Targeting DNA Damage Repair Mechanisms in Pancreas Cancer

BRCA1/2; Inhibición de PARP; Adenocarcinoma ductal pancreáticoBRCA1/2; Inhibició DE PARP; Adenocarcinoma ductal pancreàticBRCA1/2; PARP inhibition; Pancreatic ductal adenocarcinomaImpaired DNA damage repair (DDR) is increasingly recognised as a hallmark in pancreatic ductal adenocarcinoma (PDAC). It is estimated that around 14% of human PDACs harbour mutations in genes involved in DDR, including, amongst others, BRCA1/2, PALB2, ATM, MSH2, MSH6 and MLH1. Recently, DDR intervention by PARP inhibitor therapy has demonstrated effectiveness in germline BRCA1/2-mutated PDAC. Extending this outcome to the significant proportion of human PDACs with somatic or germline mutations in DDR genes beyond BRCA1/2 might be beneficial, but there is a lack of data, and consequently, no clear recommendations are provided in the field. Therefore, an expert panel was invited by the European Society of Digestive Oncology (ESDO) to assess the current knowledge and significance of DDR as a target in PDAC treatment. The aim of this virtual, international expert meeting was to elaborate a set of consensus recommendations on testing, diagnosis and treatment of PDAC patients with alterations in DDR pathways. Ahead of the meeting, experts completed a 27-question survey evaluating the key issues. The final recommendations herein should aid in facilitating clinical practice decisions on the management of DDR-deficient PDAC.This congress paper received no external funding. Additional research funding is declared: L.P. (DFG PE 3337/1-1), A.K. (DFG KL 2544/1-1, 1-2, 5-1, 6-1, 7-1, Baden-Württemberg-Foundation ExPoChip, German Cancer Aid 111879, INDIMED-Verbund PancChip, HEIST RTG DFG GRK 2254/1 and Excellence grant Else-Kröner-Fresenius-Stiftung), E.M.O. (Cancer Center Support Grant/Core Grant P30 CA008748)

Modeling plasticity and dysplasia of pancreatic ductal organoids derived from human pluripotent stem cells

Personalized in vitro models for dysplasia and carcinogenesis in the pancreas have been constrained by insufficient differentiation of human pluripotent stem cells (hPSCs) into the exocrine pancreatic lineage. Here, we differentiate hPSCs into pancreatic duct-like organoids (PDLOs) with morphological, transcriptional, proteomic, and functional characteristics of human pancreatic ducts, further maturing upon transplantation into mice. PDLOs are generated from hPSCs inducibly expressing oncogenic GNAS, KRAS, or KRAS with genetic covariance of lost CDKN2A and from induced hPSCs derived from a McCune-Albright patient. Each oncogene causes a specific growth, structural, and molecular phenotype in vitro. While transplanted PDLOs with oncogenic KRAS alone form heterogenous dysplastic lesions or cancer, KRAS with CDKN2A loss develop dedifferentiated pancreatic ductal adenocarcinomas. In contrast, transplanted PDLOs with mutant GNAS lead to intraductal papillary mucinous neoplasia-like structures. Conclusively, PDLOs enable in vitro and in vivo studies of pancreatic plasticity, dysplasia, and cancer formation from a genetically defined background

Tbx3 fosters pancreatic cancer growth by increased angiogenesis and activin/nodal-dependent induction of stemness

AbstractCell fate decisions and pluripotency, but also malignancy depend on networks of key transcriptional regulators. The T-box transcription factor TBX3 has been implicated in the regulation of embryonic stem cell self-renewal and cardiogenesis. We have recently discovered that forced TBX3 expression in embryonic stem cells promotes mesendoderm specification directly by activating key lineage specification factors and indirectly by enhancing paracrine NODAL signalling. Interestingly, aberrant TBX3 expression is associated with breast cancer and melanoma formation. In other cancers, loss of TBX3 expression is associated with a more aggressive phenotype e.g. in gastric and cervical cancer. The precise function of TBX3 in pancreatic ductal adenocarcinoma remains to be determined. In the current study we provide conclusive evidence for TBX3 overexpression in pancreatic cancer samples as compared to healthy tissue. While proliferation remains unaltered, forced TBX3 expression strongly increases migration and invasion, but also angiogenesis in vitro and in vivo. Finally, we describe the TBX3-dependency of cancer stem cells that perpetuate themselves through an autocrine TBX3–ACTIVIN/NODAL signalling loop to sustain stemness. Thus, TBX3 is a new key player among pluripotency-related genes driving cancer formation

