Exon Array Data for Colerectal Tumor and Normal Samples
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Sathish Periyasamy
PROVIDER: E-GEOD-50421 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:Exon-Level and Gene-Level Expression analysis of Tumor and Normal Samples The effect of somatic copy number alterations at the functional level can be analyzed by looking into the expression pattern of the affected genes. The task of identifying the ‘affected’ genes is facilitated by robust algorithms that carry out sensitive and confident localization of the targets of somatic copy number alterations in cancer. We had earlier identified 144 genes by GISTIC analysis that were potential targets of SCNAs. In this study we report our findings based on exon level analysis of these genes. Only a subset of these genes was found to have significant changes in expression levels. 8/24 genes were found to have fold change value >1.5 and 3 of them were reported as novel in their association with CRC. The splice index of 29 exons corresponding to 13 genes was found to be significantly altered in tumor samples. Causal network analysis was carried out to study the difference in patterns of target genes affected by transcription factors identified by the GISTIC analysis. LIMMA analysis was carried out to find differentially expressed genes and their functional significance was studied using ingenuity pathway analysis.
2014-09-01 | GSE50421 | GEO
Project description:Purpose: Age-related degeneration (AMD) is a major cause of blindness in developed countries. The molecular pathogenesis of early events in AMD is poorly understood. We investigated differential gene expression in samples of human retinal pigment epithelium (RPE)/choroid from early AMD and control maculas using exon-based arrays. Methods: Gene expression levels in nine early AMD and nine control human donor eyes were assessed using Affymetrix Human Exon ST 1.0 arrays. Two controls did not pass quality control and were removed. Differentially expressed genes were annotated using DAVID, and gene set enrichment analysis (GSEA) was performed on RPE-specific and endothelium-associated gene sets. CFH genotype was also assessed and differential expression was analyzed with respect to high AMD risk (YH/HH) and low AMD risk (YY) genotypes. Results: Seventy-five genes were identified as differentially expressed (raw p-value < 0.01; >50% fold change, mean log2 expression level in AMD or control M-bM-^IM-% median of all average gene expression values); however, no genes were significant (adj. p-value < 0.01) after correction for multiple hypothesis testing. Of 52 genes with decreased expression in AMD (fold change < 0.5; raw p-value < 0.01), 18 genes were identified by DAVID analysis as associated with vision or neurological processes. GSEA of RPE-associated and endothelium-associated genes revealed a significant decrease in genes typically expressed by endothelial cells in the early AMD group compared to controls, consistent with previous histologic and proteomic studies. Analysis with respect to CFH genotype indicated decreased expression of ADAMTS9 in eyes with high-risk genotypes (fold change = -2.61; raw p-value = 0.0008). Conclusions: GSEA results suggest that RPE transcripts are preserved or elevated in early AMD, concomitant with loss of endothelial cell marker expression. These results are consistent with the notion that choroidal endothelial cell dropout occurs early in the pathogenesis of AMD. Using AltAnalyze (ver. 2.0.7 beta), we analyzed nine early AMD and nine control eyes using Affymetrix Human Exon ST 1.0 arrays. Following initial processing in AltAnalyze, two control arrays were identified as potential outliers by tests implement in arrayQualityMetrics, a package for R.
