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Myc oncoproteins exert tumorigenic effects by regulating expression of target oncogenes. Histone H3 lysine 79 (H3K79) methylation at Myc-responsive elements of target gene promoters is a strict prerequisite for Myc-induced transcriptional activation, and DOT1L is the only known histone methyltransferase that catalyzes H3K79 methylation. Here, we show that N-Myc upregulates DOT1L mRNA and protein expression by binding to the DOT1L gene promoter. shRNA-mediated depletion of DOT1L reduced mRNA and protein expression of N-Myc target genes ODC1 and E2F2. DOT1L bound to the Myc Box II domain of N-Myc protein, and knockdown of DOT1L reduced histone H3K79 methylation and N-Myc protein binding at the ODC1 and E2F2 gene promoters and reduced neuroblastoma cell proliferation. Treatment with the small-molecule DOT1L inhibitor SGC0946 reduced H3K79 methylation and proliferation of MYCN gene–amplified neuroblastoma cells. In mice xenografts of neuroblastoma cells stably expressing doxycycline-inducible DOT1L shRNA, ablating DOT1L expression with doxycycline significantly reduced ODC1 and E2F2 expression, reduced tumor progression, and improved overall survival. In addition, high levels of DOT1L gene expression in human neuroblastoma tissues correlated with high levels of MYCN, ODC1, and E2F2 gene expression and independently correlated with poor patient survival. Taken together, our results identify DOT1L as a novel cofactor in N-Myc–mediated transcriptional activation of target genes and neuroblastoma oncogenesis. Furthermore, they characterize DOT1L inhibitors as novel anticancer agents against MYCN-amplified neuroblastoma. Cancer Res; 77(9); 2522–33. ©2017 AACR.

Supplementary Figure S1. PA2G4 is a MYCN transactivation target gene. A, Quantification of protein expression using anti-PA2G4 and anti-MYCN antibodies against whole cell protein lysates from BE(2)-C and Kelly cells, following MYCN siRNA knockdown for 48 hours. B, mRNA expression of PA2G4 and MYCN in SH-EP MYCN3 overexpression cells treated with 1µg/ml doxycycline for 24-96 hr. C, The effect of doxycycline-induced MYCN overexpression in SHEP-TRE-MYCN cells on c-MYC and PA2G4 protein expression. D, Chromatin immunoprecipitation (ChIP) assay in Kelly cells using an anti-MYCN antibody, and real-time PCR analysis with primers identifying the MYCN DNA binding sites in the PA2G4 gene promoter (500bP upstream of transcription start site [TSS]) or Intron 1a & 1b regions of the PA2G4 gene, with and without MYCN siRNA knockdown. ChIP and real-time PCR analysis using primers against a region 1200bp upstream of TSS was used as a negative control for MYCN chromatin binding. ChIP and real-time PCR analysis using primers against the ornithine decarboxylase (ODC1) gene promoter region was used as a positive control for MYCN chromatin binding. E, Immunoblot analysis of PA2G4, MYCN and MYC protein levels in a panel of human MYCN amplified and non-amplified neuroblastoma, and normal fibroblast, cell lines using antibodies recognising PA2G4, MYCN and MYC.

Supplementary Figure S1. F, Confocal microscopy of SHEP Tet21N cells using anti-PA2G4 (red) and anti-MYCN (green) antibodies. G, Immunoblot analysis of cytoplasmic and nuclear fractions from BE(2)-C and Kelly human neuroblastoma cell lines with antibodies recognizing PA2G4 and MYCN, or GAPDH and topoisomerase as loading controls. H, Confocal microscopy of neuroblastoma (BE(2)-C and Kelly) cells using anti-PA2G4 (red) and anti-MYCN (green) antibodies. Alexafluor 555 anti-rabbit (to detect PA2G4) and Alexafluor 488 anti-mouse (to detect MYCN) were used as the secondary antibodies. I, Real-time PCR mRNA expression of MYCN and PA2G4 in ganglia from homozygote TH-MYCN+/+ mice, compared to wild type littermate control mice, obtained at different postnatal age (weeks).

