@article{vonRahdenKircherLazariotouetal.2011,
  author    = {von Rahden, Burkhard H. A. and Kircher, Stefan and Lazariotou, Maria and Reiber, Christoph and Stuermer, Luisa and Otto, Christoph and Germer, Christoph T. and Grimm, Martin},
  title     = {LgR5 expression and cancer stem cell hypothesis: clue to define the true origin of esophageal adenocarcinomas with and without Barrett's Esophagus?},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68810},
  year      = {2011},
  abstract  = {Background: Investigation of the expression of an intestinal stem cell marker in esophageal adenocarcinomas (EAC) with and without Barrett's Esophagus (BE), with respect to a cancer stem cell (CSC) hypothesis. Materials and methods: Expression of a putative intestinal stem cell marker LgR5 was analyzed in esophageal cancer specimen (n = 70: 41 EAC with BE, 19 EAC without BE, and n = 10 esophageal squamous-cell carcinomas, ESCC) and in the adenocarcinoma cell line OE-33. Ki-67 and Cdx-2 were co-labelled with LgR5 in double staining experiments. Immunhistochemical expression results were confirmed by RT-PCR and correlated with tumor stage and five-year survival rates. Results: LgR5was found expressed in 35 of 41 (85\%) EAC with BE and in 16 of 19 (81\%) EAC without BE. By contrast, LgR5 was not found to be expressed in ESCC. Quantification of immunolabeling showed 15\% LgR5+ cells in EAC with BE, 32\% LgR5+ cells in adjacent BE and 13\% in EAC without BE. Immunofluorescence double staining experiments with LgR5 and Ki-67 revealed a subpopulation (~5\%) of proliferating LgR+/Ki-67+ cells. On mRNAlevel, expression of LgR5 was higher in BE in comparison to EAC (p = 0.0159). High levels of LgR5 expression in BE associated EAC were associated with poorer survival in univariate analysis. Conclusion: The stem cell marker LgR5 is expressed in EAC, irrespective of association with BE, and appears to have negative impact on survival. The subset of proliferating LgR5+ cells (<5\%) might resemble rapidly cycling CSCs, which needs to be substantiated in further investigations.},
  subject      = {Medizin},
  language  = {en}
}
@article{KlingelhoefferKaemmererKoospaletal.2012,
  author    = {Klingelhoeffer, Chr{\´i}stoph and K{\"a}mmerer, Ulrike and Koospal, Monika and M{\"u}hling, Bettina and Schneider, Manuela and Kapp, Michaela and K{\"u}bler, Alexander, and Germer, Christoph-Thomas and Otto, Christoph},
  title     = {Natural resistance to ascorbic acid induced oxidative stress is mainly mediated by catalase activity in human cancer cells and catalase-silencing sensitizes to oxidative stress},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75142},
  year      = {2012},
  abstract  = {Background: Ascorbic acid demonstrates a cytotoxic effect by generating hydrogen peroxide, a reactive oxygen species (ROS) involved in oxidative cell stress. A panel of eleven human cancer cell lines, glioblastoma and carcinoma, were exposed to serial dilutions of ascorbic acid (5-100 mmol/L). The purpose of this study was to analyse the impact of catalase, an important hydrogen peroxide-detoxifying enzyme, on the resistance of cancer cells to ascorbic acid mediated oxidative stress. Methods: Effective concentration (EC50) values, which indicate the concentration of ascorbic acid that reduced the number of viable cells by 50\%, were detected with the crystal violet assay. The level of intracellular catalase protein and enzyme activity was determined. Expression of catalase was silenced by catalase-specific short hairpin RNA (sh-RNA) in BT-20 breast carcinoma cells. Oxidative cell stress induced apoptosis was measured by a caspase luminescent assay. Results: The tested human cancer cell lines demonstrated obvious differences in their resistance to ascorbic acid mediated oxidative cell stress. Forty-five percent