Transcription profiling of human colorectal cell line HCT116 DICER Exon5 knockout cells
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ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Wayne Yu
PROVIDER: E-GEOD-6427 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Altered gene expression is a hallmark of human cancers and arises in part through abnormal epigenetic regulation of gene transcription. The best characterized epigenetic alteration involves tumor suppressor gene inactivation via transcriptional repression associated with aberrant DNA hypermethylation of promoter region CpG islands1. Despite characterization of a growing number of such genes, the majority have yet to be identified. We now describe a genome wide microarray gene expression approach for human colorectal cancer cells, which can efficiently identify hundreds of hypermethylated genes for any cancer type. We compared isogenic cells altered pharmacologically versus genetically to induce genomic demethylation, to pinpoint genes activated by DNA demethylation, but not by inhibition of class I and II histone deacetylases (HDACs). We achieve an 82% success rate in predicting genes with densely hypermethylated CpG islands and complete gene silencing. The genes are similarly hypermethylated in primary tumors and have previously undetected tumor suppressor functions. Our approach provides the first highly efficient, comprehensive, platform for defining the cancer âDNA hypermethylome" Experiment Overall Design: Cell culture and treatment. HCT116 cells and isogenic genetic knockout derivatives were maintained as previously described14. For drug treatments, log phase HCT116 cells were cultured in McCoys 5A media (Invitrogen) containing 10% BCS and 1x penicillin/streptomycin with ïµïM 5aza-deoxycytidine (DAC) (Sigma; stock solution: 1mM in PBS) for 96 hours, replacing media and DAC every 24 hours. Cell treatment with 300nM Trichostatin A (Sigma; stock solution: 1.5mM dissolved in ethanol) was performed for 18 hours. Control cells underwent mock treatment in parallel with addition of equal volume of PBS or ethanol without drugs. Experiment Overall Design: Microarray analysis. Total RNA was harvested from log phase cells using the Qiagen kit according to the manufacturers instructions, including a DNAase step. RNA was quantified using the NanoDrop ND-100 followed by quality assessment with 2100 Bioanalyzer (Agilent Technologies). RNA concentrations for individual samples were greater than 200ng/ul, with 28s/18s ratios greater than 2.2 and RNA integrity numbers of 10 (highest). Sample amplification and labeling procedures were carried out using the Low RNA Input Fluorescent Linear Amplification Kit (Agilent Technologies) according to the manufacturers instructions. The labeled cRNA was purified using the RNeasy mini kit (Qiagen) and quantified. RNA spike-in controls (Agilent Technologies) were added to RNA samples before amplification. 0.75 microgram of samples labeled with Cy3 or Cy5 were mixed with control targets (Agilent Technologies), assembled on Oligo Microarray, hybridized, and processed according to the Agilent microarray protocol. Scanning was performed with the Agilent G2565BA microarray scanner under default settings recommended by Agilent Technologies. Experiment Overall Design: Data analysis. All arrays were subject to quality checks recommended by the manufacturer. Images were visually inspected for artifacts and distributions of signal and background intensity of both red and green channels were examined to identify anomalous arrays. No irregularities were observed, and all arrays were retained and used. All calculations were performed using the R statistical computing platform37 and packages from Bioconductor bioinformatics software project38. The log ratio of red signal to green signal was calculated after background-subtraction and LoEss normalization as implemented in the limma package from Bioconductor39,40. Individual arrays were scaled to have the same inter-quartile range (75th percentile -25th percentile) Log fold changes were averaged over dye-swap replicate microarrays to produce a single set of expression values for each condition.
