title: Coupling Gd‑DTPA with a bispecific, recombinant protein anti‑EGFR‑iRGD complex improves tumor targeting in MRI.
abstract: Recombinant anti‑epidermal growth factor receptor‑internalizing arginine‑glycine‑aspartic acid (anti‑EGFR single‑domain antibody fused with iRGD peptide) protein efficiently targets the EGFR extracellular domain and integrin αvβ/β5, and shows a high penetration into cells. Thus, this protein may improve penetration of conjugated drugs into the deep zone of gastric cancer multicellular 3D spheroids. In the present study, a novel tumor‑targeting contrast agent for magnetic resonance imaging (MRI) was developed, by coupling gadolinium‑diethylene triamine pentaacetate (Gd‑DTPA) with the bispecific recombinant anti‑EGFR‑iRGD protein. The anti‑EGFR‑iRGD protein was extracted from Escherichia coli and Gd was loaded onto the recombinant protein by chelation using DTPA anhydride. Single‑targeting agent anti‑EGFR‑DTPA‑Gd, which served as the control, was also prepared. The results of the present study showed that anti‑EGFR‑iRGD‑DTPA‑Gd exhibited no significant cyto-toxicity to human gastric carcinoma cells (BGC‑823) under the experimental conditions used. Compared with a conventional contrast agent (Magnevist), anti‑EGFR‑iRGD‑DTPA‑Gd showed higher T1 relaxivity (10.157/mM/sec at 3T) and better tumor‑targeting ability. In addition, the signal intensity and the area under curve for the enhanced signal time in tumor, in vivo, were stronger than Gd‑DTPA alone or the anti‑EGFR‑Gd control. Thus, Gd‑labelled anti‑EGFR‑iRGD has potential as a tumor‑targeting contrast agent for improved MRI.
authors.affiliation: Department of Radiology, Affiliated Drum‑Tower Hospital of Nanjing University Medical School, Nanjing 210008, P.R. China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Xin
authors.affiliation: The Comprehensive Cancer Center of Drum‑Tower Hospital, Medical School of Nanjing University and Clinical Cancer Institute of Nanjing University, Nanjing 210008, P.R. China.
authors.forename: Huizi
authors.initials: H
authors.lastname: Sha
authors.affiliation: Department of Nuclear Medicine, Affiliated Drum‑Tower Hospital of Nanjing University Medical School, Nanjing 210008, P.R. China.
authors.forename: Jingtao
authors.initials: J
authors.lastname: Shen
authors.affiliation: Department of Radiology, Affiliated Drum‑Tower Hospital of Nanjing University Medical School, Nanjing 210008, P.R. China.
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Affiliated Drum‑Tower Hospital of Nanjing University Medical School, Nanjing 210008, P.R. China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.affiliation: The Comprehensive Cancer Center of Drum‑Tower Hospital, Medical School of Nanjing University and Clinical Cancer Institute of Nanjing University, Nanjing 210008, P.R. China.
authors.forename: Baorui
authors.initials: B
authors.lastname: Liu
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000493:pharmacokinetics* / Q000633:toxicity; D019540:Area Under Curve; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003287:Contrast Media / Q000493:pharmacokinetics* / Q000633:toxicity; D066246:ErbB Receptors / Q000276:immunology; D019786:Gadolinium DTPA / Q000493:pharmacokinetics* / Q000633:toxicity; D006801:Humans; D020128:Inhibitory Concentration 50; D008279:Magnetic Resonance Imaging; D008297:Male; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011994:Recombinant Proteins / Q000493:pharmacokinetics / Q000633:toxicity
chemical_list: D018033:Antibodies, Bispecific; D003287:Contrast Media; D011994:Recombinant Proteins; C512478:EGFR protein, human; D066246:ErbB Receptors; D019786:Gadolinium DTPA