of the cell lines had an EC50>20 mmol/L and fifty-five percent had an EC50<20 mmol/L. With an EC50 of 2.6-5.5 mmol/L, glioblastoma cells were the most susceptible cancer cell lines analysed in this study. A correlation between catalase activity and the susceptibility to ascorbic acid was observed. To study the possible protective role of catalase on the resistance of cancer cells to oxidative cell stress, the expression of catalase in the breast carcinoma cell line BT-20, which cells were highly resistant to the exposure to ascorbic acid (EC50: 94,9 mmol/L), was silenced with specific sh-RNA. The effect was that catalase-silenced BT-20 cells (BT-20 KD-CAT) became more susceptible to high concentrations of ascorbic acid (50 and 100 mmol/L). Conclusions: Fifty-five percent of the human cancer cell lines tested were unable to protect themselves against oxidative stress mediated by ascorbic acid induced hydrogen peroxide production. The antioxidative enzyme catalase is important to protect cancer cells against cytotoxic hydrogen peroxide. Silenced catalase expression increased the susceptibility of the formerly resistant cancer cell line BT-20 to oxidative stress.},
  subject      = {Medizin},
  language  = {en}
}
@article{GrimmLazariotouKircheretal.2010,
  author    = {Grimm, Martin and Lazariotou, Maria and Kircher, Stefan and Stuermer, Luisa and Reiber, Christoph and Hoefelmayr, Andreas and Gattenloehner, Stefan and Otto, Christoph and Germer, Christoph T. and von Rahden, Burkhard H. A.},
  title     = {MMP-1 is a (pre-)invasive factor in Barrett-associated esophageal adenocarcinomas and is associated with positive lymph node status},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68293},
  year      = {2010},
  abstract  = {Background: Esophageal adenocarcinomas (EACs) arise due to gastroesophageal reflux, with Barrett's esophagus (BE) regarded as precancerous lesion. Matrix metalloproteinases (MMPs) might play a role during the multistep carcinogenetic process. Methods: Expression of MMP-1 and -13 was analyzed in esophageal cancer (n = 41 EAC with BE, n = 19 EAC without BE, and n = 10 esophageal squamous-cell carcinomas, ESCC), furthermore in BE without intraepithelial neoplasia (IN) (n = 18), and the cell line OE-33. MMP-1 was co-labelled with Ki-67 (proliferation), Cdx-2 (marker for intestinal metaplasia, BE) and analyzed on mRNA level. MMP-1 staining results were correlated with clinicopatholocical parameters. Results: On protein level, MMP-1 expression was found in 39 of 41 (95\%) EAC with BE, in 19 of 19 (100\%) EAC without BE, in 6 of 10 (60\%) ESCC, and in 10 of 18 (56\%) BE without IN. No expression of MMP-13 was found in these specimens. Quantification showed 48\% MMP-1 positive cells in EAC with BE, compared to 35\% in adjacent BE (p < 0.05), 44\% in EAC without BE, 32\% in ESCC, and 4\% in BE without IN. Immunofluorescence double staining experiments revealed increased MMP-1 expressing in proliferating cells (MMP-1+/Ki-67+) (r = 0.943 for BE and r = 0.811 for EAC). On mRNA-level, expression of MMP-1 was significantly higher in EAC compared to BE (p = 0.01) and confirmed immunohistochemical staining results. High MMP-1 levels were associated with lymph node metastases but not with poorer survival (p = 0.307). Conclusions: Our findings suggest that MMP-1 plays a role as preinvasive factor in BE-associated EAC. Expression of MMP-1 in proliferating BE and EAC cells suggest malignant proliferation following the clonal expansion model.},
  subject      = {Medizin},
  language  = {en}
}
@article{vonRahdenKircherLazariotouetal.2011,
  author    = {von Rahden, Burkhard H.A. and Kircher, Stefan and Lazariotou, Maria and Reiber, Christoph and Stuermer, Luisa and Otto, Christoph and Germer, Christoph T. and Grimm, Martin},
