title: Bifunctional antibody-Renilla luciferase fusion protein for in vivo optical detection of tumors.
abstract: An anti-carcinoembryonic antigen (CEA) antibody fragment, the anti-CEA diabody, was fused to the bioluminescence enzyme Renilla luciferase (RLuc) to generate a novel optical imaging probe. Native RLuc or one of two stabilized variants (RLucC124A, RLuc8) was used as the bioluminescent moiety. A bioluminescence ELISA showed that diabody-luciferase could simultaneously bind to CEA and emit light. In vivo optical imaging of tumor-bearing mice demonstrated specific targeting of diabody-RLuc8 to CEA-positive xenografts, with a tumor:background ratio of 6.0 +/- 0.8 at 6 h after intravenous injection, compared with antigen-negative tumors at 1.0 +/- 0.1 (P = 0.05). Targeting and distribution was also evaluated by microPET imaging using (124)I-diabody-RLuc8 and confirmed that the optical signal was due to antibody-mediated localization of luciferase. Renilla luciferase, fused to biospecific sequences such as engineered antibodies, can be administered systemically to provide a novel, sensitive method for optical imaging based on expression of cell surface receptors in living organisms.
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular & Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Katy M
authors.initials: KM
authors.lastname: Venisnik
authors.forename: Tove
authors.initials: T
authors.lastname: Olafsen
authors.forename: Andreas M
authors.initials: AM
authors.lastname: Loening
authors.forename: Meera
authors.initials: M
authors.lastname: Iyer
authors.forename: Sanjiv S
authors.initials: SS
authors.lastname: Gambhir
authors.forename: Anna M
authors.initials: AM
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018033:Antibodies, Bispecific / Q000737:chemistry*; D002272:Carcinoembryonic Antigen / Q000737:chemistry; D045744:Cell Line, Tumor; D006801:Humans; D008156:Luciferases / Q000737:chemistry*; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000175:diagnosis* / Q000473:pathology; D015202:Protein Engineering / Q000379:methods*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry*; D048790:Renilla
chemical_list: D018033:Antibodies, Bispecific; D002272:Carcinoembryonic Antigen; D011993:Recombinant Fusion Proteins; D008156:Luciferases