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Neuroblastoma, the most frequent solid tumor in infants, shows very diverse outcomes from spontaneous regression to fatal disease. When these different tumors originate and how they evolve are not known. Here we quantify the somatic evolution of neuroblastoma by deep whole-genome sequencing, molecular clock analysis and population-genetic modeling in a comprehensive cohort covering all subtypes. We find that tumors across the entire clinical spectrum begin to develop via aberrant mitoses as early as the first trimester of pregnancy. Neuroblastomas with favorable prognosis expand clonally after short evolution, whereas aggressive neuroblastomas show prolonged evolution during which they acquire telomere maintenance mechanisms. The initial aneuploidization events condition subsequent evolution, with aggressive neuroblastoma exhibiting early genomic instability. We find in the discovery cohort (n = 100), and validate in an independent cohort (n = 86), that the duration of evolution is an accurate predictor of outcome. Thus, insight into neuroblastoma evolution may prospectively guide treatment decisions.

Aberrant expression of MYC transcription factor family members predicts poor clinical outcome in many human cancers. Oncogenic MYC profoundly alters metabolism and mediates an antioxidant response to maintain redox balance. Here we show that MYCN induces massive lipid peroxidation on depletion of cysteine, the rate-limiting amino acid for glutathione (GSH) biosynthesis, and sensitizes cells to ferroptosis, an oxidative, non-apoptotic and iron-dependent type of cell death. The high cysteine demand of MYCN-amplified childhood neuroblastoma is met by uptake and transsulfuration. When uptake is limited, cysteine usage for protein synthesis is maintained at the expense of GSH triggering ferroptosis and potentially contributing to spontaneous tumor regression in low-risk neuroblastomas. Pharmacological inhibition of both cystine uptake and transsulfuration combined with GPX4 inactivation resulted in tumor remission in an orthotopic MYCN-amplified neuroblastoma model. These findings provide a proof of concept of combining multiple ferroptosis targets as a promising therapeutic strategy for aggressive MYCN-amplified tumors.

Purpose: Amplified MYCN oncogene defines a subgroup of neuroblastomas with poor outcome. However, a substantial number of MYCN single-copy neuroblastomas exhibits an aggressive phenotype similar to that of MYCN-amplified neuroblastomas even in the absence of high MYCN mRNA and/or protein levels.Experimental Design: To identify shared molecular mechanisms that mediate the aggressive phenotype in MYCN-amplified and single-copy high-risk neuroblastomas, we defined genetic programs evoked by ectopically expressed MYCN in vitro and analyzed them in high-risk versus low-risk neuroblastoma tumors (n = 49) using cDNA microarrays. Candidate gene expression was validated in a separate cohort of 117 patients using quantitative PCR, and protein expression was analyzed in neuroblastoma tumors by immunoblotting and immunohistochemistry.Results: We identified a genetic signature characterized by a subset of MYCN/MYC and E2F targets, including Skp2, encoding the F-box protein of the SCFSkp2 E3-ligase, to be highly expressed in high-risk neuroblastomas independent of amplified MYCN. We validated the findings for Skp2 and analyzed its expression in relation to MYCN and E2F-1 expression in a separate cohort (n = 117) using quantitative PCR. High Skp2 expression proved to be a highly significant marker of dire prognosis independent of both MYCN status and disease stage, on the basis of multivariate analysis of event-free survival (hazard ratio, 3.54; 95% confidence interval, 1.56-8.00; P = 0.002). Skp2 protein expression was inversely correlated with expression of p27, the primary target of the SCFSkp2 E3-ligase, in neuroblastoma tumors.Conclusion: Skp2 may have a key role in the progression of neuroblastomas and should make an attractive target for therapeutic approaches.

Supplementary Figures S1-S2; Supplementary Materials and Methods; Supplementary Tables S1-S2.

Supplementary Table 1 from Transcriptional Repression of SKP2 Is Impaired in MYCN-Amplified Neuroblastoma

Cox proportional hazards regression for overall survival (105 neuroblastomas)

Supplementary Figure 1 from Transcriptional Repression of SKP2 Is Impaired in MYCN-Amplified Neuroblastoma

A distal portion of human chromosome 1p is often deleted in neuroblastomas and other cancers and it is generally assumed that this region harbors one or more tumor suppressor genes. In neuroblastoma, a 261 kb region at 1p36.3 that encompasses the smallest region of consistent deletion pinpoints the locus for calmodulin binding transcription activator 1 (CAMTA1). Low CAMTA1 expression is an independent predictor of poor outcome in multivariate survival analysis, but its potential functionality in neuroblastoma has not been explored. In this study, we used inducible cell models to analyze the impact of CAMTA1 on neuroblastoma biology. In neuroblastoma cells that expressed little endogenous CAMTA1, its ectopic expression slowed cell proliferation, increasing the relative proportion of cells in G1/G0 phases of the cell cycle, inhibited anchorage-independent colony formation, and suppressed the growth of tumor xenografts. CAMTA1 also induced neurite-like processes and markers of neuronal differentiation in neuroblastoma cells. Further, retinoic acid and other differentiation- inducing stimuli upregulated CAMTA1 expression in neuroblastoma cells. Transciptome analysis revealed 683 genes regulated on CAMTA1 induction and gene ontology analysis identified genes consistent with CAMTA1-induced phenotypes, with a significant enrichment for genes involved in neuronal function and differentiation. Our findings define properties of CAMTA1 in growth suppression and neuronal differentiation that support its assignment as a 1p36 tumor suppressor gene in neuroblastoma. Cancer Res; 71(8); 3142–51. ©2011 AACR.

Supplementary Table 1 from CAMTA1, a 1p36 Tumor Suppressor Candidate, Inhibits Growth and Activates Differentiation Programs in Neuroblastoma Cells

The broad clinical spectrum of neuroblastoma ranges from spontaneous regression to rapid progression despite intensive multimodal therapy. This diversity is not fully explained by known genetic aberrations, suggesting the possibility of epigenetic involvement in pathogenesis. In pursuit of this hypothesis, we took an integrative approach to analyze the methylomes, transcriptomes, and copy number variations in 105 cases of neuroblastoma, complemented by primary tumor- and cell line–derived global histone modification analyses and epigenetic drug treatment in vitro. We found that DNA methylation patterns identify divergent patient subgroups with respect to survival and clinicobiologic variables, including amplified MYCN. Transcriptome integration and histone modification–based definition of enhancer elements revealed intragenic enhancer methylation as a mechanism for high-risk–associated transcriptional deregulation. Furthermore, in high-risk neuroblastomas, we obtained evidence for cooperation between PRC2 activity and DNA methylation in blocking tumor-suppressive differentiation programs. Notably, these programs could be re-activated by combination treatments, which targeted both PRC2 and DNA methylation. Overall, our results illuminate how epigenetic deregulation contributes to neuroblastoma pathogenesis, with novel implications for its diagnosis and therapy. Cancer Res; 76(18); 5523–37. ©2016 AACR.

Description of additional methods and procedures used in the study. Also includes Supplementary References.