  title     = {LgR5 expression and cancer stem cell hypothesis: clue to define the true origin of esophageal adenocarcinomas with and without Barrett's Esophagus?},
  series = {Journal of Experimental \& Clinical Cancer Research},
  volume    = {30},
  journal   = {Journal of Experimental \& Clinical Cancer Research},
  number    = {23},
  doi       = {10.1186/1756-9966-30-23},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-137783},
  year      = {2011},
  abstract  = {Background Investigation of the expression of an intestinal stem cell marker in esophageal adenocarcinomas (EAC) with and without Barrett's Esophagus (BE), with respect to a cancer stem cell (CSC) hypothesis. Materials and methods Expression of a putative intestinal stem cell marker LgR5 was analyzed in esophageal cancer specimen (n = 70: 41 EAC with BE, 19 EAC without BE, and n = 10 esophageal squamous-cell carcinomas, ESCC) and in the adenocarcinoma cell line OE-33. Ki-67 and Cdx-2 were co-labelled with LgR5 in double staining experiments. Immunhistochemical expression results were confirmed by RT-PCR and correlated with tumor stage and five-year survival rates. Results LgR5was found expressed in 35 of 41 (85\%) EAC with BE and in 16 of 19 (81\%) EAC without BE. By contrast, LgR5 was not found to be expressed in ESCC. Quantification of immunolabeling showed 15\% LgR5+ cells in EAC with BE, 32\% LgR5+ cells in adjacent BE and 13\% in EAC without BE. Immunofluorescence double staining experiments with LgR5 and Ki-67 revealed a subpopulation (~5\%) of proliferating LgR+/Ki-67+ cells. On mRNA-level, expression of LgR5 was higher in BE in comparison to EAC (p = 0.0159). High levels of LgR5 expression in BE associated EAC were associated with poorer survival in univariate analysis. Conclusion The stem cell marker LgR5 is expressed in EAC, irrespective of association with BE, and appears to have negative impact on survival. The subset of proliferating LgR5+ cells (<5\%) might resemble rapidly cycling CSCs, which needs to be substantiated in further investigations.},
  language  = {en}
}
@article{JurowichOttoRikkalaetal.2015,
  author    = {Jurowich, Christian Ferdinand and Otto, Christoph and Rikkala, Prashanth Reddy and Wagner, Nicole and Vrhovac, Ivana and Sabolić, Ivan and Germer, Christoph-Thomas and Koepsell, Hermann},
  title     = {Ileal interposition in rats with experimental type 2 like diabetes improves glycemic control independently of glucose absorption},
  series = {Journal of Diabetes Research},
  volume    = {2015},
  journal   = {Journal of Diabetes Research},
  number    = {490365},
  doi       = {10.1155/2015/490365},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149166},
  year      = {2015},
  abstract  = {Bariatric operations in obese patients with type 2 diabetes often improve diabetes before weight loss is observed. In patients mainly Roux-en-Y-gastric bypass with partial stomach resection is performed. Duodenojejunal bypass (DJB) and ileal interposition (IIP) are employed in animal experiments. Due to increased glucose exposition of L-cells located in distal ileum, all bariatric surgery procedures lead to higher secretion of antidiabetic glucagon like peptide-1 (GLP-1) after glucose gavage. After DJB also downregulation of Na\(^{+}\)-D-glucose cotransporter SGLT1 was observed. This suggested a direct contribution of decreased glucose absorption to the antidiabetic effect of bariatric surgery. To investigate whether glucose absorption is also decreased after IIP, we induced diabetes with decreased glucose tolerance and insulin sensitivity in male rats and investigated effects of IIP on diabetes and SGLT1. After IIP, we observed weight-independent improvement of glucose tolerance, increased insulin sensitivity, and increased plasma GLP-1 after glucose gavage. The interposed ileum was increased in diameter and showed increased length of villi, hyperplasia of the epithelial layer, and increased number of L-cells. The amount of SGLT1-mediated glucose uptake in interposed ileum was increased 2-fold reaching the same level as in jejunum. Thus, improvement of glycemic control by bariatric surgery does not require decreased glucose absorption.},
