Abstracts / PancreatologS90

4 Vrije Universiteit Brussel, Belgium5The Garvan Institute of Medical Research, Australia

Introduction: The exocrine pancreas can undergo acinar to ductalmetaplasia (ADM). ADM occurs in pancreatitis and can generate precursorlesions of pancreatic ductal adenocarcinoma (PDAC). Sirtuin 1 (Sirt1), aprotein deacetylase, is an important regulator in cancer.

Aims: We aim to study the expression and the role of Sirt1 in differentstages of pancreatic carcinogenesis. In addition, we analyse the expressionof Sirt1’s key inhibitor Deleted in Breast Cancer 1 (Dbc1) and potentialdown stream targets.

Materials & methods: We analysed pancreatic samples from mousemodels and patient tumours by immunostainings, Western Blot and realtime RT-PCR. We used mouse ADM models and established human PDACcells to manipulate Sirt1’s expression and activity.

Results: Sirt1 is co-expressed with Dbc1 in nuclei of normal acinar cellsand loss of Sirt1 in normal pancreas has no apparent effects. In ADMhowever, Sirt1 but not

Dbc1 undergoes a transient cytoplasmic shuttling, suggestive of atemporary decreased nuclear and increased cytoplasmic Sirt1 activity. Ourobservations indicate that this contributes to the ADM process.

In addition to suppressive effects of a Sirtuin inhibitor on ADM, we alsofound that interference with Sirt1’s expression or application of an in-hibitor in PDAC tumours results in loss of cell viability. In addition, weshow that in PDAC, Dbc1 expression is differentially down regulated andthe sensitivity of a panel of PDAC cell lines to a Sirt1 inhibitor correlateswith Sirt1/Dbc1 expression.

Conclusion: This is the first study to show that Sirt1 is a criticalregulator and potential therapeutic target throughout pancreatic carci-nogenesis.

S-2 Abstract id: 149.

Combined pharmacological inhibition of Notch and JAK/STAT path-ways effectively suppresses conversion from acinar-ductal metaplasiato pancreatic ductal adenocarcinoma and is superior to monotherapy

Ruben Plentz 1, Vindhya Palagani 1, Przemyslaw Bozko 1, Mona ElKhatib 1, Hanane Belahmer 1, Bence Sipos 2, Nisar Malek 1.

1Department of Internal Medicine I, Medical University Hospital,Tuebingen, Germany2 Institute of Pathology, University of Tuebingen, Germany

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is an aggres-sive disease with a high rate of metastasis. Recent studies have indicatedthat Notch and JAK2/STAT3 signaling pathways are both important for theinitiation and progression of PDAC.

Aims: The purpose of this study was to determine the outcome oftargeting these two tumor signaling pathways simultaneously both in vitroand in vivo.

Materials & methods: We assessed the combinational effects of the g-secretase inhibitor IX (GSI IX) and JAK2 inhibitor (AG-490) on growth andepithelial plasticity of human pancreatic cancer cell lines, and in a genet-ically engineered mouse model (Pdx1- Cre; LSL-KrasG12D; p53 lox/þ) ofPDAC.

Results: Dual treatment with GSI IX and AG-490 significantly impairedcell proliferation, migration, invasion, soft agar growth and apoptosiswhen compared to monotherapies. Notably, inhibition of Hes1 downregulated phosphorylation of STAT3 and reflects a synergistic effect. Mostimportantly, combinational treatment significantly attenuates tumorprogression in vivo and suppresses conversion from acinar-ductal-meta-plasia (ADM) to PDAC.

Conclusion: Our results suggest that targeting Notch and JAK2/STAT3signaling pathways simultaneously is superior to single inhibitions, sup-porting combined treatment by GSI X and AG-490 as a potential thera-peutic approach for PDAC.

S-3 Abstract id: 290.

Regeneration from acute pancreatitis requires transcriptionalsilencing of NFATc1

Moritz Dyck, Nai-Ming Chen, Elisabeth Glesel, Bettina Geisel, KristinaReutlinger, Thomas M. Gress, Volker Ellenrieser.

PhilippA’s University Marburg, Germany

Introduction: Tissue injury initiates a complex regenerative pro-gramme ensuring complete restoration of organ structure and function.Understanding the molecular key events in mediation and regenerationfrom pancreas injury is critical to develop novel therapeutic strategies.Recent evidence suggests important roles for developmental and in-flammatory transcription factors in several steps of the regenerationprocess.

Aims: To analyze whether and how the inflammatory transcriptionfactor NFATc1 is involved in the course of acute pancreatitis.

Materials & methods: Caerulein and L-Arginin were used to induceacute pancreatitis in different pancreas specific transgenic micemodels with differential expression of NFATc1. Mice were sacrificed atdifferent time points after induction of acute pancreatitis to isolatepancreata for further analysis. Gene expression in mice tissue andacinar cell explants were determined by using RT-PCR, immunoblotting,immunofluorescence and immunohistochemical stainings. Local his-tone modifications on the NFATc1 promoter were investigated by ChIPanalysis.

Results: Caerulein mediated acute pancreatitis initiates acinar toductal metaplasia, which goes along with activation of NFATc1 in meta-plastic areas of the pancreas. Regeneration of the pancreas requiresinactivation of NFATc1 by H3K27 trimethylation mediated by the Poly-comb protein EZH2. While pharmacological or genetic inactivation ofNFATc1 in mice accelerates pancreas regeneration, sustained activation ofNFATc1 overcomes transcriptional silencing and fully prevents restora-tion of the organ.

Conclusion: Our results provide evidence, that transcriptionalsilencing of NFATc1 by EZH2 is an inevitable prerequisite for sufficientregeneration from acute pancreatitis.

y 13 (2013) S2–S98

S-4 Abstract id: 231.

Antidromic NFATc1 and p53 signaling at the edge of differentiationand stemness in pancreatic cancer

Shiv Singh, Nadine V€olker, Sophia Vogt, Bettina Geisel, Nai-mingChen, Elisabeth Glesel, Sandra Baumgart, Garima Singh, IreneEsposito, Thomas Gress, Volker Ellenrieder.

Signaling and Transcription Laboratory, Internal Medicine, Dept. ofGastroenterology, Philipps University of Marburg, Germany, Germany

Introduction: The current concept suggests a direct link between EMTand stemness induction in pancreatic cancer, thereby coupling cell motilityand de-differentiation with self-renewal capacities and drug resistance.Both key features of cellular plasticity are controlled by distinct intracel-lular signaling and transcription pathways. We have shown that NFATc1activation promotes PDAC and metastasis through its ability to integrateextrinsic stimuli into coordinated gene regulation.

Aims: To assess whether NFATc1 controls transcription of EMT genesand stemness in PDAC, particularly upon p53 inactivation.

Patients & methods: We generated mouse strains with combinedpancreas-specific expression of NFATc1, p53R172H and KrasG12D. These miceshowed a highly aggressive tumor growth. Mouse primary tumour cellswere used to identify NFATc1 targets by gene expression profiling andpathway analyses (ChIP seq, miRNA analyses and GSEA). NFATc1 mediated