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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6
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Publication Open Access DNA methylation profiling identifies novel markers of progression in hepatitis B-related chronic liver disease(BioMed Central, 2016) Vatansever, Sezgin; Hardy, Timothy; Sarı, Aysegül Akder; Çakalağaoğlu, Fulya; Avcı, Arzu; Zeybel, Gemma Louise; Bashton, Matthew; Mathers, John C.; Ünsal, Belkis; Mann, Jelena; N/A; Department of Molecular Biology and Genetics; Zeybel, Müjdat; Karahüseyinoğlu, Serçin; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; School of Medicine; 214694; 110772Background: Chronic hepatitis B infection is characterized by hepatic immune and inflammatory response with considerable variation in the rates of progression to cirrhosis. Genetic variants and environmental cues influence predisposition to the development of chronic liver disease; however, it remains unknown if aberrant DNA methylation is associated with fibrosis progression in chronic hepatitis B. Results: To identify epigenetic marks associated with inflammatory and fibrotic processes of the hepatitis B-induced chronic liver disease, we carried out hepatic genome-wide methylation profiling using Illumina Infinium beadarrays comparing mild and severe fibrotic disease in a discovery cohort of 29 patients. We obtained 310 differentially methylated regions and selected four loci comprising three genes from the top differentially methylated regions: hypermethylation of HOXA2 and HDAC4 along with hypomethylation of PPP1R18 were significantly linked to severe fibrosis. We replicated the prominent methylation marks in an independent cohort of 102 patients by bisulfite modification and pyrosequencing. The timing and causal relationship of epigenetic modifications with disease severity was further investigated using a cohort of patients with serial biopsies. Conclusions: Our findings suggest a linkage of widespread epigenetic dysregulation with disease progression in chronic hepatitis B infection. Cpg methylation at novel genes sheds light on new molecular pathways, which can be potentially exploited as a biomarker or targeted to attenuate inflammation and fibrosis.Publication Open Access Pancreas-specific activation of mTOR and loss of p53 induce tumors reminiscent of acinar cell carcinoma(BioMed Central, 2016) Kong, Bo; Cheng Tao; Qian, Chengjia; Wu, Weiwei; Steiger, Katja; Cao, Jing; Schlitter, Anna Melissa; Regel, Ivonne; Raulefs, Susanne; Friess, Helmut; Esposito, Irene; Kleeff, Joerg; Michalski, Christoph W.; N/A; Erkan, Murat Mert; Faculty Member; School of Medicine; 214689Background: Pancreatic acinar cell carcinoma (ACC) is a rare tumor entity with an unfavorable prognosis. Recent whole-exome sequencing identified p53 mutations in a subset of human ACC. Activation of the mammalian target of rapamycin (mTOR) pathway is associated with various pancreatic neoplasms. We thus aimed at analyzing whether activation of mTOR with a concomitant loss of p53 may initiate ACC. Methods: We generated transgenic mouse models in which mTOR was hyperactivated through pancreas-specific, homozygous tuberous sclerosis 1 (Tsc1) deficiency, with or without deletion of p53 (Tsc1(-/-) and Tsc1(-/-); p53(-/-)). Activity of mTOR signaling was investigated using mouse tissues and isolated murine cell lines. Human ACC specimens were used to corroborate the findings from the transgenic mouse models. Results: Hyperactive mTOR signaling in Tsc1(-/-) mice was not oncogenic but rather induced a near-complete loss of the pancreatic acinar compartment. Acinar cells were lost as a result of apoptosis which was associated with p53 activation. Concomitantly, ductal cells were enriched. Ablation of p53 in Tsc1-deficient mice prevented acinar cell death but promoted formation of acinar cells with severe nuclear abnormalities. One out of seven Tsc1(-/-); p53(-/-) animals developed pancreatic tumors showing a distinctive tumor morphology, reminiscent of human