Genome-wide mRNA level and mRNA translation analysis of eIF4E silencing in MCF10A cells
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE69780 | GEO | 2015/06/19
SECONDARY ACCESSION(S): PRJNA286773
REPOSITORIES: GEO
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Project description:Translation initiation factor eIF4E is overexpressed early in breast cancers in association with disease progression and reduced survival. Much remains to be understood regarding the role of eIF4E in human cancer. Using immortalized human breast epithelial cells, we report that elevated expression of elF4E translationally activates the TGFβ pathway, promoting cell invasion, loss of cell polarity, increased cell survival and other hallmarks of early neoplasia. Overexpression of eIF4E is shown to facilitate selective translation of integrin β1 mRNA, which drives the translationally controlled assembly of a TGFβ receptor signaling complex containing α3β1 integrins, β-catenin, TGFβ receptor I, E-cadherin and phosphorylated Smads2/3. This receptor complex acutely sensitizes non-malignant breast epithelial cells to activation by typically sub-stimulatory levels of activated TGFβ. TGFβ can promote cellular differentiation or invasion and transformation. As a translational coactivator of TGFβ, eIF4E confers selective mRNA translation, reprogramming non-malignant cells to an invasive phenotype by reducing the set-point for stimulation by activated TGFβ. Overexpression of eIF4E may be a pro-invasive facilitator of TGFβ activity. MCF10A cells were subjected to consitutive silencing with a non-silencing control shRNA or an shRNA to eIF4E. Total RNA, light polysomal RNA (2-3 ribosome fraction) and heavy polysomal RNA (greater than or equal to 4 ribosome fraction) were purified and used for hybridization to Affymetrix 133 2.0 Plus arrays. Data analysis was conducted using MicroArray Suite Software from Affymetrix. To remove probe sets with insignificant differences between perfect match and mismatch data, which creates a more robust data set of greater clarity without a high level of background noise, discrimination values for each probe pair were calculated for low intensity ratios using Wilcoxon signed rank test to assess significance and data re-assigned as either changed or unchanged mRNAs. Data sets were compared using Expressionist Suite software. Significance of mRNAs were assessed using fold changes and the FDRs estimated based on t-tests.
2015-06-19 | E-GEOD-69780 | biostudies-arrayexpress
Project description:Treatment of muscle-invasive bladder cancer remains a major clinical challenge. Aberrant HGF/c-MET upregulation and activation is frequently observed in bladder cancer correlating with cancer progression and invasion. However, the precise mechanisms underlying HGF/c-MET mediated invasion in bladder cancer remains unknown. As part of a negative feedback loop SMAD7 binds to the E3 ligase SMURF2 targeting the TGFβ receptor for degradation. Under these conditions SMAD7 acts as an agonist disrupting the intermolecular interactions within SMURF2, permitting SMURF2 activation. We demonstrate that HGF stimulates TGFβ signaling by inducing c-SRC mediated phosphorylation of SMURF2 at two tyrosine residues impeding SMAD7 binding and enhancing SMURF2 C2-HECT domain interaction, resulting in SMURF2 inhibition and TGFβ receptor stabilization. This upregulation of the TGFβ pathway by HGF leads to TGFβ-mediated EMT and invasion. Using biologically relevant orthotopic mouse models we show that inhibition of TGFβ signaling completely prevents HGF induced bladder cancer invasion. Furthermore, we make a rationale for the use of TGFβ receptor and MEK inhibitors in the treatment of high grade non-muscle-invasive bladder cancers or early stage muscle invasive bladder cancers.
