title: HPAF-II, a cell culture model to study pancreatic epithelial cell structure and function.
abstract: OBJECTIVE
  Epithelial cells have distinct apical and basolateral plasma membrane domains separated by tight junctions. This phenotype is essential for the directional transport functions of epithelial cells. Here we characterized a well-differentiated pancreatic epithelial cell line to establish a useful model for understanding the mechanisms involved in the regulation of junctional complexes, polarity, and disease processes in the pancreas.
  
  
  METHODS
  Immunofluorescence of cell junction marker proteins and electron microscopy were used to determine the presence of tight junctions, adherens junctions, and desmosomes. The functionality of tight junctions was tested by transepithelial resistance measurements and transepithelial permeability studies of nonionic molecules. Tight junction function in polarity was determined by laser scanning confocal microscopy.
  
  
  RESULTS
  Immunofluorescence analysis in HPAF-II cells revealed tight junction localization of ZO-1, occludin, and claudin-4; adherens junction localization of E-cadherin and beta-catenin; and desmosomal localization of desmocollin. Transmission electron microscopy showed the presence of tight junctions, adherens junctions, and des-mosomes, and freeze-fracture electron microscopy revealed the presence of distinct anastomosing tight junction strands. Transepithelial electrical resistance and permeability measurements revealed functional tight junctions. In addition, 3-dimensional images of the monolayer generated by laser scanning confocal microscopy revealed that HPAF-II cells show polarity. Immunoblotting and RT-PCR analyses revealed high expression levels of E-cadherin and Na,K-ATPase beta-subunit but low levels of the transcription factor Snail in HPAF-II cells compared with MiaPaCa-2 cells.
  
  
  CONCLUSIONS
  The HPAF-II cell line is a well-differentiated human pancreatic carcinoma cell line that should be useful as a model for studies aimed at understanding epithelial polarity, regulation of junctional complexes, and disease processes in pancreas.
authors.affiliation: Department of Pathology and Laboratory Medicine, UCLA David Geffen School of Medicine, Los Angeles, California 90095, USA.
authors.forename: Sigrid A
authors.initials: SA
authors.lastname: Rajasekaran
authors.forename: Jegan
authors.initials: J
authors.lastname: Gopal
authors.forename: Cromwell
authors.initials: C
authors.lastname: Espineda
authors.forename: Sergey
authors.initials: S
authors.lastname: Ryazantsev
authors.forename: Eveline E
authors.initials: EE
authors.lastname: Schneeberger
authors.forename: Ayyappan K
authors.initials: AK
authors.lastname: Rajasekaran
mesh_terms: D022005:Adherens Junctions / Q000737:chemistry / Q000648:ultrastructure; D015415:Biomarkers; D015820:Cadherins / Q000032:analysis; D021441:Carcinoma, Pancreatic Ductal / Q000473:pathology*; D002454:Cell Differentiation; D045744:Cell Line, Tumor / Q000473:pathology / Q000502:physiology; D016764:Cell Polarity; D062506:Claudin-4; D003598:Cytoskeletal Proteins / Q000032:analysis; D003896:Desmosomes / Q000737:chemistry / Q000648:ultrastructure; D017097:Electric Impedance; D004847:Epithelial Cells / Q000473:pathology / Q000502:physiology; D006801:Humans; D008562:Membrane Glycoproteins / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis; D062793:Occludin; D010190:Pancreatic Neoplasms / Q000473:pathology*; D010750:Phosphoproteins / Q000032:analysis; D019108:Tight Junctions / Q000737:chemistry / Q000648:ultrastructure; D015534:Trans-Activators / Q000032:analysis; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin
chemical_list: D015415:Biomarkers; C568157:CLDN4 protein, human; C495270:CTNNB1 protein, human; D015820:Cadherins; D062506:Claudin-4; D003598:Cytoskeletal Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; C569042:TJP1 protein, human; D015534:Trans-Activators; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin