked changes in transcription of specific p53 and MYCN target loci regulating apoptosis, DNA repair and cell cycle progression. Co-immunoprecipitation of endogenous and GST-fused proteins, as well as ChIP-qPCR confirms formation of p53/MYCN complexes and enrichment of both transcription factors at active loci. This p53/MYC interaction is independent of MYC/MAX complexes. Together, these data demonstrate MYCN to be a direct co-factor modulating p53 transcriptional output in MYCN amplified cancer.
2018-05-17 | GSE83327 | GEO
Project description:The net transcriptome of a cancer cell is defined by relative levels of transcription factors, activators, suppressors and co-factors. These in turn are controlled by epigenetic, genetic and metabolic restraints. Here we used RNA-Seq, ChIP-qPCR, and ChIP-Seq to determine the impact of MYCN protein levels on p53 and MYCN mediated transcription in neuroblastoma, a p53 wild-type neural crest derived pediatric malignancy. Of note, about 25% of neuroblastoma is MYCN amplified and expresses 10-100 fold higher levels of MYCN protein than non-amplified tumors. We hypothesized that p53 functions would be globally altered by extreme MYCN levels and this could help to explain aggressive biology and poor long term survival which distinguishes MYCN-amplified neuroblastoma. In fact, we found that in the context of high MYCN levels, activation of p53 results in marked changes in transcription of specific p53 and MYCN target loci regulating apoptosis, DNA repair and cell cycle progression. Co-immunoprecipitation of endogenous and GST-fused proteins, as well as ChIP-qPCR confirms formation of p53/MYCN complexes and enrichment of both transcription factors at active loci. This p53/MYC interaction is independent of MYC/MAX complexes. Together, these data demonstrate MYCN to be a direct co-factor modulating p53 transcriptional output in MYCN amplified cancer.
2018-05-17 | GSE83317 | GEO
Project description:Direct interaction of MYCN and p53 regulate transcriptional responses in neuroblastoma
| PRJNA325602 | ENA
Project description:MYCN amplification occurs in approximately 25% of neuroblastomas, where it is associated with rapid tumor progression and poor prognosis. MYCN plays a paradoxical role in driving cellular proliferation and inducing apoptosis. Based on observations of nuclear p53 accumulation in neuroblastoma, we hypothesized that MYCN may regulate p53 in this setting. Immunohistochemical analysis of 82 neuroblastoma tumors showed an association of high p53 expression with MYCN expression and amplification. In a panel of 5 MYCN-amplified and 5 nonamplified neuroblastoma cell lines, and also in the Tet21N-regulatable MYCN expression system, we further documented a correlation between the expression of MYCN and p53. In MYCN-amplified neuroblastoma cell lines, MYCN knockdown decreased p53 expression. In Tet21N MYCN+ cells, higher levels of p53 transcription, mRNA, and protein were observed relative to Tet21N MYCN- cells. In chromatin immunoprecipitation and reporter gene assays, MYCN bound directly to a Myc E-Box DNA binding motif located close to the transcriptional start site within the p53 promoter, where it could initiate transcription. E-Box mutation decreased MYCN-driven transcriptional activation. Microarray analysis of Tet21N MYCN+/- cells identified several p53-regulated genes that were upregulated in the presence of MYCN, including MDM2 and PUMA, the levels of which were reduced by MYCN knockdown. We concluded that MYCN transcriptionally upregulates p53 in neuroblastoma and uses p53 to mediate a key mechanism of apoptosis.
| S-EPMC2875109 | biostudies-literature
Project description:The MYCN oncogene is the major negative prognostic marker in neuroblastoma with important roles in both the pathogenesis and clinical behavior of this aggressive malignancy. MYC oncogenes activate both proliferative and apoptotic cellular pathways and, accordingly, inhibition of p53-mediated apoptosis is a prerequisite for MYC-driven tumorigenesis. To identify novel transcriptional targets mediating the MYCN-dependent phenotype, we screened a MYCN-amplified neuroblastoma cell line by using chromatin immunoprecipitation (ChIP) cloning. We identified the essential p53 inhibitor and protooncogene MDM2 as a putative target. MDM2 has multiple p53-independent functions modulating cell cycle and transcriptional events. Standard ChIP with MYCN antibodies established the binding of MYCN to a consensus E-box within the human MDM2 promoter. Oligonucleotide pull-down assays further established the capacity of MYCN to bind to this promoter region, confirming the ChIP results. Luciferase reporter assays confirmed the E-box-specific, MYCN-dependent regulation of the MDM2 promoter in MYCN-inducible neuroblastoma cell lines. Real-time quantitative PCR and Western blot analysis demonstrated a rapid increase in endogenous MDM2 mRNA and MDM2 protein upon induction of MYCN. Targeted inhibition of MYCN in a MYCN-amplified neuroblastoma cell line resulted in decreased MDM2 expression levels with concomitant stabilization of p53 and induction of apoptosis. Our finding that MYCN directly modulates baseline MDM2 levels suggests a mechanism contributing to the pathogenesis of neuroblastoma and other MYC-driven malignancies through inhibition of MYC-stimulated apoptosis.
