title: In vivo imaging of xenograft tumors using an epidermal growth factor receptor-specific affibody molecule labeled with a near-infrared fluorophore.
abstract: Overexpression of epidermal growth factor receptor (EGFR) is associated with many types of cancers. It is of great interest to noninvasively image the EGFR expression in vivo. In this study, we labeled an EGFR-specific Affibody molecule (Eaff) with a near-infrared (NIR) dye IRDye800CW maleimide and tested the binding of this labeled molecule (Eaff800) in cell culture and xenograft mouse tumor models. Unlike EGF, Eaff did not activate the EGFR signaling pathway. Results showed that Eaff800 was bound and taken up specifically by EGFR-overexpressing A431 cells. When Eaff800 was intravenously injected into nude mice bearing A431 xenograft tumors, the tumor could be identified 1 hour after injection and it became most prominent after 1 day. Images of dissected tissue sections demonstrated that the accumulation of Eaff800 was highest in the liver, followed by the tumor and kidney. Moreover, in combination with a human EGFR type 2 (HER2)-specific probe Haff682, Eaff800 could be used to distinguish between EGFR- and HER2-overexpressing tumors. Interestingly, the organ distribution pattern and the clearance rate of Eaff800 were different from those of Haff682. In conclusion, Eaff molecule labeled with a NIR fluorophore is a promising molecular imaging agent for EGFR-overexpressing tumors.
authors.affiliation: LI-COR Biosciences, Lincoln, NE, USA. herbert.gong@licor.com
authors.forename: Haibiao
authors.initials: H
authors.lastname: Gong
authors.forename: Joy
authors.initials: J
authors.lastname: Kovar
authors.forename: Garrick
authors.initials: G
authors.lastname: Little
authors.forename: Huaxian
authors.initials: H
authors.lastname: Chen
authors.forename: David Michael
authors.initials: DM
authors.lastname: Olive
mesh_terms: D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism*; D006801:Humans; D008301:Maleimides / Q000378:metabolism; D051379:Mice; D057054:Molecular Imaging / Q000379:methods*; D009374:Neoplasms, Experimental / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared; D023041:Xenograft Model Antitumor Assays
chemical_list: D005456:Fluorescent Dyes; D008301:Maleimides; D011993:Recombinant Fusion Proteins; C043592:maleimide; D066246:ErbB Receptors