title: Evaluation of two internalizing carcinoembryonic antigen reporter genes for molecular imaging.
abstract: OBJECTIVE
  The objective of this article is to develop internalizing positron emission tomography (PET) reporter genes for tracking genetically modified T cells in vivo.
  
  
  METHODS
  The transmembrane and cytoplasmic domains of the human transferrin receptor (TfR) and CD5 were each fused to the carcinoembryonic (CEA) minigene N-A3 and expressed in Jurkat T cells. Internalization was evaluated by confocal microscopy or by intracellular uptake of ¹²⁵I-labeled anti-CEA scFv-Fc. Reporter gene-transfected Jurkat xenografts in mice were analyzed by immunohistochemistry (IHC) and imaged by PET using ¹²⁴I- or ⁶⁴Cu-scFv-Fc as tracers.
  
  
  RESULTS
  Surface expression of TR(1-99)-NA3 was lower than that of NA3-CD5. Both reporter genes were internalized following binding of the anti-CEA antibody fragment. IHC of tumors showed strong staining of NA3-CD5, whereas TR(1-99)-NA3 stained weakly. Specific targeting of TR(1-99)-NA3 or NA3-CD5 was shown by PET in xenografted mice.
  
  
  CONCLUSIONS
  The in vivo imaging studies suggest a potential application of the internalizing form of CEA (N-A3) as a PET reporter gene.
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Box 951770, 570 Westwood Plaza, Los Angeles, CA, 90095-1770, USA.
authors.forename: Bhaswati
authors.initials: B
authors.lastname: Barat
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Box 951770, 570 Westwood Plaza, Los Angeles, CA, 90095-1770, USA.
authors.forename: Vania E
authors.initials: VE
authors.lastname: Kenanova
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Box 951770, 570 Westwood Plaza, Los Angeles, CA, 90095-1770, USA.
authors.forename: Tove
authors.initials: T
authors.lastname: Olafsen
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Box 951770, 570 Westwood Plaza, Los Angeles, CA, 90095-1770, USA. awu@mednet.ucla.edu.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Wu
mesh_terms: D000818:Animals; D002272:Carcinoembryonic Antigen / Q000235:genetics* / Q000378:metabolism; D004705:Endocytosis; D005260:Female; D005434:Flow Cytometry; D017930:Genes, Reporter / Q000235:genetics*; D006801:Humans; D007128:Immunoglobulin Fragments; D007150:Immunohistochemistry; D019169:Jurkat Cells; D051379:Mice; D008819:Mice, Nude; D057054:Molecular Imaging / Q000379:methods*; D049268:Positron-Emission Tomography; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
chemical_list: D002272:Carcinoembryonic Antigen; D007128:Immunoglobulin Fragments; D011994:Recombinant Proteins