Dendrogram and probability values for hierarchical clustering of 105 neuroblastomas based on genome-wide DNA methylation (S1); Kaplan-Meier estimates of overall survival for DNA methylation subgroups (S2); Genes whose hypermethylation and downregulation are associated with neuroblastoma high-risk disease are induced during neuronal differentiation of neuroblastoma cells (S3); Examples for genes whose hypermethylation and downregulation are associated with neuroblastoma high-risk disease and that are marked by both H3K27me3 and DNA methylation at putative regulatory regions in Be(2)-C cells (S4); MYCN deregulation is associated with activation of PRC2 components (S5); Genes whose hypermethylation and downregulation are associated with high-risk disease are H3K27me3-marked in a MYCN-dependent fashion (S6); Example for genes whose hypermethylation and downregulation are associated with neuroblastoma high-risk disease that significantly lost H3K27me3 and DNA methylation at putative regulatory regions upon treatment with DAC and EPZ-6438 in Be(2)-C cells (S7); Genes whose hypermethylation and downregulation are associated with high-risk disease are preferentially induced upon DAC/TSA treatment (S8).

The cell cycle regulator, SKP2, is overexpressed in various cancers and plays a key role in p27 degradation, which is involved in tumor cell dedifferentiation. Little is known about the mechanisms leading to impaired SKP2 transcriptional control in tumor cells. We used neuroblastoma as a model to study SKP2 regulation because SKP2 transcript levels gradually increase with aggressiveness of neuroblastoma subtypes. The highest SKP2 levels are found in neuroblastomas with amplified MYCN. Accordingly, we found 5.5-fold (range, 2–9.5) higher SKP2 core promoter activity in MYCN-amplified cells. Higher SKP2 core promoter activity in MYCN-amplified cells is mediated through a defined region at the transcriptional start site. This region includes a specific E2F-binding site that makes SKP2 activation largely independent of mitogenic signals integrated through the SP1/ELK-1 site. We show by chromatin immunoprecipitation that SKP2 activation through the transcriptional start site in MYCN-amplified cells is associated with the low abundance of pRB-E2F1 complexes bound to the SKP2 promoter. Transcriptional control of SKP2 through this regulatory mechanism can be reestablished in MYCN-amplified cells by restoring pRB activity using selective small compound inhibitors of CDK4. In contrast, doxorubicin or nutlin-3 treatment—both leading to p53-p21 activation—or CDK2 inhibition had no effect on SKP2 regulation in MYCN-amplified cells. Together, this implies that deregulated MYCN protein levels in MYCN-amplified neuroblastoma cells activate SKP2 through CDK4 induction, abrogating repressive pRB-E2F1 complexes bound to the SKP2 promoter. Cancer Res; 70(9); 3791–802. ©2010 AACR.

PURPOSE Clinical outcomes of patients with neuroblastoma range from spontaneous tumor regression to fatality. Hence, understanding the mechanisms that cause tumor progression is crucial for the treatment of patients. In this study, we show that FOXR2 activation identifies a subset of neuroblastoma tumors with unfavorable outcome and we investigate the mechanism how FOXR2 relates to poor outcome in patients. MATERIALS AND METHODS We analyzed three independent transcriptional data sets of in total 1030 primary neuroblastomas with full clinical annotation. We performed immunoprecipitation for FOXR2 and MYCN and silenced FOXR2 expression in two neuroblastoma cell lines to examine the effect on cellular processes, transcriptome, and MYCN protein levels. Tumor samples were analyzed for protein levels of FOXR2 and MYCN. RESULTS In three combined neuroblastoma data sets, 9% of tumors show expression of FOXR2 but have low levels of MYCN mRNA. FOXR2 expression identifies a group of patients with unfavorable outcome, showing 10-year overall survival rates of 53%-59%, and proves to be an independent prognostic factor compared with established risk factors. Transcriptionally, FOXR2-expressing tumors are very similar to MYCN-amplified tumors, suggesting that they might share a common mechanism of tumor initiation. FOXR2 knockdown in FOXR2-expressing neuroblastoma cell lines resulted in cell cycle arrest, reduced cell growth, cell death, and reduced MYCN protein levels, all indicating that FOXR2 is essential for these tumors. Finally, we show that FOXR2 binds and stabilizes MYCN protein and MYCN protein levels are highly increased in FOXR2-expressing tumors, in several cases comparable with MYCN-amplified samples. CONCLUSION The stabilization of MYCN by FOXR2 represents an alternative mechanism to MYCN amplification to increase MYCN protein levels. As such, FOXR2 expression identifies another subset of neuroblastoma patients with unfavorable clinical outcome.

Neuroblastoma is a pediatric tumor of the developing sympathetic nervous system. However, the cellular origin of neuroblastoma has yet to be defined. Here we studied the single-cell transcriptomes of neuroblastomas and normal human developing adrenal glands at various stages of embryonic and fetal development. We defined normal differentiation trajectories from Schwann cell precursors over intermediate states to neuroblasts or chromaffin cells and showed that neuroblastomas transcriptionally resemble normal fetal adrenal neuroblasts. Importantly, neuroblastomas with varying clinical phenotypes matched different temporal states along normal neuroblast differentiation trajectories, with the degree of differentiation corresponding to clinical prognosis. Our work highlights the roles of oncogenic MYCN and loss of TFAP2B in blocking differentiation and may provide the basis for designing therapeutic interventions to overcome differentiation blocks.

Half of the children diagnosed with neuroblastoma (NB) have high-risk disease, disproportionately contributing to overall childhood cancer-related deaths. In addition to recurrent gene mutations, there is increasing evidence supporting the role of epigenetic deregulation in disease pathogenesis. Yet, comprehensive cis-regulatory network descriptions from NB are lacking. Here, using genome-wide H3K27ac profiles across 60 NBs, covering the different clinical and molecular subtypes, we identified four major super-enhancer-driven epigenetic subtypes and their underlying master regulatory networks. Three of these subtypes recapitulated known clinical groups; namely, MYCN-amplified, MYCN non-amplified high-risk and MYCN non-amplified low-risk NBs. The fourth subtype, exhibiting mesenchymal characteristics, shared cellular identity with multipotent Schwann cell precursors, was induced by RAS activation and was enriched in relapsed disease. Notably, CCND1, an essential gene in NB, was regulated by both mesenchymal and adrenergic regulatory networks converging on distinct super-enhancer modules. Overall, this study reveals subtype-specific super-enhancer regulation in NBs. Westermann and colleagues define four subtypes of neuroblastoma based on super-enhancer profiles in primary patient samples, which could be linked to distinct clinical outcomes and cell identity characteristics.

Resistance towards cancer treatment represents a major clinical obstacle, preventing cure of cancer patients. To gain mechanistic insights, we developed a model for acquired resistance to chemotherapy by treating mice carrying patient derived xenografts (PDX) of acute lymphoblastic leukemia with widely-used cytotoxic drugs for 18 consecutive weeks. In two distinct PDX samples, tumors initially responded to treatment, until stable disease and eventually tumor re-growth evolved under therapy, at highly similar kinetics between replicate mice. Notably, replicate tumors developed different mutations in TP53 and individual sets of chromosomal alterations, suggesting independent parallel clonal evolution rather than selection, driven by a combination of stochastic and deterministic processes. Transcriptome and proteome showed shared dysregulations between replicate tumors providing putative targets to overcome resistance. In vivo CRISPR/Cas9 dropout screens in PDX revealed broad dependency on BCL2, BRIP1 and COPS2. Accordingly, venetoclax re-sensitized derivative tumors towards chemotherapy, despite genomic heterogeneity, demonstrating direct translatability of the approach. Hence, despite the presence of multiple resistance-associated genomic alterations, effective rescue treatment for polychemotherapy-resistant tumors can be identified using functional testing in preclinical models.