2019-08-26 | PXD014736 | Pride
Project description:Aberrant activation of the translation initiation machinery is a common property of malignant cells, and is essential for breast carcinoma cells to manifest a malignant phenotype. How does sustained activation of the rate limiting step in protein synthesis so fundamentally alter a cell? In this report, we test the post transcriptional operon theory as a possible mechanism, employing a model system in which apoptosis resistance is conferred on NIH 3T3 cells by ectopic expression of eIF4E. We show (i) there is a set of 255 transcripts that manifest an increase in translational efficiency during eIF4E-mediated escape from apoptosis; (ii) there is a novel prototype 55 nt RNA consensus hairpin structure that is overrepresented in the 5'-untranslated region of translationally activated transcripts; (iii) the identified consensus hairpin structure is sufficient to target a reporter mRNA for translational activation under pro-apoptotic stress, but only when eIF4E is deregulated; and (iv) that osteopontin, one of the translationally activated transcripts harboring the identified consensus hairpin structure functions as one mediator of the apoptosis resistance seen in our model. Our findings offer genome-wide insights into the mechanism of eIF4E-mediated apoptosis resistance and provide a paradigm for the systematic study of posttranscriptional control in normal biology and disease. Keywords: common reference, various polyribosome fractions
2006-10-16 | GSE2094 | GEO
Project description:Aberrant activation of the translation initiation machinery is a common property of malignant cells, and is essential for breast carcinoma cells to manifest a malignant phenotype. How does sustained activation of the rate limiting step in protein synthesis so fundamentally alter a cell? In this report, we test the post transcriptional operon theory as a possible mechanism, employing a model system in which apoptosis resistance is conferred on NIH 3T3 cells by ectopic expression of eIF4E. We show (i) there is a set of 255 transcripts that manifest an increase in translational efficiency during eIF4E-mediated escape from apoptosis; (ii) there is a novel prototype 55 nt RNA consensus hairpin structure that is overrepresented in the 5'-untranslated region of translationally activated transcripts; (iii) the identified consensus hairpin structure is sufficient to target a reporter mRNA for translational activation under pro-apoptotic stress, but only when eIF4E is deregulated; and (iv) that osteopontin, one of the translationally activated transcripts harboring the identified consensus hairpin structure functions as one mediator of the apoptosis resistance seen in our model. Our findings offer genome-wide insights into the mechanism of eIF4E-mediated apoptosis resistance and provide a paradigm for the systematic study of posttranscriptional control in normal biology and disease. To globally address the issue of which transcripts mediate the anti-apoptotic functions of eIF4E, we used a model in which NIH 3T3 cells ectopically overexpress translation initiation factor 4E (eIF4E) resulting in an apoptosis-resistant and tumorigenic phenotype. We performed a comprehensive study of apoptosis resistance in the NIH 3T3/4E model using an array containing 15k cDNAs and ESTs (NIH 15k collection printed at The Ontario Cancer Institute). To facilitate data analysis in the two-color competitive hybridization microarray approach employed, we used a universal standard mRNA [non-stratified poly(A) selected RNA derived from NIH 3T3 cells cultured in full growth medium]. We compared signals generated from this standard to both the light (fractions 4â6, <1 ribosome/transcript) and the heavy (fractions 7â10, >1 ribosomes/transcript) polyribosome fractions of RNA from NIH 3T3 and NIH 3T3/4E cells cultured either in complete growth medium or after 16 h of serum starvation, a time point before any evidence of cytochrome c release from the mitochondria, a signature step at the apex of the cell death program. We selected the 16 h time point in order to identify genes that might govern the decision to enter the apoptotic pathway, and exclude those involved in the actual process of cell execution.
