Peptoid-based PET imaging of vascular endothelial growth factor receptor (VEGFR) expression

American Journal of Nuclear Medicine and Molecular Imaging

Xiankai Sun¹  Luis M. De León-Rodríguez¹  Orhan K. Öz¹  Guiyang Hao¹  Asghar Hajibeigi¹ 

关键词: VEGFR2;    peptoid;    PET;    64Cu;    prostate cancer;    tumor angiogenesis;   

DOI  :  

学科分类：过敏症与临床免疫学

来源: e-Century Publishing Corporation

【 摘 要 】

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 (t_1/2 = 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.

【 授权许可】

Unknown