Telomere maintenance by telomerase activation or alternative lengthening of telomeres (ALT) is a major determinant of poor outcome in neuroblastoma. Here, we screen for ALT in primary and relapsed neuroblastomas (n = 760) and characterize its features using multi-omics profiling. ALT-positive tumors are molecularly distinct from other neuroblastoma subtypes and enriched in a population-based clinical sequencing study cohort for relapsed cases. They display reduced ATRX/DAXX complex abundance, due to either ATRX mutations (55%) or low protein expression. The heterochromatic histone mark H3K9me3 recognized by ATRX is enriched at the telomeres of ALT-positive tumors. Notably, we find a high frequency of telomeric repeat loci with a neuroblastoma ALT-specific hotspot on chr1q42.2 and loss of the adjacent chromosomal segment forming a neo-telomere. ALT-positive neuroblastomas proliferate slowly, which is reflected by a protracted clinical course of disease. Nevertheless, children with an ALT-positive neuroblastoma have dismal outcome., Alternative lengthening of telomeres (ALT) is associated with a poor outcome in neuroblastoma. Here, the authors find that ALT is associated with mutated ATRX and/or reduced protein abundance, frequent telomeric repeat loci and heterochromatic telomeric chromatin.

Aberrant expression of MYC family members predicts poor clinical outcome in many human cancers. Oncogenic MYC profoundly alters metabolism and mediates an antioxidant response to maintain redox balance. Here we show that MYC induces massive lipid peroxidation upon depletion of cysteine, the rate-limiting amino acid for glutathione biosynthesis and sensitizes cells to ferroptosis, an oxidative, non-apoptotic and irondependent type of cell death. In MYCN-amplified childhood neuroblastoma, MYCN mediates resistance to ferroptosis by activating transsulfuration of methionine to cysteine. MYCN may contribute to spontaneous tumor regression in low-risk neuroblastomas by promoting ferroptosis in cells with epigenetically silenced cystathionine-beta-synthase, the rate-limiting enzyme for transsulfuration. We identified enzymes and antiporter proteins crucial to ferroptotic escape, providing multiple previously unknown sites that may be acted on therapeutically.

Video and gene expression analyses coupled with the RNAi technique reveal microtubule-dependent, neuronal-like nucleokinetic migration in a noradrenergic type of neuroblastoma, providing a glimpse into the mechanism by which noradrenergic neuroblastoma cells may spread., The migrational propensity of neuroblastoma is affected by cell identity, but the mechanisms behind the divergence remain unknown. Using RNAi and time-lapse imaging, we show that ADRN-type NB cells exhibit RAC1- and kalirin-dependent nucleokinetic (NUC) migration that relies on several integral components of neuronal migration. Inhibition of NUC migration by RAC1 and kalirin-GEF1 inhibitors occurs without hampering cell proliferation and ADRN identity. Using three clinically relevant expression dichotomies, we reveal that most of up-regulated mRNAs in RAC1- and kalirin–GEF1–suppressed ADRN-type NB cells are associated with low-risk characteristics. The computational analysis shows that, in a context of overall gene set poverty, the upregulomes in RAC1- and kalirin–GEF1–suppressed ADRN-type cells are a batch of AU-rich element–containing mRNAs, which suggests a link between NUC migration and mRNA stability. Gene set enrichment analysis–based search for vulnerabilities reveals prospective weak points in RAC1- and kalirin–GEF1–suppressed ADRN-type NB cells, including activities of H3K27- and DNA methyltransferases. Altogether, these data support the introduction of NUC inhibitors into cancer treatment research.

ALK mutations occur in 10% of primary neuroblastomas and represent a major target for precision treatment. In combination with MYCN amplification, ALK mutations infer an ultra-high-risk phenotype resulting in very poor patient prognosis. To open up opportunities for future precision drugging, a deeper understanding of the molecular consequences of constitutive ALK signaling and its relationship to MYCN activity in this aggressive pediatric tumor entity will be essential. We show that mutant ALK downregulates the ‘HMG-box transcription factor 1’ (HBP1) through the PI3K-AKT–FOXO3a signaling axis. HBP1 inhibits both the transcriptional activating and repressing activity of MYCN, the latter being mediated through PRC2 activity. HBP1 itself is under negative control of MYCN through miR-17~92. Combined targeting of HBP1 by PI3K antagonists and MYCN signaling by BET- or HDAC-inhibitors blocks MYCN activity and significantly reduces tumor growth, suggesting a novel targeted therapy option for high-risk neuroblastoma.

© 2020 by the authors., Neuroblastoma (NB) is one of the most common pediatric cancers and presents a poor survival rate in affected children. Current pretreatment risk assessment relies on a few known molecular parameters, like the amplification of the oncogene MYCN. However, a better molecular knowledge about the aggressive progression of the disease is needed to provide new therapeutical targets and prognostic markers and to improve patients’ outcomes. The human protein kinase VRK1 phosphorylates various signaling molecules and transcription factors to regulate cell cycle progression and other processes in physiological and pathological situations. Using neuroblastoma tumor expression data, tissue microarrays from fresh human samples and patient-derived xenografts (PDXs), we have determined that VRK1 kinase expression stratifies patients according to tumor aggressiveness and survival, allowing the identification of patients with worse outcome among intermediate risk. VRK1 associates with cell cycle signaling pathways in NB and its downregulation abrogates cell proliferation in vitro and in vivo. Through the analysis of ChIP-seq and methylation data from NB tumors, we show that VRK1 is a MYCN gene target, however VRK1 correlates with NB aggressiveness independently of MYCN gene amplification, synergizing with the oncogene to drive NB progression. Our study also suggests that VRK1 inhibition may constitute a novel cell-cycle-targeted strategy for anticancer therapy in neuroblastoma., This research is supported by grants from the “Junta de Andalucía-Universidad de Sevilla-FEDER” (US-1262985) and the Spanish Ministry of Science and Innovation (SAF2016-80412-Pand PID2019-110817R). A.C. is the recipient of a FPI fellowship from the Spanish Ministry of Science and Innovation. MAG is supported by a fellowship from the “Asociación de familiares y amigos de pacientes con Neuroblastoma (NEN)”. A.A. is the recipient of a FPU fellowship from the Spanish Ministry of Education.