MYCN is a major driver for the childhood cancer, neuroblastoma, however, there are no inhibitors of this target. Enhanced MYCN protein stability is a key component of MYCN oncogenesis and is maintained by multiple feedforward expression loops involving MYCN transactivation target genes. Here, we reveal the oncogenic role of a novel MYCN target and binding protein, proliferation-associated 2AG4 (PA2G4). Chromatin immunoprecipitation studies demonstrated that MYCN occupies the PA2G4 gene promoter, stimulating transcription. Direct binding of PA2G4 to MYCN protein blocked proteolysis of MYCN and enhanced colony formation in a MYCN-dependent manner. Using molecular modeling, surface plasmon resonance, and mutagenesis studies, we mapped the MYCN–PA2G4 interaction site to a 14 amino acid MYCN sequence and a surface crevice of PA2G4. Competitive chemical inhibition of the MYCN–PA2G4 protein–protein interface had potent inhibitory effects on neuroblastoma tumorigenesis in vivo. Treated tumors showed reduced levels of both MYCN and PA2G4. Our findings demonstrate a critical role for PA2G4 as a cofactor in MYCN-driven neuroblastoma and highlight competitive inhibition of the PA2G4-MYCN protein binding as a novel therapeutic strategy in the disease.Significance:Competitive chemical inhibition of the PA2G4–MYCN protein interface provides a basis for drug design of small molecules targeting MYC and MYCN-binding partners in malignancies driven by MYC family oncoproteins.

Supplementary Figure S2. PA2G4 increases MYCN protein stability. A and B, Representative immunoblots from cycloheximide (CHX) chase assays measuring the half-life of MYCN protein after PA2G4 knockdown (A) or overexpression (B) in BE(2)-C and Kelly cells for 48 hours. Cells were then treated with 100 µg/µl CHX for up to 60 minutes followed by immunoblotting. C, Co-IP of total protein from BE(2)-C cells using IgG, anti-MYCN, anti-PA2G4 antibodies, followed by immunoblotting with anti-MYCN, anti-PA2G4, anti-AURKA, anti-Fbxw7 or anti-vinculin antibodies.

Supplementary Figure S4. Characterization of the PA2G4-MYCN protein-protein interface. A, BE(2)-C cells were transiently transfected with EV, wildtype PA2G4 or 6 different PA2G4 point mutants for 48 hours, then treated with 100 µg/µl Cycloheximide (CHX) for up to 60 minutes, followed by immunoblot analysis for MYCN protein half-life. B, Differential Scanning Fluorimetry (DSF) showed both the seven amino acid (DHKALST, aa248-254) and large peptide (GGDHKALSTGEDTL, aa246-259) MYCN oligopeptides, along with the MYCN oligopeptide shown not to bind via SPR (DHAALAT) changed the melting temperature of the PA2G4 protein, relative to baseline (i.e. 0mM), in a dose-response manner. Shown are the means of 3 independent experiments {plus minus} SEM. C, An example of the raw data for DHKALST, with the shift to the left correlating to an increase in concentration. D, Raw SPR data for PA2G4 triple mutant (R271A, R272A and S47A) and single mutants (S47A and R272A). Also, raw SPR data for MYCN oligopeptide mutants (DHAALST, DHAALAT and DHKALAT). For the mutants and triple mutations, no binding was observed, thus analysis could not be conducted and is not shown. E, Root Mead Squared Deviation (RMSD) of the peptide over the time of the simulation. After the first 100 frames the peptide is relatively stable. Analysis was only conducted after this time.

Supplementary Information

Supplementary Figure S6. PA2G4 increases neuroblastoma tumorigenicity. A, Representative images of athymic nude mice inoculated with neuroblastoma (SH-EP) cells stably transfected with either EV control or a PA2G4 expression vector at 10 weeks post-injection. B, Images of tumor formation after mice were culled 12 weeks post-injection. C, Real-time PCR analysis of PA2G4 mRNA expression level in tumors from mice injected with either SH-EP cells overexpressing PA2G4, or SH-EP EV control cells. β2-microglobulin was used as a reference gene for total RNA loading. D, Protein was extracted from SH-EP tumor xenografts overexpressing PA2G4 and control vectors, then analysed for PA2G4-Flag and MYCN expression by immunoblotting using anti-MYCN and anti-PA2G4 antibodies, using a Vinculin loading control. E, Immunoblots of three tumor samples from each siRNA-treated cohort showing the levels of PA2G4 and MYCN protein expression, using a Vinculin loading control. F, Real-time PCR analysis of PA2G4 and MYCN mRNA expression in tumor samples taken from tumour-bearing mice xenografted with BE(2)-C neuroblastoma cells, which had been treated with either nano-particle encapsulated siRNA control, PA2G4 siRNA or PA2G4-p48 siRNA. Data are shown as means and SD derived from 6 mice per group, P-values were calculated by t-test.

