title: In vivo NIRF imaging-guided delivery of a novel NGR-VEGI fusion protein for targeting tumor vasculature.
abstract: Pathological angiogenesis is crucial in tumor growth, invasion and metastasis. Previous studies demonstrated that the vascular endothelial growth inhibitor (VEGI), a member of the tumor necrosis factor superfamily, can be used as a potent endogenous inhibitor of tumor angiogenesis. Molecular probes containing the asparagine-glycine-arginine (NGR) sequence can specifically bind to CD13 receptor which is overexpressed on neovasculature and several tumor cells. Near-infrared fluorescence (NIRF) optical imaging for targeting tumor vasculature offers a noninvasive method for early detection of tumor angiogenesis and efficient monitoring of response to anti-tumor vasculature therapy. The aim of this study was to develop a new NIRF imaging probe on the basis of an NGR-VEGI protein for the visualization of tumor vasculature. The NGR-VEGI fusion protein was prepared from prokaryotic expression, and its function was characterized in vitro. The NGR-VEGI protein was then labeled with a Cy5.5 fluorophore to afford Cy5.5-NGR-VEGI probe. Using the NIRF imaging technique, we visualized and quantified the specific delivery of Cy5.5-NGR-VEGI protein to subcutaneous HT-1080 fibrosarcoma tumors in mouse xenografts. The Cy5.5-NGR-VEGI probe exhibited rapid HT-1080 tumor targeting, and highest tumor-to-background contrast at 8 h post-injection (pi). Tumor specificity of Cy5.5-NGR-VEGI was confirmed by effective blocking of tumor uptake in the presence of unlabeled NGR-VEGI (20 mg/kg). Ex vivo NIRF imaging further confirmed in vivo imaging findings, demonstrating that Cy5.5-NGR-VEGI displayed an excellent tumor-to-muscle ratio (18.93 ± 2.88) at 8 h pi for the non-blocking group and significantly reduced ratio (4.92 ± 0.75) for the blocking group. In conclusion, Cy5.5-NGR-VEGI provided highly sensitive, target-specific, and longitudinal imaging of HT-1080 tumors. As a novel theranostic protein, Cy5.5-NGR-VEGI has the potential to improve cancer treatment by targeting tumor vasculature.
authors.affiliation: Department of Radiology, Molecular Imaging Center, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC 103, Los Angeles, CA, 90033-9061, USA.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Ma
authors.forename: Guoquan
authors.initials: G
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Weidong
authors.initials: W
authors.lastname: Yang
authors.forename: Yingqi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Peter S
authors.initials: PS
authors.lastname: Conti
authors.forename: Kai
authors.initials: K
authors.lastname: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis; D002232:Carbocyanines / Q000737:chemistry; D016503:Drug Delivery Systems / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D057054:Molecular Imaging; D015335:Molecular Probes / Q000737:chemistry; D009369:Neoplasms / Q000737:chemistry / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D009389:Neovascularization, Pathologic / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D009842:Oligopeptides / Q000008:administration & dosage* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019265:Spectroscopy, Near-Infrared; D053380:Tumor Necrosis Factor Ligand Superfamily Member 15 / Q000008:administration & dosage* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: C098793:CY5.5 cyanine dye; D002232:Carbocyanines; D005456:Fluorescent Dyes; D015335:Molecular Probes; C526428:NGR peptide; D009842:Oligopeptides; C117026:TNFSF15 protein, human; D053380:Tumor Necrosis Factor Ligand Superfamily Member 15