Neuroblastoma is a malignant paediatric tumour of the sympathetic nervous system1. Roughly half of these tumours regress spontaneously or are cured by limited therapy. By contrast, high-risk neuroblastomas have an unfavourable clinical course despite intensive multimodal treatment, and their molecular basis has remained largely elusive2–4. Here we have performed whole-genome sequencing of 56 neuroblastomas (high-risk, n = 39; low-risk, n = 17) and discovered recurrent genomic rearrangements affecting a chromosomal region at 5p15.33 proximal of the telomerase reverse transcriptase gene (TERT). These rearrangements occurred only in high-risk neuroblastomas (12/39, 31%) in a mutually exclusive fashion with MYCN amplifications and ATRX mutations, which are known genetic events in this tumour type1,2,5. In an extended case series (n = 217), TERT rearrangements defined a subgroup of high-risk tumours with particularly poor outcome. Despite a large structural diversity of these rearrangements, they all induced massive transcriptional upregulation of TERT. In the remaining high-risk tumours, TERT expression was also elevated in MYCN-amplified tumours, whereas alternative lengthening of telomeres was present in neuroblastomas without TERT or MYCN alterations, suggesting that telomere lengthening represents a central mechanism defining this subtype. The 5p15.33 rearrangements juxtapose the TERT coding sequence to strong enhancer elements, resulting in massive chromatin remodelling and DNA methylation of the affected region. Supporting a functional role of TERT, neuroblastoma cell lines bearing rearrangements or amplified MYCN exhibited both upregulated TERT expression and enzymatic telomerase activity. In summary, our findings show that remodelling of the genomic context abrogates transcriptional silencing of TERT in high-risk neuroblastoma and places telomerase activation in the centre of transformation in a large fraction of these tumours.

Neuroblastoma is a malignancy of the developing sympathetic nervous system that is often lethal when relapse occurs. We here used whole-exome sequencing, mRNA expression profiling, array CGH and DNA methylation analysis to characterize 16 paired samples at diagnosis and relapse from individuals with neuroblastoma. The mutational burden significantly increased in relapsing tumors, accompanied by altered mutational signatures and reduced subclonal heterogeneity. Global allele frequencies at relapse indicated clonal mutation selection during disease progression. Promoter methylation patterns were consistent over disease course and were patient specific. Recurrent alterations at relapse included mutations in the putative CHD5 neuroblastoma tumor suppressor, chromosome 9p losses, DOCK8 mutations, inactivating mutations in PTPN14 and a relapse-specific activity pattern for the PTPN14 target YAP. Recurrent new mutations in HRAS, KRAS and genes mediating cell-cell interaction in 13 of 16 relapse tumors indicate disturbances in signaling pathways mediating mesenchymal transition. Our data shed light on genetic alteration frequency, identity and evolution in neuroblastoma.

// David J. Duffy 1,7,* , Aleksandar Krstic 1,* , Melinda Halasz 1,* , Thomas Schwarzl 1,8,* , Dirk Fey 1 , Kristiina Iljin 6 , Jai Prakash Mehta 1 , Kate Killick 1 , Jenny Whilde 1 , Benedetta Turriziani 1 , Saija Haapa-Paananen 6 , Vidal Fey 6 , Matthias Fischer 5 , Frank Westermann 4 , Kai-Oliver Henrich 4 , Steffen Bannert 4 , Desmond G. Higgins 1,2,3 and Walter Kolch 1,2,3 1 Systems Biology Ireland, University College Dublin, Belfield, Dublin, Ireland 2 Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin, Ireland 3 School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland 4 Division of NB Genomics, German Cancer Research Center (DKFZ), Heidelberg, Germany 5 Department of Paediatric Haematology and Oncology and Center for Molecular Medicine Cologne (CMMC), University Hospital Cologne, Cologne, Germany 6 VTT Technical Research Centre of Finland, Tietotie 2, Espoo, Finland 7 The Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, Florida, USA 8 European Molecular Biology Laboratory (EMBL), Meyerhofstrase, Heidelberg, Germany * These authors have contributed equally to this work Correspondence to: David J. Duffy, email: // Keywords : MYC (c-MYC), neuroblastoma, transcriptional regulation, mRNA sequencing (mRNA-seq), 4sU-seq Received : November 15, 2015 Accepted : November 23, 2015 Published : December 11, 2015 Abstract Despite intensive study, many mysteries remain about the MYCN oncogene’s functions. Here we focus on MYCN’s role in neuroblastoma, the most common extracranial childhood cancer. MYCN gene amplification occurs in 20% of cases, but other recurrent somatic mutations are rare. This scarcity of tractable targets has hampered efforts to develop new therapeutic options. We employed a multi-level omics approach to examine MYCN functioning and identify novel therapeutic targets for this largely un-druggable oncogene. We used systems medicine based computational network reconstruction and analysis to integrate a range of omic techniques: sequencing-based transcriptomics, genome-wide chromatin immunoprecipitation, siRNA screening and interaction proteomics, revealing that MYCN controls highly connected networks, with MYCN primarily supressing the activity of network components. MYCN’s oncogenic functions are likely independent of its classical heterodimerisation partner, MAX. In particular, MYCN controls its own protein interaction network by transcriptionally regulating its binding partners. Our network-based approach identified vulnerable therapeutically targetable nodes that function as critical regulators or effectors of MYCN in neuroblastoma. These were validated by siRNA knockdown screens, functional studies and patient data. We identified β-estradiol and MAPK/ERK as having functional cross-talk with MYCN and being novel targetable vulnerabilities of MYCN-amplified neuroblastoma. These results reveal surprising differences between the functioning of endogenous, overexpressed and amplified MYCN, and rationalise how different MYCN dosages can orchestrate cell fate decisions and cancerous outcomes. Importantly, this work describes a systems-level approach to systematically uncovering network based vulnerabilities and therapeutic targets for multifactorial diseases by integrating disparate omic data types.

Uncontrolled cell cycle entry, resulting from deregulated CDK-RB1-E2F pathway activity, is a crucial determinant of neuroblastoma cell malignancy. Here we identify neuroblastoma-suppressive functions of the p19-INK4d CDK inhibitor and uncover mechanisms of its repression in high-risk neuroblastomas. Reduced p19-INK4d expression was associated with poor event-free and overall survival and neuroblastoma risk factors including amplified MYCN in a set of 478 primary neuroblastomas. High MYCN expression repressed p19-INK4d mRNA and protein levels in different neuroblastoma cell models with conditional MYCN expression. MassARRAY and 450K methylation analyses of 105 primary neuroblastomas uncovered a differentially methylated region within p19-INK4d. Hypermethylation of this region was associated with reduced p19-INK4d expression. In accordance, p19-INK4d expression was activated upon treatment with the demethylating agent, 2'-deoxy-5-azacytidine, in neuroblastoma cell lines. Ectopic p19-INK4d expression decreased viability, clonogenicity and the capacity for anchorage-independent growth of neuroblastoma cells, and shifted the cell cycle towards the G1/0 phase. p19-INK4d also induced neurite-like processes and markers of neuronal differentiation. Moreover, neuroblastoma cell differentiation, induced by all-trans retinoic acid or NGF-NTRK1-signaling, activated p19-INK4d expression. Our findings pinpoint p19-INK4d as a neuroblastoma suppressor and provide evidence for MYCN-mediated repression and for epigenetic silencing of p19-INK4d by DNA hypermethylation in high-risk neuroblastomas.