Supplementary Figure S5 F-H F), at 72 hours post-transfection of EV or a PA2G4 expression vector. G, Cell viability measured by the Alamar Blue assay and immunoblot analyses using an antibody identifying MYC-tagged PA2G4-p42 protein expression in Kelly and SH-SY5Y cells transfected with EV or the MYC-tagged PA2G4-p42 expression vector at 48 and 72 hours post-transfection. Vinculin was used as loading control. H, Colony formation in vitro by Kelly and SH-SY5Y cells following transfection with either EV or MYC-tagged PA2G4-p42.

Supplementary Figure S3 F-G F, Left panel: Histopathologic and immunohistochemical analyses of MYCN;GFP tumors treated with vehicle (left) or WS6 (right). Left Panel, Top to Bottom: Neuroblastoma tumour sections immunohistochemically stained for Haematoxylin & Eosin (H&E), Proliferating Cell Nuclear Antigen (pCNA), Neural Hu protein C (Hu-C), MYCN, PA2G4 and Tyrosine Hydroxylase. Scale bar, 50 μm. Right Panel: Histograms illustrating the staining intensity of cells of vehicle (left) or WS6 treated neuroblastoma tumours expressing either MYCN, PA2G4 or Tyrosine Hydroxylase as measured by Image J software. Sample means (horizontal bars) were compared by students t-test (two-tailed). *** represents p-value

Supplementary Table S2. Multivariable Cox regression analysis of DOT1L expression in tumor tissues as a factor prognostic for outcome in 476 neuroblastoma patients

Supplementary Table S1 (Excel file). List of transcription factor target motifs around transcription start sites of genes down-regulated by DOT1L shRNA, as identified by gene set enrichment analysis.

Supplementary Figure S6 G-K G, Overall patient survival using Kaplan-Meier survival probability plots from the Cologne data set (http://r2.amc.nl) for PA2G4 mRNA expression subdivided around the median PA2G4 expression level among 477 neuroblastoma patients. H, Kaplan-Meier plot for event-free survival of 649 neuroblastoma patients from the kocak dataset (R2 microarray analysis and visualization platform, http://r2.amc.nl) I, Real-time PCR mRNA expression of PA2G4 among 40 neuroblastoma patient tumors treated at Sydney Children's Hospital, subdivided by MYCN amplification status. J, Multivariate event-free survival analysis using cox regression modelling. The p-values were obtained from the cox-regression analysis. K, Incidence of PA2G4 amplification among a range of different human cancer types within The Cancer Genome Atlas (TCGA). Results were generated using cBioportal for Cancer Genomics (https://cancergenome.nih.gov/). NEPC, neuroendocrine prostate cancer; CS, carcinosarcoma.

Supplementary Materials and Methods, Figures, Figure Legends. Fig. S1, N-Myc up-regulates ODC1 and E2F2. Fig. S2, DOT1L and N-Myc do not regulate HIF1α and VEGF. Fig. S3, knocking down DOT1L gene expression does not induce neuroblastoma cell death. Fig. S4, knocking down DOT1L reduces ODC1 and E2F2 expression in neuroblastoma tissues in mice. Fig. S5, DOT1L expression correlates with ODC1 and E2F2 expression in human neuroblastoma tissues.

Supplementary Figure S5. PA2G4 expression enhances the malignant neuroblastoma phenotype in vitro. A, Neurite formation in SH-SY5Y and BE(2)-C cells transfected with PA2G4 siRNA and then treated with 2 µM 13-cis-retinoic acid. B, Immunoblots assessing PA2G4-p48 and PA2G4-p42 protein expression levels using an anti-PA2G4 antibody against whole cell protein lysates from a panel of neuroblastoma and non-malignant myofibroblast cell lines. C, Immunoblots assessing the effect of PA2G4-p48 knockdown on PA2G4 and MYCN protein levels in BE(2)-C and CHP-134 cells. D, Immunoblots confirming transfection of PA2G4-p48 siRNA and MYCN expression plasmid DNA for 72 hours. E and F Cell proliferation measured by BrdU incorporation (E), and, cell viability measured by the Alamar Blue assay.

