The microRNA landscape of MYCN-amplified neuroblastoma
Ontology highlight
ABSTRACT: Neuroblastoma is a common childhood cancer with almost a third of those affected still dying, thus new therapeutic strategies need to be explored. Current experimental therapies focus mostly on inhibiting oncogenic transcription factor signalling. Dysregulation of miRNAs has oncogenic or suppressive tumor functions in a variety of cancer, also including neuroblastoma. Therefore, we investigated the miRNA landscape in 97 neuroblastoma samples from different INSS stages, including MYCN-amplified (MNA) tumor samples.
Project description:MYCN amplification (MNA) is a defining feature of high-risk neuroblastoma (NB) that predicts poor prognosis. However, whether genes within or in close proximity to the MYCN amplicon also contribute to aggressiveness in MNA+ NB remains poorly understood. Here we identify that GREB1, a transcription factor encoding gene neighboring the MYCN locus, is frequently co-expressed with MYCN, and promotes cell survival in MNA+ NB. GREB1 controls gene expression independently of MYCN in MNA+ NB, among which we uncover Myosin 1B (MYO1B) as being highly expressed in MNA+ NB. MYO1B promotes aggressive features, including invasive capacity in vitro, as well as extravasation and distant metastasis in vivo. Global secretome and proteome profiling further delineate MYO1B as a major regulator of secretome reprogramming in MNA+ NB cells. Moreover, we identify the cytokine MIF as an important pro-invasive and pro-metastatic mediator of MYO1B activity. Together, we have identified a putative GREB1-MYO1B-MIF axis as an unconventional mechanism that promotes the aggressiveness of MNA+ NB, and independently of MYCN. Furthermore, we find that MYO1B is upregulated in association with other oncoproteins during cellular transformation, and is dramatically increased in multiple human cancer types, suggesting a crucial role of MYO1B in cancers in addition to MNA+ NB.
Project description:Neuroblastoma with MYCN amplification (MNA) is a high-risk disease that requires long-term intensive multimodal therapies. Less than 50% survival rate of high-risk patients has prompted active and extensive studies to seek more effective therapies against MNA neuroblastomas but with few successes. We show that MYCN transdifferentiates the neuroblastoma cells from mesenchymal state to adrenergic state accompanied with induction of histone lysine demethylase 4 family members (KDM4A-C), all of which act in concert to control the expression of MYCN and adrenergic core regulatory transcription factors (CRC TF). Pharmacologic inhibition of KDM4 blocks expression of MYCN and adrenergic CRC transcriptome with genome-wide induction of transcriptionally repressive H3K9me3, resulting in potent anticancer activity against MNA neuroblastomas by inducing differentiation, apoptosis and type I interferon response. KDM4 inhibition in combination with chemotherapy leads to complete tumor response of MNA xenografts, without overt toxicity in animals. Thus, KDM4 blockade may be a transformative strategy to target the dependency of adrenergic CRC TFs in MNA neuroblastomas.
Project description:Neuroblastoma with MYCN amplification (MNA) is a high-risk disease that requires long-term intensive multimodal therapies. Despite this, high-risk patients have a poor survival rate, which has prompted extensive studies aimed at identifying more effective therapies against neuroblastomas with MNA. Neuroblastoma displays cellular heterogeneity, including more differentiated (adrenergic) and more primitive (mesenchymal) cellular states. Here, we demonstrate that MYCN oncoprotein can promote a cellular state switch in mesenchymal cells to an adrenergic state. This cellular state transition is accompanied by induction of histone lysine demethylase 4 family members (KDM4A-C), which act in concert to control the expression of MYCN and adrenergic core regulatory transcription factors (CRC TF). Pharmacologic inhibition of KDM4 blocks expression of MYCN and the adrenergic CRC transcriptome with genome-wide induction of transcriptionally repressive H3K9me3, resulting in potent anticancer activity against neuroblastomas with MNA by inducing neuroblastic differentiation, apoptosis, and a type I interferon response. Further, KDM4 inhibition in combination with conventional, cytotoxic chemotherapy results in complete tumor responses of xenografts with MNA, without overt toxicity in animals. Thus, KDM4 blockade may be a novel and transformative strategy to target the adrenergic CRC dependencies in MNA neuroblastomas.
Project description:MYCN amplification in neuroblastoma leads to aberrant expression of MYCN oncoprotein, which binds active genes promoting transcriptional amplification. Yet how MYCN coordinates transcription elongation to meet productive transcriptional amplification and which elongation machinery represents MYCN-driven vulnerability remain to be identified. We conducted a targeted screen of transcription elongation factors and identified the super elongation complex (SEC) as a unique vulnerability in MYCN-amplified neuroblastomas. MYCN directly binds EAF1 and recruits SEC to enhance processive transcription elongation. Depletion of EAF1 or AFF1/AFF4, another core subunit of SEC, leads to a global reduction in transcription elongation and elicits selective apoptosis of MYCN-amplified neuroblastoma cells. A combination screen reveals SEC inhibition synergistically potentiates the therapeutic efficacies of FDA-approved BCL2 antagonist ABT-199, in part due to suppression of MCL1 expression, both in MYCN-amplified neuroblastoma cells and in patient-derived xenografts. These findings identify disruption of the MYCN-SEC regulatory axis as a promising therapeutic strategy in neuroblastoma.
