Myc Cooperates with Ras by Programming Inflammation and Immune Suppression.

The two oncogenes KRas and Myc cooperate to drive tumorigenesis, but the mechanism underlying this remains unclear. In a mouse lung model of KRasG12D-driven adenomas, we find that co-activation of Myc drives the immediate transition to highly proliferative and invasive adenocarcinomas marked by highly inflammatory, angiogenic, and immune-suppressed stroma. We identify epithelial-derived signaling molecules CCL9 and IL-23 as the principal instructing signals for stromal reprogramming. CCL9 mediates recruitment of macrophages, angiogenesis, and PD-L1-dependent expulsion of T and B cells. IL-23 orchestrates exclusion of adaptive T and B cells and innate immune NK cells. Co-blockade of both CCL9 and IL-23 abrogates Myc-induced tumor progression. Subsequent deactivation of Myc in established adenocarcinomas triggers immediate reversal of all stromal changes and tumor regression, which are independent of CD4+CD8+ T cells but substantially dependent on returning NK cells. We show that Myc extensively programs an immune suppressive stroma that is obligatory for tumor progression

Lipid Remodeling in Hepatocyte Proliferation and Hepatocellular Carcinoma.

BACKGROUND AND AIMS: Hepatocytes undergo profound metabolic rewiring when primed to proliferate during compensatory regeneration and in hepatocellular carcinoma (HCC). However, the metabolic control of these processes is not fully understood. In order to capture the metabolic signature of proliferating hepatocytes, we applied state-of-the-art systems biology approaches to models of liver regeneration, pharmacologically and genetically activated cell proliferation, and HCC. APPROACH AND RESULTS: Integrating metabolomics, lipidomics, and transcriptomics, we link changes in the lipidome of proliferating hepatocytes to altered metabolic pathways including lipogenesis, fatty acid desaturation, and generation of phosphatidylcholine (PC). We confirm this altered lipid signature in human HCC and show a positive correlation of monounsaturated PC with hallmarks of cell proliferation and hepatic carcinogenesis. CONCLUSIONS: Overall, we demonstrate that specific lipid metabolic pathways are coherently altered when hepatocytes switch to proliferation. These represent a source of targets for the development of therapeutic strategies and prognostic biomarkers of HCC.J.L.G., Z.H. and M.V. are funded by the Medical Research Council (MRC grant MC UP A90 1006 & MC PC 13030). J.L.G. and Z.H. are supported by the Imperial Biomedical Research Centre, NIHR. M.A., A.V-P., F.O., Q.M.A. and M.V. are members of the EPoS consortium, which is funded by the Horizon 2020 Framework Program of the European Union under Grant Agreement 634413. F.O. is supported by MRC program grants (MR/K0019494/1 and MR/R023026/1). J.L is supported by MRC PhD studentship and a CRUK program grant (C18342/A23390). M.V. and A.V-P. are supported by MRC MDU and MRC DMC (MC UU 12012/2). Q.M.A. received additional research support from The Liver Research Trust and is a Newcastle NIHR Biomedical Research Centre investigator. M.A., M.V., A.V-P. and J.L.G. received research support from the Evelyn Trust and the NIHR Cambridge Biomedical Research Centre (Gastroenterology Theme)