Supplementary Figure S3. Competitive chemical inhibition of MYCN-PA2G4 binding. A, Chemical structure of WS6. B, Cycloheximide chase assay measuring the half-life of MYCN protein in BE(2)-C and Kelly cells following 0.8 µM WS6 treatment for 24 hours, then treatment with 100 µg/µl CHX for up to 60 minutes. C, BE(2)-C and Kelly cells treated with 0.2 µM or 0.4 µM WS6, followed by colony formation assessment, compared to untreated cells. D, Immunoblotting with an anti-MYC-Tag antibody to quantify PA2G4 protein expression from SH-SY5Y and Kelly cells transfected with the MYC-tagged PA2G4 vector. E, Densitometric quantification of MYCN and PA2G4 protein levels of immunoblots using tumor tissues of TH-MYCN mice treated with either DMSO (n=5) or WS6 (n=5), and quantified by Image J software. Sample means were compared by students t-test. * Represents p-value

Supplementary Table 1: siRNA sequences Supplementary Table 2: qRT-PCR primers Supplementary Table 3: Primers for chromatin immunoprecipitation Supplementary Table 4: Multivariate analysis of event free survival and overall survival of neuroblastoma patients

List of N-Myc-binding gene promoters at which H3K4me3 was reduced by WDR5 siRNA.

List of N-Myc non-binding gene promoters at which H3K4me3 was reduced by WDR5 siRNA.

Supporting data; Supplementary Figure 1:Correlation analysis of DKC1 mRNA and dyskerin protein quantity in neuroblastoma cell lines Supplementary Figure 2:Correlation analysis of telomerase activity gene expression in neuroblastoma cells Supplementary Figure 3:Correlation analysis of TERT and MYC gene expression in neuroblastoma tumor samples Supplementary Figure 4:High DKC1 expression is a marker of poor prognosis in neuroblastoma Supplementary Figure 5:Analysis of TERT expression in neuroblastoma tumor samples Supplementary Figure 7: Upregulation of p21cip1 in NB69, but not SK-N-BE(2) cells following down regulation of dyskerin Supplementary Figure 8: Cell cycle and viability following downregulation of dyskerin

Supplementary Figures 1-5 from p53 Is a Direct Transcriptional Target of MYCN in Neuroblastoma

List of N-Myc-binding gene promoters at which H3K4me3 was not reduced by WDR5 siRNA.

Supplementary Methods-Figures-Tables

Supplementary Tables 1-4 from p53 Is a Direct Transcriptional Target of MYCN in Neuroblastoma

Genes differentially down- or up-regulated by WDR5 siRNAs by more than 1.5 fold, as shown by Affymetrix microarray, in BE(2)-C neuroblastoma cells 40 hours after siRNA transfection.

Text file containing detailed methods.

List of N-Myc non-binding gene promoters at which H3K4me3 was not reduced by WDR5 siRNA.

The RNA-binding protein dyskerin, encoded by the DKC1 gene, functions as a core component of the telomerase holoenzyme as well as ribonuclear protein complexes involved in RNA processing and ribosome biogenesis. The diverse roles of dyskerin across many facets of RNA biology implicate its potential contribution to malignancy. In this study, we examined the expression and function of dyskerin in neuroblastoma. We show that DKC1 mRNA levels were elevated relative to normal cells across a panel of 15 neuroblastoma cell lines, where both N-Myc and c-Myc directly targeted the DKC1 promoter. Upregulation of MYCN was shown to dramatically increase DKC1 expression. In two independent neuroblastoma patient cohorts, high DKC1 expression correlated strongly with poor event-free and overall survival (P < 0.0001), independently of established prognostic factors. RNAi-mediated depletion of dyskerin inhibited neuroblastoma cell proliferation, including cells immortalized via the telomerase-independent ALT mechanism. Furthermore, dyskerin attenuation impaired anchorage-independent proliferation and tumor growth. Overexpression of the telomerase RNA component, hTR, demonstrated that this proliferative impairment was not a consequence of telomerase suppression. Instead, ribosomal stress, evidenced by depletion of small nucleolar RNAs and nuclear dispersal of ribosomal proteins, was the likely cause of the proliferative impairment in dyskerin-depleted cells. Accordingly, dyskerin suppression caused p53-dependent G1 cell-cycle arrest in p53 wild-type cells, and a p53-independent pathway impaired proliferation in cells with p53 dysfunction. Together, our findings highlight dyskerin as a new therapeutic target in neuroblastoma with crucial telomerase-independent functions and broader implications for the spectrum of malignancies driven by MYC family oncogenes. Cancer Res; 76(12); 3604–17. ©2016 AACR.

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Text file of Figure Legends to Supplementary data

Supporting data; Supplementary Figure 6:Nucleolar dispersal of rpl5

The molecular mechanisms and gene regulatory networks sustaining cell proliferation in neuroblastoma (NBL) cells are still not fully understood. In this tumor context, it has been proposed that anti-proliferative drugs, such as the pan-HDAC inhibitor panobinostat, could be tested to mitigate tumor progression. Here, we set out to investigate the effects of panobinostat treatment at the unprecedented resolution offered by single-cell sequencing. We identified a global senescence signature paired with reduction in proliferation in treated Kelly cells and more isolated transcriptional responses compatible with early neuronal differentiation. Using master regulator analysis, we identified BAZ1A, HCFC1, MAZ, and ZNF146 as the transcriptional regulators most significantly repressed by panobinostat. Experimental silencing of these transcription factors (TFs) confirmed their role in sustaining NBL cell proliferation in vitro.

