1,720,971 research outputs found
Genetic Predisposition to Solid Pediatric Cancers
No full textProgresses over the past years have extensively improved our capacity to use genome-scale analyses-including high-density genotyping and exome and genome sequencing-to identify the genetic basis of pediatric tumors. In particular, exome sequencing has contributed to the evidence that about 10% of children and adolescents with tumors have germline genetic variants associated with cancer predisposition. In this review, we provide an overview of genetic variations predisposing to solid pediatric tumors (medulloblastoma, ependymoma, astrocytoma, neuroblastoma, retinoblastoma, Wilms tumor, osteosarcoma, rhabdomyosarcoma, and Ewing sarcoma) and outline the biological processes affected by the involved mutated genes. A careful description of the genetic basis underlying a large number of syndromes associated with an increased risk of pediatric cancer is also reported. We place particular emphasis on the emerging view that interactions between germline and somatic alterations are a key determinant of cancer development. We propose future research directions, which focus on the biological function of pediatric risk alleles and on the potential links between the germline genome and somatic changes. Finally, the importance of developing new molecular diagnostic tests including all the identified risk germline mutations and of considering the genetic predisposition in screening tests and novel therapies is emphasized
Integrative genomic analyses identify neuroblastoma risk genes involved in neuronal differentiation
No full text: Genome-Wide Association Studies (GWAS) have been decisive in elucidating the genetic predisposition of neuroblastoma (NB). The majority of genetic variants identified in GWAS are found in non-coding regions, suggesting that they can be causative of pathogenic dysregulations of gene expression. Nonetheless, pinpointing the potential causal genes within implicated genetic loci remains a major challenge. In this study, we integrated NB GWAS and expression Quantitative Trait Loci (eQTL) data from adrenal gland to identify candidate genes impacting NB susceptibility. We found that ZMYM1, CBL, GSKIP and WDR81 expression was dysregulated by NB predisposing variants. We further investigated the functional role of the identified genes through computational analysis of RNA sequencing (RNA-seq) data from single-cell and whole-tissue samples of NB, neural crest, and adrenal gland tissues, as well as through in vitro differentiation assays in NB cell cultures. Our results indicate that dysregulation of ZMYM1, CBL, GSKIP, WDR81 may lead to malignant transformation by affecting early and late stages of normal program of neuronal differentiation. Our findings enhance the understanding of how specific genes contribute to NB pathogenesis by highlighting their influence on neuronal differentiation and emphasizing the impact of genetic risk variants on the regulation of genes involved in critical biological processes
Somatic mutations enriched in cis-regulatory elements affect genes involved in embryonic development and immune system response in neuroblastoma
No full text: Noncoding cis-regulatory variants have gained interest as cancer drivers, yet progress in understanding their significance is hindered by the numerous challenges and limitations of variant prioritization. To overcome these limitations, we focused on active cis-regulatory elements (aCRE) in order to design a customized panel for the deep sequencing of 56 neuroblastoma tumor and normal DNA sample pairs. In order to search for driver mutations, aCREs were defined by reanalysis of H3K27ac ChiP-seq peaks in 25 neuroblastoma cell lines. These regulatory genomic regions were tested for an excess of somatic mutations and assessed for statistical significance using a global approach that accounted for chromatin accessibility and replication timing. Additional validation was provided by whole genome sequence analysis of 151 neuroblastomas. Analysis of Hi-C data determined the presence of candidate target genes interacting with mutated regions. An excess of somatic mutations in aCREs of diverse genes were identified, including IPO7, HAND2, and ARID3A. CRISPR-Cas9 editing was utilized to assess the functional consequences of mutations in the IPO7 aCRE. Patients with noncoding mutations in aCREs showed inferior overall and event-free survival independent of age at diagnosis, stage, risk stratification, and MYCN status. Expression of aCRE-interacting genes correlated strongly with negative prognostic markers and low survival rates. Moreover, a convergence between the biological functions of aCRE target genes and transcription factors with mutated binding motifs was associated with embryonic development and immune system response. Overall, this strategy enabled the identification of somatic mutations in regulatory elements that collectively promote neuroblastoma tumorigenesis
CFDP1 is a neuroblastoma susceptibility gene that regulates transcription factors of the noradrenergic cell identity
