PET Imaging of Dll4 Expression in Glioblastoma and Colorectal Cancer Xenografts Using (64)Cu-Labeled Monoclonal Antibody 61B.
Delta-like ligand 4 (Dll4) expressed in tumor cells plays a key role to promote tumor growth of numerous cancer types. Based on a novel antihuman Dll4 monoclonal antibody (61B), we developed a (64)Cu-labeled probe for positron emission tomography (PET) imaging of tumor Dll4 expression. In this study, 61B was conjugated with the (64)Cu-chelator DOTA through lysine on the antibody. Human IgG (hIgG)-DOTA, which did not bind to Dll4, was also prepared as a control. The Dll4 binding activity of the probes was evaluated through the bead-based binding assay with Dll4-alkaline phosphatase. The resulting PET probes were evaluated in U87MG glioblastoma and HT29 colorectal cancer xenografts in athymic nude mice. Our results demonstrated that the 61B-DOTA retained (77.2 ± 3.7) % Dll4 binding activity of the unmodified 61B, which is significantly higher than that of hIgG-DOTA (0.06 ± 0.03) %. Confocal microscopy analysis confirmed that 61B-Cy5.5, but not IgG-Cy5.5, predominantly located within the U87MG and HT29 cells cytoplasm. U87MG cells showed higher 61B-Cy5.5 binding as compared to HT29 cells. In U87MG xenografts, 61B-DOTA-(64)Cu demonstrated remarkable tumor accumulation (10.5 ± 1.7 and 10.2 ± 1.2%ID/g at 24 and 48 h postinjection, respectively). In HT29 xenografts, tumor accumulation of 61B-DOTA-(64)Cu was significantly lower than that of U87MG (7.3 ± 1.3 and 6.6 ± 1.3%ID/g at 24 and 48 h postinjection, respectively). The tumor accumulation of 61B-DOTA-(64)Cu was significantly higher than that of hIgG-DOTA-(64)Cu in both xenografts models. Immunofluorescence staining of the tumor tissues further confirmed that tumor accumulation of 61B-Cy5.5 was correlated well with in vivo PET imaging data using 61B-DOTA-(64)Cu. In conclusion, 61B-DOTA-(64)Cu PET probe was successfully synthesized and demonstrated prominent tumor uptake by targeting Dll4. 61B-DOTA-(64)Cu has great potential to be used for noninvasive Dll4 imaging, which could be valuable for tumor detection, Dll4 expression level evaluation, and Dll4-based treatment monitoring.
Department of Radiology, The Third Affiliated Hospital of Sun Yat-sen University , Guangzhou 510630, China.|Biomedical Research Imaging Center, Department of Radiology, University of North Carolina , Chapel Hill, North Carolina 27514, United States.
Bin
B
Zhou
Biomedical Research Imaging Center, Department of Radiology, University of North Carolina , Chapel Hill, North Carolina 27514, United States.
Hui
H
Wang
Department of Pathology, University of Southern California , Los Angeles, California 90033, United States.
Ren
R
Liu
Biomedical Research Imaging Center, Department of Radiology, University of North Carolina , Chapel Hill, North Carolina 27514, United States.
Mengzhe
M
Wang
Biomedical Research Imaging Center, Department of Radiology, University of North Carolina , Chapel Hill, North Carolina 27514, United States.
Huaifu
H
Deng
Biomedical Research Imaging Center, Department of Radiology, University of North Carolina , Chapel Hill, North Carolina 27514, United States.
Benjamin C
BC
Giglio
Department of Pathology, University of Southern California , Los Angeles, California 90033, United States.
Parkash S
PS
Gill
Department of Radiology, The Third Affiliated Hospital of Sun Yat-sen University , Guangzhou 510630, China.|Interventional Radiology Institute, Sun Yat-sen University , Guangzhou 510630, China.
Hong
H
Shan
Biomedical Research Imaging Center, Department of Radiology, University of North Carolina , Chapel Hill, North Carolina 27514, United States.
Zibo
Z
Li
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000627:therapeutic use; D002135:Calcium-Binding Proteins; D045744:Cell Line, Tumor / Q000637:transplantation; D015179:Colorectal Neoplasms / Q000378:metabolism*; D003301:Copper Radioisotopes / Q000627:therapeutic use; D005260:Female; D005909:Glioblastoma / Q000378:metabolism*; D019073:HT29 Cells / Q000637:transplantation; D006573:Heterocyclic Compounds, 1-Ring / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000276:immunology; D051379:Mice; D008819:Mice, Nude; D018613:Microscopy, Confocal; D009368:Neoplasm Transplantation; D049268:Positron-Emission Tomography
D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins; D003301:Copper Radioisotopes; C424126:DLL4 protein, human; D006573:Heterocyclic Compounds, 1-Ring; D036341:Intercellular Signaling Peptides and Proteins; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid
64Cu; Dll4; colorectal cancer; glioblastoma; microPET