  language  = {en}
}
@article{OttoHahlbrockEichetal.2016,
  author    = {Otto, Christoph and Hahlbrock, Theresa and Eich, Kilian and Karaaslan, Ferdi and J{\"u}rgens, Constantin and Germer, Christoph-Thomas and Wiegering, Armin and K{\"a}mmerer, Ulrike},
  title     = {Antiproliferative and antimetabolic effects behind the anticancer property of fermented wheat germ extract},
  series = {BMC Complementary and Alternative Medicine},
  volume    = {16},
  journal   = {BMC Complementary and Alternative Medicine},
  number    = {160},
  doi       = {10.1186/s12906-016-1138-5},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-146013},
  year      = {2016},
  abstract  = {Background Fermented wheat germ extract (FWGE) sold under the trade name Avemar exhibits anticancer activity in vitro and in vivo. Its mechanisms of action are divided into antiproliferative and antimetabolic effects. Its influcence on cancer cell metabolism needs further investigation. One objective of this study, therefore, was to further elucidate the antimetabolic action of FWGE. The anticancer compound 2,6-dimethoxy-1,4-benzoquinone (DMBQ) is the major bioactive compound in FWGE and is probably responsible for its anticancer activity. The second objective of this study was to compare the antiproliferative properties in vitro of FWGE and the DMBQ compound. Methods The IC\(_{50}\) values of FWGE were determined for nine human cancer cell lines after 24 h of culture. The DMBQ compound was used at a concentration of 24 μmol/l, which is equal to the molar concentration of DMBQ in FWGE. Cell viability, cell cycle, cellular redox state, glucose consumption, lactic acid production, cellular ATP levels, and the NADH/NAD\(^+\) ratio were measured. Results The mean IC\(_{50}\) value of FWGE for the nine human cancer cell lines tested was 10 mg/ml. Both FWGE (10 mg/ml) and the DMBQ compound (24 μmol/l) induced massive cell damage within 24 h after starting treatment, with changes in the cellular redox state secondary to formation of intracellular reactive oxygen species. Unlike the DMBQ compound, which was only cytotoxic, FWGE exhibited cytostatic and growth delay effects in addition to cytotoxicity. Both cytostatic and growth delay effects were linked to impaired glucose utilization which influenced the cell cycle, cellular ATP levels, and the NADH/NAD\(^+\) ratio. The growth delay effect in response to FWGE treatment led to induction of autophagy. Conclusions FWGE and the DMBQ compound both induced oxidative stress-promoted cytotoxicity. In addition, FWGE exhibited cytostatic and growth delay effects associated with impaired glucose utilization which led to autophagy, a possible previously unknown mechanism behind the influence of FWGE on cancer cell metabolism.},
  language  = {en}
}
@article{WiegeringKorbThalheimeretal.2014,
  author    = {Wiegering, Armin and Korb, Doreen and Thalheimer, Andreas and K{\"a}mmerer, Ulrike and Allmanritter, Jan and Matthes, Niels and Linnebacher, Michael and Schlegel, Nicolas and Klein, Ingo and Erg{\"u}n, S{\"u}leyman and Germer, Christoph-Thomas and Otto, Christoph},
  title     = {E7080 (Lenvatinib), a Multi-Targeted Tyrosine Kinase Inhibitor, Demonstrates Antitumor Activities Against Colorectal Cancer Xenografts},
  doi       = {10.1016/j.neo.2014.09.008},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-111165},
  year      = {2014},