The Intestinal Epithelium:Role of Notch Signaling

The mammalian intestine is a prototype of a self-renewing organ. The rapid cellular turnover is supported by proliferating progenitors located in the intestinal crypt, which is also the stem cell location. Homeostasis of the intestinal epithelium has to be under stringent control to ensure lifelong self-renewal. Processes like proliferation and differentiation (often deregulated in cancer) seem to be controlled by a relative small number of signaling pathways, including Wnt and Notch. Notch signaling is playing a crucial role in the maintenance of the intestinal homeostasis by controlling progenitors proliferation and their cell fate. In this thesis project we studied Notch signaling and its role in the murine intestine focusing on 1) Its downstream mediators; 2) The identification of the physiological Notch ligands; 3) Its role on the stem cell compartment, and 4) the potential cross talk between Notch and Wnt. Furthermore, 5) we investigated the role of Notch signaling in Wnt induced intestinal tumorigenesis. This study evidenced that Hes1 is not the unique Notch signaling mediator in the intestinal epithelium. Moreover the transcription factor Klf4 is not required for goblet cell differentiation. The in vivo role of the Notch ligands Dll1, Dll4 and Jag1 was assessed deriving inducible intestine specific single and double gene-targeted mice. Inactivation of individual ligands did not show any loss of Notch phenotype with the exception of Dll1 mutant mice. Only by deriving double mutants we identified Dll1 and Dll4 as the physiological Notch ligands in the intestine. We provided evidence for the first time that Notch1 signaling is active in intestinal stem cell. Furthermore we demonstrated that Notch signaling is required for the maintenance of intestinal stem cells, as well as for the transit-amplifying progenitor compartment. Using different genetic gain and loss-off function approaches we investigated the relation between the Notch and Wnt cascade for the maintenance of the proliferative crypt compartment. A synergistic relation was observed between Notch and Wnt in intestinal tumorigenesis. Collectively our data highlight Notch signaling as a key player for the maintenance of intestinal homeostasis

Myc Cooperates with Ras by Programming Inflammation and Immune Suppression.

The two oncogenes KRas and Myc cooperate to drive tumorigenesis, but the mechanism underlying this remains unclear. In a mouse lung model of KRasG12D-driven adenomas, we find that co-activation of Myc drives the immediate transition to highly proliferative and invasive adenocarcinomas marked by highly inflammatory, angiogenic, and immune-suppressed stroma. We identify epithelial-derived signaling molecules CCL9 and IL-23 as the principal instructing signals for stromal reprogramming. CCL9 mediates recruitment of macrophages, angiogenesis, and PD-L1-dependent expulsion of T and B cells. IL-23 orchestrates exclusion of adaptive T and B cells and innate immune NK cells. Co-blockade of both CCL9 and IL-23 abrogates Myc-induced tumor progression. Subsequent deactivation of Myc in established adenocarcinomas triggers immediate reversal of all stromal changes and tumor regression, which are independent of CD4+CD8+ T cells but substantially dependent on returning NK cells. We show that Myc extensively programs an immune suppressive stroma that is obligatory for tumor progression

Dll1- and Dll4-mediated Notch signaling is required for homeostasis of intestinal stem cells

BACKGROUND & AIMS: Ablation of Notch signaling within the intestinal epithelium results in loss of proliferating crypt progenitors, due to their conversion into post-mitotic secretory cells. We aimed to confirm that Notch was active in stem cells (SC), investigate consequences of loss of Notch signaling within the intestinal SC compartment, and identify the physiological ligands of Notch in mouse intestine. Furthermore, we investigated whether the induction of goblet cell differentiation that results from loss of Notch requires the transcription factor Krüppel-like factor 4 (Klf4). METHODS: Transgenic mice that carried a reporter of Notch1 activation were used for lineage tracing experiments. The in vivo functions of the Notch ligands Jagged1 (Jag1), Delta-like1 (Dll1), Delta-like4 (Dll4), and the transcription factor Klf4 were assessed in mice with inducible, gut-specific gene targeting (Vil-Cre-ERT2). RESULTS: Notch1 signaling was found to be activated in intestinal SC. Although deletion of Jag1 or Dll4 did not perturb the intestinal epithelium, inactivation of Dll1 resulted in a moderate increase in number of goblet cells without noticeable effects of progenitor proliferation. However, simultaneous inactivation of Dll1 and Dll4 resulted in the complete conversion of proliferating progenitors into post-mitotic goblet cells, concomitant with loss of SC (Olfm4+, Lgr5+ and Ascl2+). Klf4 inactivation did not interfere with goblet cell differentiation in adult wild-type or in Notch pathway-deficient gut. CONCLUSIONS: Notch signaling in SC and progenitors is activated by Dll1 and Dll4 ligands and is required for maintenance of intestinal progenitor and SC. Klf4 is dispensable for goblet cell differentiation in intestines of adult Notch-deficient mice

Spearman Correlation between pharmacological stress MPRI and CPT MPRI.

