title: COSMC knockdown mediated aberrant O-glycosylation promotes oncogenic properties in pancreatic cancer.
abstract: BACKGROUND
  Human pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal malignancies in the world and despite great efforts in research types of treatment remain limited. A frequently detected alteration in PDACs is a truncated O-linked N-acetylgalactosamine (GalNAc) glycosylation with expression of the Tn antigen. Changes in O-glycosylation affect posttranslationally modified O-GalNAc proteins resulting in profound cellular alterations. Tn antigen is a tumor associated glycan detected in 75-90 % of PDACs and up to 67 % in its precursor lesions. Since the role of Tn antigen expression in PDAC is insufficiently understood we analyzed the impact of COSMC mediated Tn antigen expression in two human PDAC cell lines on cellular oncogenic properties.
  
  
  METHODS
  Forced expression of Tn antigen on O-glycosylated proteins in pancreatic cancer cells was induced by lentiviral-mediated knockdown of the COSMC chaperone, which prevented O-glycan elongation beyond the initial GalNAcα1- residue on O-linked glycoproteins. Altered O-GalNAc glycosylation was analyzed in human pancreatic cancer cell lines Panc-1 and L3.6pl using Western and Far-Western blot as well as immunocytochemical techniques. To assess the biological implications of COSMC function on oncogenic properties, cell viability assays, scratch assays combined with live cell imaging, migration and apoptosis assays were performed. Lectin based glycoprotein enrichment with subsequent mass spectrometric analysis identified new cancer O-GalNAc modified proteins. Expression of Tn antigen bearing Nucleolin in patient derived PDAC tumor specimens was evaluated and correlated with clinicopathological data.
  
  
  RESULTS
  Tn antigen expression was induced on various O-GalNAc glycoproteins in COSMC deficient cell lines compared to the control. Proliferation was reduced (p < 0.001) in COSMC knockdown cells, whereas migration was increased (p < 0.001) and apoptosis was decreased (p = 0.03), highlighting the importance of Tn antigen expression on metastatic and anti-apoptotic behavior of PDAC derived cells. Nucleolin was identified as O-GalNAc modified protein in COSMC deficient PDAC cell lines. Interestingly, immunohistochemical staining and co-localization studies of patient derived PDACs revealed poor survival for patients with strong co-localization of Tn antigen and Nucleolin (p = 0.037).
  
  
  CONCLUSIONS
  This study substantiates the influence of altered O-glycan (Tn/STn) expression on oncogenic properties in pancreatic cancer and identifies O-GalNAc modified Nucleolin as novel prognostic marker.
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. bi.hofmann@uke.de.|Department of Anatomy and Experimental Morphology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. bi.hofmann@uke.de.
authors.forename: Bianca T
authors.initials: BT
authors.lastname: Hofmann
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. Lauraschlueter88@web.de.
authors.forename: Laura
authors.initials: L
authors.lastname: Schlüter
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. philip_lange@gmx.de.
authors.forename: Philip
authors.initials: P
authors.lastname: Lange
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. b.mercanoglu@uke.de.
authors.forename: Baris
authors.initials: B
authors.lastname: Mercanoglu
authors.affiliation: Department of Hepatobiliary and Transplant Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. f.ewald@uke.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Ewald
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. aljonna@foefi.de.
authors.forename: Aljonna
authors.initials: A
authors.lastname: Fölster
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. 6362331@stud.uke.uni-hamburg.de.
authors.forename: Aeint-Steffen
authors.initials: AS
authors.lastname: Picksak
authors.affiliation: Department of Clinical Chemistry, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. harder@uke.de.
authors.forename: Sönke
authors.initials: S
authors.lastname: Harder
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. a.el-gammal@uke.de.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: El Gammal
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. k.grupp@uke.de.
authors.forename: Katharina
authors.initials: K
authors.lastname: Grupp
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. c.guengoer@uke.de.
authors.forename: Cenap
authors.initials: C
authors.lastname: Güngör
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. a.drenckhan@uke.de.
authors.forename: Astrid
authors.initials: A
authors.lastname: Drenckhan
authors.affiliation: Department of Clinical Chemistry, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. hschluet@uke.de.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Schlüter
authors.affiliation: Department of Clinical Chemistry, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. christoph.wagener@me.com.
authors.forename: Christoph
authors.initials: C
authors.lastname: Wagener
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. izbicki@uke.de.
authors.forename: Jakob R
authors.initials: JR
authors.lastname: Izbicki
authors.affiliation: Institute for Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. juecker@uke.de.
authors.forename: Manfred
authors.initials: M
authors.lastname: Jücker
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. m.bockhorn@uke.de.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Bockhorn
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. ge.wolters@uke.de.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Wolters-Eisfeld
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology / Q000473:pathology; D015295:Antigens, Tumor-Associated, Carbohydrate; D063646:Carcinogenesis / Q000235:genetics / Q000473:pathology*; D021441:Carcinoma, Pancreatic Ductal / Q000201:enzymology / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D002470:Cell Survival; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006031:Glycosylation; D006801:Humans; D013058:Mass Spectrometry; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology*; D010750:Phosphoproteins / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D000097796:Nucleolin
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; D018832:Molecular Chaperones; D017350:N-Acetylgalactosaminyltransferases; D009363:Neoplasm Proteins; D010750:Phosphoproteins; D011134:Polysaccharides; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D000097796:Nucleolin; C505369:C1GALT1C1 protein, human; C040286:Tn antigen