Human pluripotent stem cell-derived acinar/ductal organoids generate human pancreas upon orthotopic transplantation and allow disease modelling

Objective The generation of acinar and ductal cells from human pluripotent stem cells (PSCs) is a poorly studied process, although various diseases arise from this compartment. Design We designed a straightforward approach to direct human PSCs towards pancreatic organoids resembling acinar and ductal progeny. Results Extensive phenotyping of the organoids not only shows the appropriate marker profile but also ultrastructural, global gene expression and functional hallmarks of the human pancreas in the dish. Upon orthotopic transplantation into immunodeficient mice, these organoids form normal pancreatic ducts and acinar tissue resembling fetal human pancreas without evidence of tumour formation or transformation. Finally, we implemented this unique phenotyping tool as a model to study the pancreatic facets of cystic fibrosis (CF). For the first time, we provide evidence that in vitro, but also in our xenograft transplantation assay, pancreatic commitment occurs generally unhindered in CF. Importantly, cystic fibrosis transmembrane conductance regulator (CFTR) activation in mutated pancreatic organoids not only mirrors the CF phenotype in functional assays but also at a global expression level. We also conducted a scalable proof-of-concept screen in CF pancreatic organoids using a set of CFTR correctors and activators, and established an mRNA-mediated gene therapy approach in CF organoids. Conclusions Taken together, our platform provides novel opportunities to model pancreatic disease and development, screen for disease-rescuing agents and to test therapeutic procedures.This study was funded by the Deutsche Forschungsgemeinschaft (DFG, K.L. 2544/1-1 and 1-2), the Forschungskern SyStaR to AK, BIU (Böhringer Ingelheim Ulm to AK), the Fritz-Thyssen Foundation (Az. 10.15.2.040), the German Cancer Aid (111879) and the Else-Kröner-Fresenius-Stiftung (2011_A200). AK is indebted to the Baden-Württemberg Stiftung for the financial support of this research project by the Eliteprogramme for Postdocs. AK is also an Else-Kröner-Fresenius Memorial Fellow. LP is supported by a research fellowship of the Else-Kröner-Fresenius-Stiftung. MH was supported by the International Graduate School in Molecular Medicine and the Bausteinprogramme (L.SBN. 110), Ulm University. MM is supported by a grant of Ulm University (Baustein for Senior Clinician Scientists). IGC is funded by the Interdisciplinary Center for Clinical Research (IZKF Aachen) and Start Program, RWTH Aachen University Medical School, Aachen, German

Immunhistochemische Charakterisierung Atm depletierter Pankreata im Mausmodell des duktalen pankreatischen Adenokarzinoms

Das humane duktale Pankreaskarzinom (PDAC) gehört zu den Krebserkrankungen mit der höchsten Mortalität. Klinische Charakteristika sind ein aggressives Wachstum mit einer frühzeitigen Metastasierung und einer hohen Therapieresistenz. Die zu Grunde liegenden Mechanismen sind jedoch weiterhin nur unzu- reichend bekannt und erfordern eine weitere tiefgreifende Erforschung der molekularen Pathomechanismen, um daraus möglicherweise zukünftige Therapieoptionen ableiten zu können. Ataxia telangiectasia mutiert (ATM) ist eine Serin-/Threoninkinase mit wichtiger Funktion in der Reparatur von DNA-Doppelstrangbrüchen. Zunehmendes Wissen über die biologische Relevanz von ATM deutet nebst anderen, auch auf eine mögliche Rolle im humanen Pankreaskarzinom hin. Daraus abgeleitet liegt der vorliegenden Arbeit als grundlegende Fragestellung die Aufarbeitung möglicher Einflüsse von Atm auf die Tumorentwicklung zu Grunde. Zu diesem Zweck wurde ein neues Mausmodell generiert, in das basierend auf dem p48-Cre+//LSL-KrasG12D+ Mausmodell (KC) eine pankreasspezifische Atm Deletion (AKC) eingebracht wurde. Die Charakterisierung des neuen AKC Mausmodells erfolgte anhand immun- histochemischer Methoden, im Vergleich zum derzeitigen Standard PDAC Mausmodell der KC Maus. Darüber hinaus erfolgte ein Übertrag der Befunde ins humane PDAC mittels Tissue Microarray, bestehend aus Gewebeproben von resezierten PDAC Patienten sowie gesundem Gewebe. Zusammenfassend konnte dem Verlust von Atm eine relevante Rolle in der Tumorgenese des murinen PDAC zugewiesen werden. Der Verlust von Atm korreliert dabei mit einem Epithelial-Mesenchymalen-Transitions Phänotyp der Tumoren, einer erhöhten Metastasierungsrate, sowie dem signifikant verkürzten Überleben der Mäuse. Auffällig zeigt sich darüber hinaus eine kompensatorische Aktivie- rung von TP53, unabhängig von P21, sowie eine erhöhte Proliferationsrate bei Verlust von Atm. Diese Befunde konnten auch partiell auf das humane PDAC übertragen werden. Hier konnte eine Korrelation mit fortgeschritteneren Tumorstadien und dem Verlust der ATM Expression gezeigt werden

