V Ellenrieder

Higher Adenoma Detection Rates with Endocuff-Assisted Colonoscopy – A Randomized Controlled Multicenter Trial

Objectives The Endocuff is a device mounted on the tip of the colonoscope to help flatten the colonic folds during withdrawal. This study aimed to compare the adenoma detection rates between Endocuff-assisted (EC) colonoscopy and standard colonoscopy (SC). Methods This randomized prospective multicenter trial was conducted at four academic endoscopy units in Germany. Participants: 500 patients (235 males, median age 64[IQR 54–73]) for colon adenoma detection purposes were included in the study. All patients were either allocated to EC or SC. The primary outcome measure was the determination of the adenoma detection rates (ADR). Results The ADR significantly increased with the use of the Endocuff compared to standard colonoscopy (35.4%[95% confidence interval{CI} 29–41%] vs. 20.7%[95%CI 15–26%], p<0.0001). Significantly more sessile polyps were detected by EC. Overall procedure time and withdrawal time did not differ. Caecal and ileum intubation rates were similar. No major adverse events occurred in both groups. In multivariate analysis, age (odds ratio [OR] 1.03; 95%[CI] 1.01–1.05), male sex (OR 1.74; 95%CI 1.10–2.73), withdrawal time (OR 1.16; 95%CI 1.05–1.30), procedure time (OR 1.07; 95%CI 1.04–1.10), colon cleanliness (OR 0.60; 95%CI 0.39–0.94) and use of Endocuff (OR 2.09; 95%CI 1.34–3.27) were independent predictors of adenoma detection rates. Conclusions EC increases the adenoma detection rate by 14.7%(95%CI 6.9–22.5%). EC is safe, effective, easy to handle and might reduce colorectal interval carcinomas. Trial Registration ClinicalTrials.gov NCT02034929.

Role of Extracellular Matrix in Pancreatic Diseases

Accessible online at: http://BioMedNet.com/karger The extracellular matrix (ECM) has been traditionally thought of as the structurally stable material that provides support for cells and tissues. However, a number of discoveries over the past decades have changed this view. First, it has been shown that four major classes of macromolecules – the collagens, proteoglycans, structural glycoproteins, and elastin – collectively comprise the ECM of animal cells [1–6]. Furthermore, with the exception of elastin, each class of matrix macromolecules has been found to contain families of related proteins with each member being a unique gene product. Second, individual members of each class and family of ECM molecules were found to exhibit a degree of tissue-specific distribution implicating the matrix in development and tissue function [7, 8]. Third, specific cell-surface receptors for ECM components were identified, which provided a rational basis for linking the ECM with the cell [9–11]. From these discoveries it is now evident that the extracellular matrix is composed of a number of different macromolecules whose structural integrity and functional composition are important in maintaining normal tissue architecture, in development and in tissue-specific function [2, 4, 6, 8, 12]. Finally, it has been recognized that dysfunctional matrix components and abnormalities in ECM biosynthesis and catabolism are of importance in both inherited and acquired diseases and in normal wound healing [2, 3, 5, 6]. In particular pancreatic diseases as, e.g., pancreatic cancer and chronic pancreatitis are characterized by profound alterations of ECM formation and composition. The following review summarizes some of the major aspects that have emerged in the recent years concerning composition, formation and regulation of the ECM in human pancreatic diseases and in experimental models of pancreatic fibrosis.

Inflammation-Induced NFATc1–STAT3 Transcription Complex Promotes Pancreatic Cancer Initiation by KrasG12D

UNLABELLED Cancer-associated inflammation is a molecular key feature in pancreatic ductal adenocarcinoma. Oncogenic KRAS in conjunction with persistent inflammation is known to accelerate carcinogenesis, although the underlying mechanisms remain poorly understood. Here, we outline a novel pathway whereby the transcription factors NFATc1 and STAT3 cooperate in pancreatic epithelial cells to promote Kras(G12D)-driven carcinogenesis. NFATc1 activation is induced by inflammation and itself accelerates inflammation-induced carcinogenesis in Kras(G12D) mice, whereas genetic or pharmacologic ablation of NFATc1 attenuates this effect. Mechanistically, NFATc1 complexes with STAT3 for enhancer-promoter communications at jointly regulated genes involved in oncogenesis, for example, Cyclin, EGFR and WNT family members. The NFATc1-STAT3 cooperativity is operative in pancreatitis-mediated carcinogenesis as well as in established human pancreatic cancer. Together, these studies unravel new mechanisms of inflammatory-driven pancreatic carcinogenesis and suggest beneficial effects of chemopreventive strategies using drugs that are currently available for targeting these factors in clinical trials. SIGNIFICANCE Our study points to the existence of an oncogenic NFATc1-STAT3 cooperativity that mechanistically links inflammation with pancreatic cancer initiation and progression. Because NFATc1-STAT3 nucleoprotein complexes control the expression of gene networks at the intersection of inflammation and cancer, our study has significant relevance for potentially managing pancreatic cancer and other inflammatory-driven malignancies.

