@article{DischingerHeckelBischleretal.2021,
  author    = {Dischinger, Ulrich and Heckel, Tobias and Bischler, Thorsten and Hasinger, Julia and K{\"o}nigsrainer, Malina and Schmitt-B{\"o}hrer, Angelika and Otto, Christoph and Fassnacht, Martin and Seyfried, Florian and Hankir, Mohammed Khair},
  title     = {Roux-en-Y gastric bypass and caloric restriction but not gut hormone-based treatments profoundly impact the hypothalamic transcriptome in obese rats},
  series = {Nutrients},
  volume    = {14},
  journal   = {Nutrients},
  number    = {1},
  issn      = {2072-6643},
  doi       = {10.3390/nu14010116},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-252392},
  year      = {2021},
  abstract  = {Background: The hypothalamus is an important brain region for the regulation of energy balance. Roux-en-Y gastric bypass (RYGB) surgery and gut hormone-based treatments are known to reduce body weight, but their effects on hypothalamic gene expression and signaling pathways are poorly studied. Methods: Diet-induced obese male Wistar rats were randomized into the following groups: RYGB, sham operation, sham + body weight-matched (BWM) to the RYGB group, osmotic minipump delivering PYY3-36 (0.1 mg/kg/day), liraglutide s.c. (0.4 mg/kg/day), PYY3-36 + liraglutide, and saline. All groups (except BWM) were kept on a free choice of high- and low-fat diets. Four weeks after interventions, hypothalami were collected for RNA sequencing. Results: While rats in the RYGB, BWM, and PYY3-36 + liraglutide groups had comparable reductions in body weight, only RYGB and BWM treatment had a major impact on hypothalamic gene expression. In these groups, hypothalamic leptin receptor expression as well as the JAK-STAT, PI3K-Akt, and AMPK signaling pathways were upregulated. No significant changes could be detected in PYY3-36 + liraglutide-, liraglutide-, and PYY-treated groups. Conclusions: Despite causing similar body weight changes compared to RYGB and BWM, PYY3-36 + liraglutide treatment does not impact hypothalamic gene expression. Whether this striking difference is favorable or unfavorable to metabolic health in the long term requires further investigation.},
  language  = {en}
}
@article{OttoKastnerSchmidtetal.2022,
  author    = {Otto, Christoph and Kastner, Carolin and Schmidt, Stefanie and Uttinger, Konstantin and Baluapuri, Apoorva and Denk, Sarah and Rosenfeldt, Mathias T. and Rosenwald, Andreas and Roehrig, Florian and Ade, Carsten P. and Schuelein-Voelk, Christina and Diefenbacher, Markus E. and Germer, Christoph-Thomas and Wolf, Elmar and Eilers, Martin and Wiegering, Armin},
  title     = {RNA polymerase I inhibition induces terminal differentiation, growth arrest, and vulnerability to senolytics in colorectal cancer cells},
  series = {Molecular Oncology},
  volume    = {16},
  journal   = {Molecular Oncology},
  number    = {15},
  doi       = {10.1002/1878-0261.13265},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312806},
  pages     = {2788-2809},
  year      = {2022},
  abstract  = {Ribosomal biogenesis and protein synthesis are deregulated in most cancers, suggesting that interfering with translation machinery may hold significant therapeutic potential. Here, we show that loss of the tumor suppressor adenomatous polyposis coli (APC), which constitutes the initiating event in the adenoma carcinoma sequence for colorectal cancer (CRC), induces the expression of RNA polymerase I (RNAPOL1) transcription machinery, and subsequently upregulates ribosomal DNA (rDNA) transcription. Targeting RNAPOL1 with a specific inhibitor, CX5461, disrupts nucleolar integrity, and induces a disbalance of ribosomal proteins. Surprisingly, CX5461-induced growth arrest is irreversible and exhibits features of senescence and terminal differentiation. Mechanistically, CX5461 promotes differentiation in an MYC-interacting zinc-finger protein 1 (MIZ1)- and retinoblastoma protein (Rb)-dependent manner. In addition, the inhibition of RNAPOL1 renders CRC cells vulnerable towards senolytic agents. We validated this therapeutic effect of CX5461 in murine- and patient-derived organoids, and in a xenograft mouse model. These results show that targeting ribosomal biogenesis together with targeting the consecutive, senescent phenotype using approved drugs is a new therapeutic approach, which can rapidly be transferred from bench to bedside.},
  language  = {en}
}
@article{ZaitsevaHoffmannOttoetal.2022,
  author    = {Zaitseva, Olena and Hoffmann, Annett and Otto, Christoph and Wajant, Harald},