Neuroblastoma (NB) is one of the primary causes of death for pediatric malignancies. Given the high heterogeneity in NB’s mutation landscape, optimizing individualized therapies is still challenging. In the context of genomic alterations, MYCN amplification is the most correlated event with poor outcomes. MYCN is involved in the regulation of several cellular mechanisms, including cell cycle. Thus, studying the influence of MYCN overexpression in the G1/S transition checkpoint of the cell cycle may unveil novel druggable targets for the development of personalized therapeutical approaches. Here, we show that high expression of E2F3 and MYCN correlate with poor prognosis in NB despite the RB1 mRNA levels. Moreover, we demonstrate through luciferase reporter assays that MYCN bypasses RB function by incrementing E2F3-responsive promoter activity. We showed that MYCN overexpression leads to RB inactivation by inducing RB hyperphosphorylation during the G1 phase through cell cycle synchronization experiments. Moreover, we generated two MYCN-amplified NB cell lines conditionally knockdown (cKD) for the RB1 gene through a CRISPRi approach. Indeed, RB KD did not affect cell proliferation, whereas cell proliferation was strongly influenced when a non-phosphorylatable RB mutant was expressed. This finding revealed the dispensable role of RB in regulating MYCN-amplified NB’s cell cycle. The described genetic interaction between MYCN and RB1 provides the rationale for using cyclin/CDK complexes inhibitors in NBs carrying MYCN amplification and relatively high levels of RB1 expression.

Half of high-risk neuroblastoma patients have MYCN amplification. Here, the authors show that MYCN induces fatty acid uptake and synthesis to support neuroblastoma and inhibition of a fatty acid transporter impairs tumor progression in preclinical models.Neuroblastoma (NB) is a childhood cancer arising from sympatho-adrenal neural crest cells. MYCN amplification is found in half of high-risk NB patients; however, no available therapies directly target MYCN. Using multi-dimensional metabolic profiling in MYCN expression systems and primary patient tumors, we comprehensively characterized the metabolic landscape driven by MYCN in NB. MYCN amplification leads to glycerolipid accumulation by promoting fatty acid (FA) uptake and biosynthesis. We found that cells expressing amplified MYCN depend highly on FA uptake for survival. Mechanistically, MYCN directly upregulates FA transport protein 2 (FATP2), encoded by SLC27A2. Genetic depletion of SLC27A2 impairs NB survival, and pharmacological SLC27A2 inhibition selectively suppresses tumor growth, prolongs animal survival, and exerts synergistic anti-tumor effects when combined with conventional chemotherapies in multiple preclinical NB models. This study identifies FA uptake as a critical metabolic dependency for MYCN-amplified tumors. Inhibiting FA uptake is an effective approach for improving current treatment regimens.

Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Amplification of the MYCN oncogene is associated with an aggressive phenotype and poor outcome in childhood neuroblastoma. Polyamines are highly regulated essential cations that are frequently elevated in cancer cells, and the rate-limiting enzyme in polyamine synthesis, ornithine decarboxylase 1 (ODC1), is a direct transcriptional target of MYCN. Treatment of neuroblastoma cells with the ODC1 inhibitor difluoromethylornithine (DFMO), although a promising therapeutic strategy, is only partially effective at impeding neuroblastoma cell growth due to activation of compensatory mechanisms resulting in increased polyamine uptake from the surrounding microenvironment. In this study, we identified solute carrier family 3 member 2 (SLC3A2) as the key transporter involved in polyamine uptake in neuroblastoma. Knockdown of SLC3A2 in neuroblastoma cells reduced the uptake of the radiolabeled polyamine spermidine, and DFMO treatment increased SLC3A2 protein. In addition, MYCN directly increased polyamine synthesis and promoted neuroblastoma cell proliferation by regulating SLC3A2 and other regulatory components of the polyamine pathway. Inhibiting polyamine uptake with the small-molecule drug AMXT 1501, in combination with DFMO, prevented or delayed tumor development in neuroblastoma-prone mice and extended survival in rodent models of established tumors. Our findings suggest that combining AMXT 1501 and DFMO with standard chemotherapy might be an effective strategy for treating neuroblastoma.

