Project description:In several developmental lineages, an increase in expression of the MYC proto-oncogene drives the transition from quiescent stem cells to transit amplifying cells. The mechanism by which MYC restricts self-renewal of adult stem cells is unknown. Here, we show that MYC activates a stereotypic transcriptional program of genes involved in protein translation and mitochondrial biogenesis in mammary epithelial cells and indirectly inhibits the YAP/TAZ co-activators that are essential for mammary stem cell self-renewal. We identify a phospholipase of the mitochondrial outer membrane, PLD6, as the mediator of MYC activity. PLD6 mediates a change in the mitochondrial fusion/fission balance that promotes nuclear export of YAP/TAZ in a LATS- and RHO-independent manner. Mouse models and human pathological data confirm that MYC suppresses YAP/TAZ activity in mammary tumors. PLD6 is also required for glutaminolysis, arguing that MYC-dependent changes in mitochondrial dynamics balance cellular energy metabolism with the self-renewal potential of adult stem cells. ChIP-Seq experiments for MYC-HA (HA-IP) performed in IMEC primary breast epithelial cells. Input-samples were sequenced as controlls.
Project description:In several developmental lineages, an increase in expression of the MYC proto-oncogene drives the transition from quiescent stem cells to transit amplifying cells. The mechanism by which MYC restricts self-renewal of adult stem cells is unknown. Here, we show that MYC activates a stereotypic transcriptional program of genes involved in protein translation and mitochondrial biogenesis in mammary epithelial cells and indirectly inhibits the YAP/TAZ co-activators that are essential for mammary stem cell self-renewal. We identify a phospholipase of the mitochondrial outer membrane, PLD6, as the mediator of MYC activity. PLD6 mediates a change in the mitochondrial fusion/fission balance that promotes nuclear export of YAP/TAZ in a LATS- and RHO-independent manner. Mouse models and human pathological data confirm that MYC suppresses YAP/TAZ activity in mammary tumors. PLD6 is also required for glutaminolysis, arguing that MYC-dependent changes in mitochondrial dynamics balance cellular energy metabolism with the self-renewal potential of adult stem cells.
Project description:In several developmental lineages, an increase in expression of the MYC proto-oncogene drives the transition from quiescent stem cells to transit amplifying cells. The mechanism by which MYC restricts self-renewal of adult stem cells is unknown. Here, we show that MYC activates a stereotypic transcriptional program of genes involved in protein translation and mitochondrial biogenesis in mammary epithelial cells and indirectly inhibits the YAP/TAZ co-activators that are essential for mammary stem cell self-renewal. We identify a phospholipase of the mitochondrial outer membrane, PLD6, as the mediator of MYC activity. PLD6 mediates a change in the mitochondrial fusion/fission balance that promotes nuclear export of YAP/TAZ in a LATS- and RHO-independent manner. Mouse models and human pathological data confirm that MYC suppresses YAP/TAZ activity in mammary tumors. PLD6 is also required for glutaminolysis, arguing that MYC-dependent changes in mitochondrial dynamics balance cellular energy metabolism with the self-renewal potential of adult stem cells.
Project description:In several developmental lineages, an increase in expression of the MYC proto-oncogene drives the transition from quiescent stem cells to transit amplifying cells. The mechanism by which MYC restricts self-renewal of adult stem cells is unknown. Here, we show that MYC activates a stereotypic transcriptional program of genes involved in protein translation and mitochondrial biogenesis in mammary epithelial cells and indirectly inhibits the YAP/TAZ co-activators that are essential for mammary stem cell self-renewal. We identify a phospholipase of the mitochondrial outer membrane, PLD6, as the mediator of MYC activity. PLD6 mediates a change in the mitochondrial fusion/fission balance that promotes nuclear export of YAP/TAZ in a LATS- and RHO-independent manner. Mouse models and human pathological data confirm that MYC suppresses YAP/TAZ activity in mammary tumors. PLD6 is also required for glutaminolysis, arguing that MYC-dependent changes in mitochondrial dynamics balance cellular energy metabolism with the self-renewal potential of adult stem cells. RNA-Seq Experiments in 2 different primary breast epithelial cell lines (HMLE, which were sorted according to CD44/CD24 surface markers & unsorted IMEC). Both cell lines expressed a doxycycline-inducible version of MYC. For the HMLE cell line DGE analysis was performed for the uninduced (EtOH) situation, comparing CD44high vs CD44 low and for the induced situation Dox vs. EtOH for the CD44high population. For the IMEC cell line DGE was performed by comparing Dox-treated populations expressing either Dox-inducible MYC or a vector control which allows to filter out potential effects due to doxycycline treatment.
Project description:The crosstalk between tumor cells and the adjacent normal epithelium contributes to cancer progression, but its regulators have remained elusive. Here, we show that breast cancer cells maintained in hypoxia release small extracellular vesicles (sEV) that activate mitochondrial dynamics, stimulate mitochondrial movements and promote organelle accumulation at the cortical cytoskeleton in normal mammary epithelial cells. This results in Akt activation, membrane focal adhesion turnover and increased epithelial cell migration. RNA-Seq profiling identified Integrin-Linked Kinase (ILK) as the most upregulated pathway in sEV-treated epithelial cells and genetic or pharmacologic targeting of ILK reversed mitochondrial reprogramming and suppressed sEV-induced cell movements. In a three-dimensional model of mammary gland morphogenesis, sEV treatment induced hallmarks of malignant transformation, with deregulated cell death/cell proliferation, loss of apical-basal polarity and appearance of epithelial-to-mesenchymal transition (EMT) markers. Therefore, sEV released by hypoxic breast cancer cells reprogram mitochondrial dynamics and induce oncogenic changes in a normal mammary epithelium
Project description:Purpose: discover the downstream pathways and the mechanism of target activation by the p53:Myc axis in normal mammary and cancer stem cells Methods: we performed ChIPseq experiments from NMuMG cells grown in adhesion under standard conditions Results: the p53:Myc axis orchestrates its transcriptional response in mammary-epithelial cells via a dual and overlapping mechanism: i) a tightly controlled epistasis driven by p53 and executed by Myc, and ii) a co-operative double occupancy of their downstream effectors at different regulatory regions
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:MYC and hypoxia gene clusters are the two most commonly recurring transcriptional programs in heterogenous tumors. Understanding the cellular fitness of MYC-driven cancer cells in normoxia and hypoxia may lead to identification of distinct cancer cell vulnerabilities. Using genome-wide CRISPR screenings of MYC-driven liver cancer cells cultured over 4 weeks in 21% and 1% oxygen in monolayer, and 21% oxygen in 3D spheroid, we not only identify over 600 essential genes under all three conditions but also context-specific fitness genes and pathways. Knockout of VHL-HIF1 pathway results in incompatible fitness defects under 21% oxygen versus 1% oxygen or 3D. Genetic deletion of each of the mitochondrial respiratory complex I-V has distinct cellular fitness outcomes. Notably, the organogenesis signaling pathways such as TGF-SMAD specifically limits the uncontrolled cell proliferation of 3D spheroids while inactivation of epigenetic modifiers (Bcor, Kmt2d, Mettl3 and Mettl14) has opposite outcomes in monolayer versus 3D. We also discover distinct metabolic requirement for fatty acid and cholesterol synthesis in three conditions. Chemical perturbations using 125 FDA approved oncology drugs reveal that MYC-driven liver cancer cells have different sensitivity to inhibition of tyrosine kinase receptors under hypoxia and 3D. Our resource study highlights unique epigenetic and metabolic dependency of MYC-driven cancer cells in different tumor environmental settings.