2013-12-23 | E-GEOD-50195 | biostudies-arrayexpress
Project description:The incidence of cancer is not only influenced by exposure to environmental factors such as toxic substances and chemotherapy, but is also a result of individual predispositions. Single Nucleotide Polymorphisms (SNPs) represent one such individual predisposition to cancer1. Gfi136N is a SNP in the coding region of the gene “Growth factor independence 1 (Gfi1)” predisposing to development of Acute myeloid leukemia (AML). However, the mechanisms how this polymorphism is associated with AML are unknown. Here we present a mouse model in which the presence of Gfi136N leads to altered epigenetic modifications in the myeloid progenitor fraction “Granulocytic Monocytic Progenitor (GMP)” and demonstrates how this might predispose to AML. Presence of Gfi136N leads to a different epigenetic programming of the GMPs resulting in higher levels of the leukemogenic transcription factor Hoxa9. To our knowledge, this is the first mouse model of a SNP leading to epigenetic changes. Thus, SNPs not only result in an altered structure or expression level of certain proteins but here we show that SNPs might also lead to different cancer related epigenetic modifications. We used microarrays to detail the changes in the program of gene expression of GMPs induced by the knock in of human Gfi1 variants in the mouse Gfi1 locus Bone marrow derived granulocyte monocyte precursors (GMPs) from wt.-,Gfi1 knock-out.-, human Gfi1-knock in and human Gfi1-SNP36N knock in mice were collected by fluorescence activated cell sorting (FACS) for total RNA extraction and gene expression analysis on affymetrix mouse Gene 1.0 ST arrays. We aimed to identify differentially regulated target genes of the human Gfi1-SNP36N variant in a mouse model system which mit contribute to the development of acute myeloid leukemia (AML).
2012-11-22 | E-GEOD-25551 | biostudies-arrayexpress
Project description:Genomic abnormalities leading to colorectal cancer (CRC) include somatic events causing copy number aberrations (CNAs) as well as copy neutral manifestations such as loss of heterozygosity (LOH) and uniparental disomy (UPD). We studied the causal effect of these events by analyzing high resolution cytogenetic microarray data of 15 tumor-normal paired samples. We detected 144 genes affected by CNAs. A subset of 91 genes are known to be CRC related yet high GISTIC scores indicate 24 genes on chromosomes 7, 8, 18 and 20 to be strongly relevant. Combining GISTIC ranking with functional analyses and degree of loss/gain we identify three genes in regions of significant loss (ATP8B1, NARS, and ATP5A1) and eight in regions of gain (CTCFL, SPO11, ZNF217, PLEKHA8, HOXA3, GPNMB, IGF2BP3 and PCAT1) as novel in their association with CRC. Pathway analysis indicates TGF-β signaling pathway to be affected by the cytogenetic events causing CRC as evidenced by the action of genes impacted by CNAs on SMAD family of proteins. Finally, LOH and UPD collectively affected nine cancer related genes. Transcription factor binding sites on regions of >35% copy number loss/gain influenced 16 CRC genes. Our analysis shows patient specific CRC manifestations at the genomic level and that these different events affect individual CRC patients differently. Copy number analysis of Affymetrix CytoScanHD arrays was performed for 15 Tumors and 15 Adjacent Normals from Colorectal Tissue was used as reference for the study.
2013-09-01 | E-GEOD-47204 | biostudies-arrayexpress
Project description:Alternative RNA splicing analysis in Hep3B cell cultured under 21% (N1,3,5) or 1.2% (H2,4,6) oxygen Hypoxia is a common characteristic of many solid tumors. The hypoxic microenvironment stabilizes hypoxia-inducible transcription factor 1? (HIF1?) and 2? (HIF2?) to activate gene transcription, which promotes tumor cell survival. 