| S-EPMC545522 | biostudies-literature
Project description:The MYC oncogenes and p53 have opposing yet interrelated roles in normal development and tumorigenesis. How MYCN expression alters the biology and clinical responsiveness of pediatric neuroblastoma remains poorly defined. Neuroblastoma is p53 wild type at diagnosis and repression of p53 signaling is required for tumorigenesis. Here, we tested the hypothesis that MYCN amplification alters p53 transcriptional activity in neuroblastoma. Interestingly, we found that MYCN directly binds to the tetrameric form of p53 at its C-terminal domain, and this interaction is independent of MYCN/MAX heterodimer formation. Chromatin analysis of MYCN and p53 targets reveals dramatic changes in binding, as well as co-localization of the MYCN-p53 complex at p53-REs and E-boxes of genes critical to DNA damage responses and cell cycle progression. RNA sequencing studies show that MYCN-p53 co-localization significantly modulated the expression of p53 target genes. Furthermore, MYCN-p53 interaction leads to regulation of alternative p53 targets not regulated in the presence of low MYCN levels. These novel targets include a number of genes involved in lipid metabolism, DNA repair, and apoptosis. Taken together, our findings demonstrate a novel oncogenic role of MYCN as a transcriptional co-regulator of p53 in high-risk MYCN amplified neuroblastoma. Targeting this novel oncogenic function of MYCN may enhance p53-mediated responses and sensitize MYCN amplified tumors to chemotherapy.
| S-EPMC5945521 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2016-09-01 | E-GEOD-80154 | biostudies-arrayexpress
Project description:Amplification of the locus encoding the oncogenic transcription factor MYCN is a defining feature of high-risk neuroblastoma. Here we present the first dynamic chromatin and transcriptional landscape of MYCN perturbation in neuroblastoma. At oncogenic levels, MYCN associates with E-box binding motifs in an affinity-dependent manner, binding to strong canonical E-boxes at promoters and invading abundant weaker non-canonical E-boxes clustered at enhancers. Loss of MYCN leads to a global reduction in transcription, which is most pronounced at MYCN target genes with the greatest enhancer occupancy. These highly occupied MYCN target genes show tissue-specific expression and are linked to poor patient survival. The activity of genes with MYCN-occupied enhancers is dependent on the tissue-specific transcription factor TWIST1, which co-occupies enhancers with MYCN and is required for MYCN-dependent proliferation. These data implicate tissue-specific enhancers in defining often highly tumor-specific 'MYC target gene signatures' and identify disruption of the MYCN enhancer regulatory axis as a promising therapeutic strategy in neuroblastoma.
| S-EPMC6310397 | biostudies-literature
Project description:Noradrenergic neuroblastoma is characterized by a core transcriptional regulatory circuitry (CRC) comprised of transcription factors (TF) such as PHOX2B, HAND2, and GATA3, which form a network with MYCN. At normal physiologic levels, MYCN mainly binds to promoters but when aberrantly upregulated as in neuroblastoma, MYCN also binds to enhancers. Here, we investigated how MYCN invades enhancers and whether CRC TFs play a role in this process. HAND2 was found to regulate chromatin accessibility and to assist MYCN binding to enhancers. Moreover, HAND2 cooperated with MYCN to compete with nucleosomes to regulate global gene transcription. The cooperative interaction between MYCN and HAND2 could be targeted with an Aurora A kinase inhibitor plus a histone deacetylase inhibitor, resulting in potent downregulation of both MYCN and the CRC TFs and suppression of MYCN-amplified neuroblastoma tumor growth. This study identifies cooperation between MYCN and HAND2 in neuroblastoma and demonstrates that simultaneously targeting MYCN and CRC TFs is an effective way to treat this aggressive pediatric tumor.SignificanceHAND2 and MYCN compete with nucleosomes to regulate global gene transcription and to drive a malignant neuroblastoma phenotype.
| S-EPMC10240397 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2017-12-02 | GSE85432 | GEO