Integrative transcriptomic analysis reveals mechanisms controlling the reciprocity of epithelial and mesenchymal genes during epithelial-to-mesenchymal transition
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ABSTRACT: Epithelial-to-mesenchymal transition (EMT) is an important developmental process that is also activated during disease progressions. Many genes involved in EMT have been identified to date, but the key molecules governing the coupling between the dynamics of epithelial genes and that of the mesenchymal genes are unclear. In addition, it has been shown that there is a remarkable diversity of EMT phenotypes in different pathological conditions or microenvironments, but its mechanistic basis remains elusive. In this study, we used transcriptomic analysis to identify the roles of an EMT-inducing transcription factor ZEB1 in controlling epithelial and mesenchymal genes. We found that the mesenchymal genes exhibit a significant diversity in terms of their responsiveness to ZEB1. We applied machine learning approaches to the transcriptome data and identified three groups of M-genes that are controlled by EMT promoting factors via different types of regulatory circuits. We inferred the functional differences among the M-gene clusters in motility regulation of cultured cells and in survival of breast cancer patients. We characterized the roles of ZEB1 in controlling the reciprocity and reversibility of EMT using mathematical modeling. Our integrative analysis reveals the key roles of ZEB1 in coordinating the dynamics of a large number of genes during EMT, and it provides new insights into the mechanisms for the diversity of EMT phenotypes.
Project description:Epithelial to Mesenchymal Transition (EMT) has been associated with cancer cell heterogeneity, plasticity and metastasis. It has been the subject of several modeling effort. This logical model of the EMT cellular network aims to assess microenvironmental signals controlling cancer-associated phenotypes amid the EMT continuum. Its outcomes relate to the qualitative degrees of cell adhesions by adherent junctions and focal adhesions, two features affected during EMT. Model attractors recover epithelial, mesenchymal and hybrid phenotypes, and simulations show that hybrid phenotypes may arise through independent molecular paths, involving stringent extrinsic signals.
Of particular interest, model predictions and their experimental validations indicated that: 1) ECM stiffening is a prerequisite for cells overactivating FAK-SRC to upregulate SNAIL1 and acquire a mesenchymal phenotype, and 2) FAK-SRC inhibition of cell-cell contacts through the Receptor Protein Tyrosine Phosphates kappa leads to the acquisition of a full mesenchymal rather than a hybrid phenotype.
Project description:The epithelial–mesenchymal transition (EMT) is a dynamic transdifferentiation of epithelial cells into mesenchymal cells. EMT programs exhibit great diversity, based primarily on the distinct impact of molecular activities of the EMT transcription factors. Using a panel of cancer cell lines and a series of 71 triple-negative primary breast tumors, we report that the EMT transcription factor ZEB1 modulates site-specific chemical modifications of ribosomal RNA (rRNA). Overexpression of ZEB1 and ZEB2, but not TWIST1, decreased the level of 2′-O-ribose methylation (2′Ome) of 28S rRNA at position Um2402. ZEB1 overexpression specifically reduced the expression of the corresponding C/D box small nucleolar RNAs (snoRNAs) SNORD143/144, which guide the rRNA 2′Ome complex at the 28S_Um2402 site. During ZEB1-induced EMT induction/reversion, the levels of both 2′Ome at 28S_Um2402 and SNORD143/144 were dynamically comodulated. Taken together, these data demonstrate that 2′Ome rRNA epitranscriptomics is a novel marker of ZEB1-induced EMT.
Project description:Idiopathic pulmonary fibrosis (IPF) is the prototypic progressive fibrotic lung disease with a median survival of 2-4 years. Injury to and/or dysfunction of alveolar epithelium are strongly implicated in IPF disease initiation, but what factors determine why fibrosis progresses rather than normal tissue repair occurs remain poorly understood. We previously demonstrated that ZEB1-mediated epithelial-mesenchymal transition (EMT) in human alveolar epithelial type II (ATII) cells augments TGF-β-induced profibrogenic responses in underlying lung fibroblasts by paracrine signalling. Here we investigated bi-directional epithelial-mesenchymal crosstalk and its potential to drive fibrosis progression. RNA sequencing (RNA-seq) of lung fibroblasts exposed to conditioned media from ATII cells undergoing RAS-induced EMT identified many differentially expressed genes including those involved in cell migration and extracellular matrix (ECM) regulation. We confirmed that paracrine signalling between AS-activated ATII cells and fibroblasts augmented fibroblast recruitment and demonstrated that this involved a ZEB1-tissue plasminogen activator (tPA) axis. In a reciprocal fashion, paracrine signalling from TGF-β-activated lung fibroblasts or IPF fibroblasts induced RAS activation in ATII cells, at least partially via the secreted protein, SPARC. Together these data identify that aberrant bi-directional epithelial-mesenchymal crosstalk in IPF drives a chronic feedback loop that maintains a wound-healing phenotype and provides self-sustaining pro-fibrotic signals.
