title: Nuclear death receptor TRAIL-R2 inhibits maturation of let-7 and promotes proliferation of pancreatic and other tumor cells.
abstract: OBJECTIVE
  Tumor necrosis factor-related apoptosis inducing ligand (TRAIL-R1) (TNFRSF10A) and TRAIL-R2 (TNFRSF10B) on the plasma membrane bind ligands that activate apoptotic and other signaling pathways. Cancer cells also might have TRAIL-R2 in the cytoplasm or nucleus, although little is known about its activities in these locations. We investigated the functions of nuclear TRAIL-R2 in cancer cell lines.
  
  
  METHODS
  Proteins that interact with TRAIL-R2 initially were identified in pancreatic cancer cells by immunoprecipitation, mass spectrometry, and immunofluorescence analyses. Findings were validated in colon, renal, lung, and breast cancer cells. Functions of TRAIL-R2 were determined from small interfering RNA knockdown, real-time polymerase chain reaction, Drosha-activity, microRNA array, proliferation, differentiation, and immunoblot experiments. We assessed the effects of TRAIL-R2 overexpression or knockdown in human pancreatic ductal adenocarcinoma (PDAC) cells and their ability to form tumors in mice. We also analyzed levels of TRAIL-R2 in sections of PDACs and non-neoplastic peritumoral ducts from patients.
  
  
  RESULTS
  TRAIL-R2 was found to interact with the core microprocessor components Drosha and DGCR8 and the associated regulatory proteins p68, hnRNPA1, NF45, and NF90 in nuclei of PDAC and other tumor cells. Knockdown of TRAIL-R2 increased Drosha-mediated processing of the let-7 microRNA precursor primary let-7 (resulting in increased levels of mature let-7), reduced levels of the let-7 targets (LIN28B and HMGA2), and inhibited cell proliferation. PDAC tissues from patients had higher levels of nuclear TRAIL-R2 than non-neoplastic pancreatic tissue, which correlated with increased nuclear levels of HMGA2 and poor outcomes. Knockdown of TRAIL-R2 in PDAC cells slowed their growth as orthotopic tumors in mice. Reduced nuclear levels of TRAIL-R2 in cultured pancreatic epithelial cells promoted their differentiation.
  
  
  CONCLUSIONS
  Nuclear TRAIL-R2 inhibits maturation of the microRNA let-7 in pancreatic cancer cell lines and increases their proliferation. Pancreatic tumor samples have increased levels of nuclear TRAIL-R2, which correlate with poor outcome of patients. These findings indicate that in the nucleus, death receptors can function as tumor promoters and might be therapeutic targets.
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Verena
authors.initials: V
authors.lastname: Haselmann
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kurz
authors.affiliation: Institute of Immunology, University of Kiel, Kiel, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Bertsch
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Hübner
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Olempska-Müller
authors.affiliation: Institute of Immunology, University of Kiel, Kiel, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Fritsch
authors.affiliation: Institute of Clinical Molecular Biology, University of Kiel, Kiel, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Häsler
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Pickl
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Fritsche
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Franka
authors.initials: F
authors.lastname: Annewanter
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Engler
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Fleig
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Bernt
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Röder
authors.affiliation: Institute of Immunology, University of Kiel, Kiel, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Schmidt
authors.affiliation: Zoological Institute, University of Kiel, Kiel, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Gelhaus
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany; Clinic for General Surgery, Visceral, Thoracic, Transplantation and Pediatric Surgery, University of Kiel, Kiel, Germany.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Hauser
authors.affiliation: Clinic for General Surgery, Visceral, Thoracic, Transplantation and Pediatric Surgery, University of Kiel, Kiel, Germany.
authors.forename: Jan-Hendrik
authors.initials: JH
authors.lastname: Egberts
authors.affiliation: Clinic for Diagnostic Radiology, University of Kiel, Kiel, Germany.
authors.forename: Carola
authors.initials: C
authors.lastname: Heneweer
authors.affiliation: Center for Anatomy, Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Rohde
authors.affiliation: Institute of Pathology, University of Kiel, Kiel, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Böger
authors.affiliation: Department of General, Visceral and Transplantation Surgery, Centre of Surgery, University of Ulm, Ulm, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Knippschild
authors.affiliation: Institute of Pathology, University of Kiel, Kiel, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Röcken
authors.affiliation: Institute of Immunology, University of Kiel, Kiel, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Adam
authors.affiliation: Centre for Cell Death, Cancer and Inflammation, University College London Cancer Institute, London, United Kingdom.
authors.forename: Henning
authors.initials: H
authors.lastname: Walczak
authors.affiliation: Institute of Immunology, University of Kiel, Kiel, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schütze
authors.affiliation: Institute of Immunology, University of Kiel, Kiel, Germany.
authors.forename: Ottmar
authors.initials: O
authors.lastname: Janssen
authors.affiliation: Center for Anatomy, Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: F Gregory
authors.initials: FG
authors.lastname: Wulczyn
authors.affiliation: Division of Molecular Internal Medicine, Department of Internal Medicine II, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Wajant
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Kalthoff
authors.affiliation: Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany. Electronic address: atrauzold@email.uni-kiel.de.
authors.forename: Anna
authors.initials: A
authors.lastname: Trauzold
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D001943:Breast Neoplasms / Q000378:metabolism; D021441:Carcinoma, Pancreatic Ductal / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000378:metabolism; D006801:Humans; D007680:Kidney Neoplasms / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D035683:MicroRNAs / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism* / Q000502:physiology
chemical_list: D051017:Apoptosis Regulatory Proteins; D035683:MicroRNAs; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; C487931:mirnlet7 microRNA, human
keywords: Apoptosis Regulation; DGCR8; EGFP; HMGA2; LNA; LSM; MALDI-TOF; PCR; PDAC; Pancreatic Cancer; TRAIL; diGeorge syndrome critical region gene 8; enhanced green fluorescent protein; heterogenous ribonucleoprotein A1; high mobility group AT-hook protein 2; hnRNPA1; laser scanning microscopy; locked nucleic acid; miRNA; microRNA; microRNA Processing; nTRAIL-R2; nuclear TRAIL-R2; pancreatic ductal adenocarcinoma; polymerase chain reaction; pri-; primary; siRNA; small interfering RNA; tumor necrosis factor-related apoptosis inducing ligand