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Medulloblastoma, the most common malignant paediatric brain tumour, is currently treated with nonspecific cytotoxic therapies including surgery, whole-brain radiation, and aggressive chemotherapy. As medulloblastoma exhibits marked intertumoural heterogeneity, with at least four distinct molecular variants, previous attempts to identify targets for therapy have been underpowered because of small samples sizes. Here we report somatic copy number aberrations (SCNAs) in 1,087 unique medulloblastomas. SCNAs are common in medulloblastoma, and are predominantly subgroup-enriched. The most common region of focal copy number gain is a tandem duplication of SNCAIP , a gene associated with Parkinson’s disease, which is exquisitely restricted to Group 4α. Recurrent translocations of PVT1 , including PVT1-MYC and PVT1-NDRG1 , that arise through chromothripsis are restricted to Group 3. Numerous targetable SCNAs, including recurrent events targeting TGF-β signalling in Group 3, and NF-κB signalling in Group 4, suggest future avenues for rational, targeted therapy. Medulloblastoma is the most common malignant brain tumour in children; having assembled over 1,000 samples the authors report that somatic copy number aberrations are common in medulloblastoma, in particular a tandem duplication of SNCAIP , a gene associated with Parkinson’s disease, which is restricted to subgroup 4α, and translocations of PVT1 , which are restricted to Group 3. The medulloblastoma genome dissected Medulloblastoma is the most common malignant brain tumour in children. Four papers published in the 2 August 2012 issue of Nature use whole-genome and other sequencing techniques to produce a detailed picture of the genetics and genomics of this condition. Notable findings include the identification of recurrent mutations in genes not previously implicated in medulloblastoma, with significant genetic differences associated with the four biologically distinct subgroups and clinical outcomes in each. Potential avenues for therapy are suggested by the identification of targetable somatic copy-number alterations, including recurrent events targeting TGFβ signalling in Group 3, and NF-κB signalling in Group 4 medulloblastomas.

Background Chemoresistance to cisplatin (DDP) remains a major challenge in advanced gastric cancer (GC) treatment. Although accumulating evidence suggests an association between dysregulation of long non‐coding RNAs (lncRNAs) and chemoresistance, the regulatory functions and complexities of lncRNAs in modulating DDP‐based chemotherapy in GC remain under‐investigated. This study was designed to explore the critical chemoresistance‐related lncRNAs in GC and identify novel therapeutic targets for patients with chemoresistant GC. Methods Chemoresistance‐related lncRNAs were identified through microarray and verified through a quantitative real‐time polymerase chain reaction (qRT‐PCR). Proteins bound by lncRNAs were identified through a human proteome array and validated through RNA immunoprecipitation (RIP) and RNA pull‐down assays. Co‐immunoprecipitation and ubiquitination assays were performed to explore the molecular mechanisms of the Musashi2 (MSI2) post‐modification. The effects of LINC00942 (LNC942) and MSI2 on DDP‐based chemotherapy were investigated through MTS, apoptosis assays and xenograft tumour formation in vivo. Results LNC942 was found to be up‐regulated in chemoresistant GC cells, and its high expression was positively correlated with the poor prognosis of patients with GC. Functional studies indicated that LNC942 confers chemoresistance to GC cells by impairing apoptosis and inducing stemness. Mechanically, LNC942 up‐regulated the MSI2 expression by preventing its interaction with SCFβ‐TRCP E3 ubiquitin ligase, eventually inhibiting ubiquitination. Then, LNC942 stabilized c‐Myc mRNA in an N6‐methyladenosine (m6A)‐dependent manner. As a potential m6A recognition protein, MSI2 stabilized c‐Myc mRNA with m6A modifications. Moreover, inhibition of the LNC942‐MSI2‐c‐Myc axis was found to restore chemosensitivity both in vitro and in vivo. Conclusions These results uncover a chemoresistant accelerating function of LNC942 in GC, and disrupting the LNC942‐MSI2‐c‐Myc axis could be a novel therapeutic strategy for GC patients undergoing chemoresistance. 1. LNC942 is a vital chemoresistant‐related lncRNA in gastric cancer. 2. LNC942 prevents β‐Trcp‐mediated MSI2 degradation. Then, MSI2 recognizes and stabilizes the c‐Myc mRNA in an m6A‐dependent manner. 3. Treatment with MSI2 inhibitor FK228 could overcome LNC942‐induced cisplatin resistance in gastric cancer.

