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Am J Nucl Med Mol Imaging 2011;1(1):65-75.
Original article
Peptoid-based PET imaging of vascular endothelial growth factor receptor
(VEGFR) expression
Guiyang Hao, Asghar Hajibeigi, Luis M. De León-Rodríguez, Orhan K. Öz, Xiankai Sun
Department of Radiology, Advanced Imaging Research Center, The University of Texas Southwestern Medical Center at Dallas,
Dallas, Texas, United States of America. Department of Chemistry, University of Guanajuato, Guanajuato, Mexico.
Received July 28, 2011; accepted August 1, 2011; Epub August 2, 2011; Published August 15, 2011
Abstract: Non-invasive detection of vascular endothelial growth factor receptor 2 (VEGFR2) by positron emission tomography (PET)
would allow the evaluation of tumor vascular activity in vivo. Recently a dimeric peptoid, GU40C4, was reported as a highly potent
antagonist of VEGFR2 activation inhibiting angiogenesis and tumor growth in vivo. The purpose of this work was to evaluate the
potential of this peptoid for PET imaging of VEGFR2 expression. To label GU40C4 and a control peptoid with a positron emitter,
64Cu (t1/2 = 12.7 h; β+: 0.653 MeV, 17.4%), a cysteine was introduced to the C-terminus of the peptoids and then conjugated to a
bifunctional chelator (DOTA: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) through the maleimide-thiol coupling
chemistry. The in vitro binding assay showed a negligible effect of the DOTA conjugation on the VEGFR2 binding affinity of GU40C4.
Both peptoid conjugates were efficiently labeled with 64Cu in high radiochemical yields (> 90%); the specific activity was in the range
of 10 – 80 GBq/μmol. PET imaging evaluation using a prostate cancer xenograft (PC3) mouse model showed that 64Cu-DOTA-
GU40C4 had a prominent and steady accumulation in the VEGFR2 positive PC3 tumors (2.25 ± 0.24, 2.15 ± 0.34, and 1.90 ± 0.18 %
ID/g at 1, 4, and 20 h p.i., respectively; n = 3), which is significantly higher than the control peptoid conjugate (0.3 – 0.5 %ID/g; p <
0.001 at 1, 4, and 20 h p.i.). Interestingly, the mouse salivary glands were also clearly visualized by 64Cu-DOTA-GU40C4 (3.17 ±
0.25, 3.00 ± 0.36, and 1.83 ± 0.21 %ID/g at 1, 4, and 20 h p.i., respectively; n = 3) rather than its control peptoid conjugate. VEGFR2
expression in the salivary glands was shown by polymerase chain reaction (PCR) assay. Our results demonstrate that 64Cu-DOTA-
GU40C4 can be used to image the expression of VEGFR2 in vivo. (ajnmmi1107002).
Keywords: VEGFR2, peptoid, PET, 64Cu, prostate cancer, tumor angiogenesis
Full text PDF
Address all correspondence to:
Dr. Xiankai Sun
Department of Radiology
Advanced Imaging Research Center
The University of Texas Southwestern Medical Center at Dallas
Dallas, TX, USA.
E-mail: xiankai.sun@utsouthwestern.edu
Original article
Peptoid-based PET imaging of vascular endothelial growth factor receptor
(VEGFR) expression
Guiyang Hao, Asghar Hajibeigi, Luis M. De León-Rodríguez, Orhan K. Öz, Xiankai Sun
Department of Radiology, Advanced Imaging Research Center, The University of Texas Southwestern Medical Center at Dallas,
Dallas, Texas, United States of America. Department of Chemistry, University of Guanajuato, Guanajuato, Mexico.
Received July 28, 2011; accepted August 1, 2011; Epub August 2, 2011; Published August 15, 2011
Abstract: Non-invasive detection of vascular endothelial growth factor receptor 2 (VEGFR2) by positron emission tomography (PET)
would allow the evaluation of tumor vascular activity in vivo. Recently a dimeric peptoid, GU40C4, was reported as a highly potent
antagonist of VEGFR2 activation inhibiting angiogenesis and tumor growth in vivo. The purpose of this work was to evaluate the
potential of this peptoid for PET imaging of VEGFR2 expression. To label GU40C4 and a control peptoid with a positron emitter,
64Cu (t1/2 = 12.7 h; β+: 0.653 MeV, 17.4%), a cysteine was introduced to the C-terminus of the peptoids and then conjugated to a
bifunctional chelator (DOTA: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) through the maleimide-thiol coupling
chemistry. The in vitro binding assay showed a negligible effect of the DOTA conjugation on the VEGFR2 binding affinity of GU40C4.
Both peptoid conjugates were efficiently labeled with 64Cu in high radiochemical yields (> 90%); the specific activity was in the range
of 10 – 80 GBq/μmol. PET imaging evaluation using a prostate cancer xenograft (PC3) mouse model showed that 64Cu-DOTA-
GU40C4 had a prominent and steady accumulation in the VEGFR2 positive PC3 tumors (2.25 ± 0.24, 2.15 ± 0.34, and 1.90 ± 0.18 %
ID/g at 1, 4, and 20 h p.i., respectively; n = 3), which is significantly higher than the control peptoid conjugate (0.3 – 0.5 %ID/g; p <
0.001 at 1, 4, and 20 h p.i.). Interestingly, the mouse salivary glands were also clearly visualized by 64Cu-DOTA-GU40C4 (3.17 ±
0.25, 3.00 ± 0.36, and 1.83 ± 0.21 %ID/g at 1, 4, and 20 h p.i., respectively; n = 3) rather than its control peptoid conjugate. VEGFR2
expression in the salivary glands was shown by polymerase chain reaction (PCR) assay. Our results demonstrate that 64Cu-DOTA-
GU40C4 can be used to image the expression of VEGFR2 in vivo. (ajnmmi1107002).
Keywords: VEGFR2, peptoid, PET, 64Cu, prostate cancer, tumor angiogenesis
Full text PDF
Address all correspondence to:
Dr. Xiankai Sun
Department of Radiology
Advanced Imaging Research Center
The University of Texas Southwestern Medical Center at Dallas
Dallas, TX, USA.
E-mail: xiankai.sun@utsouthwestern.edu
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