Project description:Integrative transcriptomic analysis reveals mechanisms controlling the reciprocity of epithelial and mesenchymal genes during epithelial-to-mesenchymal transition
Project description:Epithelial-mesenchymal transition (EMT) involves profound changes in cell morphology, driven by transcriptional and epigenetic reprogramming. However, it emerges that translation and the ribosome composition play also key role in establishing physio-pathological phenotypes. Using genome-wide analyses, we report significant rearrangement of the translational landscape and machinery during EMT. Specifically, a mesenchymal cell line overexpressing the EMT transcription factor ZEB1 shows alterations in translational reprogramming and fidelity. Considering the change in translational activity of ZEB1-overexpressing mesenchymal cells, including in fidelity activity, we sought for changes in ribosome composition. We thus performed a riboproteome approach, i.e., mass spectrometry (MS)-based quantitative proteomic analysis of purified cytoplasmic ribosomes to highlight any change in relative amount of individual ribosomal proteins between wild-type and ZEB1-overexpressing human mammary epithelial cells.
Project description:Multiple EMT-promoting/inhibiting transcription factors have been identified including Snail, Zeb1 and Ovol2. To understand differential roles of these factors, we performed gene expression profiling by RNA-seq upon Snail-/Zeb1-induced EMT or Ovol2-induced MET in human mammary epithelial MCF10A cells.
Project description:The epithelial-mesenchymal transition (EMT), considered essential for metastatic cancer, has been a focus of much research, but important questions remain. Here, we show that silencing or removing H2A.X, a histone H2A variant involved in cellular DNA repair and robust growth, induced mesenchymal-like characteristics including activation of EMT transcription factors, Slug and ZEB1, in HCT116 human colon cancer cells. Ectopic H2A.X re-expression partially reversed these changes; as did silencing Slug and ZEB1. In an experimental metastasis model, the HCT116 parental and H2A.X-null cells exhibited similar metastases levels, but the cells with re-expressed H2A.X exhibited substantially elevated levels. We surmise that H2A.X re-expression led to partial EMT reversal and increased robustness in the HCT116 cells, permitting them to both form tumors and to metastasize. In a human adenocarcinoma panel, H2A.X levels correlated inversely with Slug and ZEB1 levels. Together, these results point to H2A.X as a novel regulator of EMT. 9 samples in total including 4 replicates of control shRNA and 5 replicates of shH2A.X.
Project description:Epithelial-mesenchymal transition (EMT) is a reversible transcriptional program subverted by cancer cells to drive cancer progression. Transcription factor ZEB1 is a master regulator of EMT, driving disease recurrence in poor outcome triple negative breast cancer (TNBC). Here, we silence ZEB1 in TNBC models by CRISPR-mediated epigenetic editing, resulting in nearly complete repression of ZEB1 in vivo, accompanied by long-lasting tumor inhibition. Integrated transcriptomic and epigenetic profiling identified a ZEB1-dependent gene-signature associated with transcriptional up-regulation, promoter DNA demethylation and enhanced chromatin accessibility in core cell adhesion loci, demonstrating epigenetic reprogramming towards a more epithelial state. Epigenetic shifts induced by ZEB1-silencing are enriched in a subset of human breast tumors, illuminating a clinically-relevant hybrid-like state. Thus, the synthetic epi-silencing of ZEB1 induces stable “lock-in” epigenetic reprogramming of mesenchymal tumors associated with a distinct epigenetic landscape. We outline approaches to stably reprogram EMT for targeting poor outcome breast cancers driven by oncogenic transcription factors.
Project description:Epithelial-mesenchymal transition (EMT) is a reversible transcriptional program subverted by cancer cells to drive cancer progression. Transcription factor ZEB1 is a master regulator of EMT, driving disease recurrence in poor outcome triple negative breast cancer (TNBC). Here, we silence ZEB1 in TNBC models by CRISPR-mediated epigenetic editing, resulting in nearly complete repression of ZEB1 in vivo, accompanied by long-lasting tumor inhibition. Integrated transcriptomic and epigenetic profiling identified a ZEB1-dependent gene-signature associated with transcriptional up-regulation, promoter DNA demethylation and enhanced chromatin accessibility in core cell adhesion loci, demonstrating epigenetic reprogramming towards a more epithelial state. Epigenetic shifts induced by ZEB1-silencing are enriched in a subset of human breast tumors, illuminating a clinically-relevant hybrid-like state. Thus, the synthetic epi-silencing of ZEB1 induces stable “lock-in” epigenetic reprogramming of mesenchymal tumors associated with a distinct epigenetic landscape. We outline approaches to stably reprogram EMT for targeting poor outcome breast cancers driven by oncogenic transcription factors.
Project description:Epithelial-mesenchymal transition (EMT) is a reversible transcriptional program subverted by cancer cells to drive cancer progression. Transcription factor ZEB1 is a master regulator of EMT, driving disease recurrence in poor outcome triple negative breast cancer (TNBC). Here, we silence ZEB1 in TNBC models by CRISPR-mediated epigenetic editing, resulting in nearly complete repression of ZEB1 in vivo, accompanied by long-lasting tumor inhibition. Integrated transcriptomic and epigenetic profiling identified a ZEB1-dependent gene-signature associated with transcriptional up-regulation, promoter DNA demethylation and enhanced chromatin accessibility in core cell adhesion loci, demonstrating epigenetic reprogramming towards a more epithelial state. Epigenetic shifts induced by ZEB1-silencing are enriched in a subset of human breast tumors, illuminating a clinically-relevant hybrid-like state. Thus, the synthetic epi-silencing of ZEB1 induces stable “lock-in” epigenetic reprogramming of mesenchymal tumors associated with a distinct epigenetic landscape. We outline approaches to stably reprogram EMT for targeting poor outcome breast cancers driven by oncogenic transcription factors.