Expression data from iPS cells
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Keiki Kumano
PROVIDER: E-GEOD-37982 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Evi1 is essential for proliferation of hematopoietic stem cells and implicated in the development of myeloid disorders. Particularly, high Evi1 expression defines one of the largest clusters in acute myeloid leukemia and is significantly associated with extremely poor prognosis. Improvement of the therapeutic outcome of leukemia with activated Evi1 is one of the most challenging issues. However, mechanistic basis of Evi1-mediated leukemogenesis has not been fully elucidated. Here we show that Evi1 directly represses PTEN transcription in the murine bone marrow, which leads to activation of AKT/mTOR signaling. In a murine bone marrow transplantation model, Evi1 leukemia showed remarkable sensitivity to an mTOR inihibitor rapamycin. Furthermore, we found that Evi1 binds to several polycomb group proteins and recruits polycomb repressive complexes for PTEN downregulation, which reveals a novel epigenetic mechanism of AKT/mTOR activation in leukemia. Expression analyses and chromatin immunoprecipitation assays using human samples indicate that our findings in mice models are recapitulated in human leukemic cells. Dependence of Evi1-expressing leukemic cells on AKT/mTOR signaling provides the first example of targeted therapeutic modalities that suppress the leukemogenic activity of Evi1. The PTEN/AKT/mTOR signaling pathway and the Evi1-polycomb interaction can be promising therapeutic targets for leukemia with activated Evi1. Gene expression analysis for the purpose of identifying the target genes of Evi1 in primary bone marrow. 5-FU-primed mononuclear bone marrow cells harvested from C57/B6 mice were retrovirally transduced with Evi1-GFP or GFP. GFP positive cells were sorted and analyzed by Affymetrix® Mouse Genome 430 2.0 Array® for gene expression. Four independent experiments were performed.
2010-07-08 | E-GEOD-22434 | biostudies-arrayexpress
Project description:The resistance of CML leukemic stem cells (LSC) to tyrosine kinase inhibitor therapies targeting BCR-ABL leads to persistence of disease in most cases. We have identified novel putative therapeutic targets that are differentially expressed in CML LSCs compared to normal hematopoietic stem cells (HSC) by transciptional profiling of stem and progenitor cell populations from CML patients and normal donors. These data are used to obtain 97 genes that are differentially expressed in CML vs. normal stem and progenitor cells and 236 transcripts that show evidence of alternative exon usage in CML vs. normal stem cells. Bone marrow stem and progenitor cell fractions from 5 patients with newly diagnosed and untreated chronic phase CML and 5 healthy donors were analyzed. Contrasts between CML vs. normal stem and progenitors overall and CML vs. normal stem cells were performed using Partek Genomic Suite software. Genes with |log2(fold-change) > 1| and false discovery rate (FDR) of 0.05 were identified as significantly differentially expressed. To identify genes with evidence of alternative exon useage, contrasts between CML and normal stem cell populations were performed, and genes with an alternative splicing FDR of 0.01 were considered to be alternatively spliced.
2013-05-08 | E-GEOD-43754 | biostudies-arrayexpress
Project description:Conventional transgenic and knockout models do not allow selective introduction of oncogenic alterations into the progenitor population of mammary cells; thus, the role of progenitor cells in mammary tumorigenesis is yet unknown. By generating transgenic mice expressing tva – encoding the receptor for avian leukosis virus subgroup A (ALV/A) – from the Keratin 6a (K6) gene promoter, we found that K6+ mammary cells are bipotential progenitor cells, but not stem cells. These K6+ cells were readily induced to form tumors by intraductal injection of RCAS (an ALV/A-derived vector) carrying the gene encoding polyoma middle T antigen. Compared with tumors induced by the same oncogene-expressing virus in transgenic mice expressing tva from the commonly used MMTV LTR or other murine models of breast cancer, tumors in this K6-tva line were unique in that they resemble the normal breast-like subtype of human breast cancer. Consequently, these observations suggest that the cell of origin affects mammary tumor phenotypes. This K6-tva model may be useful for preclinical testing of targeted therapy for normal-like breast cancers in patients. Keywords: Three group comparison We carried out Affymetrix array analysis of five RCAS-PyMT-induced tumors each from K6-tva mice and MMTV-tva mice, as well as five mammary tumors from MMTV-PyMT transgenic mice.