No full textPleiotropic genetic factors (e.g., DNA polymorphisms) may be involved in the initiation of neuroblastoma (NB) and coronary artery disease (CAD) given their common origin from defects in neural crest development. To discover novel NB susceptibility genes, we conducted a three-stage survey including a meta-analysis of NB and CAD genome-wide association data, prioritization of NB causal variants, and validation in an independent cohort of affected individuals–control subjects. The lead SNP, rs13337397 at the 16q23.1 locus, associated with both diseases in the meta-analysis and with NB in the validation study. All the SNPs in linkage disequilibrium with rs13337397 were annotated using the H3K27ac epigenetic marker of neural crest cells (NCC) and NB cell lines. Indeed, we identified the functional SNP rs13337017, mapping within an enhancer of NCCs and NB cell lines and showing long-range interactions with CFDP1 by Hi-C analysis. Luciferase assays indicated that the risk allele of rs13337017 increased CFDP1 expression in NB cell lines. Of note, CFDP1 high expression associated with unfavorable prognostic markers in an analysis including 498 NB transcriptomes. Moreover, depletion of CFDP1 markedly decreased viability and migration and increased apoptotic rates in NB cell lines. Finally, transcriptome and qPCR analyses revealed that the depletion of CFDP1 may affect noradrenergic neuron differentiation by downregulating master regulators of sympathetic noradrenergic identity, including PHOX2B, HAND2, and GATA3. Our data strongly suggest that CFDP1 acts as oncogene in NB. In addition, we provide evidence that genetic predisposition to NB can be mediated by the alteration of noradrenergic lineage-specific gene expression
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Single-cell transcriptomics of neuroblastoma identifies chemoresistance-associated genes and pathways
No full textHigh-Risk neuroblastoma (NB) survival rate is still <50%, despite treatments being more and more aggressive. The biggest hurdle liable to cancer therapy failure is the drug resistance by tumor cells that is likely due to the intra-tumor heterogeneity (ITH). To investigate the link between ITH and therapy resistance in NB, we performed a single cell RNA sequencing (scRNAseq) of etoposide and cisplatin resistant NB and their parental cells. Our analysis showed a clear separation of resistant and parental cells for both conditions by identifying 8 distinct tumor clusters in etoposide-resistant/parental and 7 in cisplatin-resistant/parental cells. We discovered that drug resistance can affect NB cell identities; highlighting the bi-directional ability of adrenergic-to-mesenchymal transition of NB cells. The biological processes driving the identified resistant cell subpopulations revealed genes such as (BARD1, BRCA1, PARP1, HISTH1 axis, members of RPL family), suggesting a potential drug resistance due to the acquisition of DNA repair mechanisms and to the modification of the drug targets. Deconvolution analysis of bulk RNAseq data from 498 tumors with cell subpopulation signatures showed that the transcriptional heterogeneity of our cellular models reflected the ITH of NB tumors and allowed the identification of clusters associated with worse/better survival. Our study demonstrates the distinct cell populations characterized by genes involved in different biological processes can have a role in NB drug treatment failure. These findings evidence the importance of ITH in NB drug resistance studies and the chance that scRNA-seq analysis offers in the identification of genes and pathways liable for drug resistance
HIF-1 transcription activity: HIF1A driven response in normoxia and in hypoxia
No full textAbstract Background HIF1A (Hypoxia-Inducible-Factor 1A) expression in solid tumors is relevant to establish resistance to therapeutic approaches. The use of compounds direct against hypoxia signaling and HIF1A does not show clinical efficiency because of changeable oxygen concentrations in solid tumor areas. The identification of HIF1A targets expressed in both normoxia and hypoxia and of HIF1A/hypoxia signatures might meliorate the prognostic stratification and therapeutic successes in patients with high-risk solid tumors. Methods In this study, we conducted a combined analysis of RNA expression and DNA methylation of neuroblastoma cells silenced or unsilenced for HIF1A expression, grown in normoxia and hypoxia conditions. Results The analysis of pathways highlights HIF-1 (heterodimeric transcription factor 1) activity in normoxia in metabolic process and HIF-1 activity in hypoxia in neuronal differentiation process. HIF1A driven transcriptional response in hypoxia depends on epigenetic control at DNA methylation status of gene regulatory regions. Furthermore, low oxygen levels generate HIF1A-dependent or HIF1A-independent signatures, able to stratify patients according to risk categories. Conclusions These findings may help to understand the molecular mechanisms by which low oxygen levels reshape gene signatures and provide new direction for hypoxia targeting in solid tumor
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