ACC. Hyperactive mTOR signaling was also detected in a subset of human ACC. Conclusion: Hyperactive mTOR signaling combined with loss of p53 in mice induces tumors similar to human ACC.Publication Open Access Molecular response to combined molecular- and external radiotherapy in head and neck squamous cell carcinoma (HNSCC)(Multidisciplinary Digital Publishing Institute (MDPI), 2021) Rassamegevanon, Treewut; Feindt, Louis; Koi, Lydia; Müller, Johannes; Freudenberg, Robert; Löck, Steffen; Sihver, Wiebke; Kühn, Ariane Christel; Von Neubeck, Cläre; Linge, Annett; Pietzsch, Hans-Jürgen; Kotzerke, Jörg; Baumann, Michael; Krause, Mechthild; Dietrich, Antje; Çevik, Enes; School of MedicineCombination treatment of molecular targeted and external radiotherapy is a promising strategy and was shown to improve local tumor control in a HNSCC xenograft model. To enhance the therapeutic value of this approach, this study investigated the underlying molecular response. Subcutaneous HNSCC FaDuDD xenografts were treated with single or combination therapy (X-ray: 0, 2, 4 Gy; anti-EGFR antibody (Cetuximab) (un-)labeled with Yttrium-90 (90Y)). Tumors were excised 24 h post respective treatment. Residual DNA double strand breaks (DSB), mRNA expression of DNA damage response related genes, immunoblotting, tumor histology, and immunohistological staining were analyzed. An increase in number and complexity of residual DNA DSB was observed in FaDuDD tumors exposed to the combination treatment of external irradiation and90Y-Cetuximab relative to controls. The increase was observed in a low oxygenated area, suggesting the expansion of DNA DSB damages. Upregulation of genes encoding p21cip1/waf1 (CDKN1A) and GADD45? (GADD45A) was determined in the combination treatment group, and immunoblotting as well as immunohistochemistry confirmed the upregulation of p21cip1/waf1. The increase in residual H2AX foci leads to the blockage of cell cycle transition and subsequently to cell death, which could be observed in the upregulation of p21cip1/waf1 expression and an elevated number of cleaved caspase-3 positive cells. Overall, a complex interplay between DNA damage repair and programmed cell death accounts for the potential benefit of the combination therapy using90Y-Cetuximab and external radiotherapy.Publication Open Access Hypoxia-induced endoplasmic reticulum stress characterizes a necrotic phenotype of pancreatic cancer(Impact Journals, 2015) Kong, Bo; Cheng, Tao; Wu, Weiwei; Regel, Ivonne; Raulefs, Susanne; Friess, Helmut; Esposito, Irene; Kleeff, Joerg; Michalski, Christoph W.; N/A; Erkan, Murat Mert; Faculty Member; School of Medicine; 214689Stromal fibrosis and tissue necrosis are major histological sequelae of hypoxia. The hypoxia-to-fibrosis sequence is well-documented in pancreatic ductal adenocarcinoma (PDAC). However, hypoxic and necrotic PDAC phenotypes are insufficiently characterized. Recently, reduction of tuberous sclerosis expression in mice together with oncogenic Kras demonstrated a rapidly metastasizing phenotype with histologically eccentric necrosis, transitional hypoxia and devascularisation. We established cell lines from these tumors and transplanted them orthotopically into wild-type mice to test their abilities to recapitulate the histological features of the primary lesions. Notably, the necrotic phenotype was reproduced by only a subset of cell lines while others gave rise to dedifferentiated tumors with significantly reduced necrosis. In vitro analysis of the necrotic tumor-inducing cell lines revealed that these cells released a significant amount of vascular endothelial growth factor A (Vegfa). However, its release was not further increased under hypoxic conditions. Defective hypoxia-induced Vegfa secretion was not due to impaired Vegfa transcription or hypoxia-inducible factor 1-alpha activation, but rather a result of hypoxia-induced endoplasmic reticulum (ER) stress. We thus identified hypoxia-induced ER stress as an important pathway in PDACs with tissue necrosis and rapid metastasis.