<p>Spearman Correlation between pharmacological stress MPRI and CPT MPRI.</p

Myc instructs and maintains pancreatic adenocarcinoma phenotype

The signature features of pancreatic ductal adenocarcinoma (PDAC) are its fibroinflammatory stroma, poor immune activity and dismal prognosis. We show that acute activation of Myc in indolent PanIN epithelial cells in vivo is, alone, sufficient to trigger immediate release of instructive signals that together coordinate changes in multiple stromal and immune cell types and trigger transition to pancreatic adenocarcinomas that share all the characteristic stromal features of their spontaneous human counterpart. We also demonstrate that this Myc-driven PDAC switch is completely and immediately reversible: Myc deactivation/inhibition triggers meticulous disassembly of advanced PDAC tumor and stroma and concomitant death of tumor cells. Hence, both the formation and deconstruction of the complex PDAC phenotype are continuously dependent on a single, reversible Myc switch.The study was supported by program grants to G.I.E. (Cancer Research UK C4750/A12077 and C4750/A19013A, European Research Council (294851), and a Stand Up To Cancer-Cancer Research UKLustgarten Foundation Pancreatic Cancer Dream Team Research Grant (Grant Number: SU2C-AACR-DT20-16). Stand Up To Cancer is a division of the Entertainment Industry Foundation and the research grant is administered by the American Association for Cancer Research, the Scientific Partner of SU2C

Loss of intestinal crypt progenitor cells owing to inactivation of both Notch1 and Notch2 is accompanied by derepression of CDK inhibitors p27Kip1 and p57Kip2

The crucial role of individual Notch receptors and the mechanism by which they maintain intestinal crypt progenitor cells were assessed by using a series of inducible gut-specific Notch mutant mice. We found that Notch1 and Notch2 receptors function redundantly in the gut, as only simultaneous loss of both receptors results in complete conversion of proliferating crypt progenitors into post-mitotic goblet cells. This conversion correlates with the loss of Hes1 expression and derepression of the cyclin-dependent kinase (CDK) inhibitors p27Kip1 and p57Kip2. We also found that the promoter of both CDK inhibitor genes is occupied by the Notch effector Hes1 in wild-type crypt progenitor cells. Thus, our results indicate that Notch-mediated Hes1 expression contributes to the maintenance of the proliferative crypt compartment of the small intestine by transcriptionally repressing two CDK inhibitors

Reversible Myc hypomorphism identifies a key Myc-dependency in early cancer evolution

Germ-line hypomorphism of the pleiotropic transcription factor Myc in mice, either through Myc gene haploinsufficiency or deletion of Myc enhancers, delays onset of various cancers while mice remain viable and exhibit only relatively mild pathologies. Using a genetically engineered mouse model in which Myc expression may be systemically and reversibly hypomorphed at will, we asked whether this resistance to tumour progression is also emplaced when Myc hypomorphism is acutely imposed in adult mice. Indeed, adult Myc hypomorphism profoundly blocked KRasG12D-driven lung and pancreatic cancers, arresting their evolution at the early transition from indolent pre-tumour to invasive cancer. We show that such arrest is due to the incapacity of hypomorphic levels of Myc to drive release of signals that instruct the microenvironmental remodelling necessary to support invasive cancer. The cancer protection afforded by long-term adult imposition of Myc hypomorphism is accompanied by only mild collateral side effects, principally in haematopoiesis. However, by metronomically imposing Myc hypomorphism even these mild deficits are circumvented, while potent cancer protection is retained