title: Polarization of the vacuolar adenosine triphosphatase delineates a transition to high-grade pancreatic intraepithelial neoplasm lesions.
abstract: OBJECTIVE
  A functional vacuolar adenosine triphosphatase (v-ATPase) complex regulates canonical Wnt/β-catenin signaling. The goal of this study was to identify the distribution of the v-ATPase in human and murine models of pancreatic intraepithelial neoplasms (PanINs) and assess its role in Wnt/β-catenin signaling.
  
  
  METHODS
  We evaluated the immunolabeling pattern of the v-ATPase in human PanIN specimens and murine PanIN-1 and PanIN-2 lesions obtained from Ptf1a(Cre/+); LSL-Kras(G12D) mice. Wnt/β-catenin signaling was interrogated in primary PanIN cells by examining the phosphorylated levels of its surface coreceptor, low-density lipoprotein receptor-related protein-6 (LRP6), and its intracellular effector, nonphosphorylated β-catenin. The response of primary PanIN cells to epidermal growth factor (EGF) was assessed in the absence and presence of the v-ATPase inhibitor, concanamycin.
  
  
  RESULTS
  In advanced (PanIN-2), but not early (PanIN-1), lesions, the v-ATPase assumed a polarized phenotype. Blocking the v-ATPase disrupted Wnt/β-catenin signaling in primary PanIN cells despite significantly higher levels of the total and activated Wnt cell surface coreceptor, LRP6. Vacuolar adenosine triphosphatase blockade significantly decreased the total and activated levels of EGF receptor, a determinant of PanIN progression. The activation of EGF receptor and its intracellular mediator, p44/42 mitogen-activated protein kinase, was also reduced by v-ATPase blockade. This led to diminished proliferation in response to EGF ligand.
  
  
  CONCLUSIONS
  The v-ATPase regulates Wnt/β-catenin and EGF receptor signaling in PanINs.
authors: From the *Department of Medicine, Yale University School of Medicine, New Haven, CT; †Second Department of Internal Medicine, Klinikum rechts der Isar, Technical University, Munich, Germany; ‡Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, MI; and §Veterans Administration CT Healthcare System, West Haven, CT.
authors: Bharath K
authors: BK
authors: Sreekumar
authors: Glenn S
authors: GS
authors: Belinsky
authors: Henrik
authors: H
authors: Einwachter
authors: Andrew D
authors: AD
authors: Rhim
authors: Roland
authors: R
authors: Schmid
authors: Chuhan
authors: C
authors: Chung
mesh_terms: D065311:Adenocarcinoma in Situ / Q000201:enzymology / Q000648:ultrastructure; D000423:Alcian Blue; D000818:Animals; D021441:Carcinoma, Pancreatic Ductal / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D045744:Cell Line, Tumor; D016764:Cell Polarity; D018450:Disease Progression; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000032:analysis / Q000187:drug effects; D006801:Humans; D007515:Islets of Langerhans / Q000201:enzymology / Q000648:ultrastructure; D060488:Low Density Lipoprotein Receptor-Related Protein-6 / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis*; D051379:Mice; D008817:Mice, Mutant Strains; D048052:Mitogen-Activated Protein Kinase 3 / Q000032:analysis / Q000502:physiology; D060787:Neoplasm Grading; D009363:Neoplasm Proteins / Q000032:analysis* / Q000502:physiology; D010190:Pancreatic Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D021381:Protein Transport; D013194:Staining and Labeling; D025262:Vacuolar Proton-Translocating ATPases / Q000032:analysis* / Q000502:physiology; D060449:Wnt Signaling Pathway / Q000502:physiology*
chemical_list: D060488:Low Density Lipoprotein Receptor-Related Protein-6; C555476:Lrp6 protein, mouse; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D004815:Epidermal Growth Factor; C512478:EGFR protein, human; D066246:ErbB Receptors; D048052:Mitogen-Activated Protein Kinase 3; D025262:Vacuolar Proton-Translocating ATPases; D000423:Alcian Blue