This study focuses on a lightweight syntactic foam constituted by an epoxy matrix filled with polydispersed Glass Microballoons (GMs) up to 0.75 volume fraction. We present experimental results on hydrostatic loading which demonstrate the possibility of different failure modes depending on whether the surface of the composite is painted/coated or not. In order to explain this surprising behaviour, we propose a three-dimensional Finite Element (FE) micromechanical model. First, we develop a cubic MultiParticle Unit Cell (MPUC) which includes 100 randomly placed GMs and accounting for their polydispersion, in terms of both size and radius ratio. This model is validated by subjecting it to effective uniaxial stress and comparing its predictions of the elastic moduli with experimental findings and an analytical homogenisation technique. Second, towards modelling failure, we implement a structural criterion proposed by our group, which posits that any GM undergoes brittle failure when its average elastic energy density reaches a critical value. We then utilise our measurements of the effective strength under uniaxial compressive stress to identify different critical values for selected types of GMs. Third, on the basis of the MPUC, we reach our goal by developing a larger FE model, including 300 GMs, which enables the study of the stress diffusion from the external surface through an appropriately thick layer of composite, under macroscopic uniform pressure. This micromechanical model allows us to demonstrate the influence of the paint/coating on the syntactic foam failure mode through a detailed analysis of the collapsed GMs and the matrix stress state.

Neuroblastoma (NB) is one of the most frequently occurring neurogenic extracranial solid cancers in childhood and infancy. Over the years, many pieces of evidence suggested that NB development is controlled by gene expression dysregulation. These unleashed programs that outline NB cancer cells make them highly dependent on specific tuning of gene expression, which can act co-operatively to define the differentiation state, cell identity, and specialized functions. The peculiar regulation is mainly caused by genetic and epigenetic alterations, resulting in the dependency on a small set of key master transcriptional regulators as the convergence point of multiple signalling pathways. In this review, we provide a comprehensive blueprint of transcriptional regulation bearing NB initiation and progression, unveiling the complexity of novel oncogenic and tumour suppressive regulatory networks of this pathology. Furthermore, we underline the significance of multi-target therapies against these hallmarks, showing how novel approaches, together with chemotherapy, surgery, or radiotherapy, can have substantial antineoplastic effects, disrupting a wide variety of tumorigenic pathways through combinations of different treatments.

Neuroblastoma (NB) arises from oncogenic disruption of neural crest (NC) differentiation. Treatment with retinoic acid (RA) to induce differentiation has improved survival in some NB patients, but not all patients respond, and most NBs eventually develop resistance to RA. Loss of the chromatin modifier chromatin assembly factor 1 subunit p150 (CHAF1A) promotes NB cell differentiation; however, the mechanism by which CHAF1A drives NB oncogenesis has remained unexplored. This study shows that CHAF1A gain‐of‐function supports cell malignancy, blocks neuronal differentiation in three models (zebrafish NC, human NC, and human NB), and promotes NB oncogenesis. Mechanistically, CHAF1A upregulates polyamine metabolism, which blocks neuronal differentiation and promotes cell cycle progression. Targeting polyamine synthesis promotes NB differentiation and enhances the anti‐tumor activity of RA. The authors' results provide insight into the mechanisms that drive NB oncogenesis and suggest a rapidly translatable therapeutic approach (DFMO plus RA) to enhance the clinical efficacy of differentiation therapy in NB patients., This manuscript utilizes three different models to demonstrate that the chromatin assembly factor 1 subunit p150 (CHAF1A) blocks neuronal differentiation and promotes neuroblastoma oncogenesis. CHAF1A functions in part by reprogramming cell metabolism and activating polyamine synthesis. Blocking polyamine synthesis is a clinically translatable approach to improve retinoic acid‐based differentiation therapy.

The majority of patients with neuroblastoma due to MYCN oncogene amplification and consequent N-Myc oncoprotein over-expression die of the disease. Here our analyses of RNA sequencing data identify the long noncoding RNA lncNB1 as one of the transcripts most over-expressed in MYCN-amplified, compared with MYCN-non-amplified, human neuroblastoma cells and also the most over-expressed in neuroblastoma compared with all other cancers. lncNB1 binds to the ribosomal protein RPL35 to enhance E2F1 protein synthesis, leading to DEPDC1B gene transcription. The GTPase-activating protein DEPDC1B induces ERK protein phosphorylation and N-Myc protein stabilization. Importantly, lncNB1 knockdown abolishes neuroblastoma cell clonogenic capacity in vitro and leads to neuroblastoma tumor regression in mice, while high levels of lncNB1 and RPL35 in human neuroblastoma tissues predict poor patient prognosis. This study therefore identifies lncNB1 and its binding protein RPL35 as key factors for promoting E2F1 protein synthesis, N-Myc protein stability and N-Myc-driven oncogenesis, and as therapeutic targets., MYCN amplification is common in neuroblastomas. Here, the authors identify a long noncoding RNA, lncNB1 in these cancers and show that it promotes tumorigenesis by binding to ribosomal protein, RPL35 to enhance E2F1 and DEPDC1B protein synthesis, which phosphorylates ERK to stabilise N-Myc.

