Unknown,Transcriptomics,Genomics,Proteomics

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EGFRvIII/STAT3 targets in glioblastoma pathogenesis

ABSTRACT: Next generation sequencing platforms were used to identify STAT3 targets in the background of EGFRvIII expresssion mRNA of 3 EGFRvIII positive brain tumor stem cell lines (BTSC #68, 73, and 90) were compared to an EGFRvIII negative line (#41) to identify EGFRvIII-regulated targets in human BTSC. EGFRvIII-dependent targets in mouse astrocytes were identified by mRNA-seq analyses of EGFRvIII- or MSCV-expressing astrocytes. STAT3-differentially regulated genes in EGFRvIII expressing mouse astrocytes were obtained by subjecting EGFRvIII,STAT3f/f and EGFRvIII, STAT3-/- astrocytes to mRNA-Seq analyses. Sites of STAT3 occupancy in EGFRvIII expressing astrocytes were identified by ChIP-Seq using a STAT3 antibody or IgG control. We identified OSMR as a direct target of STAT3 in both EGFRvIII-expressing human BTSC and mouse astrocytes. Therefore to identify OSMR-regulated genes, we used a lentiviral mediated RNAi system to knockdown OSMR in EGFRvIII-expressing astrocytes. OSMR-dependent differentially expressed genes were obtained by comparison of OSMR knockdown (KD1 and KD2) astrocytes to control groups (ShRNA control and Vector control)

ORGANISM(S): Mus musculus

SUBMITTER: Carol Perez-Iratxeta

PROVIDER: E-GEOD-51281 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Signaling by the cytokine LIF and its downstream transcription factor, STAT3, prevents differentiation of pluripotent embryonic stem cells (ESCs) by opposing MAP kinase signaling. This contrasts with most cell types where STAT3 signaling induces differentiation. We find that STAT3 binding across the pluripotent genome is dependent upon Brg, the ATPase subunit of a specialized chromatin remodeling complex (esBAF) found in ESCs. Brg is required to establish chromatin accessibility at STAT3 binding targets, in essence preparing these sites to respond to LIF signaling. Moreover, Brg deletion leads to rapid Polycomb (PcG) binding and H3K27me3-mediated silencing of many Brg-activated targets genome-wide, including the target genes of the LIF signaling pathway. Hence, one crucial role of Brg in ESCs involves its ability to potentiate LIF signaling by opposing PcG. Contrary to expectations, Brg also facilitates PcG function at classical PcG target including all four Hox loci, reinforcing their repression in ESCs. These findings reveal that esBAF does not simply antagonize PcG, but rather, the two chromatin regulators act both antagonistically and synergistically with the common goal of supporting pluripotency. Brg conditional embryonic stem cell (ESC) line was prepared from Brg(lox/lox);Actin-CreER mice that allow conditional deletion of Brg upon addition of 4-hydroxytamoxifen (4OHT, Sigma). Brg conditional ESCs were treated with 4-OHT for 72 hours to delete Brg. Brg protein levels completely abolished only at 48 hours (Brg-KO). RNA from Brg conditional ESCs (WT), Brg-KO ESCs, Brg conditional ESCs starved of LIF (Lif-WD) for 48 hours were extracted using Trizol reagent (Invitrogen), followed by RNeasy kit with DNaseI digestion to eliminate genomic DNA. Purified RNA was processed and hybridized onto Affymetrix Mouse MOE 4.0 3’ expression arrays according to the manufacturer's instructions. ChIP-Seq was used to detect and measure STAT3 occupancy and levels of H3K27me3 in the genome before and after the removal of the SWI/SNF ATPase Brg in mouse ESCs. Total of 4 samples (WT and KO STAT3; WT and KO H3K27me3). Input DNA was sequenced as control.

Project description:For many oncogenes, increased expression resulting from copy number gain confers a selective advantage to cells that consequently make up the tumour bulk. To identify oncogenes of potential biological significance in cervical squamous cell carcinoma (SCC), 36 primary samples and ten cell lines were screened by array comparative genomic hybridization (CGH). The most commonly occurring regions of copy number gain that also showed amplification were 5p15.2–14.3 (59%), 5p13.3 (65%), and 5p13.2–13.1 (63%). Gene copy numbers were significantly associated with expression levels for three candidate oncogenes at these loci: OSMR (oncostatin M receptor) (p = 0.03), PDZK3 (PDZ domain containing protein 3) (p = 0.04), and TRIO (triple functional domain) (p = 0.03). Further examination by fluorescence in situ hybridization on a tissue microarray of 110 primary cervical SCC samples revealed copy number gain frequencies of 60.9%, 57.3%, and 54.5% for OSMR, PDZK3, and TRIO, respectively, with OSMR adversely influencing overall patient survival independently of tumour stage (p = 0.046). By array CGH, copy number gain of OSMR was not seen in any of 40 microdissected precursor cervical squamous intraepithelial lesions (SILs). Moreover, global mRNA expression analysis, using Affymetrix U133A 2.0 Arrays, showed no overexpression of OSMR in SILs, suggesting that OSMR gain and overexpression are relatively late steps in cervical carcinogenesis. In the cervical SCC cell lines CaSki and SW756, exogenous OSM activated downstream-signalling elements of OSMR including STAT3, p44/42 MAPK, and S6 ribosomal protein, and induced transcription of the angiogenic factor VEGF, effects that were reduced by OSMR depletion using RNA interference. We conclude that copy number gain of OSMR is frequently found in cervical SCC and is associated with adverse clinical outcome. As well as being a potential prognostic marker, OSMR is a candidate cell surface therapeutic target aCGH of high grade late stage primary cervical SCCs obtained from the archives of the Kidwai Memorial Institute of Oncology,

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EGFRvIII/STAT3 targets in glioblastoma pathogenesis

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