Project description:Purpose: Identify new targets in MYCN-amplified Neuroblastoma Methods: Kelly and LAN-1 neuroblastoma cells were treated in duplicate with 2 uM GSK126 (Excess Biosciences M60071-2) or DMSO for 2 or 5 days. RNA was extracted from cells with the RNeasy Kit (Qiagen). RNA libraries were prepared for sequencing using standard Illumina protocols. The pool of sixteen samples was sequenced on two lanes of an Illumina HiSeq, generating single end reads of 32-76 bp length. Transcript abundance (reads and FPKM scores) at GRCh37/hg19 RefSeq gene level was computed with the Feature Counts method implemented in the Bioconductor v3.2 Rsubread package (Liao et al., 2014). Results: Pharmacological suppression of EZH2 inhibited neuroblastoma growth. Transcriptomic analysis revealed that EZH2 serves a PRC2-dependent function in neuroblastoma, repressing neural differentiation. Moreover, EZH2-regulated genes were strongly repressed in MYCN-amplified and high risk primary tumors. These observations demonstrate that MYCN upregulates EZH2 leading to inactivation of a tumor suppressor program in neuroblastoma. Conclusion: Our study supports testing EZH2 inhibitors in patients with MYCN-amplified neuroblastoma.
Project description:The MYCN locus is amplified in about half of high-risk neuroblastoma tumors. To identify genomic loci occupied by MYCN protein in the MYCN-amplified neuroblastoma cell lines NGP, Kelly and NB-1643, we performed chromatin immunoprecipitation coupled with Next-Generation Sequencing (ChIP-seq) using an anti-MYCN antibody.
Project description:Inducible MYCN-knockdown, followed by RNA-seq analysis in the MYCN-amplified neuroblastoma cell line IMR5-75, reveals profound time-dependent transcriptome changes. For modulation of MYCN levels, stable neuroblastoma cell models were used where MYCN can be downregulated via vector-based hairpin RNA induction upon addition of 1µg/ml tetracycline (IMR5-75-shMYCN. From cells treated either with tetracycline or solvent (ethanol), RNA was isolated at time points 6 hours, 12 hours and 24 hours. Experiments were done in duplicates. RNA was sequenced.
Project description:Purpose: Identify new targets in MYCN-amplified Neuroblastoma Methods: ChIP-Seq experiments were performed on Kelly and LAN-1 neuroblastoma cells by using the following antibodies: anti-EZH2 (Cell Signaling 5246S); anti-H3K27me3 (Millipore 07-449); anti-H3K4me3 (Abcam ab8580). We evaluated the global EZH2 PRC2-dependence by identifiying direct genome-wide target genes for EZH2, H3K27me3 and H3K4me3. Results: We found that EZH2 serves a PRC2-dependent function in neuroblastoma, repressing neuronal differentiation. Moreover, EZH2-regulated genes were strongly repressed in MYCN-amplified and high-risk primary tumors. Conclusion: Our study supports testing EZH2 inhibitors in patients with MYCN-amplified neuroblastoma.
Project description:The aims of this study are to compare transcripts that are differentially expressed in the MYCN amplified compare to the MYCN non-amplified neuroblastoma cell lines, in particular, long non-coding RNAs. Methods: Ribosomal depleted RNAs from six human neuroblastoma cell lines were subjected to deep sequencing, using Illumina Hiseq. Results: We identified 459 transcripts are differentially expressed betweeen the MYCN amplified and the MYCN non-amplified cell lines. Conclusions: We have identified a novel long noncoding RNA lncNB1 that is highly expressed in the MYCN amplified compared to the MYCN non-amplified cell lines.
Project description:In neuroblastoma, amplification of the oncogenic basic helix-loop-helix (bHLH) transcription factor (TF) MYCN is the defining prognosticator of high-risk disease, occurs in one-third of neuroblastoma, and drastically reduces overall survival rates. As a proto-oncogene, targeted MYCN overexpression in peripheral neural crest is sufficient to initiate disease in mouse models. In MYCN amplified neuroblastoma, elevated expression of the factor is crucial to maintain tumor stemness and is associated with increased proliferation and aberrant cell cycle progression, as these tumors lack the ability to arrest in G1 in response to irradiation. MYCN down-regulation broadly reverses these oncogenic phenotypes in a variety of neuroblastoma models and recent thereapeutic strategies to indirectly target MYCN production or protein stability have reduced tumor growth in vivo. These observations motivate an investigation of MYCN binding in MYCN amplified tumors as it remains fundamentally unclear how elevated levels of the factor occupy the genome and alter transcriptional programs in neuroblastoma. Here we present the first dynamic chromatin and transcriptional landscape of direct MYCN perturbation in neuroblastoma. We find that at oncogenic levels, MYCN associates with E-box (CANNTG) binding motifs in an affinity dependent manner across most active cis-regulatory promoters and enhancers. MYCN shutdown globally reduces histone acetylation and transcription, consistent with prior descriptions of MYC proteins as non-linear amplifiers of gene expression. We establish that MYCN load at the promoter and proximal enhancers predicts transcriptional responsiveness to MYCN shutdown and that MYCN enhancer binding occurs prominently at the most strongly occupied and down-regulated genes, suggesting a role for these tissue specific elements in predicating MYCN responsive âtargetâ genes. At these invaded enhancers, we identify the lineage specific bHLH TWIST1 as a key collaborator and dependency of oncogenic MYCN. These data suggest that MYCN enhancer invasion helps shape transcriptional amplification of the neuroblastoma gene expression program to promote tumorigenesis. ChIP-Seq in SHEP21, BE2C, KELLY, and NGP neuroblastoma cell lines for H3K27ac, H3K4me3, RNA PolII, MYCN, BRD4, or TWIST1