  title     = {Targeting fibroblast growth factor (FGF)-inducible 14 (Fn14) for tumor therapy},
  series = {Frontiers in Pharmacology},
  volume    = {13},
  journal   = {Frontiers in Pharmacology},
  issn      = {1663-9812},
  doi       = {10.3389/fphar.2022.935086},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-290238},
  year      = {2022},
  abstract  = {Fibroblast growth factor-inducible 14 (Fn14) is a member of the tumor necrosis factor (TNF) receptor superfamily (TNFRSF) and is activated by its ligand TNF-like weak inducer of apoptosis (TWEAK). The latter occurs as a homotrimeric molecule in a soluble and a membrane-bound form. Soluble TWEAK (sTWEAK) activates the weakly inflammatory alternative NF-κB pathway and sensitizes for TNF-induced cell death while membrane TWEAK (memTWEAK) triggers additionally robust activation of the classical NF-κB pathway and various MAP kinase cascades. Fn14 expression is limited in adult organisms but becomes strongly induced in non-hematopoietic cells by a variety of growth factors, cytokines and physical stressors (e.g., hypoxia, irradiation). Since all these Fn14-inducing factors are frequently also present in the tumor microenvironment, Fn14 is regularly found to be expressed by non-hematopoietic cells of the tumor microenvironment and most solid tumor cells. In general, there are three possibilities how the tumor-Fn14 linkage could be taken into consideration for tumor therapy. First, by exploitation of the cancer associated expression of Fn14 to direct cytotoxic activities (antibody-dependent cell-mediated cytotoxicity (ADCC), cytotoxic payloads, CAR T-cells) to the tumor, second by blockade of potential protumoral activities of the TWEAK/Fn14 system, and third, by stimulation of Fn14 which not only triggers proinflammtory activities but also sensitizes cells for apoptotic and necroptotic cell death. Based on a brief description of the biology of the TWEAK/Fn14 system and Fn14 signaling, we discuss the features of the most relevant Fn14-targeting biologicals and review the preclinical data obtained with these reagents. In particular, we address problems and limitations which became evident in the preclinical studies with Fn14-targeting biologicals and debate possibilities how they could be overcome.},
  language  = {en}
}
@article{MetznerHerzogHeckeletal.2022,
  author    = {Metzner, Valentin and Herzog, Gloria and Heckel, Tobias and Bischler, Thorsten and Hasinger, Julia and Otto, Christoph and Fassnacht, Martin and Geier, Andreas and Seyfried, Florian and Dischinger, Ulrich},
  title     = {Liraglutide + PYY\(_{3-36}\) combination therapy mimics effects of Roux-en-Y bypass on early NAFLD whilst lacking-behind in metabolic improvements},
  series = {Journal of Clinical Medicine},
  volume    = {11},
  journal   = {Journal of Clinical Medicine},
  number    = {3},
  issn      = {2077-0383},
  doi       = {10.3390/jcm11030753},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-255244},
  year      = {2022},
  abstract  = {Background: Treatment options for NAFLD are still limited. Bariatric surgery, such as Roux-en-Y gastric bypass (RYGB), has been shown to improve metabolic and histologic markers of NAFLD. Glucagon-like-peptide-1 (GLP-1) analogues lead to improvements in phase 2 clinical trials. We directly compared the effects of RYGB with a treatment using liraglutide and/or peptide tyrosine tyrosine 3-36 (PYY\(_{3-36}\)) in a rat model for early NAFLD. Methods: Obese male Wistar rats (high-fat diet (HFD)-induced) were randomized into the following treatment groups: RYGB, sham-operation (sham), liraglutide (0.4 mg/kg/day), PYY\(_{3-36}\) (0.1 mg/kg/day), liraglutide+PYY\(_{3-36}\), and saline. After an observation period of 4 weeks, liver samples were histologically evaluated, ELISAs and RNA sequencing + RT-qPCRs were performed. Results: RYGB and liraglutide+PYY\(_{3-36}\) induced a similar body weight loss and, compared to sham/saline, marked histological improvements with significantly less steatosis. However, only RYGB induced significant metabolic improvements (e.g., adiponectin/leptin ratio 18.8 ± 11.8 vs. 2.4 ± 1.2 in liraglutide+PYY\(_{3-36}\)- or 1.4 ± 0.9 in sham-treated rats). Furthermore, RNA sequencing revealed a high number of differentially regulated genes in RYGB treated animals only. Conclusions: The combination therapy of liraglutide+PYY\(_{3-36}\) partly mimics the positive effects of RYGB on weight reduction and on hepatic steatosis, while its effects on metabolic function lack behind RYGB.},
  language  = {en}
}
@article{HankirRotzingerNordbecketal.2021,