Depletion of the cohesin-associated protein Wapl in mice is shown to increase the residence time of cohesin on DNA, which leads to clustering of cohesin in axial structures, and causes chromatin condensation in interphase chromosomes; the findings suggest that cohesin could have an architectural role in interphase chromosome organization. Wapl protein's role in chromosome organization Cohesin has important functions during chromosome segregation but is also thought to help organize chromatin fibres into loops during interphase. Here, Jan-Michael Peters and colleagues show that depletion of the cohesin-associated protein Wapl increases the residence time of cohesin on DNA, which in turn leads to clustering of cohesin in axial structures and causes chromatin condensation in interphase chromosomes. Depletion of Wapl also affects gene expression and leads to defects in chromosome segregation. These findings indicate that the dynamic interaction of cohesin with DNA, as mediated by Wapl, is an important determinant of chromatin structure, and that cohesin could have an architectural role in interphase chromosome organization. Mammalian genomes contain several billion base pairs of DNA that are packaged in chromatin fibres. At selected gene loci, cohesin complexes have been proposed to arrange these fibres into higher-order structures 1 , 2 , 3 , 4 , 5 , 6 , 7 , but how important this function is for determining overall chromosome architecture and how the process is regulated are not well understood. Using conditional mutagenesis in the mouse, here we show that depletion of the cohesin-associated protein Wapl 8 , 9 stably locks cohesin on DNA, leads to clustering of cohesin in axial structures, and causes chromatin condensation in interphase chromosomes. These findings reveal that the stability of cohesin–DNA interactions is an important determinant of chromatin structure, and indicate that cohesin has an architectural role in interphase chromosome territories. Furthermore, we show that regulation of cohesin–DNA interactions by Wapl is important for embryonic development, expression of genes such as c-myc (also known as Myc ), and cell cycle progression. In mitosis, Wapl-mediated release of cohesin from DNA is essential for proper chromosome segregation and protects cohesin from cleavage by the protease separase, thus enabling mitotic exit in the presence of functional cohesin complexes.

Myc proteins (c-myc, Mycn and Mycl) target proliferative and apoptotic pathways vital for progression in cancer. Amplification of the MYCN gene has emerged as one of the clearest indicators of aggressive and chemotherapy-refractory disease in children with neuroblastoma, the most common extracranial solid tumor of childhood. Phosphorylation and ubiquitin-mediated modulation of Myc protein influence stability and represent potential targets for therapeutic intervention. Phosphorylation of Myc proteins is controlled in-part by the receptor tyrosine kinase/phosphatidylinositol 3-kinase/Akt/mTOR signaling, with additional contributions from Aurora A kinase. Myc proteins regulate apoptosis in part through interactions with the p53/Mdm2/Arf signaling pathway. Mutation in p53 is commonly observed in patients with relapsed neuroblastoma, contributing to both biology and therapeutic resistance. This review examines Myc function and regulation in neuroblastoma, and discusses emerging therapies that target Mycn.

Glis1 substitutes for c-Myc in stem-cell generation Reprogramming of differentiated somatic cells to induced pluripotent stem (iPS) cells by exogenous expression of key transcription factors (Oct4, Sox2, Klf4 and c-Myc) has potential therapeutic applications. c-Myc enhances the efficiency of reprogramming, but the safety of using this oncogene has long been a concern. Now, Shinya Yamanaka and colleagues have found that the transcription factor Glis1 effectively and specifically promotes reprogramming of human and mouse somatic cells to iPS cells. Glis1 is highly enriched in unfertilized eggs and one-cell-stage embryos, and might be a link between reprogramming during iPS cell generation and after nuclear transfer into zygotes. Induced pluripotent stem cells (iPSCs) are generated from somatic cells by the transgenic expression of three transcription factors collectively called OSK: Oct3/4 (also called Pou5f1), Sox2 and Klf4 1 . However, the conversion to iPSCs is inefficient. The proto-oncogene Myc enhances the efficiency of iPSC generation by OSK but it also increases the tumorigenicity of the resulting iPSCs 2 . Here we show that the Gli-like transcription factor Glis1 (Glis family zinc finger 1) markedly enhances the generation of iPSCs from both mouse and human fibroblasts when it is expressed together with OSK. Mouse iPSCs generated using this combination of transcription factors can form germline-competent chimaeras. Glis1 is enriched in unfertilized oocytes and in embryos at the one-cell stage. DNA microarray analyses show that Glis1 promotes multiple pro-reprogramming pathways, including Myc, Nanog, Lin28, Wnt, Essrb and the mesenchymal–epithelial transition. These results therefore show that Glis1 effectively promotes the direct reprogramming of somatic cells during iPSC generation.

Pseudogenes have long been considered as nonfunctional genomic sequences. Recent studies have shown that they can potentially regulate the expression of protein-coding genes and are dysregulated in diseases including cancer. However, the potential roles of pseudogenes in ovarian cancer have not been well studied. Here we characterized the pseudogene expression profile in HGSOC (high-grade serous ovarian carcinoma) by microarray. We identified 577 dysregulated pseudogenes and most of them were up-regulated (538 of 577). HMGA1P6 (High mobility group AT-hook 1 pseudogene 6) was one of the overexpressed pseudogenes and its expression was inversely correlated with patient survival. Mechanistically, HMGA1P6 promoted ovarian cancer cell malignancy by acting as a ceRNA (competitive endogenous RNA) that led to enhanced HMGA1 and HMGA2 expression. Importantly, HMGA1P6 was transcriptionally activated by oncogene MYC in ovarian cancer. Our findings reveal that MYC may contribute to oncogenesis through transcriptional regulation of pseudogene HMGA1P6 in ovarian cancer.