Aberrant expression of MYC family members predicts poor clinical outcome in many human cancers. Oncogenic MYC profoundly alters metabolism and mediates an antioxidant response to maintain redox balance. The purpose of the study was to analyze the interplay of oncogenic MYCN or c-MYC, referred to here as MYC(N), activity with cysteine metabolism and ferroptosis, an oxidative, non-apoptotic, and iron dependent form of regulated cell death caused by ROS-mediated massive lipid peroxidation (L-ROS), using MYC(N)-driven childhood neuroblastoma as a model.The intracellular amino acid levels at MYC(N)-high and MYC(N)-low cellular states were analyzed by HPLC. Effects on cell viability upon depletion of individual amino acids from the growth medium was tested in various cancer cell lines with regulable MYC(N). An unbiased high-throughput MYCN synthetic lethal siRNA screen was used to identify genes preferentially acting in the 'MYC(N)-high' state and protecting cells from ROS accumulation and ferroptosis. The capacity of cyst(e)ine uptake, intracellular cysteine synthesis via transsulfuration and glutathione biosynthesis was assessed in various neuroblastoma cell lines and tissues using metabolome, RNAseq, ChiP-seq and global proteome analyses. To investigate L-ROS formation at various conditions cells were stained with the lipid peroxidation sensor, C11-BODIPY, and flow cytometrically analyzed. Ferroptosis inducers (FINs) and inhibitors of transsulfuration were used to test their activity in various MYC(N)-dependent neuroblastoma cell lines and in vivo xenografts.We found that intracellular cysteine depletion in a 'MYC(N)-high' context induces cell death by ferroptosis and identified multiple points in glutathione synthesis and metabolism, particularly detoxification of L-ROS, that are vulnerable in the 'MYC(N)-high' state as compared to the 'MYC(N)-low' context. We could show that ferroptosis was dependent on MYC(N) expression and was enhanced by iron. We further demonstrated that both cystine import and intracellular cysteine synthesis via transulfuration achieved the intracellular state supportive of oncogenic MYC(N)-driven growth without endangering the cell to ferroptosis. We demonstrated the MYC(N) drives increased transsulfuration activity, rather than cysteine import, in tumor cells to maintain the cellular cysteine supply for glutathione synthesis. Our findings together with new descriptions of the ferroptotic process establish a novel functional link between oncogenic MYC(N) and ferroptosis, and imply regulation by cysteine-dependent glutathione availability. In MYCN-amplified childhood neuroblastoma, MYCN mediates resistance to ferroptosis by activating transsulfuration of methionine to cysteine. We identified enzymes and antiporter proteins crucial to ferroptotic escape, providing multiple previously unknown sites that may be acted on therapeutically. Citation Format: Frank Westermann, Hamed Alborzinia, Sina Gogolin, Andrés F. Flórez, Lena M. Brückner, Moritz Gartlgruber, Sabine Hartlieb, Daniel Dreidax, Michal Nadler-Holly, Matthias Ziehm, Chunxuan Shao, Matthias Selbach, Carlo Stresemann, Gernot Poschet, Barbara Nicke, Stefan Wölfl, Kai O. Henrich, Thomas Höfer. MYCN mediates cysteine addiction and sensitizes to ferroptosis in cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4973.

Purpose: Amplified MYCN oncogene defines a subgroup of neuroblastomas with poor outcome. However, a substantial number of MYCN single-copy neuroblastomas exhibits an aggressive phenotype similar to that of MYCN-amplified neuroblastomas even in the absence of high MYCN mRNA and/or protein levels. Experimental Design: To identify shared molecular mechanisms that mediate the aggressive phenotype in MYCN-amplified and single-copy high-risk neuroblastomas, we defined genetic programs evoked by ectopically expressed MYCN in vitro and analyzed them in high-risk versus low-risk neuroblastoma tumors (n = 49) using cDNA microarrays. Candidate gene expression was validated in a separate cohort of 117 patients using quantitative PCR, and protein expression was analyzed in neuroblastoma tumors by immunoblotting and immunohistochemistry. Results: We identified a genetic signature characterized by a subset of MYCN/MYC and E2F targets, including Skp2, encoding the F-box protein of the SCFSkp2 E3-ligase, to be highly expressed in high-risk neuroblastomas independent of amplified MYCN. We validated the findings for Skp2 and analyzed its expression in relation to MYCN and E2F-1 expression in a separate cohort (n = 117) using quantitative PCR. High Skp2 expression proved to be a highly significant marker of dire prognosis independent of both MYCN status and disease stage, on the basis of multivariate analysis of event-free survival (hazard ratio, 3.54; 95% confidence interval, 1.56-8.00; P = 0.002). Skp2 protein expression was inversely correlated with expression of p27, the primary target of the SCFSkp2 E3-ligase, in neuroblastoma tumors. Conclusion: Skp2 may have a key role in the progression of neuroblastomas and should make an attractive target for therapeutic approaches.

Neuroblastoma is an embryonal pediatric tumor that originates from the developing sympathetic nervous system and shows a broad range of clinical behavior, ranging from fatal progression to differentiation into benign ganglioneuroma. In experimental neuroblastoma systems, retinoic acid (RA) effectively induces neuronal differentiation, and RA treatment has been therefore integrated in current therapies. However, the molecular mechanisms underlying differentiation are still poorly understood. We here investigated the role of transcription factor activating protein 2 beta (TFAP2B), a key factor in sympathetic nervous system development, in neuroblastoma pathogenesis and differentiation. Microarray analyses of primary neuroblastomas (n = 649) demonstrated that low TFAP2B expression was significantly associated with unfavorable prognostic markers as well as adverse patient outcome. We also found that low TFAP2B expression was strongly associated with CpG methylation of the TFAP2B locus in primary neuroblastomas (n = 105) and demethylation with 5-aza-2'-deoxycytidine resulted in induction of TFAP2B expression in vitro, suggesting that TFAP2B is silenced by genomic methylation. Tetracycline inducible re-expression of TFAP2B in IMR-32 and SH-EP neuroblastoma cells significantly impaired proliferation and cell cycle progression. In IMR-32 cells, TFAP2B induced neuronal differentiation, which was accompanied by up-regulation of the catecholamine biosynthesizing enzyme genes DBH and TH, and down-regulation of MYCN and REST, a master repressor of neuronal genes. By contrast, knockdown of TFAP2B by lentiviral transduction of shRNAs abrogated RA-induced neuronal differentiation of SH-SY5Y and SK-N-BE(2)c neuroblastoma cells almost completely. Taken together, our results suggest that TFAP2B is playing a vital role in retaining RA responsiveness and mediating noradrenergic neuronal differentiation in neuroblastoma.

The broad clinical spectrum of neuroblastoma ranges from spontaneous regression to rapid progression despite intensive multimodal therapy. This diversity is not fully explained by known genetic aberrations, suggesting the possibility of epigenetic involvement in pathogenesis. In pursuit of this hypothesis, we took an integrative approach to analyze the methylomes, transcriptomes, and copy number variations in 105 cases of neuroblastoma, complemented by primary tumor- and cell line–derived global histone modification analyses and epigenetic drug treatment in vitro. We found that DNA methylation patterns identify divergent patient subgroups with respect to survival and clinicobiologic variables, including amplified MYCN. Transcriptome integration and histone modification–based definition of enhancer elements revealed intragenic enhancer methylation as a mechanism for high-risk–associated transcriptional deregulation. Furthermore, in high-risk neuroblastomas, we obtained evidence for cooperation between PRC2 activity and DNA methylation in blocking tumor-suppressive differentiation programs. Notably, these programs could be re-activated by combination treatments, which targeted both PRC2 and DNA methylation. Overall, our results illuminate how epigenetic deregulation contributes to neuroblastoma pathogenesis, with novel implications for its diagnosis and therapy. Cancer Res; 76(18); 5523–37. ©2016 AACR.