  author    = {Hankir, Mohammed K. and Rotzinger, Laura and Nordbeck, Arno and Corteville, Caroline and Dischinger, Ulrich and Knop, Juna-Lisa and Hoffmann, Annett and Otto, Christoph and Seyfried, Florian},
  title     = {Leptin receptors are not required for Roux-en-Y gastric bypass surgery to normalize energy and glucose homeostasis in rats},
  series = {Nutrients},
  volume    = {13},
  journal   = {Nutrients},
  number    = {5},
  issn      = {2072-6643},
  doi       = {10.3390/nu13051544},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239550},
  year      = {2021},
  abstract  = {Sensitization to the adipokine leptin is a promising therapeutic strategy against obesity and its comorbidities and has been proposed to contribute to the lasting metabolic benefits of Roux-en-Y gastric bypass (RYGB) surgery. We formally tested this idea using Zucker fatty fa/fa rats as an established genetic model of obesity, glucose intolerance, and fatty liver due to leptin receptor deficiency. We show that the changes in body weight in these rats following RYGB largely overlaps with that of diet-induced obese Wistar rats with intact leptin receptors. Further, food intake and oral glucose tolerance were normalized in RYGB-treated Zucker fatty fa/fa rats to the levels of lean Zucker fatty fa/+ controls, in association with increased glucagon-like peptide 1 (GLP-1) and insulin release. In contrast, while fatty liver was also normalized in RYGB-treated Zucker fatty fa/fa rats, their circulating levels of the liver enzyme alanine aminotransferase (ALT) remained elevated at the level of obese Zucker fatty fa/fa controls. These findings suggest that the leptin system is not required for the normalization of energy and glucose homeostasis associated with RYGB, but that its potential contribution to the improvements in liver health postoperatively merits further investigation.},
  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}
}
@article{BachmannEhlertBeckeretal.2020,
  author    = {Bachmann, Julia and Ehlert, Elias and Becker, Matthias and Otto, Christoph and Radeloff, Katrin and Blunk, Torsten and Bauer-Kreisel, Petra},
  title     = {Ischemia-like stress conditions stimulate trophic activities of adipose-derived stromal/stem cells},
  series = {Cells},
  volume    = {9},
  journal   = {Cells},
  number    = {9},
  issn      = {2073-4409},
  doi       = {10.3390/cells9091935},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-211233},
  year      = {2020},
  abstract  = {Adipose-derived stromal/stem cells (ASCs) have been shown to exert regenerative functions, which are mainly attributed to the secretion of trophic factors. Upon transplantation, ASCs are facing an ischemic environment characterized by oxygen and nutrient deprivation. However, current knowledge on the secretion capacity of ASCs under such conditions is limited. Thus, the present study focused on the secretory function of ASCs under glucose and oxygen deprivation as major components of ischemia. After exposure to glucose/oxygen deprivation, ASCs maintained distinct viability, but the metabolic activity was greatly reduced by glucose limitation. ASCs were able to secrete a broad panel of factors under glucose/oxygen deprivation as revealed by a cytokine antibody array. Quantification of selected factors by ELISA demonstrated that glucose deprivation in combination with hypoxia led to markedly higher secretion levels of the angiogenic and anti-apoptotic factors IL-6, VEGF, and stanniocalcin-1 as compared to the hypoxic condition alone. A conditioned medium of glucose/oxygen-deprived ASCs promoted the viability and tube formation of endothelial cells, and the proliferation and migration of fibroblasts. These findings indicate that ASCs are stimulated by ischemia-like stress conditions to secrete trophic factors and would be able to exert their beneficial function in an ischemic environment.},
  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{DischingerHasingerKoenigsraineretal.2021,
  author    = {Dischinger, Ulrich and Hasinger, Julia and K{\"o}nigsrainer, Malina and Corteville, Carolin and Otto, Christoph and Fassnacht, Martin and Hankir, Mohamed and Seyfried, Florian Johannes David},
  title     = {Toward a Medical Gastric Bypass: Chronic Feeding Studies With Liraglutide + PYY\(_{3-36}\) Combination Therapy in Diet-Induced Obese Rats},
  series = {Frontiers in Endocrinology},
  volume    = {11},
  journal   = {Frontiers in Endocrinology},
  issn      = {1664-2392},