95% of human genes are alternatively spliced, producing RNA isoforms that code functionally distinct proteins. Thus, effective hypoxia response requires increased HIF target gene transcription as well as proper RNA splicing of these HIF target genes. However, it is unclear if and how hypoxia regulates RNA splicing of HIF target genes. This study determined the effects of hypoxia on alternative splicing (AS) of HIF and non-HIF target genes in Hep3B cells and characterized the role of HIF in regulating AS of HIF induced genes. The results indicated that hypoxia generally promotes exon inclusion for hypoxia-induced, but reduces exon inclusion for hypoxia reduced genes. Mechanistically, HIF activity, but not hypoxia per se is found to be necessary and sufficient to increase exon inclusion of several HIF target genes including pyruvate dehydrogenase kinase 1 (PDK1). PDK1 splicing reporters confirmed that transcriptional activation by HIF is sufficient to increase exon inclusion of PDK1 splicing reporter. In contrast, transcriptional activation of the PDK1 minigene by other transcription factor in the absence of endogenous HIF target gene activation fails to alter PDK1 RNA splicing, demonstrating a novel role of HIF target gene(s) in regulating RNA splicing of HIF target genes. Implications:This study demonstrates a novel function of HIF in regulating RNA splicing of HIF target genes. We analyzed total RNA from Hep3B cells cultured under 21% (N1,3,5) or 1.2% (H2,4,6) oxygen using the Affymetrix Human Exon 1.0 ST platform. Array data was processed by Altanalyze software version 2.0.7. Techinical replicates were performed for Nx and Hx treated Hep3B cells
2014-05-14 | E-GEOD-57613 | biostudies-arrayexpress
Project description:Exon and expression analysis of HeLa cells after knockdown of SON Serine-arginine-rich (SR) proteins play a key role in alternative pre-mRNA splicing in eukaryotes. Our laboratory recently showed that a large SR protein called Son has unique repeat motifs that are essential for maintaining the subnuclear organization of pre-mRNA processing factors in nuclear speckles. Motif analysis of Son highlights putative RNA interaction domains that suggest a direct role for Son in pre-mRNA splicing. A genome-wide screen was performed to identify putative human transcription and splicing targets of Son. HeLa cells were transfected with siRNA against SON or a control siRNA (siLuciferase) for 48 hours. Five biological replicates were used for each condition.
2011-12-22 | E-GEOD-28672 | biostudies-arrayexpress
Project description:Using bone marrow cells of GFP:Gfi1 knock in mice, we separated Gfi1-high and Gfi1-low expressing cells in the classical CD11b+, GR1-low monocytic cell fraction. We sorted CD11b+, GR1-low GFP:Gfi1-high and low cells as well as CD11b+, GR1-high granulocytes and CD11b-high, GR1-intermediate cells from Gfi1-knock-out mice for further analysis. We used Affymetrix Mouse Genome 430A 2.0 arrays (GPL8321) The study should determine how Gfi1 regulates the cell fate of monocytes/granulocytes in mice
2012-12-19 | E-GEOD-35970 | biostudies-arrayexpress
Project description:Alternative mRNA splicing is a major mechanism for gene regulation and transcriptome diversity. Despite the extent of the phenomenon, the regulation and specificity of the splicing machinery are only partially understood. Adenosine-to-inosine (A-to-I) RNA editing of pre-mRNA by ADAR enzymes has been linked to splicing regulation in several cases. Here we used bioinformatics approaches, RNA-seq and exon-specific microarray of ADAR knockdown cells to globally examine how ADAR and its A-to-I RNA editing activity influence alternative mRNA splicing. Although A-to-I RNA editing only rarely targets canonical splicing acceptor, donor, and branch sites, it was found to affect splicing regulatory elements (SREs) within exons. Cassette exons were found to be significantly enriched with A-to-I RNA editing sites compared with constitutive exons. RNA-seq and exon-specific microarray revealed that ADAR knockdown in hepatocarcinoma and myelogenous leukemia cell lines leads to global changes in gene expression, with hundreds of genes changing their splicing patterns in both cell lines. This global change in splicing pattern cannot be explained by putative editing sites alone. Genes showing significant changes in their splicing pattern are frequently involved in RNA processing and splicing activity. Analysis of recently published RNA-seq data from glioblastoma cell lines showed similar results. Our global analysis reveals that ADAR plays a major role in splicing regulation. Although direct editing of the splicing motifs does occur, we suggest it is not likely to be the primary mechanism for ADAR-mediated regulation of alternative splicing. Rather, this regulation is achieved by modulating trans-acting factors involved in the splicing machinery. HepG2 and K562 cell lines were stably transfected with plasmids containing siRNA designed to specifically knock down ADAR expression (ADAR KD). This in order to examine how ADAR affects alternative splicing globally.
