Promoter hypermethylation and transcriptional silencing is a common epigenetic mechanism of tumour suppressor inactivation in cancer, including malignant brain tumours.
Epigenetic genome-wide analysis identifies BEX1 as a candidate tumour suppressor gene in paediatric intracranial ependymoma.
Specimen part, Treatment
View SamplesUnr (upstream of N-ras) is a cytoplasmic RNA-binding protein with cold shock domains, involved in regulation of messenger RNA stability and translation. To address the biological role of Unr, we inactivated the unr gene by homologous recombination in mice and embryonic stem (ES) cells. Embryos deficient for Unr die at mid-gestation, and the main phenotypic defects observed, growth deficiency and absence of neural tube closure, suggest a role of Unr in the balance proliferation/differentiation during early development. Here, we report that in Unr-null ES cell cultures, we observed a greater proportion of partially differentiated colonies, together with dispersed, refractile cells with stellate morphology, reminiscent of primitive endoderm (PrE) cells. DNA microarray, immunostaining, and RNA analyses revealed that Unr-null ES cells express a set of PrE markers, including the GATA6 transcription factor, a key inducer of PrE. Although Unr-deficient cells did not downregulate the pluripotency regulators Oct4, Nanog and Sox2, they grew more slowly than the wild-type lines, and their clonogenicity was lower. Silencing of Unr by RNA interference in ES E14 (129 genetic background) resulted in similar phenotypic and molecular changes as those observed in unr-/- ES cells (C57Bl/6 background). Finally, we show that ectopic expression of Unr in unr-/- ES cells partially reverses the endoderm-specific gene expression and the differentiation phenotype.
The RNA-binding protein Unr prevents mouse embryonic stem cells differentiation toward the primitive endoderm lineage.
Specimen part, Treatment
View SamplesThe exposure to and contamination by Persistent Organic Pollutants (POPs), which include pesticides used worldwide and polyaromatic hydrocarbons, is detrimental to human health and diverse ecosystems. Although most mechanistic studies have focused on single compounds, living organisms are exposed to multiple environmental xenobiotics, simultaneously, throughout their lives. The experimental evidence useful for assessing the effects of exposure to pollutant mixtures is scarce. We investigated the effects of exposure to a combination of two POPs, which employ different xenosensors, on global gene expression in a human hepatocyte cell model, HepaRG.
Two persistent organic pollutants which act through different xenosensors (alpha-endosulfan and 2,3,7,8 tetrachlorodibenzo-p-dioxin) interact in a mixture and downregulate multiple genes involved in human hepatocyte lipid and glucose metabolism.
Specimen part
View SamplesTo define and compare the genome-wide transcriptional signatures of Notch1+ cells in intestinal tumors and in normal ISCs we performed Affymetrix analyses of these two populations.
Lineage tracing of Notch1-expressing cells in intestinal tumours reveals a distinct population of cancer stem cells.
Specimen part
View SamplesPrimary liver tumours include hepatocellular carcinomas (HCC), cholangiocarcinomas (CC) and a group of rare tumours exhibiting biliary and hepatocytic differentiation called combined hepatocholangiocarcinomas (cHCC-CC). To better define this latter group, we take advantage of a series of these tumours based on their morphological characteristics and we performed transcriptional analysis allowing thereafter global comparison with published data. We show that most cHCC-CCs express progenitor cell traits, are committed to biliary lineage and are mainly associated to the activation of Wnt/beta-catenin and TGFbeta signalling pathways. Wnt/beta-catenin pathway activation in cHCC-CC is evidenced by the expression of both its direct targets such as LEF1 and EPCAM. In addition, extracellular matrix (ECM) genes and ECM-remodelling genes which are upon the control of TGF profibrotic program were found up-regulated in cHCC-CC. Interestingly, we show that CC and most cHCC-CC share characteristics associated to a subtype of poorly differentiated HCC suggesting that these tumours could originate from a stem/progenitor cell. The plasticity of these cells may explain the phenotypical heterogeneity of these tumors with the maintenance of some hepatocellular differentiation features such as albumin expression. Interestingly, this is shared by at least one third of CC, raising the hypothesis of a potential continuum between CC, cHCC-CC and poorly differentiated HCC.
Combined hepatocellular-cholangiocarcinomas exhibit progenitor features and activation of Wnt and TGFβ signaling pathways.
Sex, Specimen part
View SamplesThe development of high-throughput genomic technologies has revealed that a large fraction of the genomes of eukaryotes is associated with the expression of noncoding RNAs. One class of noncoding RNA, the cis-natural antisense transcripts (cis-NATs), are particularly interesting as they are at least partially complementary to the protein-coding mRNAs. Although most studies described cis-NATs involved in the regulation of transcription, a few reports have shown recently that cis-NATs can also regulate translation of the cognate sense coding genes in plants and mammals. In order to identify novel examples of translation regulator cis-NATs in Arabidopsis thaliana, we designed a high-throughput experiment based on polysome profiling and RNA-sequencing. Expression of cis-NATs and translation efficiency of the cognate coding mRNAs were measured in roots and shoots in response to various conditions, including phosphate deficiency and treatment with phytohormones. We identified several promising candidates, and validated a few of them experimentally, in Arabidopsis thaliana transgenic lines over-expressing in trans the translation regulator candidate cis-NATs. Overall design: total RNA and polysomal RNA was sequenced from Arabidopsis thaliana whole seedlings grown in high or low pohsphate content, or from roots or shoots from seedlings treated or not with different phytohormones (Ctrl, IAA, ABA,MeJA and ACC). 3 biological replicates were analyzed for each of the 12 experimental conditions.
Prediction of regulatory long intergenic non-coding RNAs acting in trans through base-pairing interactions.
Specimen part, Treatment, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Comparative expression analysis reveals lineage relationships between human and murine gliomas and a dominance of glial signatures during tumor propagation in vitro.
Sex, Age, Specimen part, Disease stage
View SamplesIn this study, we screened a cohort of 57 paediatric brain tumours, with a wide range of pathologies to identify gene expression profiles
Comparative expression analysis reveals lineage relationships between human and murine gliomas and a dominance of glial signatures during tumor propagation in vitro.
Sex, Age, Specimen part, Disease stage
View SamplesThe intestinal epithelium is continuously renewed by a pool of intestinal stem cells expressing Lgr5. We show that deletion of the key autophagy gene Atg7 affects the survival of Lgr5+ intestinal stem cells. Mechanistically, this involves defective DNA repair, oxidative stress, and altered interactions with the microbiota. This study highlights the importance of autophagy in maintaining the integrity of intestinal stem cells.
Essential role for autophagy protein ATG7 in the maintenance of intestinal stem cell integrity.
Specimen part
View SamplesMetastasis is a complex process involving loss of adhesion, migration, invasion and proliferation of cancer cells. Cell adhesion molecules play a pivotal role in this phenomenon by regulating cell-cell and cell-matrix interactions. CD146 (MCAM) is associated with advanced tumor stage in melanoma, prostate and ovarian cancers.
CD146 expression is associated with a poor prognosis in human breast tumors and with enhanced motility in breast cancer cell lines.
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