2010-06-10 | E-GEOD-2094 | biostudies-arrayexpress
Project description:Background: Translation deregulation is an important mechanism that causes aberrant cell growth, proliferation and survival. eIF4E, the mRNA 5 prime capâ??binding protein, plays a major role in translational control. To understand how eIF4E affects cellular proliferation and cell survival, we identified mRNA targets that are translationally responsive to eIF4E. Methodology/ principal findings: Microarray analysis of polysomal mRNA from an eIF4E-inducible NIH 3T3 cell line was performed. Induction of eIF4E expression resulted in increased translation of a defined set of mRNAs; many of the mRNAs are novel targets, including those that encode large- and small-subunit ribosomal proteins and cell growthâ??related factors. eIF4E overexpression also led to augmented translation of mRNAs encoding anti-apoptotic proteins, which conferred resistance to endoplasmic reticulumâ??mediated apoptosis. Conclusions/ significance: Our results shed new light on the mechanisms by which eIF4E prevents apoptosis and transforms cells. Downregulation of eIF4E and its downstream targets is a therapeutic option for the development of novel anti-cancer drugs. Keywords: time course Comparison of total and polysomal RNA upon eIF4E iinduction in NIH3T3/parental and NIH3T3/eIF4E cells Each of the following pairs were generated from one hybridization: GSM153931 GSM153932 GSM153933 GSM153934 GSM153935 GSM153936 GSM153937 GSM153938 GSM153939 GSM153940 GSM153941 GSM153942 GSM153943 GSM153944 GSM153945 GSM153946 GSM153947 GSM153948 GSM153949 GSM153950 GSM153951 GSM153952 GSM153953 GSM153954 GSM153955 GSM153956 GSM153957 GSM153958 GSM153959 GSM153960 GSM153961 GSM153962
2010-06-11 | E-GEOD-6639 | biostudies-arrayexpress
Project description:Background: Translation deregulation is an important mechanism that causes aberrant cell growth, proliferation and survival. eIF4E, the mRNA 5 prime cap–binding protein, plays a major role in translational control. To understand how eIF4E affects cellular proliferation and cell survival, we identified mRNA targets that are translationally responsive to eIF4E. Methodology/ principal findings: Microarray analysis of polysomal mRNA from an eIF4E-inducible NIH 3T3 cell line was performed. Induction of eIF4E expression resulted in increased translation of a defined set of mRNAs; many of the mRNAs are novel targets, including those that encode large- and small-subunit ribosomal proteins and cell growth–related factors. eIF4E overexpression also led to augmented translation of mRNAs encoding anti-apoptotic proteins, which conferred resistance to endoplasmic reticulum–mediated apoptosis. Conclusions/ significance: Our results shed new light on the mechanisms by which eIF4E prevents apoptosis and transforms cells. Downregulation of eIF4E and its downstream targets is a therapeutic option for the development of novel anti-cancer drugs. Keywords: time course
2007-04-21 | GSE6639 | GEO
Project description:mTOR regulates mRNA translation. Whereas ribosome-profiling suggested that mTOR exclusively stimulates translation of TOP (containing a 5â-terminal oligopyrimidine [5âTOP] motif) and TOP-like mRNAs, polysome-profiling implied that mTOR also modulates translation of non-TOP mRNAs. We show that ribosome-, but not polysome-profiling, is biased towards identification of TOP mRNAs as differentially translated while obscuring detection of changes in non-TOP mRNA translation. Transcription start site profiling by Nano-Cap Analysis of Gene Expression (nanoCAGE) revealed that many mTOR-sensitive mRNAs do not have 5âTOP motifs. Moreover, nanoCAGE showed that 5â UTR features distinguish two functionally and translationally distinct subsets of mTOR-sensitive mRNAs: i) those with short 5â UTRs enriched for mitochondrial functions such as respiration, that are translated in an eIF4E, but not eIF4A1-dependent manner and ii) mRNAs encoding proliferation- and survival-promoting proteins, that harbor long 5â UTRs, and require both eIF4E and eIF4A1 for their efficient translation. Selective inhibition of translation of mRNAs harboring long 5â UTRs via suppression of eIF4A leads to uncoupling of expression of proteins involved in respiration (e.g. ATP5O) from those protecting mitochondrial integrity (e.g. BCL-2) ultimately resulting in apoptosis. Conversely, simultaneous translational downregulation of both long and short 5â UTR mRNAs by mTOR inhibitors results in suppression of mitochondrial respiration and predominantly cytostatic effects. Therefore, 5â UTR features define differential modes of translation of functionally distinct mTOR-sensitive mRNAs, which explains discrepancies between the effects of mTOR and eIF4A inhibitors on neoplastic cells. Determination of 5'UTR lengths using nanoCAGE in MCF7 cells
2016-03-14 | E-GEOD-77033 | biostudies-arrayexpress
Project description:Deregulation of N-myc is a leading cause of malignant brain tumors in children. To target N-myc-driven medulloblastoma, most research has focused on identifying genomic alterations or on the analysis of the medulloblastoma transcriptome. Here, we have broadly characterized the translatome of medulloblastoma and shown that N-myc unexpectedly drives selective translation of transcripts that promote protein homeostasis. Cancer cells are constantly exposed to proteotoxic stress associated with alterations in protein production or folding. It remains poorly understood how cancers cope with proteotoxic stress to promote their growth. Here, our data unexpectedly revealed that N-myc regulates the expression of specific components (~5%) of the protein folding machinery at the translational level through the major cap binding protein, eukaryotic initiation factor eIF4E. Reducing eIF4E levels in mouse models of medulloblastoma blocked tumorigenesis. Importantly, targeting Hsp70, a protein folding chaperone translationally regulated by N-myc, suppressed tumor growth in mouse and human medulloblastoma xenograft models. These findings reveal a previously hidden molecular program that promotes medulloblastoma formation and identify new therapies that may have impact in the clinic.