2013-06-17 | E-GEOD-47997 | biostudies-arrayexpress
Project description:Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine tumor with high mortality rates. Merkel cell polyomavirus (MCPyV), identified in the majority of MCC, may drive tumorigenesis via viral T antigens. However, mechanisms underlying pathogenesis in MCPyV-negative MCC remain poorly understood. To nominate genes contributing to pathogenesis of MCPyV-negative MCC, we performed DNA microarray analysis on 30 MCCs. MCPyV status of MCCs was determined by PCR for viral DNA and RNA. 1593 probe-sets were differentially expressed between MCPyV-negative and -positive MCC, with significant differential expression defined as at least 2-fold change in either direction and p-value of ≤ 0.05. MCPyV-negative tumors showed decreased RB1 expression, whereas MCPyV-positive tumors were enriched for immune response genes. Validation studies included immunohistochemistry demonstration of decreased RB protein expression in MCPyV-negative tumors and increased peritumoral CD8+ T lymphocytes surrounding MCPyV-positive tumors. In conclusion, our data suggest that loss of RB1 expression may play an important role in tumorigenesis of MCPyV-negative MCC. Functional and clinical validation studies are needed to determine whether this tumor suppressor pathway represents an avenue for targeted therapy. We used microarrays to characterize global gene expression patterns related to Merkel cell polyomavirus status in Merkel cell carcinoma. Furthermore, we compared Merkel cell carcinoma to less aggressive primary cutaneous carcinomas. We utilized flash-frozen tumor tissue from primary Merkel cell carcinomas, metastatic Merkel cell carcinomas, primary cutaneous squamous cell carcinomas, and basal cell carcinomas. Merkel cell carcinoma cell lines, which represent a pure population of tumor cells, were also included. Merkel cell polyomavirus status was determined at the DNA and RNA level using multiple primers for viral T-antigen and capsid protein sequences. This Series represents two analyses - one with new Samples normalized together, and another with some of the new Samples re-normalized with Samples previously submitted under Series GSE13355. The latter group contain 'renormalized' in the titles.
2012-10-18 | E-GEOD-39612 | biostudies-arrayexpress
Project description:In this study we performed a genome wide analysis of the entire complement of mRNAs in clear cell renal cell carcinomas (ccRCC) by means of the Affymetrix Exon Array platform. The analyses were performed both at gene and exon level. Under our parameters over 2,000 genes resulted differentially expressed, and about 250 genes resulted alternative spliced showing differential inclusion of specific cassette exons comparing tumor and non tumoral tissues. 20 total samples were used for exon array analysis: 10 ccRCC tumor sample (T) and their matched non-tumor (NT) kidney tissues samples. All exon array data were analyzed using Partek Genomic Suite 6.4 software (Partek). The robust multi-array average (RMA) algorithm was used for the gene- and exon-level intensity analyses. Data were M-oM-,M-^Altered to consider only those probe sets included in the M-bM-^@M-^\Core Meta-ProbesetM-bM-^@M-^]. Lists of genes and exons with significant variation of the expression levels were generated by using a 0.01 FDR criterion as a significant cutoff. Partek list of significant exon-level probesets (FDR corrected p-value < 0.01) and exon level ANOVA test list were used to create - by an ad hoc Python script - a database of significant probesets from Exon Array experiments. To make more stringent the analysis criteria we excluded from the final exon lists all those cases in which Exon Array revealed a significant change at gene-level. This database we created has been used to explore simple exon skipping events using as reference ASPicDB single exon skipping splicing events after mapping Affymetrix probesets on ASPicDB .gtf files. A single exon from the Partek list was defined significantly skipped only if its adjacent exons were not, by using 0.01 and 0.05 p-value criterions as a significant cutoff for the M-bM-^@M-^\skippedM-bM-^@M-^] and adjacent exons, respectively.
2013-09-06 | E-GEOD-47032 | biostudies-arrayexpress