  abstract  = {Clinical prognosis of metastasized colorectal carcinoma (CRC) is still not at desired levels and novel drugs are needed. Here, we focused on the multi-tyrosine kinase inhibitor E7080 (Lenvatinib) and assessed its therapeutic efficacy against human CRC cell lines in vitro and human CRC xenografts in vivo. The effect of E7080 on cell viability was examined on 10 humanCRCcell lines and humanendothelial cells (HUVEC). The inhibitory effect of E7080 on VEGF-induced angiogenesis was studied in an ex vivo mouse aortic ring angiogenesis assay. In addition, the efficacy of E7080 against xenografts derived fromCRC cell lines and CRC patient resection specimenswithmutated KRASwas investigated in vivo. Arelatively low cytotoxic effect of E7080 on CRC cell viabilitywas observed in vitro. Endothelial cells (HUVEC)weremore susceptible to the incubation with E7080. This is in line with the observation that E7080 demonstrated an anti-angiogenic effect in a three-dimensional ex vivo mouse aortic ring angiogenesis assay. E7080 effectively disrupted CRC cell-mediated VEGF-stimulated growth of HUVEC in vitro. Daily in vivo treatment with E7080 (5 mg/kg) significantly delayed the growth of KRAS mutated CRC xenografts with decreased density of tumor-associated vessel formations and without tumor regression. This observation is in line with results that E7080 did not significantly reduce the number of Ki67-positive cells in CRC xenografts. The results suggest antiangiogenic activity of E7080 at a dosage thatwas well tolerated by nudemice. E7080 may provide therapeutic benefits in the treatment of CRC with mutated KRAS.},
  language  = {en}
}
@article{WiegeringPfannUtheetal.2013,
  author    = {Wiegering, Armin and Pfann, Christina and Uthe, Friedrich Wilhelm and Otto, Christoph and Rycak, Lukas and M{\"a}der, Uwe and Gasser, Martin and Waaga-Gasser, Anna-Maria and Eilers, Martin and Germer, Christoph-Thomas},
  title     = {CIP2A Influences Survival in Colon Cancer and Is Critical for Maintaining Myc Expression},
  series = {PLoS ONE},
  journal   = {PLoS ONE},
  doi       = {10.1371/journal.pone.0075292},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-97252},
  year      = {2013},
  abstract  = {The cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncogenic factor that stabilises the c-Myc protein. CIP2A is overexpressed in several tumours, and expression levels are an independent marker for long-term outcome. To determine whether CIP2A expression is elevated in colon cancer and whether it might serve as a prognostic marker for survival, we analysed CIP2A mRNA expression by real-time PCR in 104 colon cancer samples. CIP2A mRNA was overexpressed in colon cancer samples and CIP2A expression levels correlated significantly with tumour stage. We found that CIP2A serves as an independent prognostic marker for disease-free and overall survival. Further, we investigated CIP2A-dependent effects on levels of c-Myc, Akt and on cell proliferation in three colon cancer cell lines by silencing CIP2A using small interfering (si) and short hairpin (sh) RNAs. Depletion of CIP2A substantially inhibited growth of colon cell lines and reduced c-Myc levels without affecting expression or function of the upstream regulatory kinase, Akt. Expression of CIP2A was found to be dependent on MAPK activity, linking elevated c-Myc expression to deregulated signal transduction in colon cancer.},
  language  = {en}
}
@article{OttoFriedrichMadunićetal.2020,
  author    = {Otto, Christoph and Friedrich, Alexandra and Madunić, Ivana Vrhovac and Baumeier, Christian and Schwenk, Robert W. and Karaica, Dean and Germer, Christoph-Thomas and Sch{\"u}rmann, Annette and Sabolić, Ivan and Koepsell, Hermann, Hermann},
  title     = {Antidiabetic Effects of a Tripeptide That Decreases Abundance of Na\(^+\)-D-glucose Cotransporter SGLT1 in the Brush-Border Membrane of the Small Intestine},
  series = {ACS Omega},
  volume    = {5},