nab-Paclitaxel: novel clinical and experimental evidence in pancreatic cancer.

The past few decades have seen virtually no treatment advances for patients with metastatic pancreatic cancer. Clinical hallmark features of pancreatic ductal adenocarcinoma (PDA) include late symptom onset, invasive growth, early liver and lymph node metastasis, and resistance to available chemotherapies. nab-Paclitaxel (Abraxane®) is generated through high-pressure homogenization of human albumin and conventional paclitaxel resulting in non-covalently bound, water-soluble albumin-paclitaxel particles with an approximate diameter of 130 nm. Results from the recently completed Metastatic Pancreatic Adenocarcinoma Trial (MPACT) (phase III trial) showed a significant survival benefit for patients treated with nab-paclitaxel in combination with gemcitabine, and this treatment regimen is currently being implemented in national and international guidelines for PDA patients. Therefore, this regimen provides a much needed vantage point of attack for this recalcitrant tumor offering potential new hope for our patients. Mechanisms such as stromal depletion, selective intratumoral accumulation, synergism with gemcitabine metabolism and secreted protein acidic and rich in cysteine (SPARC) mediated anti-tumor activity have been suggested for nab-paclitaxel. This review discusses the clinical and experimental advances of nab-paclitaxel in pancreatic cancer.

Fibroblast drug scavenging increases intratumoural gemcitabine accumulation in murine pancreas cancer

Objective Desmoplasia and hypovascularity are thought to impede drug delivery in pancreatic ductal adenocarcinoma (PDAC). However, stromal depletion approaches have failed to show clinical responses in patients. Here, we aimed to revisit the role of the tumour microenvironment as a physical barrier for gemcitabine delivery. Design Gemcitabine metabolites were analysed in LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) murine tumours and matched liver metastases, primary tumour cell lines, cancer-associated fibroblasts (CAFs) and pancreatic stellate cells (PSCs) by liquid chromatography-mass spectrometry/mass spectrometry. Functional and preclinical experiments, as well as expression analysis of stromal markers and gemcitabine metabolism pathways were performed in murine and human specimen to investigate the preclinical implications and the mechanism of gemcitabine accumulation. Results Gemcitabine accumulation was significantly enhanced in fibroblast-rich tumours compared with liver metastases and normal liver. In vitro, significantly increased concentrations of activated 2′,2′-difluorodeoxycytidine-5′-triphosphate (dFdCTP) and greatly reduced amounts of the inactive gemcitabine metabolite 2′,2′-difluorodeoxyuridine were detected in PSCs and CAFs. Mechanistically, key metabolic enzymes involved in gemcitabine inactivation such as hydrolytic cytosolic 5′-nucleotidases (Nt5c1A, Nt5c3) were expressed at low levels in CAFs in vitro and in vivo, and recombinant expression of Nt5c1A resulted in decreased intracellular dFdCTP concentrations in vitro. Moreover, gemcitabine treatment in KPC mice reduced the number of liver metastases by >50%. Conclusions Our findings suggest that fibroblast drug scavenging may contribute to the clinical failure of gemcitabine in desmoplastic PDAC. Metabolic targeting of CAFs may thus be a promising strategy to enhance the antiproliferative effects of gemcitabine.