Background: Heterozygous deletions within distal 1p are observed in 30% of neuroblastomas. So far, several potential 1p tumor suppressor genes have been identified. However, in this study we are focussing on 1p genes whose inactivation is not necessarily linked to tumor development but which mediate cell-essential functions, rendering cells with copy number loss vulnerable to further impairment. These genes are candidate therapeutic targets according to the concept of CYCLOPS (copy number alterations yielding cancer liabilities owing to partial loss). Methods: To identify a subset of 1p genes for which heterozygous loss may be tolerated but further reduction leads to cell death, we performed siRNA screens mediating the systematic knock-down of distal 1p genes in five 1p-deleted versus five non-1p-deleted neuroblastoma cell lines. We used 3 different siRNAs per gene in a liquid forward approach. After 96h Hoechst stained nuclei were count. Among others, a neuron-related candidate gene has been identified as a potential CYCLOPS. The candidate gene was validated by viability assays, immunocytochemistry and cell cycle analysis via FACS. Results: We identified many potential CYCLOPS genes mapping on the distal end of chromosome arm 1p. One of these genes is involved in neuronal and embryonic development and has been further validated. Knock-down of the gene impaired cell viability in 1p-deleted cell lines but did not in 1p-non-deleted cells. G1/G0 phase arrest with corresponding S phase decrease was observed in both 1p-deleted and 1p-non-deleted cells. Additionally, neurite-like outgrowth could be observed in 1p-non-deleted cells indicating an induction of differentiation. Conclusion: This study identified a candidate CYCLOPS gene in neuroblastoma. Heterozygous deletions of chromosome arm 1p are also frequently observed in other cancers including melanoma, colorectal and breast cancer. We hypothesize that this proof-of-principle opens a new therapeutic window for tumors harbouring a heterozygous deletion of our candidate gene or other cell essential genes on chromosome arm 1p. Citation Format: Alica Torkov, Kai-Oliver Henrich, Chunxuan Shao, Moritz Gartlgruber, Frank Westermann. Blinding the CYCLOPS - Cancer vulnerabilities unveiled by genomic loss [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1426. doi:10.1158/1538-7445.AM2017-1426

Background Neuroblastoma (NB) is a pediatric tumor derived from precursor cells of the sympathetic nervous system. NB accounts for 12% of all childhood cancer deaths with ~50% high-risk cases which frequently harbor amplified proto-oncogene MYCN. Evidence accumulates that epigenetic deregulation, including aberrant DNA methylation in high-risk disease or oncogene activation by enhancer hijacking, plays a prominent role in NB. The present study applies a comprehensive approach integrating chromatin modification data with genomic and expression data to elucidate NB subtype specific super-enhancer (SE) landscapes and core regulatory circuitries (CRCs) consisting of lineage-specific interconnected loops of SE-driven, auto-regulatory master transcription factors. Methods Chromatin immunoprecipitation sequencing (ChIP-seq) of histone 3 lysine 27 acetylation (H3K27ac) was used to identify active enhancer elements in 23 primary NBs. A validation cohort consisting of 16 NB cell lines and two human neural crest cell lines was used. ChIPmentation was applied to validate predicted transcription factor (TF) binding events. Circular chromatin conformation capture sequencing (4C-seq) was used to assay physical promoter-enhancer interactions. Results Unsupervised clustering of 23 primary NBs according to H3K27ac signal intensity at the most variable SEs (genome-wide) revealed two main subgroups, MYCN-amplified (n = 8) and MYCN single copy tumors (n = 15), with distinctive activity patterns. Calling of CRCs in the 23 primary NBs yielded a core set of NB master TFs (CRC TFs). Amongst the top ten of them are HAND2, PHOX2B and MYCN, all of which are implicated in NB biology and playing essential roles in the development of the sympathetic nervous system. In line with this, gene ontology analyses of the top 50 CRC TFs converge on biological processes like development of neural crest cells, sympathetic nervous system and peripheral nervous system neurons. ChIPmentation analyses of selected CRC TFs confirmed auto-binding to their assigned SEs and those of other CRC TFs in their respective network. Interactions between promoters and SEs of selected CRC TFs were verified via 4C-seq. Intriguingly, expression analysis of the top 50 CRC TFs in a cohort of 498 primary NBs revealed that less than 20% of the CRC TFs are up-regulated in MYCN-amplified tumors while the remaining 80% are down-regulated in that subgroup. This suggests a superordinate role of MYCN in differentially orchestrating NB master TFs. Conclusion The study identifies the core set of NB master transcription factors and assigns established NB regulators like HAND2, PHOX2B and MYCN to well-defined CRCs. It reveals an association of MYCN amplification with the global SE landscape of primary NBs and suggests a role for MYCN in differentially controlling subsets of CRC TFs and their networks. Specific targeting of the SE-dependent CRC networks may open a therapeutic window for epigenetic drugs, including BET inhibitors, CDK7 or EZH2 inhibition, in NB. Citation Format: Moritz Gartlgruber, Daniel Dreidax, Daria Doncevic, Sebastian Steinhauser, Stefan Gröschel, Kai Oliver Henrich, Young-Gyu Park, Carl Herrmann, Frank Westermann. Core transcriptional regulatory circuitries in neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-083. doi:10.1158/1538-7445.AM2017-LB-083

Background: Neuroblastoma (NB), a neural crest-derived tumor of the sympathetic nervous system, is the most common extracranial solid tumor in children. We have previously shown that genomic rearrangements activate proto-oncogenic telomerase by juxtaposing active enhancer elements to the TERT gene in a large fraction of high-risk NBs. In the present study, we applied a global approach integrating whole genome sequencing (WGS), Chromatin immunoprecipitation sequencing (ChIP-seq) and RNA sequencing (RNA-seq) data of NB cells and tumors to identify further key oncogenes activated by enhancer-hijacking in NB. Methods: WGS was applied to search for structural rearrangements in 120 NB tumors and five NB cell lines. Corresponding RNA-seq data were used to discover mono-allelic and/or outlier expression of candidate genes potentially involved in enhancer hijacking events. ChIP-seq of 34 NB tumors and 17 NB cell lines was applied to identify active enhancer elements in NB. Circular chromatin conformation capture sequencing (4C-seq) was used to confirm physical promoter-enhancer interactions in NB cell lines. Results: WGS analyses revealed that chromosomal rearrangements are common events in NB tumors and cell lines and frequently affect regions harboring proto-oncogenes and lineage specific enhancers. ChIP-seq analyses of the chromatin mark histone 3 lysine 27 acetylation (H3K27ac), surrogate for enhancer activity, confirmed that these rearrangements recurrently juxtapose active enhancer elements to oncogenes including MYCN and MYC in NB. Intriguingly, quantification of H3K27ac ChIP-seq profiles uncovered that the enhancer elements translocated to MYC were among the most active ones within the respective epigenomes. 4C-seq analyses proofed physical interactions between translocated enhancer elements and promoters of the respective oncogenes, which is in line with their elevated expression in rearranged cases. Conclusions: Our study reveals that structural rearrangements in high-risk neuroblastoma frequently juxtapose strong enhancers to key oncogenes, including MYCN and MYC, leading to physical promoter-enhancer interactions which likely drive overexpression of the oncogenes observed in rearranged cases. The common mechanism of oncogene activation by enhancer-hijacking may open a therapeutic window for epigenetic drugs including BET or CDK7 inhibitors in high-risk NBs. Citation Format: Daniel Dreidax, Moritz Gartlgruber, Sebastian Steinhauser, Larisa Savelyeva, Ron Schwessinger, Umut Toprak, Nati Ha, Dilafruz Juraeva, Martin Peifer, Matthias Fischer, Stefan Gröschel, Kai-Oliver Henrich, Young-Gyu Park, Benedikt Brors, Matthias Schlesner, Carl Herrmann, Frank Westermann. Activation of proto-oncogenes by enhancer-hijacking in high-risk neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1023. doi:10.1158/1538-7445.AM2017-1023