Neuroblastoma (NBL) is a pediatric cancer responsible for more than 15% of cancer deaths in children, with 800 new cases each year in the United States alone. Genomic amplification of the MYC oncogene family member MYCN characterizes a subset of high-risk pediatric neuroblastomas. Several cellular models have been implemented to study this disease over the years. Two of these, SK-N-BE-2-C (BE2C) and Kelly, are amongst the most used worldwide as models of MYCN-Amplified human NBL. Here, we provide a transcriptome-wide quantitative measurement of gene expression and transcriptional network activity in BE2C and Kelly cell lines at an unprecedented single-cell resolution. We obtained 1105 Kelly and 962 BE2C unsynchronized cells, with an average number of mapped reads/cell of roughly 38,000. The single-cell data recapitulate gene expression signatures previously generated from bulk RNA-Seq. We highlight low variance for commonly used housekeeping genes between different cells (ACTB, B2M and GAPDH), while showing higher than expected variance for metallothionein transcripts in Kelly cells. The high number of samples, despite the relatively low read coverage of single cells, allowed for robust pathway enrichment analysis and master regulator analysis (MRA), both of which highlight the more mesenchymal nature of BE2C cells as compared to Kelly cells, and the upregulation of TWIST1 and DNAJC1 transcriptional networks. We further defined master regulators at the single cell level and showed that MYCN is not constantly active or expressed within Kelly and BE2C cells, independently of cell cycle phase. The dataset, alongside a detailed and commented programming protocol to analyze it, is fully shared and reusable.

// Giorgia Giordani 1, 5, * , Marilena Barraco 1, 6, * , Angela Giangrande 2 , Giovanni Martinelli 3 , Viviana Guadagnuolo 3 , Giorgia Simonetti 3 , Giovanni Perini 1, 4 , Roberto Bernardoni 1, 4 1 Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Bologna, Italy 2 Institut de Genetique et de Biologie Moleculaire et Cellulaire, CNRS/INSERM/ULP 67404 Illkirch, France 3 Department of Experimental, Diagnostic and Specialty Medicine (DIMES), Institute of Hematology "L. e A. Seragnoli", University of Bologna, Bologna, Italy 4 Health Sciences and Technology - Interdepartmental Center for Industrial Research (HST-ICIR), University of Bologna, Ozzano Emilia, Italy 5 Present address: Department of Biological Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield, UK 6 Present address: Institute of Hematology, “L e A Seragnoli”, S. Orsola-Malpighi Hospital, Bologna, Italy * These authors contributed equally to this work Correspondence to: Roberto Bernardoni, email: roberto.bernardoni@unibo.it Giovanni Perini, email: giovanni.perini@unibo.it Keywords: PF-04449913, Smoothened inhibitor, leukemia, Drosophila, prohemocytes Received: December 09, 2015 Accepted: June 26, 2016 Published: July 28, 2016 ABSTRACT The efficient treatment of hematological malignancies as Acute Myeloid Leukemia, myelofibrosis and Chronic Myeloid Leukemia, requires the elimination of cancer-initiating cells and the prevention of disease relapse through targeting pathways that stimulate generation and maintenance of these cells. In mammals, inhibition of Smoothened, the key mediator of the Hedgehog signaling pathway, reduces Chronic Myeloid Leukemia progression and propagation. These findings make Smo a candidate target to inhibit maintenance of leukemia-initiating cells. In Drosophila melanogaster the same pathway maintains the hematopoietic precursor cells of the lymph gland, the hematopoietic organ that develops in the larva. Using Drosophila as an in vivo model, we investigated the mode of action of PF-04449913, a small-molecule inhibitor of the human Smo protein. Drosophila larvae fed with PF-04449913 showed traits of altered hematopoietic homeostasis. These include the development of melanotic nodules, increase of circulating hemocytes, the size increase of the lymph gland and accelerated differentiation of blood cells likely due to the exit of multi-potent precursors from quiescence. Importantly, the Smo inhibition can lead to the complete loss of hematopoietic precursors. We conclude that PF-04449913 inhibits Drosophila Smo blocking the Hh signaling pathway and causing the loss of hematopoietic precursor cells. Interestingly, this is the effect expected in patients treated with PF-04449913: number decrease of cancer initiating cells in the bone marrow to reduce the risk of leukemia relapse. Altogether our results indicate that Drosophila comprises a model system for the in vivo study of molecules that target evolutionary conserved pathways implicated in human hematological malignancies.

