Loss of function of the tumor suppressor BRCA1 (Breast Cancer 1) protein is responsible for numerous familial and sporadic breast cancers. We previously identified PABP1 as a novel BRCA1 partner and showed that BRCA1 modulates translation through its interaction with PABP1. We showed that the global translation was diminished in BRCA1-depleted cells and increased in BRCA1-overexpressing cells. Our findings raised the question whether BRCA1 affects translation of all cytoplasmic cellular mRNAs or whether it specifically targets a subset of mRNAs.
BRCA1-Dependent Translational Regulation in Breast Cancer Cells.
Cell line
View SamplesWe have demonstrated that the oncogenic activation of B-RAF (using a truncated delta-BRAF-ER version inducible with tamoxifen) in the melan-a melanocyte cell line triggers the activation of Zeb1 and Twist1 at the expanse of Zeb2 and Snail2. Enforced maintenance of Zeb2 or Snail2 expression reduces the B-RAF oncogenic potential while ectopic expression of Zeb1 or Twist1 cooperates with B-RAF in melan-a cell transformation. To get an insight into the properties of these embryonic transcription factors, gene expression profiles of melan-a-derived cell lines either expressing a non-activated B-RAF (- tamoxifen) or an activated BRAF (+ tamoxifen) alone or in combination with Snail2, Zeb2, Twist1 or Zeb1 have been established.
A switch in the expression of embryonic EMT-inducers drives the development of malignant melanoma.
Cell line
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EMT inducers catalyze malignant transformation of mammary epithelial cells and drive tumorigenesis towards claudin-low tumors in transgenic mice.
Specimen part, Cell line
View SamplesThe newly identified claudin-low subtype of cancer is believed to represent the most primitive breast malignancies, having arisen from transformation of an early epithelial precursor with inherent stemness properties and metaplastic features. Challenging this hypothesis, we show both in vitro and in vivo that transcription factors inducing epithelial-mesenchymal transition can drive the development of claudin-low tumors from differentiated mammary epithelial cells, by playing a dual role in cell transformation and dedifferentiation.
EMT inducers catalyze malignant transformation of mammary epithelial cells and drive tumorigenesis towards claudin-low tumors in transgenic mice.
Specimen part, Cell line
View SamplesThe newly identified claudin-low subtype of cancer is believed to represent the most primitive breast malignancies, having arisen from transformation of an early epithelial precursor with inherent stemness properties and metaplastic features. Challenging this hypothesis, we show both in vitro and in vivo that transcription factors inducing epithelial-mesenchymal transition can drive the development of claudin-low tumors from differentiated mammary epithelial cells, by playing a dual role in cell transformation and dedifferentiation.
EMT inducers catalyze malignant transformation of mammary epithelial cells and drive tumorigenesis towards claudin-low tumors in transgenic mice.
Specimen part, Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
A stemness-related ZEB1-MSRB3 axis governs cellular pliancy and breast cancer genome stability.
Specimen part, Cell line
View SamplesAberrant cell proliferation, a hallmark of most cancers, requires the escape from intrinsic antitumour barriers. Primary among these is the DNA damage response (DDR). In both cell culture-models and in early stages of tumorigenesis in vivo, activated oncogenes induce DNA replication stress and DNA double-strand breaks (DSBs), leading to DDR activation and p53-dependent apoptosis and/or senescence. The means by which tumour-initiating cells, also termed cancer stem cells (CSCs), circumvent this oncosuppressive response is unknown. Here we demonstrate that the ZEB1 transcription factor provides breast CSCs with the ability to withstand an aberrant mitogenic activity. Its forced expression in human mammary epithelial cells is sufficient to alleviate DNA replicative stress and to decrease the production of reactive oxygen species, an important contributor to DDR and oncogene-induced senescence. Consistently, human breast cancer cells with endogenous ZEB1 expression show two characteristic features: low levels of DSBs and DDR markers, reflecting mitigation of the DNA replication stress, and a low p53 mutation frequency, reflecting a weak selective pressure for inactivation. Using high-throughput sequencing analysis of controlled cellular models, we further demonstrate that ZEB1 delays the onset of structural chromosomal instability (CIN), a known consequence of replicative stress and prevents the emergence of chromosome 8p deletions and 8q amplifications, two prevalent abnormalities in high-grade breast cancers. Supporting these findings, ZEB1 expression discriminates human breast tumours by their copy number alterations (CNAs) and chromosome 8 aberrations. We propose that the tumorigenic potential of CSCs relies upon their unique capacity to tolerate oncogenic stimuli through the alleviation of DNA replication stress.
A stemness-related ZEB1-MSRB3 axis governs cellular pliancy and breast cancer genome stability.
Specimen part
View SamplesIn most embryos, the mid-blastula transition is a complex process featuring maternal RNA degradation, cell cycle pause, zygotic transcriptional activation and morphological changes. The nucleocytoplasmic (N/C) ratio has been proposed to control the multiple events at MBT. To understand the global transcriptional response to the changes of the N/C ratio, we profiled wild type and haploid embryos using cDNA microarrays at three developmental stages.
Coupling of zygotic transcription to mitotic control at the Drosophila mid-blastula transition.
No sample metadata fields
View SamplesKaposis sarcoma-associated hepesvirus (KSHV) encodes four genes with homology to human interferon regulatory factors (IRFs). One of these IRFs, the viral interferon regulatory factor 3 (vIRF-3) is expressed in latently infected PEL cells and required for their continuous proliferation. Moreover, vIRF-3 is known to be involved in modulation of the type I interferon response.
Kaposi's sarcoma-associated herpesvirus viral interferon regulatory factor 3 inhibits gamma interferon and major histocompatibility complex class II expression.
Specimen part, Cell line
View SamplesThe Early Growth Response (Egr) family of transcription factors consists of 4 members (Egr1-4) that are expressed in a wide variety of cell types. A large body of evidence point to a role for Egr transcription factors in growth, survival, and differentiation. A major unanswered question is whether Egr transcription factors serve similar functions in diverse cell types by activating a common set of target genes. Signal transduction cascades in neurons and lymphocytes show striking parallels. Activation of either cell type activates the Ras-MAPK pathway and, in parallel, leads to increases in intracellular calcium stimulating the calcineurin-NFAT pathway. In both cell types, the strength of the activation signal affects the cellular outcomes and very strong stimuli lead to cell death. Notably both these pathways converge on the induction of Egr genes. We believe that downstream targets of Egr transcription factors in lymphocytes may also be activated by Egr factors in activated neurons. There is precedence for common target gene activation in these two cell types: apoptosis in both activated T cells and methamphetamine stimulated neurons occurs via FasL induction by NFAT transcription factors. We propose to use developing T lymphocytes (thymocytes) as a model system for discovery of Egr-dependent target genes for several reasons. First, we have observed a prominent survival defect in thymocytes from mice deficient in both Egr1 and Egr3 (1/3 DKO) and a partial differention block in the immature double negative (DN) stage. In addition, thymocytes are an easily manipulatable cell type, and the DN subpopulation affected in 1/3 DKO mice can be isolated to very high purity. We anticipate that 1/3 DKO thymocytes will provide an excellent experimental system that will provide insight into Egr-dependent transcription in neuronal development, activation, and death.
Redundant role for early growth response transcriptional regulators in thymocyte differentiation and survival.
No sample metadata fields
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