2011-05-09 | E-GEOD-20614 | biostudies-arrayexpress
Project description:A tissue like buccal mucosa (from cheek swabs) would be an ideal sample material for rapid, easy collection for testing of biomarkers as an alternative to blood. A limited number of studies, primarily in the smoker/oral cancer literature, address this tissue's efficacy for quantitative PCR or microarray gene expression analysis. In this study both qPCR and microarray analyses were used to evaluate gene expression in buccal cells. An initial study comparing blood and buccal cells from the same individuals looked at relative amounts of four genes. The RNA isolated from buccal cells was degraded but was of sufficient quality to be used with RT-qPCR to detect expression of specific genes. Second, buccal cell RNA was used for microarray-based differential gene expression studies by comparing gene expression between smokers and nonsmokers. The isolation and amplification protocol allowed use of 150-fold less buccal cell RNA than had been reported previously with human microarrays. We report here the finding of a small number of significant gene expression differences between smokers and nonsmokers, using buccal cells as target material. Additionally, Gene Set Enrichment Analysis confirmed that these genes were changing expression in the same pattern as seen in an earlier buccal cell study performed by another group. Our results suggest that in spite of a high degree of RNA degradation, buccal cells from cheek mucosa could be used to detect differential gene expression between smokers and nonsmokers. However the RNA degradation, increase in sample variability and microarray failure rate show that buccal samples should be used with caution as source material in expression studies. Samples were collected from eight subjects, four smokers (Sm)and four nonsmokers (NS). Each cheek was sampled creating an a and b sample for each subject which is reflected in the array name. All samples were isolated separately for total RNA. Each was hybridzed to microarrays to examine for differential gene expression between smokers and nonsmokers. There are 14 total samples in the main dataset (Set 2). One cheek sample failed in microarray analysis for two individuals, 08BCNS23 a and 08BCSm27 a, and so are not included here. A sample set (Set 1) was created which contains the four samples shown in this file. They represent repeated sampling of both cheeks for two individuals to test for reproducibility. There is a separate RMA file and metadata file (this file) for these data. These included samples 08BC11Sm a and b, a smoker, and 08BC12NSa and b a nonsmoker.
2010-03-07 | E-GEOD-16149 | biostudies-arrayexpress
Project description:Gene expression profiles were collected from HEK-HT cells expressing H-Ras with Ras-activating (G12V), Raf-activating (G12V,T35S), RalGEF-activating (G12V,E37G), or PI3K-activating (G12V,Y40C) mutations. Keywords: Comparison of Ras pathway components. THX=control; 12V=G12V mutation; 35S=G12V,T35S mutation; 37G=G12V,E37G mutation; 40C=G12V,Y40C mutation. 5 replicates of each. Total of 25 samples.
2009-02-21 | E-GEOD-14934 | biostudies-arrayexpress
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2013-02-15 | E-GEOD-44335 | biostudies-arrayexpress
Project description:This study was performed to evaluated RNA extraction and gene expression analysis of FFPE specimen stored for more than 20 years. Using long time stored FFPE material; large retrospective studies correlating molecular features with therapeutic response and clinical outcome, can be performed. Quantitative PCR (qPCR) was used to evaluate RNA extraction methods and to compare gene expression profiles of FFPE and fresh frozen (FF) tissue. Extracted RNA was subsequently subjected to microarray analysis and compared to qPCR data. The Ambion RecoverAll kit appears to be particularly suited for RNA extraction of long time stored FFPE tissues. Gene expression analysis using Affymetrix platform displayed a high degree of correlation for endogenous control genes comparing FF and FFPE tissues. We conclude that high quality gene expression signatures can be recognized using Affymetrix gene expression platform on FFPE tissue stored for more than 20 years. However, a general interpretation must be done with caution as different FFPE procedures have varying effects on RNA quality. Three RNA extraction methods from Roche (Basel, Switzerland), Ambion (Austin, TX, USA) and Qiagen (Hilden, Germany), designed for FFPE material was used. The methods were compared using qPCR. For the qPCR analysis, two different concentrations of input cDNA were used (20ng and 100ng) and 32 human endogenous control genes were examined. RNA from the Ambion FFPE kit was further analyzed by using microarray. Amplification of RNA prior to microarray analysis was performed using Nugen technologies (San Carlos, CA, USA). Nugen has developed amplification kits both for FFPE and FF materials: WT- ovation FFPE RNA amplification System V2 (Nugen FFPE), Ovation FF RNA Amplification System V2 (Nugen V2 FF) and Ovation FF Pico RNA Amplification System (Nugen PICO FF). The Nugen FFPE kit, designed for FFPE material was only used for FFPE tissue. The Nugen Pico FF kit, designed to target small amounts of FF RNA (>500 pg) and the Nugen V2 FF kit designed to target total FF RNA, were only used for FF tissue. Affymetrix standard amplification protocol (Affy FF) designed for FF RNA was also included as the standard method for amplification.
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