Genome-wide maps of XBP1 binding sites in different breast cancer cell lines.
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Xiaole Liu
PROVIDER: E-GEOD-49955 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:We report the application of ChIP-seq, which combines chromatin immunoprecipitation (ChIP) with massively parallel DNA sequencing, to map genome-wide XBP1 binding sites in different breast cancer cell lines. We showed that HIF1M-NM-1 motif was enriched in XBP1 binding sites in triple negative breast cancer (TNBC) cell lines, but not enriched in ER positive breast cancer cell line. We also demonstrated that different breast cancer cell lines of the same sub-type had similar XBP1 binding sites, whereas different breast cancer sub-types had majorly different XBP1 binding sites. Finally, a model was applied to integrate XBP1 ChIP-seq data with expression data to predict XBP1's direct targets in TNBC cell line; the predicted direct targets were shown to be predictive of patient survival, and the prediction power was specific to TNBC patients. The above evidence indicates that XBP1 performs important functions in TNBC by interacting with HIF1M-NM-1, and such regulation mechanism is specific to TNBC, which is later proved by follow-up experiments.This study represents the first detailed anaysis of XBP1 binding sites in different breast cancer cell lines. Examination of XBP1 binding sites in 2 cell types (3 cell lines).
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Project description:During cancer progression, carcinoma cells encounter a variety of cytotoxic stresses such as hypoxia, nutrient deprivation, and low pH as a result of inadequate vascularization. To maintain survival and growth in the face of these physiologic stressors, a set of adaptive response pathways are induced. One adaptive pathway well studied in other contexts is the unfolded protein response (UPR), of which XBP1 is an important component. We used microarrays to detect transcriptome profile changes after XBP1 knockdown in breast cancer cell lines, and identify genes and pathways regulated by XBP1, which could help elucidate how XBP1 mediates the adaptive response of breast cancer to cytotoxic stresses. We extracted RNA and hybridized it to Affymetrix microarrays in two breast cancer cell lines (T47D and MDA-MB-231) under treated (hypoxia and glucose deprivation) or untreated conditions with XBP1 knockdown or not.
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Project description:With the onset of resistance, ovarian cancer cells display almost unpredictable adaptive potential. This may derive from genetic ancestry of the tumor cells and can be additionally tailored by post translational protein modifications (PTMs). The latter are profoundly shaped by the physical and chemical cues of the cancer microenvironment which, for ovarian cancer, is primarily the abdominal cavity. In this study, we took advantage of high-end proteome and phosphoproteome analyses combined with multiparametric morphometric profiling for the description of the proteome signatures of high-grade serous carcinomas (OVCAR-3) and non-serous carcinomas (SKOV-3) ovarian cancer cells. For the functional experiments, we applied two different protocols, representing typical stimuli of the peritoneal cavity and of the growing tumor mass: on the one side hypoxia (oxygen 1%) which develops within the tumor mass or is experienced during migration/extravasation in non-vascularized tissues. For comparison, fluid shear stress (2.8 dyn/cm2, orbital shaker method) which characterizes the tumor surface in peritoneal cavity or metastases spread in the bloodstream. After 3 hours incubation, treatment groups were clearly distinguishable by PCA analysis. Whereas basal proteome profile of SKOV-3 and OVCAR-3 cells appeared almost unchanged, phosphoproteome analysis revealed multiple regulations. These affected primarily cellular structure and proliferative potential and consolidated after 24h treatment. Albeit maintaining their individuality, hypoxia modified cell metabolism and morphology of both OVCAR-3 and SKOV-3: upon oxygen reduction cell size increased in concerted regulation of pathways related to Rho-GTPases and/or cytoskeletal elements (proteome and phosphoproteome). Also shear stress stimulation sharpened the response profile of SKOV-3 and OVCAR-3: this retraced their pathophysiological behavior and actively modified structural proteins as well as metabolism (e.g. delta(14)-sterol reductase, Kinesin-like proteins (KIF-22/20A) and Actin-related protein 2/3 complex). In conclusion, we characterized a biochemical and structural fingerprinting describing the adaptive potential of ovarian cancer cells to physical/chemical stressors typical for the abdominal cavity.
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2013-03-20 | E-GEOD-45301 | biostudies-arrayexpress
Project description:Altered metabolism is a hallmark of cancer, but little is still known about its regulation. Here we measure transcriptomic, proteomic, phospho-proteomic and fluxomics data in a breast cancer cell-line across three different conditions. Integrating these multiomics data within a genome scale human metabolic model in combination with machine learning we systematically chart the different layers of metabolic regulation in breast cancer, predicting which enzymes and pathways are regulated at which level. We distinguish between two types of reactions, directly or indirectly regulated. Directly-regulated reactions include those whose flux is regulated by transcriptomic alterations (~890) or via proteomic or phospho-proteomics alterations (~140) in the enzymes catalyzing them. Indirectly regulated reactions are those that currently lack evidence for direct regulation in our measurements or predictions (~930). Remarkably, we find that the flux of indirectly regulated reactions is strongly coupled to the flux of the directly regulated ones, uncovering a hierarchical organization of breast cancer metabolism. Furthermore, the predicted indirectly regulated reactions are predominantly bi-directional. Taken together, this architecture may facilitate the formation of stochiometrically consistent flux distributions in response to the varying environmental conditions incurred by the tumor cells. The approach presented lays a conceptual and computational basis for a more complete mapping of metabolic regulation in different cancers with incoming additional data.
