Ring1b-dependent epigenetic remodelling is an essential prerequisite for pancreatic carcinogenesis

BACKGROUND AND AIMS Besides well-defined genetic alterations, the dedifferentiation of mature acinar cells is an important prerequisite for pancreatic carcinogenesis. Acinar-specific genes controlling cell homeostasis are extensively downregulated during cancer development; however, the underlying mechanisms are poorly understood. Now, we devised a novel in vitro strategy to determine genome-wide dynamics in the epigenetic landscape in pancreatic carcinogenesis. DESIGN With our in vitro carcinogenic sequence, we performed global gene expression analysis and ChIP sequencing for the histone modifications H3K4me3, H3K27me3 and H2AK119ub. Followed by a comprehensive bioinformatic approach, we captured gene clusters with extensive epigenetic and transcriptional remodelling. Relevance of Ring1b-catalysed H2AK119ub in acinar cell reprogramming was studied in an inducible Ring1b knockout mouse model. CRISPR/Cas9-mediated Ring1b ablation as well as drug-induced Ring1b inhibition were functionally characterised in pancreatic cancer cells. RESULTS The epigenome is vigorously modified during pancreatic carcinogenesis, defining cellular identity. Particularly, regulatory acinar cell transcription factors are epigenetically silenced by the Ring1b-catalysed histone modification H2AK119ub in acinar-to-ductal metaplasia and pancreatic cancer cells. Ring1b knockout mice showed greatly impaired acinar cell dedifferentiation and pancreatic tumour formation due to a retained expression of acinar differentiation genes. Depletion or drug-induced inhibition of Ring1b promoted tumour cell reprogramming towards a less aggressive phenotype. CONCLUSIONS Our data provide substantial evidence that the epigenetic silencing of acinar cell fate genes is a mandatory event in the development and progression of pancreatic cancer. Targeting the epigenetic repressor Ring1b could offer new therapeutic options

Glycemic Variability Promotes Both Local Invasion and Metastatic Colonization by Pancreatic Ductal Adenocarcinoma

Background & Aims: Although nearly half of pancreatic ductal adenocarcinoma (PDAC) patients have diabetes mellitus with episodes of hyperglycemia, its tumor microenvironment is hypoglycemic. Thus, it is crucial for PDAC cells to develop adaptive mechanisms dealing with oscillating glucose levels. So far, the biological impact of such glycemic variability on PDAC biology remains unknown. Methods: Murine PDAC cells were cultured in low- and high-glucose medium to investigate the molecular, biochemical, and metabolic influence of glycemic variability on tumor behavior. A set of in vivo functional assays including orthotopic implantation and portal and tail vein injection were used. Results were further confirmed on tissues from PDAC patients. Results: Glycemic variability has no significant effect on PDAC cell proliferation. Hypoglycemia is associated with local invasion and angiogenesis, whereas hyperglycemia promotes metastatic colonization. Increased metastatic colonization under hyperglycemia is due to increased expression of runt related transcription factor 3 (Runx3), which further activates expression of collagen, type VI, alpha 1 (Col6a1), forming a glycemic pro-metastatic pathway. Through epigenetic machinery, retinoic acid receptor beta (Rarb) expression fluctuates according to glycemic variability, acting as a critical sensor relaying the glycemic signal to Runx3/Col6a1. Moreover, the signal axis of Rarb/Runx3/Col6a1 is pharmaceutically accessible to a widely used antidiabetic substance, metformin, and Rar modulator. Finally, PDAC tissues from patients with diabetes show an increased expression of COL6A1. Conclusions: Glycemic variability promotes both local invasion and metastatic colonization of PDAC. A pro-metastatic signal axis Rarb/Runx3/Col6a1 whose activity is controlled by glycemic variability is identified. The therapeutic relevance of this pathway needs to be explored in PDAC patients, especially in those with diabetes

Syndecan-2 promotes perineural invasion and cooperates with K-ras to induce an invasive pancreatic cancer cell phenotype

Abstract Background We have identified syndecan-2 as a protein potentially involved in perineural invasion of pancreatic adenocarcinoma (PDAC) cells. Methods Syndecan-2 (SDC-2) expression was analyzed in human normal pancreas, chronic pancreatitis and PDAC tissues. Functional in vitro assays were carried out to determine its role in invasion, migration and signaling. Results SDC-2 was expressed in the majority of the tested pancreatic cancer cell lines while it was upregulated in nerve-invasive PDAC cell clones. There were 2 distinct expression patterns of SDC-2 in PDAC tissue samples: SDC-2 positivity in the cancer cell cytoplasm and a peritumoral expression. Though SDC-2 silencing (using specific siRNA oligonucleotides) did not affect anchorage-dependent growth, it significantly reduced cell motility and invasiveness in the pancreatic cancer cell lines T3M4 and Su8686. On the transcriptional level, migration-and invasion-associated genes were down-regulated following SDC-2 RNAi. Furthermore, SDC-2 silencing reduced K-ras activity, phosphorylation of Src and - further downstream - phosphorylation of ERK2 while levels of the putative SDC-2 signal transducer p120GAP remained unaltered. Conclusion SDC-2 is a novel (perineural) invasion-associated gene in PDAC which cooperates with K-ras to induce a more invasive phenotype.</p