Increased activity of MYC protein-family members is a common feature in many cancers. Using neuroblastoma as a tumor model, we established a microRNA (miRNA) signature for activated MYCN/c-MYC signaling in two independent primary neuroblastoma tumor cohorts and provide evidence that c-MYC and MYCN have overlapping functions. On the basis of an integrated approach including miRNA and messenger RNA (mRNA) gene expression data we show that miRNA activation contributes to widespread mRNA repression, both in c-MYC- and MYCN-activated tumors. c-MYC/MYCN-induced miRNA activation was shown to be dependent on c-MYC/MYCN promoter binding as evidenced by chromatin immunoprecipitation. Finally, we show that pathways, repressed through c-MYC/MYCN miRNA activation, are highly correlated to tumor aggressiveness and are conserved across different tumor entities suggesting that c-MYC/MYCN activate a core set of miRNAs for cooperative repression of common transcriptional programs related to disease aggressiveness. Our results uncover a widespread correlation between miRNA activation and c-MYC/MYCN-mediated coding gene expression modulation and further substantiate the overlapping functions of c-MYC and MYCN in the process of tumorigenesis.

The Sleeping Beauty (SB) transposon mutagenesis system is a powerful tool that facilitates the discovery of mutations that accelerate tumorigenesis. In this study, we sought to identify mutations that cooperate with MYC, one of the most commonly dysregulated genes in human malignancy. We performed a forward genetic screen with a mouse model of MYC-induced liver cancer using SB-mediated mutagenesis. We sequenced insertions in 63 liver tumor nodules and identified at least 16 genes/loci that contribute to accelerated tumor development. RNAi-mediated knockdown in a liver progenitor cell line further validate three of these genes, Ncoa2/Src-2, Zfx, and Dtnb, as tumor suppressors in liver cancer. Moreover, deletion of Ncoa2/Src-2 in mice predisposes to diethylnitrosamine-induced liver tumorigenesis. These findings reveal genes and pathways that functionally restrain MYC-mediated liver tumorigenesis and therefore may provide targets for cancer therapy.

Hydra is a unique model for studying the mechanisms underlying stem cell biology. The activity of the three stem cell lineages structuring its body constantly replenishes mature cells lost due to normal tissue turnover. By a poorly understood mechanism, stem cells are maintained through self-renewal while concomitantly producing differentiated progeny. In vertebrates, one of many genes that participate in regulating stem cell homeostasis is the protooncogene c-myc, which has been recently identified also in Hydra, and found expressed in the interstitial stem cell lineage. In the present paper, by developing a novel strategy of RNA interference-mediated gene silencing (RNAi) based on an enhanced uptake of small interfering RNAi (siRNA), we provide molecular and biological evidence for an unexpected function of the Hydra myc gene (Hymyc1) in the homeostasis of the interstitial stem cell lineage. We found that Hymyc1 inhibition impairs the balance between stem cell self renewal/differentiation, as shown by the accumulation of stem cell intermediate and terminal differentiation products in genetically interfered animals. The identical phenotype induced by the 10058-F4 inhibitor, a disruptor of c-Myc/Max dimerization, demonstrates the specificity of the RNAi approach. We show the kinetic and the reversible feature of Hymyc1 RNAi, together with the effects displayed on regenerating animals. Our results show the involvement of Hymyc1 in the control of interstitial stem cell dynamics, provide new clues to decipher the molecular control of the cell and tissue plasticity in Hydra, and also provide further insights into the complex myc network in higher organisms. The ability of Hydra cells to uptake double stranded RNA and to trigger a RNAi response lays the foundations of a comprehensive analysis of the RNAi response in Hydra allowing us to track back in the evolution and the origin of this process.

The proto-oncogene MYC is important for development and cell growth, however, its abnormal regulation causes cancer. Recent studies identified distinct enhancers of MYC in various cancers, but any MYC enhancer(s) in hepatocellular carcinoma (HCC) remain(s) elusive. By analyzing H3K27ac enrichment and enhancer RNA (eRNA) expression in cultured HCC cells, we identified six putative MYC enhancer regions. Amongst these, two highly active enhancers, located ~ 800 kb downstream of the MYC gene, were identified by qRT-PCR and reporter assays. We functionally confirmed these enhancers by demonstrating a significantly reduced MYC expression and cell proliferation upon CRISPR/Cas9-based deletion and/or antisense oligonucleotide (ASO)-mediated inhibition. In conclusion, we identified potential MYC enhancers of HCC and propose that the associated eRNAs may be suitable targets for HCC treatment.