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Project description:Background: Cancers are commonly characterised by hypoxia and also by global reductions in the levels of mature microRNAs. We have examined the hypothesis that hypoxia might mediate this reduction through repressive effects on microRNA biogenesis proteins. Methods: Breast cancer cell lines were exposed to hypoxia and manipulations of hypoxia inducible factor (HIF) and HIF hydroxylase activity. The effects of hypoxia on the mRNA and protein levels of enzymes involved in microRNA biogenesis (Dicer, Drosha, TARPB2, DCGR8, XPO5) was determined by RT PCR and immunoblotting. The effect of hypoxia on microRNAs was determined with microarray studies, RT PCR and reporter assays. Results: In breast cancer lines there was significant reduction of Dicer mRNA and protein levels in cells exposed to hypoxia. This effect was independent of HIF but dependent on the HIF hydroxylase PHD2 and was partly mediated by feedback effects via microRNAs. Furthermore, several other proteins with critical roles in microRNA biogenesis (Drosha, TARBP2 and DCGR8) also showed significant and co-ordinated repression under hypoxic conditions. Despite these substantial alterations no, or modest, changes were observed in mature microRNA production Conclusion: These observations provide further and important interfaces between oxygen availability and gene expression and a potential mechanistic explanation for the reduced levels of microRNAs observed in some cancers. They provide further support for the existence of feedback mechanisms in the regulation of the microRNA biogenesis pathway and the relative stability of microRNAs. MCF7 cells were treated with three different conditions. Treatment-1: MCF7 cells were exposed to hypoxia (0.1% O2) for 48 h and harvested for RNA extraction (n=3). Treatment-2: MCF7 cells were exposed to normoxia for 48 h and harvested for RNA extraction (n=3). Treatment-3: Dicer inhibition in MCF7 cells by transient transfection of siRNAs targeting Dicer. Cells were transfected with 20 nM siRNA duplexes (Shanghai GenePharma Co., Ltd, China), using Lipofectamine 2000 reagent (Invitrogen) following the manufacturerM-bM-^@M-^Ys protocol. A second transfection was carried out after 24 h following the same protocol. Cells were harvested 24 h after the second transfection and used for RNA extraction (n=3). RNA integrity was assessed using the Agilent 2100 Bioanalyzer. Affymetrix miRNA 3.1 Array Strip was used for RNA analysis. This array consisted probe sets unique to human mature and pre-miRNA hairpins. A detailed protocol can be found in the miRNA 3.1 Array Strips technical manual (Affymetrix). In summary, 100-300 ng of total RNA was used to synthesise double stranded cDNA using random hexamers. The cDNA was then amplified to produce antisense cRNA, which was then reverse transcribed in a second cycle of cDNA synthesis. The second cycle incorporates dUTP into the cDNA sequence, which allows it to be fragmented using uracil DNA glycosylase and apurinic/apyrimidic endonuclease I. Following biotinylation, these fragments were hybridised overnight to a Affymetrix miRNA 3.1 array. The arrays were then washed, stained using a fluorescently-labelled antibody, and scanned using a high-resolution scanner. Intensity data were analysed using PartekM-BM-. software (Partek Inc.). Data were normalised by quantile normalisation and log 2 transformed. Differential expression was determined by ANOVA and corrected for false discovery.
2014-07-25 | E-GEOD-49999 | biostudies-arrayexpress
Project description:This study investigates the processes of angiogenesis and lymphangiogenesis in an in vitro mouse Embryoid Body (EB) model while maintaining as closely as possible an in vivo environment that is observed in human and murine placental development. Several studies have documented that human placental development is profoundly influenced by oxygen tension. Further the developing murine embryo also experiences hypoxic conditions prior to parturition, which regulates early organogenesis and embryonic blood vessel formation in vivo. Embryonic stem (ES) cells derived from 129/SvJ mice were differentiated into embryoid bodies (EBs) and were subjected to two oxygen treatments: normoxia (21% O2) and hypoxia (2.6%). Hypoxia was achieved in a humidified chamber flushed with 95% N2/5% CO2 until the oxygen level was stably maintained at 2.6%. EBs were transferred on days E8, E12, E15 and E18 to hypoxia or maintained in normoxia. After 2 days of differential oxygen treatments, these EBs were analyzed at E10, E14, E17 and E20 respectively. A 4 x 2, reference-based, experimental design was utilized consisting of 4 timepoints (E10, E14, E17 and E20) subjected to 2 oxygen treatments (normoxia, hypoxia) with n=4 biological replicates present in each group. All EB samples were handled in parallel through all experimental steps. Each EB RNA sample was amplified, labeled with Cy5, and compared to the same Mouse Universal Reference RNA sample (Stratagene, La Jolla, CA) that was amplified and labeled with Cy3 dye. No dye swaps were utilized.
2012-08-11 | E-GEOD-17613 | biostudies-arrayexpress