Natural Killer (NK) cells are innate effector cells that are able to recognize and eliminate tumor cells through engagement of their surface receptors. NKp30 is a potent activating NK cell receptor that elicits efficient NK cell-mediated target cell killing. Recently, B7-H6 was identified as tumor cell surface expressed ligand for NKp30. Enhanced B7-H6 mRNA levels are frequently detected in tumor compared to healthy tissues. To gain insight in the regulation of expression of B7-H6 in tumors, we investigated transcriptional mechanisms driving B7-H6 expression by promoter analyses. Using luciferase reporter assays and chromatin immunoprecipitation we mapped a functional binding site for Myc, a proto-oncogene overexpressed in certain tumors, in the B7-H6 promoter. Pharmacological inhibition or siRNA/shRNA-mediated knock-down of c-Myc or N-Myc significantly decreased B7-H6 expression on a variety of tumor cells including melanoma, pancreatic carcinoma and neuroblastoma cell lines. In tumor cell lines from different origin and primary tumor tissues of hepatocellular carcinoma (HCC), lymphoma and neuroblastoma, mRNA levels of c-Myc positively correlated with B7-H6 expression. Most importantly, upon inhibition or knock-down of c-Myc in tumor cells impaired NKp30-mediated degranulation of NK cells was observed. Thus, our data imply that Myc driven tumors could be targets for cancer immunotherapy exploiting the NKp30/B7-H6 axis.

Five polymorphic microsatellite loci were developed for the ant Myrmica scabrinodis using a magnetic bead hybridization selection protocol. The number of alleles per locus varied between three and six. Cross-species amplification of four of the loci yielded positive amplification products in four Myrmica species, suggesting their general suitability for microsatellite analysis within this taxonomic group.

A broad range of human malignancies is associated with nonrandom 1p36 deletions, suggesting the existence of tumor suppressors encoded in this region. Evidence for tumor-specific inactivation of 1p36 genes in the classic “two-hit” manner is scarce; however, many tumor suppressors do not require complete inactivation but contribute to tumorigenesis by partial impairment. We discuss recent data derived from both human tumors and functional cancer models indicating that the 1p36 genes CHD5, CAMTA1, KIF1B, CASZ1, and miR-34a contribute to cancer development when reduced in dosage by genomic copy number loss or other mechanisms. We explore potential interactions among these candidates and propose a model where heterozygous 1p36 deletion impairs oncosuppressive pathways via simultaneous downregulation of several dosage-dependent tumor suppressor genes. Cancer Res; 72(23); 6079–88. ©2012 AACR.

Review on CAMTA1 (calmodulin binding transcription activator 1), with data on DNA, on the protein encoded, and where the gene is implicated.

The cell cycle regulator, SKP2, is overexpressed in various cancers and plays a key role in p27 degradation, which is involved in tumor cell dedifferentiation. Little is known about the mechanisms leading to impaired SKP2 transcriptional control in tumor cells. We used neuroblastoma as a model to study SKP2 regulation because SKP2 transcript levels gradually increase with aggressiveness of neuroblastoma subtypes. The highest SKP2 levels are found in neuroblastomas with amplified MYCN. Accordingly, we found 5.5-fold (range, 2–9.5) higher SKP2 core promoter activity in MYCN-amplified cells. Higher SKP2 core promoter activity in MYCN-amplified cells is mediated through a defined region at the transcriptional start site. This region includes a specific E2F-binding site that makes SKP2 activation largely independent of mitogenic signals integrated through the SP1/ELK-1 site. We show by chromatin immunoprecipitation that SKP2 activation through the transcriptional start site in MYCN-amplified cells is associated with the low abundance of pRB-E2F1 complexes bound to the SKP2 promoter. Transcriptional control of SKP2 through this regulatory mechanism can be reestablished in MYCN-amplified cells by restoring pRB activity using selective small compound inhibitors of CDK4. In contrast, doxorubicin or nutlin-3 treatment—both leading to p53-p21 activation—or CDK2 inhibition had no effect on SKP2 regulation in MYCN-amplified cells. Together, this implies that deregulated MYCN protein levels in MYCN-amplified neuroblastoma cells activate SKP2 through CDK4 induction, abrogating repressive pRB-E2F1 complexes bound to the SKP2 promoter. Cancer Res; 70(9); 3791–802. ©2010 AACR.

We analysed the expression of BIRC5 and BIRC5-2B in primary neuroblastoma (NB) tumors and NB model systems. In tumors, overexpression of BIRC5 correlated closely with its isoform BIRC5-2B. Expression of both transcripts was stage-dependent, associated with poor prognosis and with the expression of the transcription factor E2F1. In cell culture, we identified BIRC5 as a direct transcriptional target of activating E2Fs, primarily when p21(Cip1) and p27(Kip1), two other E2F1 targets, are strongly suppressed. Deregulated MYCN indirectly induces BIRC5 through suppression of CDKN1A/p21(Cip1) and induction of Skp2, which in turn favors the degradation of p27(Kip1). In addition, increased BIRC5 protein stability via phosphorylation is mediated by expression of E2F targets such as CDC2. In line with this, selective knock down of CDC2 inhibited BIRC5 abundance and suppressed its anti-apoptotic activities. We conclude that BIRC5 is induced via a functional cooperation between MYCN and E2F1.

AFAR genes play a key role in the detoxification of the carcinogen Aflatoxin B(1) (AFB(1)). In the rat, Afar1 induction can prevent AFB(1)-induced liver cancer. It has been proposed that AFAR enzymes can metabolise endogenous diketones and dialdehydes that may be cytotoxic and/or genotoxic. Furthermore, human AFAR1 catalyses the rate limiting step in the synthesis of the neuromodulator gamma-hydroxybutyrate (GHB) and was found elevated in neurodegenerative diseases such as Alzheimer's and dementia with Lewy bodies (DLB). The human AFAR gene family maps to a genomic region in 1p36 of frequent hemizygous deletions in various human cancers. To investigate, if genetic variation of AFAR1 and AFAR2 exists that may alter protein detoxification capabilities and confer susceptibility to cancer, we have analysed a spectrum of human tumours and tumour cell lines for genetic heterogeneity. From 110 DNA samples, we identified nine different amino acid changes; two were in AFAR1 and seven in AFAR2. In AFAR1, we found genetic variation in the proposed substrate-binding amino acid 113, encoding Ala(113) or Thr(113). An AFAR2 variant had a Glu(55) substituted by Lys(55) at a position that is conserved among many aldo-keto reductases. This polarity change may have an effect on the proposed substrate binding amino acids nearby (Met(47), Tyr(48), Asp(50)). Further population analyses and functional studies of the nine variants detected may show if these variants are disease-related.

