We used DNA microarray technology to assess changes in gene expression after treatment of 11 lymphoma cell lines with epigenetic drugs. We identified genes with upregulated expression in treated cell lines and with downregulated expression in B-cell lymphoma patient samples when compared to normal B cells.
Identification of highly methylated genes across various types of B-cell non-hodgkin lymphoma.
Specimen part, Disease, Disease stage
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Enhanced stability of microRNA expression facilitates classification of FFPE tumour samples exhibiting near total mRNA degradation.
Specimen part, Cell line
View SamplesSamples were taken from colorectal cancers in surgically resected specimens in 290 colorectal cancer patients. The expression profiles were determined using Affymetrix Human Genome U133Plus 2.0 arrays. The training set of our prognosis classifier included the stage A and D samples. Validation used our stage B and C samples.
Metastasis-Associated Gene Expression Changes Predict Poor Outcomes in Patients with Dukes Stage B and C Colorectal Cancer.
No sample metadata fields
View SamplesThe analysis of several mammalian genomes has revealed between 20,000 to 30,000 genes in each genome, a number that may seem hard to reconcile with the large number of cell types and complex functions of these organisms. The solution to this paradox partly lies in the large array of transcripts that each gene can potentially generate through usage of alternative promoters and the variable levels of transcripts that each gene produces in different tissues and cell types. Thus, in order to understand the mechanisms that control diverse patterns of gene expression in mammals, it is necessary to accurately define the active promoters and monitor their cell or tissue-dependent activity. Previous high throughput strategies for assaying tissue-specific gene expression have primarily relied on measurements of steady-state transcript levels by microarrays or tag sequencing. Here, we employ a new experimental strategy to identify and characterize tissue specific promoters by integrating genome-wide maps of RNA polymerase II (Pol II) binding, chromatin modifications and gene expression profiles. We applied this strategy to mouse embryonic stem cells (mES), and adult brain, heart, kidney, and liver. Our results delineated 24,363 Pol II binding sites throughout the genome, 91% of which correspond to 5 end annotation based on known transcripts and cap-analysis of gene expression (CAGE) and can be regarded as promoters. A majority of these experimentally defined promoters are active in all tissues, while only 4,396 can be characterized as tissue-specific using a quantitative measure of Pol II occupancy. In general, Pol II occupancy at these tissue specific promoters is correlated with the presence of active histone modification marks. However, a set of mES- specific promoters display persistent levels of H3K4me3 in non-ES tissues despite undetectable Pol II binding and transcript. Broadly, our results expand the knowledge of tissue-specific mammalian genes and provide a resource for understanding the transcriptional programs in mammalian development and differentiation.
Genome-wide mapping and analysis of active promoters in mouse embryonic stem cells and adult organs.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Genomic hallmarks of localized, non-indolent prostate cancer.
Specimen part, Disease, Disease stage
View SamplesThe size and scope of microarray experiments continue to increase. However, datasets generated on different platforms or at different centres contain biases. Improved techniques are needed to remove platform- and batch-specific biases. One experimental control is the replicate hybridization of a subset of samples at each site or on each platform to learn the relationship between the two platforms. To date, no algorithm exists to specifically use this type of control. LTR is a linear-modelling-based algorithm that learns the relationship between different microarray batches from replicate hybridizations. LTR was tested on a new benchmark dataset of 20 samples hybridized to different Affymetrix microarray platforms. Before LTR, the two platforms were significantly different; application of LTR removed this bias. LTR was tested with six separate data pre-processing algorithms, and its effectiveness was independent of the pre-processing algorithm. Sample-size experiments indicate that just three replicate hybridizations can significantly reduce bias. An R library implementing LTR is available.
LTR: Linear Cross-Platform Integration of Microarray Data.
Sex
View SamplesBackground: As degradation of formalin-fixed paraffin-embedded (FFPE) samples limits ability to expression profile, we explored factors predicting success for FFPE profiling and investigated an approach overcoming this limitation.
No associated publication
Specimen part
View SamplesBackground: As degradation of formalin-fixed paraffin-embedded (FFPE) samples limits ability to expression profile, we explored factors predicting success for FFPE profiling and investigated an approach overcoming this limitation.
No associated publication
Specimen part
View SamplesSamples were taken from colorectal cancers in surgically resected specimens from 74 patients. The expression profiles were determined using Affymetrix Human Genome U133Plus 2.0 arrays. Our MSI/MSS classifer was applied to these samples.
DNA copy-number alterations underlie gene expression differences between microsatellite stable and unstable colorectal cancers.
No sample metadata fields
View SamplesProstate tumours are highly variable in their response to therapies, but clinically available prognostic factors can explain only a fraction of this heterogeneity. Here we analysed 200 whole-genome sequences and 277 additional whole-exome sequences from localized, non-indolent prostate tumours with similar clinical risk profiles, and carried out RNA and methylation analyses in a subset. These tumours had a paucity of clinically actionable single nucleotide variants, unlike those seen in metastatic disease. Rather, a significant proportion of tumours harboured recurrent non-coding aberrations, large-scale genomic rearrangements, and alterations in which an inversion repressed transcription within its boundaries. Local hypermutation events were frequent, and correlated with specific genomic profiles. Numerous molecular aberrations were prognostic for disease recurrence, including several DNA methylation events, and a signature comprised of these aberrations outperformed well-described prognostic biomarkers. We suggest that intensified treatment of genomically aggressive localized prostate cancer may improve cure rates.
Genomic hallmarks of localized, non-indolent prostate cancer.
Specimen part
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