2022-10-18 | GSE215298 | GEO
Project description:One of the most regulated steps of translation initiation is the recruitment of an mRNA by the translation machinery. In eukaryotes, this step is mediated by the 5´end cap-binding factor eIF4E bound to the bridge protein eIF4G and forming the eIF4F complex. In plants, different isoforms of eIF4E and eIF4G form the antigenically distinct eIF4F and eIF(iso)4F complexes proposed to mediate selective translation. Using a microarray analysis of polyribosome- and non-polyribosome-purified mRNAs from 15 day-old Arabidopsis thaliana wild type [WT] and eIF(iso)4E knockout mutant [AteIF(iso)4E-1] seedlings we found 79 transcripts shifted from polyribosomes toward non-polyribosomes, and 47 mRNAs with the opposite behavior in the mutant. The translationally decreased mRNAs were overrepresented in root-preferentially expressed genes and proteins from the endomembrane system, including several transporters such as the phosphate transporter PHOSPHATE1 (PHO1), Sucrose transporter 3 (SUC3), the ABC transporter-like with ATPase activity (MRP11) and five electron transporters, as well as signal transduction-, protein modification- and transcription-related proteins.
2013-07-26 | GSE29386 | GEO
Project description:Accumulating data indicate translation plays a role in cancer biology, particularly its rate limiting stage of initiation. Despite this evolving recognition, the function and importance of specific translation initiation factors is unresolved. The eukaryotic translation initiation complex eIF4F consists of eIF4E and eIF4G at a 1:1 ratio. Although it is expected that they display interdependent functions, several publications suggest independent mechanisms. This study is the first to directly assess the relative contribution of eIF4F components to the expressed cellular proteome, transcription factors, microRNAs, and phenotype in a malignancy known for extensive protein synthesis- multiple myeloma (MM). Previously, we have shown that eIF4E/eIF4GI attenuation (siRNA/ Avastin) deleteriously affected MM cells' fate and reduced levels of eIF4E/eIF4GI established targets. Here, we demonstrated that eIF4E/eIF4GI indeed have individual influences on cell proteome. We used an objective, high throughput assay of mRNA microarrays to examine the significance of eIF4E/eIF4GI silencing to several cellular facets such as transcription factors, microRNAs and phenotype. We showed different imprints for eIF4E and eIF4GI in all assayed aspects. These results promote our understanding of the relative contribution and importance of eIF4E and eIF4GI to the malignant phenotype and shed light on their function in eIF4F translation initiation complex. This study concentrated on a particular cancer model and studied the role of eIF4E and eIF4GI in the design of the cells' proteome. We used an unbiased, high throughput system to evaluate the individual importance of eIF4E and eIF4GI levels in MM. We used models of eIF4E or eIF4GI knocked down (KD) MM cell line RPMI 8226 and profiled their respective translated transcription factors (TF), often tumor suppressors or oncogenes. Furthermore, we assessed the KDs' microRNAs repertoires and cells' phenotype. Significant differences were observed between eIF4E and eIF4GI knockdown imprints.
2015-10-29 | E-GEOD-62821 | biostudies-arrayexpress