Udgivelsesdato: 2007-Feb Deletion of a distal portion of 1p is seen in a wide range of human malignancies, including neuroblastoma. Here, a 1p36.3 commonly deleted region of 216 kb has been defined encompassing two genes, CAMTA1 and FLJ10737. Low expression of CAMTA1 has been recently shown to be an independent predictor of poor outcome in neuroblastoma patients. The present study surveys CAMTA1 and FLJ10737 for genetic alterations by fluorescence-based single strand conformation polymorphism (SSCP) using a panel of DNAs from 88 neuroblastomas, their matching blood samples and 97 unaffected individuals. Nucleotide variants encoding amino acid substitutions were found in both genes. One CAMTA1 variant (T1336I) was not detected in 97 unaffected individuals, another (N1177K) resides in a conserved domain of the CAMTA1 protein and was found hemizygous in six neuroblastomas. We found no evidence for somatic mutations in FLJ10737 or CAMTA1. Further investigations are needed to address the functional impact of the identified variants and their possible significance for neuroblastoma.

Amplification of HER2, C-MYC and CCND1 oncogenes is a hallmark of breast cancer (BC); however, its involvement in the bilateral form of this disease has not been investigated yet. In this study, 50 bilateral BC (biBC) pairs (100 tumors) and 72 control unilateral BC were examined using real-time PCR analysis of microdissected archival tissues. In biBC, the frequency of >3-fold oncogene amplification was 6/100 (6%) for HER2, 6/100 (6%) for C-MYC and 7/100 (7%) for CCND1. Altogether, 18/100 (18%) biBC tumors had increased gene dosage of at least one oncogene. Tumors forming synchronous biBC pairs had amplification in 11/46 cases (24%). In 3 of 8 patients with amplification-positive carcinomas, the amplification was detected in both neoplasms: 2 biBC had concordant activation of the same oncogene (HER2 and CCND1, respectively), and in the remaining case distinct oncogenes were affected (HER2 and C-MYC). In contrast, amplifications in metachronous biBC were strongly discordant: none of 27 first carcinomas carried this abnormality, while the frequency of amplification in second tumors (7/27; 26%) was similar to the one observed in unilateral BC (20/72; 28%). The trend toward concordance of oncogene amplification status in synchronous but not in metachronous biBC pairs can be explained by the nearly identical natural history of the disease in simultaneously arising tumors. The skewed pattern of amplifications in metachronous biBC might be attributed to their association with adverse BC prognosis; it appears that only patients with amplification-negative first BC have sufficient chances to survive until the development of the contralateral carcinoma.

Purpose: A distal portion of 1p is frequently deleted in human neuroblastomas, and it is generally assumed that this region harbors at least one gene relevant for neuroblastoma development. A 1p36.3 commonly deleted region, bordered by D1S2731 and D1S214 has been defined. The present study surveys whether expression of genes mapping to this region is associated with tumor behavior.Experimental Design: Candidate genes localized within the deleted region were identified by sequence data analysis. Their expression was assessed in a cohort of 49 primary neuroblastomas using cDNA microarray analysis. Gene expression patterns associated with known prognostic markers and patient outcome were further evaluated by quantitative real-time reverse transcription-PCR in a cohort of 102 neuroblastomas.Results: The commonly deleted region spans 261 kb and encompasses two genes, FLJ10737 and CAMTA1. We found no evidence for an association of FLJ10737 expression with established prognostic variables or outcome. In contrast, low CAMTA1 expression characterized tumors with 1p deletion, MYCN amplification, and advanced tumor stages 3 and 4. Moreover, low CAMTA1 expression was significantly associated with poor outcome (P < 0.001). In multivariate analysis of event-free survival, the prognostic information of low CAMTA1 expression was independent of 1p status, MYCN status, tumor stage, and age of the patient at diagnosis (hazard ratio, 3.52; 95% confidence interval, 1.21-10.28; P = 0.02).Conclusions: Our data suggest that assessment of CAMTA1 expression may improve the prognostic models for neuroblastoma and that it will be important to define the biological function of CAMTA1 in this disease.

The cell cycle regulator, SKP2, is overexpressed in various cancers, and plays a key role in p27 degradation, which is involved in tumor cell dedifferentiation. Little is known about the mechanisms leading to impaired SKP2 transcriptional control in tumor cells. We used neuroblastoma as a model to study SKP2 regulation because SKP2 transcript levels gradually increase with aggressiveness of neuroblastoma subtypes. Highest SKP2 levels are found in neuroblastomas with amplified MYCN. Accordingly, we found 5.5-fold (range 2-9.5) higher SKP2 core promoter activity in MYCN-amplified cells. Higher SKP2 core promoter activity in MYCN-amplified cells is mediated through a defined region at the transcriptional start site (TSSR). This region includes a specific E2F-binding site that makes SKP2 activation largely independent of mitogenic signals integrated through the SP1/ELK-1 site. We demonstrate by chromatin immunoprecipitation that SKP2 activation through the TSSR in MYCN-amplified cells is associated with low abundance of pRB-E2F1 complexes bound to the SKP2 promoter. Transcriptional control of SKP2 via this regulatory mechanism can be re-established in MYCN-amplified cells by restoring pRB activity using selective small compound inhibitors of CDK4. In contrast, doxorubicin or nutlin-3 treatment - both leading to p53-p21 activation - or CDK2 inhibition had no effect on SKP2 regulation in MYCN-amplified cells. Together, this implies that deregulated MYCN protein levels in MYCN-amplified neuroblastoma cells activate SKP2 through CDK4 induction, abrogating repressive pRB-E2F1 complexes bound to the SKP2 promoter. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 568.

MYCN transcriptionally represses CD9 to trigger an invasion-metastasis cascade in neuroblastoma Johannes Fabian, Desiree Opitz, Kristina Althoff, Marco Lodrini, Kathy Astrahantseff, Barbara Hero, Ruth Volland, Anneleen Beckers, Katleen de Preter, Nitin S Patil, Mohammed L Abba, Theresa M Thole, Jasmin Wunschel, Annette Kunkele, Jamie Hu, Leonille Schweizer, Gunhild Mechtersheimer, Daniel R Carter, Belamy B Cheung, Odilia Popanda, Andreas von Deimling, Kai-Oliver Henrich, Frank Westermann, Manfred Schwab, Jan Koster, Rogier Versteeg, Glenn M Marshall, Frank Speleman, Margot Zoeller, Heike Allgayer, Matthias Fischer, Frank Berthold, Andreas E Kulozik, Olaf Witt, Angelika Eggert, Johannes H Schulte, Hedwig E Deubzer