  journal   = {ACS Omega},
  number    = {45},
  doi       = {10.1021/acsomega.0c03844},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230654},
  pages     = {29127-29139},
  year      = {2020},
  abstract  = {In enterocytes, protein RS1 (RSC1A1) mediates an increase of glucose absorption after ingestion of glucose-rich food via upregulation of Na+-D-glucose cotransporter SGLT1 in the brush-border membrane (BBM). Whereas RS1 decelerates the exocytotic pathway of vesicles containing SGLT1 at low glucose levels between meals, RS1-mediated deceleration is relieved after ingestion of glucose-rich food. Regulation of SGLT1 is mediated by RS1 domain RS1-Reg, in which Gln-Ser-Pro (QSP) is effective. In contrast to QSP and RS1-Reg, Gln-Glu-Pro (QEP) and RS1-Reg with a serine to glutamate exchange in the QSP motif downregulate the abundance of SGLT1 in the BBM at high intracellular glucose concentrations by about 50\%. We investigated whether oral application of QEP improves diabetes in db/db mice and affects the induction of diabetes in New Zealand obese (NZO) mice under glucolipotoxic conditions. After 6-day administration of drinking water containing 5 mM QEP to db/db mice, fasting glucose was decreased, increase of blood glucose in the oral glucose tolerance test was blunted, and insulin sensitivity was increased. When QEP was added for several days to a high fat/high carbohydrate diet that induced diabetes in NZO mice, the increase of random plasma glucose was prevented, accompanied by lower plasma insulin levels. QEP is considered a lead compound for development of new antidiabetic drugs with more rapid cellular uptake. In contrast to SGLT1 inhibitors, QEP-based drugs may be applied in combination with insulin for the treatment of type 1 and type 2 diabetes, decreasing the required insulin amount, and thereby may reduce the risk of hypoglycemia.},
  language  = {en}
}
@article{BurkardMeirKannapinetal.2021,
  author    = {Burkard, Natalie and Meir, Michael and Kannapin, Felix and Otto, Christoph and Petzke, Maximilian and Germer, Christoph-Thomas and Waschke, Jens and Schlegel, Nicolas},
  title     = {Desmoglein2 Regulates Claudin2 Expression by Sequestering PI-3-Kinase in Intestinal Epithelial Cells},
  series = {Frontiers in Immunology},
  volume    = {12},
  journal   = {Frontiers in Immunology},
  issn      = {1664-3224},
  doi       = {10.3389/fimmu.2021.756321},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-247059},
  year      = {2021},
  abstract  = {Inflammation-induced reduction of intestinal desmosomal cadherin Desmoglein 2 (Dsg2) is linked to changes of tight junctions (TJ) leading to impaired intestinal epithelial barrier (IEB) function by undefined mechanisms. We characterized the interplay between loss of Dsg2 and upregulation of pore-forming TJ protein Claudin2. Intraperitoneal application of Dsg2-stablising Tandem peptide (TP) attenuated impaired IEB function, reduction of Dsg2 and increased Claudin2 in DSS-induced colitis in C57Bl/6 mice. TP blocked loss of Dsg2-mediated adhesion and upregulation of Claudin2 in Caco2 cells challenged with TNFα. In Dsg2-deficient Caco2 cells basal expression of Claudin2 was increased which was paralleled by reduced transepithelial electrical resistance and by augmented phosphorylation of AKT\(^{Ser473}\) under basal conditions. Inhibition of phosphoinositid-3-kinase proved that PI-3-kinase/AKT-signaling is critical to upregulate Claudin2. In immunostaining PI-3-kinase dissociated from Dsg2 under inflammatory conditions. Immunoprecipitations and proximity ligation assays confirmed a direct interaction of Dsg2 and PI-3-kinase which was abrogated following TNFα application. In summary, Dsg2 regulates Claudin2 expression by sequestering PI-3-kinase to the cell borders in intestinal epithelium.},
  language  = {en}
}