2008-06-13 | E-GEOD-4763 | biostudies-arrayexpress
Project description:This study analyzes gene expression associated with papilloma development in Tg.AC v-Ha-ras transgenic mice and identifies novel genes and biological processes that may be critical to skin carcinogenesis in these mice. Epidermal abrasion was used to synchronously induce epidermal regeneration in FVB/N wild type and transgenic Tg.AC mice. Skin papillomagenesis was uniquely induced in Tg.AC mice, and gene expression profiling was carried out using a 22,000 element mouse DNA microarray. Histological analysis showed that papillomas developed at a high rate by day 30 after abrasion in transgenic animals, while no papilloma developed in wild type mice. Transgene specific differentially expressed genes were identified at day 30 post-abrasion and these genes were annotated using EASE software and literature mining. Annotated and non-annotated genes associated with papilloma development were identified and clustering analysis revealed groups of genes that are coordinately expressed. A number of genes associated with differentiation and development were also physically clustered on mouse chromosome 16, including 16B3 that contains several Stefins and stefin-like genes, and 16A1 containing a number of keratin associated protein genes. Additional analyses presented here yield novel insights into the genes and processes involved in papilloma development in Tg.AC mice. Experiment Overall Design: Strains: Tg.AC vs FVB/N; Treatment: epidermal abrasion vs sham treatment, samples collected 3, 5, 9, 18, and 30 days post treatment; Microarray: 2-channel, pooled total RNA from 5 animals, 2 technical replicate arrays with dye-swaps.
2008-06-11 | E-GEOD-11136 | biostudies-arrayexpress
Project description:Tumor-associated breast stroma was laser-capture microdissected from IDC breast cancer cases. The goal of the study was to characterize the heterogeneity of breast tumor-assocaited stroma and identify gene expression signatures predictive of clinical outcome. Experiment Overall Design: Common reference design, 53 samples, with dye-swap replicates. Some samples replicated three or four times, a total of 111 arrays.
2008-06-16 | E-GEOD-9014 | biostudies-arrayexpress
Project description:Proper regulation of chromatin structure is necessary for the maintenance of cell type-specific gene expression patterns. The embryonic stem cell (ESC) expression pattern governs self-renewal and pluripotency. Here, we present an RNAi screen in mouse ESCs of 1008 loci encoding chromatin proteins. We identified 68 proteins that exhibit diverse phenotypes upon knockdown (KD), including seven subunits of the Tip60-p400 complex. Phenotypic analyses revealed that Tip60-p400 is necessary to maintain characteristic features of ESCs. We show that p400 localization to the promoters of both silent and active genes is dependent upon histone H3 lysine 4 trimethylation (H3K4me3). Furthermore, the Tip60-p400 KD gene expression profile is enriched for developmental regulators and significantly overlaps with that of the transcription factor Nanog. Depletion of Nanog reduces p400 binding to target promoters without affecting H3K4me3 levels. Together, these data indicate that Tip60-p400 integrates signals from Nanog and H3K4me3 to regulate gene expression in ESCs. Experiment Overall Design: We identified genes encoding subunits of the Tip60-p400 complex in an RNAi screen of chromatin proteins in mouse embryonic stem cells (ESCs), which upon depletion resulted in a dramatic phenotype. To investigate the role of this complex in gene expression in ESCs, we performed expression profiling upon depletion of the catalytic subunits. We performed 4 biological replicates of p400 or Tip60 knockdown and compared them to biological replicates of control EGFP knockdown. The p400 (Ep400) experiment was performed as competitive two-color hybridizations on one 4x44K array with dye swaps and the Tip60 (Htatip) experiment was performed as single color hybridizations on two 4x44K arrays. Note: the Tip60 KD replicate 3 was excluded from downstream analysis of differential expression, because the intensity profile was an outlier in diagnostic analyses
2008-10-20 | E-GEOD-11240 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the following subset Series:; GSE17658: Cdx and Hox genes differentially regulate posterior axial growth in mammalian embryos - 5/6 somites embryonic stage; GSE17660: Cdx and Hox genes differentially regulate posterior axial growth in mammalian embryos -13 somites embryonic stage Experiment Overall Design: Refer to individual Series
2009-10-23 | E-GEOD-17663 | biostudies-arrayexpress
Project description:Hox and Cdx transcription factors regulate embryonic positional identities. Cdx mutant mice display posterior body truncations of the axial skeleton, neuraxis, and caudal uro-rectal structures. We show that trunk Hox genes stimulate axial extension as they can largely rescue these Cdx mutant phenotypes. Conversely, posterior (paralog group 13) Hox genes can prematurely arrest posterior axial growth when precociously expressed. Our data suggest that the transition from trunk to tail Hox gene expression successively regulates construction and termination of axial structures in the mouse embryo. Thus, Hox genes seem to differentially orchestrate posterior expansion of embryonic tissues during axial morphogenesis as an integral part of their function in specifying head-to-tail identity. In addition, we present evidence that Cdx and Hox transcription factors exert these effects by controlling Wnt signaling. Concomitant regulation of Cyp26a1 expression, restraining retinoic acid signaling in the posterior growth zone, may likewise play a role in timing the trunk-tail transition. Experiment Overall Design: A micro-array screen of down regulated and upregulated genes in Cdx2+/-Cdx4-/- mutant embryos versus wildtype embryos was performed at the embryonic stage of 5/6 somites. RNA was isolated from the posterior part of the embryos dissected at the same axial level using the last somite boundary as a landmark. Posterior tissues from pools of 10 embryos of each genotype were pooled. The labeled cRNAs were hybridized on 4X44K Agilent Whole Mouse Genome dual colour Microarrays (G4122F) in two dye swap experiments, resulting in four individual microarrays.