NFATc4 Regulates Sox9 Gene Expression in Acinar Cell Plasticity and Pancreatic Cancer Initiation

Acinar transdifferentiation toward a duct-like phenotype constitutes the defining response of acinar cells to external stress signals and is considered to be the initial step in pancreatic carcinogenesis. Despite the requirement for oncogenic Kras in pancreatic cancer (PDAC) development, oncogenic Kras is not sufficient to drive pancreatic carcinogenesis beyond the level of premalignancy. Instead, secondary events, such as inflammation-induced signaling activation of the epidermal growth factor (EGFR) or induction of Sox9 expression, are required for tumor formation. Herein, we aimed to dissect the mechanism that links EGFR signaling to Sox9 gene expression during acinar-to-ductal metaplasia in pancreatic tissue adaptation and PDAC initiation. We show that the inflammatory transcription factor NFATc4 is highly induced and localizes in the nucleus in response to inflammation-induced EGFR signaling. Moreover, we demonstrate that NFATc4 drives acinar-to-ductal conversion and PDAC initiation through direct transcriptional induction of Sox9. Therefore, strategies designed to disrupt NFATc4 induction might be beneficial in the prevention or therapy of PDAC.

Krüppel-like Transcription Factor KLF10 Suppresses TGFβ-Induced Epithelial-to-Mesenchymal Transition via a Negative Feedback Mechanism

TGFβ-SMAD signaling exerts a contextual effect that suppresses malignant growth early in epithelial tumorigenesis but promotes metastasis at later stages. Longstanding challenges in resolving this functional dichotomy may uncover new strategies to treat advanced carcinomas. The Krüppel-like transcription factor, KLF10, is a pivotal effector of TGFβ/SMAD signaling that mediates antiproliferative effects of TGFβ. In this study, we show how KLF10 opposes the prometastatic effects of TGFβ by limiting its ability to induce epithelial-to-mesenchymal transition (EMT). KLF10 depletion accentuated induction of EMT as assessed by multiple metrics. KLF10 occupied GC-rich sequences in the promoter region of the EMT-promoting transcription factor SLUG/SNAI2, repressing its transcription by recruiting HDAC1 and licensing the removal of activating histone acetylation marks. In clinical specimens of lung adenocarcinoma, low KLF10 expression associated with decreased patient survival, consistent with a pivotal role for KLF10 in distinguishing the antiproliferative versus prometastatic functions of TGFβ. Our results establish that KLF10 functions to suppress TGFβ-induced EMT, establishing a molecular basis for the dichotomy of TGFβ function during tumor progression. Cancer Res; 77(9); 2387-400. ©2017 AACR.

GSK-3β Governs Inflammation-Induced NFATc2 Signaling Hubs to Promote Pancreatic Cancer Progression

We aimed to investigate the mechanistic, functional, and therapeutic role of glycogen synthase kinase 3β (GSK-3β) in the regulation and activation of the proinflammatory oncogenic transcription factor nuclear factor of activated T cells (NFATc2) in pancreatic cancer. IHC, qPCR, immunoblotting, immunofluorescence microscopy, and proliferation assays were used to analyze mouse and human tissues and cell lines. Protein–protein interactions and promoter regulation were analyzed by coimmunoprecipitation, DNA pulldown, reporter, and ChIP assays. Preclinical assays were performed using a variety of pancreatic cancer cells lines, xenografts, and a genetically engineered mouse model (GEMM). GSK-3β–dependent SP2 phosphorylation mediates NFATc2 protein stability in the nucleus of pancreatic cancer cells stimulating pancreatic cancer growth. In addition to protein stabilization, GSK-3β also maintains NFATc2 activation through a distinct mechanism involving stabilization of NFATc2–STAT3 complexes independent of SP2 phosphorylation. For NFATc2–STAT3 complex formation, GSK-3β–mediated phosphorylation of STAT3 at Y705 is required to stimulate euchromatin formation of NFAT target promoters, such as cyclin-dependent kinase-6, which promotes tumor growth. Finally, preclinical experiments suggest that targeting the NFATc2–STAT3–GSK-3β module inhibits proliferation and tumor growth and interferes with inflammation-induced pancreatic cancer progression in KrasG12D mice. In conclusion, we describe a novel mechanism by which GSK-3β fine-tunes NFATc2 and STAT3 transcriptional networks to integrate upstream signaling events that govern pancreatic cancer progression and growth. Furthermore, the therapeutic potential of GSK-3β is demonstrated for the first time in a relevant Kras and inflammation-induced GEMM for pancreatic cancer. Mol Cancer Ther; 15(3); 491–502. ©2016 AACR.