  doi       = {10.3389/fendo.2020.598843},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-223113},
  year      = {2021},
  abstract  = {Background Combination therapies of anorectic gut hormones partially mimic the beneficial effects of bariatric surgery. Thus far, the effects of a combined chronic systemic administration of Glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine 3-36 (PYY\(_{3-36}\)) have not been directly compared to Roux-en-Y gastric bypass (RYGB) in a standardized experimental setting. Methods High-fat diet (HFD)-induced obese male Wistar rats were randomized into six treatment groups: (1) RYGB, (2) sham-operation (shams), (3) liraglutide, (4) PYY\(_{3-36}\), (5) PYY\(_{3-36}\)+liraglutide (6), saline. Animals were kept on a free choice high- and low-fat diet. Food intake, preference, and body weight were measured daily for 4 weeks. Open field (OP) and elevated plus maze (EPM) tests were performed. Results RYGB reduced food intake and achieved sustained weight loss. Combined PYY\(_{3-36}\)+liraglutide treatment led to similar and plateaued weight loss compared to RYGB. Combined PYY\(_{3-36}\)+liraglutide treatment was superior to PYY\(_{3-36}\) (p ≤ 0.0001) and liraglutide (p ≤ 0.05 or p ≤ 0.01) mono-therapy. PYY\(_{3-36}\)+liraglutide treatment and RYGB also reduced overall food intake and (less pronounced) high-fat preference compared to controls. The animals showed no signs of abnormal behavior in OF or EPM. Conclusions Liraglutide and PYY\(_{3-36}\) combination therapy vastly mimics reduced food intake, food choice and weight reducing benefits of RYGB.},
  language  = {en}
}
@article{WiegeringMatthesMuehlingetal.2017,
  author    = {Wiegering, Armin and Matthes, Niels and M{\"u}hling, Bettina and Koospal, Monika and Quenzer, Anne and Peter, Stephanie and Germer, Christoph-Thomas and Linnebacher, Michael and Otto, Christoph},
  title     = {Reactivating p53 and Inducing Tumor Apoptosis (RITA) Enhances the Response of RITA-Sensitive Colorectal Cancer Cells to Chemotherapeutic Agents 5-Fluorouracil and Oxaliplatin},
  series = {Neoplasia},
  volume    = {19},
  journal   = {Neoplasia},
  number    = {4},
  doi       = {10.1016/j.neo.2017.01.007},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171067},
  pages     = {301-309},
  year      = {2017},
  abstract  = {Colorectal carcinoma (CRC) is the most common cancer of the gastrointestinal tract with frequently dysregulated intracellular signaling pathways, including p53 signaling. The mainstay of chemotherapy treatment of CRC is 5-fluorouracil (5FU) and oxaliplatin. The two anticancer drugs mediate their therapeutic effect via DNA damage-triggered signaling. The small molecule reactivating p53 and inducing tumor apoptosis (RITA) is described as an activator of wild-type and reactivator of mutant p53 function, resulting in elevated levels of p53 protein, cell growth arrest, and cell death. Additionally, it has been shown that RITA can induce DNA damage signaling. It is expected that the therapeutic benefits of 5FU and oxaliplatin can be increased by enhancing DNA damage signaling pathways. Therefore, we highlighted the antiproliferative response of RITA alone and in combination with 5FU or oxaliplatin in human CRC cells. A panel of long-term established CRC cell lines (n = 9) including p53 wild-type, p53 mutant, and p53 null and primary patient-derived, low-passage cell lines (n = 5) with different p53 protein status were used for this study. A substantial number of CRC cells with pronounced sensitivity to RITA (IC\(_{50}\)< 3.0 μmol/l) were identified within established (4/9) and primary patient-derived (2/5) CRC cell lines harboring wild-type or mutant p53 protein. Sensitivity to RITA appeared independent of p53 status and was associated with an increase in antiproliferative response to 5FU and oxaliplatin, a transcriptional increase of p53 targets p21 and NOXA, and a decrease in MYC mRNA. The effect of RITA as an inducer of DNA damage was shown by a strong elevation of phosphorylated histone variant H2A.X, which was restricted to RITA-sensitive cells. Our data underline the primary effect of RITA, inducing DNA damage, and demonstrate the differential antiproliferative effect of RITA to CRC cells independent of p53 protein status. We found a substantial number of RITA-sensitive CRC cells within both panels of established CRC cell lines and primary patient-derived CRC cell lines (6/14) that provide a rationale for combining RITA with 5FU or oxaliplatin to enhance the antiproliferative response to both chemotherapeutic agents.},
  language  = {en}
}