2009-10-23 | E-GEOD-17658 | biostudies-arrayexpress
Project description:Hox and Cdx transcription factors regulate embryonic positional identities. Cdx mutant mice display posterior body truncations of the axial skeleton, neuraxis, and caudal uro-rectal structures. We show that trunk Hox genes stimulate axial extension as they can largely rescue these Cdx mutant phenotypes. Conversely, posterior (paralog group 13) Hox genes can prematurely arrest posterior axial growth when precociously expressed. Our data suggest that the transition from trunk to tail Hox gene expression successively regulates construction and termination of axial structures in the mouse embryo. Thus, Hox genes seem to differentially orchestrate posterior expansion of embryonic tissues during axial morphogenesis as an integral part of their function in specifying head-to-tail identity. In addition, we present evidence that Cdx and Hox transcription factors exert these effects by controlling Wnt signaling. Concomitant regulation of Cyp26a1 expression, restraining retinoic acid signaling in the posterior growth zone, may likewise play a role in timing the trunk-tail transition. Experiment Overall Design: A micro-array screen of down regulated and upregulated genes in Cdx2+/-Cdx4-/- mutant embryos versus wildtype embryos was performed at the embryonic stage of 13 somites. RNA was isolated from the posterior part of the embryos dissected at the same axial level using the last somite boundary as a landmark. Posterior tissues from pools of 7 embryos of each genotype were pooled. The labeled cRNAs were hybridized on 4X44K Agilent Whole Mouse Genome dual colour Microarrays (G4122F) in a dye swap experiment, resulting in two individual microarrays.
2009-10-23 | E-GEOD-17660 | biostudies-arrayexpress
Project description:Many cancers may originate in stem or early progenitor cells 1-4 which depend on epigenetic modulation of gene expression for normal function (ref). We have studied whether epigenetic states in cancers, and particularly abnormal gene silencing associated with promoter DNA hypermethylation in CpG rich regions (refs), may represent links between cancer and stem cell epigenetic patterns. We studied embryonal carcinomas (EC) which are malignancies of embryonic stem (ES) cells, but retain high potential for multi-lineage differentiation 5-8. Surprisingly, genes DNA hypermethylated and silenced in adult cancers are unmethylated in ES and EC cells. Remarkably, the promoter chromatin of the genes in EC cells is virtually identical to the same genes in adult cancers when the latter are induced to de-methylate. This chromatin, as recently reported for CpG island promoters of low expression, developmentally related, genes in ES cells (refs), is âbivalentâ and contains both active and repressive histone modifications. The latter includes trimethyl lysine 27 of histone H3 (H3K27me3), which may recruit DNA methylation (refs), and the promoter regions are enriched for polycomb group (PcG) proteins which place this H3K27me3 mark. Thus, many genes which undergo abnormal DNA methylation and permanent silencing in adult cancers may be programmed to do so by a pre-existent stem cell-like chromatin pattern inherent to the cells in which they arise. Experiment Overall Design: Data analysis. All arrays were subject to quality checks recommended by the manufacturer. Images were visually inspected for artifacts and distributions of signal and background intensity of both red and green channels are examined to identify anomalous arrays. No irregularities were observed, and all arrays were retained and used. Experiment Overall Design: All calculations were performed using the R statistical computing platform, (cite R) and packages from Bioconductor bioinformatics software project (cite Bioconductor). The log ratio of red median signal to green median signal was calculated after background-subtraction and loess normalzation as implemented in the limma package from Bioconductor. ( cite Smyth) Individual arrays were scaled to have the same inter-quartile range (75th percentile -25th percentile) Log fold changes were averaged over dye-swap replicate microarrays to produce a single set of expression values for each condition.