Background: Individuals with Down syndrome suffer from mental retardation due to severe neurogenesis impairment.

The oncoprotein BCR-ABL1 triggers chronic myeloid leukemia. It is clear that the disease relies on constitutive BCR-ABL1 kinase activity, but not all the interactors and regulators of the oncoprotein are known. We describe and validate a Drosophila leukemia model based on inducible human BCR-ABL1 expression controlled by tissue-specific promoters. The model was conceived to be a versatile tool for performing genetic screens. BCR-ABL1 expression in the developing eye interferes with ommatidia differentiation and expression in the hematopoietic precursors increases the number of circulating blood cells. We show that BCR-ABL1 interferes with the pathway of endogenous dAbl with which it shares the target protein Ena. Loss of function of ena or Dab, an upstream regulator of dAbl, respectively suppresses or enhances both the BCR-ABL1-dependent phenotypes. Importantly, in patients with leukemia decreased human Dab1 and Dab2 expression correlates with more severe disease and Dab1 expression reduces the proliferation of leukemia cells. Globally, these observations validate our Drosophila model, which promises to be an excellent system for performing unbiased genetic screens aimed at identifying new BCR-ABL1 interactors and regulators in order to better elucidate the mechanism of leukemia onset and progression.

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.

Neocentromeres contribute to cancer progression by mitotically stabilizing acentric chromosomes containing amplified oncogenes. Macchia et al. show that... Genome amplification in the form of rings or giant rod-shaped marker chromosomes (RGMs) is a common genetic alteration in soft tissue tumors. The mitotic stability of these structures is often rescued by perfectly functioning analphoid neocentromeres, which therefore significantly contribute to cancer progression. Here, we disentangled the genomic architecture of many neocentromeres stabilizing marker chromosomes in well-differentiated liposarcoma and lung sarcomatoid carcinoma samples. In cells carrying heavily rearranged RGMs, these structures were assembled as patchworks of multiple short amplified sequences, disclosing an extremely high level of complexity and definitely ruling out the existence of regions prone to neocentromere seeding. Moreover, by studying two well-differentiated liposarcoma samples derived from the onset and the recurrence of the same tumor, we documented an expansion of the neocentromeric domain that occurred during tumor progression, which reflects a strong selective pressure acting toward the improvement of the neocentromeric functionality in cancer. In lung sarcomatoid carcinoma cells we documented, extensive “centromere sliding” phenomena giving rise to multiple, closely mapping neocentromeric epialleles on separate coexisting markers occur, likely due to the instability of neocentromeres arising in cancer cells. Finally, by investigating the transcriptional activity of neocentromeres, we came across a burst of chimeric transcripts, both by extremely complex genomic rearrangements, and cis/trans-splicing events. Post-transcriptional editing events have been reported to expand and variegate the genetic repertoire of higher eukaryotes, so they might have a determining role in cancer. The increased incidence of fusion transcripts, might act as a driving force for the genomic amplification process, together with the increased transcription of oncogenes.

Childhood neuroblastoma, a disease of the sympathetic nervous system, is the most common solid tumour of infancy, remarkably refractory to therapeutic treatments. One of the most powerful independent prognostic indicators for this disease is the amplification of the MYCN oncogene, which occurs at high levels in approximately 25% of neuroblastomas. Interestingly, amplification and not just expression of MYCN has a strong prognostic value, although this fact appears quite surprising as MYCN is a transcription factor that requires dimerising with its partner MAX, to exert its function. This observation greatly suggests that the role of MYCN in neuroblastoma should be examined in the context of MAX expression. In this report, we show that, in contrast to what is found in normal cells, MAX expression is significantly different among primary NBs, and that its level appears to correlate with the clinical outcome of the disease. Importantly, controlled modulation of MAX expression in neuroblastoma cells with different extents of MYCN amplification, demonstrates that MAX can instruct gene transcription programs that either reinforce or weaken the oncogenic process enacted by MYCN. In general, our work illustrates that it is the MAX to MYCN ratio that can account for tumour progression and clinical outcome in neuroblastoma and proposes that such a ratio should be considered as an important criterion to the design and development of anti-MYCN therapies.