Nuclear Factor of Activated T Cells-dependent Down-regulation of the Transcription Factor Glioma-associated Protein 1 (GLI1) Underlies the Growth Inhibitory Properties of Arachidonic Acid.

Numerous reports have demonstrated a tumor inhibitory effect of polyunsaturated fatty acids (PUFAs). However, the molecular mechanisms modulating this phenomenon are in part poorly understood. Here, we provide evidence of a novel antitumoral mechanism of the PUFA arachidonic acid (AA). In vivo and in vitro experiments showed that AA treatment decreased tumor growth and metastasis and increased apoptosis. Molecular analysis of this effect showed significantly reduced expression of a subset of antiapoptotic proteins, including BCL2, BFL1/A1, and 4-1BB, in AA-treated cells. We demonstrated that down-regulation of the transcription factor glioma-associated protein 1 (GLI1) in AA-treated cells is the underlying mechanism controlling BCL2, BFL1/A1, and 4-1BB expression. Using luciferase reporters, chromatin immunoprecipitation, and expression studies, we found that GLI1 binds to the promoter of these antiapoptotic molecules and regulates their expression and promoter activity. We provide evidence that AA-induced apoptosis and down-regulation of antiapoptotic genes can be inhibited by overexpressing GLI1 in AA-sensitive cells. Conversely, inhibition of GLI1 mimics AA treatments, leading to decreased tumor growth, cell viability, and expression of antiapoptotic molecules. Further characterization showed that AA represses GLI1 expression by stimulating nuclear translocation of NFATc1, which then binds the GLI1 promoter and represses its transcription. AA was shown to increase reactive oxygen species. Treatment with antioxidants impaired the AA-induced apoptosis and down-regulation of GLI1 and NFATc1 activation, indicating that NFATc1 activation and GLI1 repression require the generation of reactive oxygen species. Collectively, these results define a novel mechanism underlying AA antitumoral functions that may serve as a foundation for future PUFA-based therapeutic approaches.

Context-Dependent Epigenetic Regulation of Nuclear Factor of Activated T Cells 1 in Pancreatic Plasticity

BACKGROUND & AIMS The ability of exocrine pancreatic cells to change the cellular phenotype is required for tissue regeneration upon injury, but also contributes to their malignant transformation and tumor progression. We investigated context-dependent signaling and transcription mechanisms that determine pancreatic cell fate decisions toward regeneration and malignancy. In particular, we studied the function and regulation of the inflammatory transcription factor nuclear factor of activated T cells 1 (NFATC1) in pancreatic cell plasticity and tissue adaptation. METHODS We analyzed cell plasticity during pancreatic regeneration and transformation in mice with pancreas-specific expression of a constitutively active form of NFATC1, or depletion of enhancer of zeste 2 homologue 2 (EZH2), in the context of wild-type or constitutively activate Kras, respectively. Acute and chronic pancreatitis were induced by intraperitoneal injection of caerulein. EZH2-dependent regulation of NFATC1 expression was studied in mouse in human pancreatic tissue and cells by immunohistochemistry, immunoblotting, and quantitative reverse transcription polymerase chain reaction. We used genetic and pharmacologic approaches of EZH2 and NFATC1 inhibition to study the consequences of pathway disruption on pancreatic morphology and function. Epigenetic modifications on the NFATC1 gene were investigated by chromatin immunoprecipitation assays. RESULTS NFATC1 was rapidly and transiently induced in early adaptation to acinar cell injury in human samples and in mice, where it promoted acinar cell transdifferentiation and blocked proliferation of metaplastic pancreatic cells. However, in late stages of regeneration, Nfatc1 was epigenetically silenced by EZH2-dependent histone methylation, to enable acinar cell redifferentiation and prevent organ atrophy and exocrine insufficiency. In contrast, oncogenic activation of KRAS signaling in pancreatic ductal adenocarcinoma cells reversed the EZH2-dependent effects on the NFATC1 gene and was required for EZH2-mediated transcriptional activation of NFATC1. CONCLUSIONS In studies of human and mouse pancreatic cells and tissue, we identified context-specific epigenetic regulation of NFATc1 activity as an important mechanism of pancreatic cell plasticity. Inhibitors of EZH2 might therefore interfere with oncogenic activity of NFATC1 and be used in treatment of pancreatic ductal adenocarcinoma.