The Impact of Biomarkers in Pancreatic Ductal Adenocarcinoma on Diagnosis, Surveillance and Therapy

Pancreatic ductal adenocarcinoma (PDAC) is still difficult to treat due to insufficient methods for early diagnosis and prediction of therapy response. Furthermore, surveillance after curatively intended surgery lacks adequate methods for timely detection of recurrence. Therefore, several molecules have been analyzed as predictors of recurrence or early detection of PDAC. Enhanced understanding of molecular tumorigenesis and treatment response triggered the identification of novel biomarkers as predictors for response to conventional chemotherapy or targeted therapy. In conclusion, progress has been made especially in the prediction of therapy response with biomarkers. The use of molecules for early detection and recurrence of PDAC is still at an early stage, but there are promising approaches in noninvasive biomarkers, composite panels and scores that can already ameliorate the current clinical practice. The present review summarizes the current state of research on biomarkers for diagnosis and therapy of pancreatic cancer

Self-Expandable Metal Stents for Persisting Esophageal Variceal Bleeding after Band Ligation or Injection-Therapy: A Retrospective Study.

Despite a pronounced reduction of lethality rates due to upper gastrointestinal bleeding, esophageal variceal bleeding remains a challenge for the endoscopist and still accounts for a mortality rate of up to 40% within the first 6 weeks. A relevant proportion of patients with esophageal variceal bleeding remains refractory to standard therapy, thus making a call for additional tools to achieve hemostasis. Self-expandable metal stents (SEMS) incorporate such a tool.We evaluated a total number of 582 patients admitted to our endoscopy unit with the diagnosis "gastrointestinal bleeding" according to our documentation software between 2011 and 2014. 82 patients suffered from esophageal variceal bleeding, out of which 11 cases were refractory to standard therapy leading to SEMS application. Patients with esophageal malignancy, fistula, or stricture and a non-esophageal variceal bleeding source were excluded from the analysis. A retrospective analysis reporting a series of clinically relevant parameters in combination with bleeding control rates and adverse events was performed.The initial bleeding control rate after SEMS application was 100%. Despite this success, we observed a 27% mortality rate within the first 42 days. All of these patients died due to non-directly hemorrhage-associated reasons. The majority of patients exhibited an extensive demand of medical care with prolonged hospital stay. Common complications were hepatic decompensation, pulmonary infection and decline of renal function. Interestingly, we found in 7 out of 11 patients (63.6%) stent dislocation at time of control endoscopy 24 h after hemostasis or at time of stent removal. The presence of hiatal hernia did not affect obviously stent dislocation rates. Refractory patients had significantly longer hospitalization times compared to non-refractory patients.Self-expandable metal stents for esophageal variceal bleeding seem to be safe and efficient after failed standard therapy. Stent migration appeared to be a common incident that did not lead to reactivation of bleeding in any of our patients. SEMS should be considered a reasonable treatment option for refractory esophageal variceal bleeding after treatment failure of ligature and sclerotherapy and non-availability of or contraindication for other measures (e.g. TIPS)