Sca-1 is a marker for cell plasticity in murine pancreatic epithelial cells and induced by IFN-β in vitro

BACKGROUND & AIMS: Sca-1 is a surface marker for murine hematopoietic stem cells (HSCs) and type-I interferon is a key regulator for Lin$^{-}$Sca-1$^{+}$ HSCs expansion through Ifnar/Stat-1/Sca-1-signaling. In this study we aimed to characterize the role and regulation of Sca-1$^{+}$ cells in pancreatic regeneration. METHODS: To characterize Sca-1 in vivo, immunohistochemistry and immunofluorescence staining of Sca-1 was conducted in normal pancreas, in cerulein-mediated acute pancreatitis, and in Kras-triggered cancerous lesions. Ifnar/Stat-1/Sca-1-signaling was studied in type-I IFN-treated epithelial explants of adult wildtype, Ifnar$^{-}$$^{/-}$, and Stat-1$^{-}$$^{/}$$^{-}$ mice. Sca-1 induction was analyzed by gene expression and FACS analysis. After isolation of pancreatic epithelial Lin$^{-}$Sca-1$^{+}$cells, pancreatosphere-formation and immunofluorescence-assays were carried out to investigate self-renewal and differentiation capabilities. RESULTS: Sca-1$^{+}$ cells were located in periacinar and periductal spaces and showed an enrichment during cerulein-induced acute pancreatitis (23.2/100 μm$^{2}$ ± 4.9 SEM) and in early inflammation-mediated carcinogenic lesions of the pancreas of Kras$^{G12D}$ mice (35.8/100 μm$^{2}$ ± SEM 1.9) compared to controls (3.6/100 μm$^{2}$ ± 1.3 SEM). Pancreatic Lin$^{-}$Sca-1$^{+}$ cells displayed a small population of 1.46% ± 0.12 SEM in FACS. In IFN-β treated pancreatic epithelial explants, Sca-1 expression was increased, and Lin$^{-}$Sca-1$^{+}$ cells were enriched in vitro (from 1.49% ± 0.36 SEM to 3.85% ± 0.78 SEM). Lin$^{-}$Sca-1$^{+}$ cells showed a 12 to 51-fold higher capacity for clonal self-renewal compared to Lin$^{-}$Sca-1$^{-}$ cells and generated cells express markers of the acinar and ductal compartment. CONCLUSIONS: Pancreatic Sca-1$^{+}$ cells enriched during parenchymal damage showed a significant capacity for cell renewal and in vitro plasticity, suggesting that corresponding to the type I interferon-dependent regulation of Lin$^{-}$Sca-1$^{+}$ hematopoietic stem cells, pancreatic Sca-1$^{+}$ cells also employ type-I-interferon for regulating progenitor-cell-homeostasis

Metabolism gene signatures and surgical site infections in abdominal surgery

Introduction: Surgical site infections (SSI) represent a significant cause of morbidity in abdominal surgery. The objective of this study was to determine the gene expression signature in subcutaneous tissues in relation to SSI. Methods: To determine differences in gene expression, microarray analysis were performed from bulk tissue mRNA of subcutaneous tissues prospectively collected in 92 patients during open abdominal surgery. 10 patients (11%) developed incisional (superficial and deep) SSI. Results: Preoperative risk factors in patients with SSI were not significantly different from those in patients without wound infections. 1025 genes were differentially expressed between the groups, of which the AZGP1 and ALDH1A3 genes were the highest down- and upregulated ones. Hierarchical clustering demonstrated strong similarity within the respective groups (SSI vs. no-SSI) indicating inter-group distinctness. In a functional classification, genes controlling cell metabolism were mostly downregulated in subcutaneous tissues of patients that subsequently developed SSI. Conclusion: Altered expression of metabolism genes in subcutaneous tissues might constitute a risk factor for postoperative abdominal SSI

Pancreatic inflammation after caerulein- induced injury is limited in Ifnar^del mice.

<p>(A) Representative H&E staining of the pancreas from WT and Ifnar^del mice, 24 and 48 hours following caerulein-induced injury (original magnification, 100x). (B) Representative H&E staining of the pancreas from WT and Ifnar^del mice, 3, 7 and 14 days following caerulein-induced injury (original magnification, 100x). (C-E) Combined and individual scoring of pancreatic histological parameters from WT and Ifnar^del mice, 24, 48 hours, 3, 5, 7 and 14 days following caerulein-induced injury (n = 3–9 per group. Bars indicate mean +/- SD. *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001, Mann-Whitney-test).</p