2008-06-13 | E-GEOD-4809 | biostudies-arrayexpress
Project description:The clinical results obtained with organ allografts from marginal or extended donors are less satisfactory over both the short-term and long-term than the outcome of grafting from living donors. Early postoperative graft function depends on several pretransplant factors, with the major donor influences being brain death (BD) and ischemia/reperfusion(I/R) injury. The effects of BD and I/R injury not only reduce the number of functioning nephrons, but also trigger a host immune response to the grafted kidney. It has been hypothesized that allografts from marginal sources may not be biologically inert at the time of surgery, but may already be programmed to initiate or amplify a host response. To exclude the effects of allogenicity, we established a rat renal isograft model using dead donors and compared the results with those obtained after grafting from living donors. In this study, we performed an analysis of the changes of gene expression in rat kidney isografts using samples obtained at 0(pre-transplant) and 1 hour time points since transplantation procedure. The results enhanced our insight into the pathways and cascades that are activated or down-regulated by BD and/or I/R injury. Better knowledge of the key components of BD or I/R injury will provide clues to the factors triggering progression that leads to a decline of organ viability, as well as ideas on how to overcome such graft failures. Such data may also allow us to identify novel biomarkers as predictors of adverse outcomes. Experiment Overall Design: Inbred male Lewis rats were used for these experiments as recipients and donors. The left kidney was transplanted orthotopically by end-to-end anastomosis. The contralateral right kidney was removed at the time of transplantation. The time of operative ischemia for transplantation was 30 min, which did not vary between animals. Donor animals were divided into two groups. The experimental group received kidneys from BD rats, while kidneys from living donors were used in the control group. Brain death was produced by gradually increasing the intracranial pressure that led to brain stem herniation. The rats were mechanically ventilated for a period of 6 hours. We compared the gene expression profiles of renal isografts from BD donors and grafts from living donors using a high-density oligonucleotide microarray that contained approximately 20,500 genes. Experiment Overall Design: For DNA microarray experiments, 200 ng aliquots of total RNA were labeled using the Agilent Low RNA Input Fluorescent Linear Amplification Kit (Agilent Technologies Product) according to the manufacturerâ??s instructions. RNA purified from each kidney graft was used for microarray analysis (Cy3-labeled), with pooled RNA derived from normal kidneys as a template control (Cy5-labeled). After checking the labeling efficiency, 1ï?g aliquots of Cy5-labeled normal control RNA and Cy3-labeled RNA from individual grafts (control 0 hour, 1 hour, BD 0 hour, BD 1 hour, n=3/group) were mixed, and then hybridized to Agilent Rat Oligo Microarrays (Product No. G4130A). After washing, the microarray slides were analyzed with an Agilent Microarray scanner and software (scanner model G2565BA). Data analysis was performed using Agilent Feature Extraction software (Ver. A.7.1.1), and Excel 2003 (Microsoft). The data were imported into GeneSpring 7.0 (Silicon Genetics, Redwood City, CA), with per spot, per chip, and intensity dependent (lowess) normalization being applied for each array. The ratio of the normalized channels (Cy3/Cy5) was used to assess the level of expression.
2008-05-07 | E-GEOD-5104 | biostudies-arrayexpress
Project description:The object of this study was to explore whether the loss of mRNA decapping in the Arabidopsis mutant tdt-1 resulted in global dfferences of RNA profiles, as compared to wild type. Experiment Overall Design: In this experiment we compared expression in tdt-1 and wild type 3 day whole seedlings. We performed three biological replicates, in which one experiment was dye-swapped.
2008-06-15 | E-GEOD-7359 | biostudies-arrayexpress