Synthesis and in vitro and in vivo evaluation of an (18)F-labeled neuropeptide Y analogue for imaging of breast cancer by PET
Hofmann S, Maschauer S, Kuwert T, Beck-Sickinger AG, Prante O (2015)
Publication Type: Journal article
Publication year: 2015
Journal
Book Volume: 12
Pages Range: 1121-30
Journal Issue: 4
DOI: 10.1021/mp500601z
Abstract
Imaging of Y1R expression in breast cancer is still a challenging task. Herein, we report a suitable (18)F-labeled high-molecular-weight glycopeptide for imaging of peripheral neuropeptide Y (NPY) Y1 receptor (Y1R)-positive tumors by preclinical small-animal positron emission tomography (PET). The Y1R-preferring NPY [F(7),P(34)]NPY analogue was functionalized with an alkyne-bearing propargylglycine (Pra) in position 4. The corresponding fluoroglycosylated (FGlc) peptide analogue [Pra(4)(FGlc),F(7),P(34)]NPY and its (18)F-labeled analogue were synthesized by click chemistry-based fluoroglycosylation. The radiosynthesis was performed by (18)F-fluoroglycosylation starting from the 2-triflate of the ?-mannosylazide and the alkyne peptide [Pra(4),F(7),P(34)]NPY. The radiosynthesis of the(18)F-labeled analogue was optimized using a minimum amount of peptide precursor (40 nmol), proceeding with an overall radiochemical yield of 20-25% (nondecay corrected) in a total synthesis time of 75 min with specific activities of 40-70 GBq/?mol. In comparison to NPY and [F(7),P(34)]NPY, in vitro Y1R and Y2R activation studies with the cold [Pra(4)(FGlc),F(7),P(34)]NPY on stably transfected COS-7 cells displayed a high potency for the induction of Y1R-specific inositol accumulation (pEC50 = 8.5 ± 0.1), whereas the potency at Y2R was significantly decreased. Internalization studies on stably transfected HEK293 cells confirmed a strong glycopeptide-mediated Y1R internalization and a substantial Y1R subtype selectivity over Y2R. In vitro autoradiography with Y1R-positive MCF-7 tumor tissue slices indicated high specific binding of the (18)F-labeled glycopeptide, when binding was reduced by 95% ([Pra(4),F(7),P(34)]NPY) and by 86% (BIBP3226 Y1R antagonist) in competition studies. Biodistribution and small-animal PET studies on MCF-7 breast tumor-bearing nude mice revealed radiotracer uptake in the MCF-7 tumor of 1.8%ID/g at 20 min p.i. and 0.7%ID/g at 120 min p.i. (n = 3-4), increasing tumor-to-blood ratios from 1.2 to 2.4, and a tumor retention of 76 ± 4% (n = 4; 45-90 min p.i.). PET imaging studies with MCF-7 tumor-bearing nude mice demonstrated uptake of the (18)F-labeled glycopeptide in the tumor region at 60 min p.i., whereas only negligible tumor uptake was observed in animals injected with a nonbinding (18)F-labeled glycopeptide pendant as a measure of nonspecific binding. In conclusion, PET imaging experiments with the (18)F-labeled NPY glycopeptide revealed Y1R-specific binding uptake in MCF-7 tumors in vivo together with decreased kidney uptake compared to DOTA-derivatives of this peptide. We consider this glycopeptide to be a potent lead peptide for the design of improved (18)F-glycopeptides with shorter amino acid sequences that would further facilitate PET imaging studies of Y1R-positive breast tumors.
Authors with CRIS profile
Simone Maschauer
Professur für Molekulare Bildgebung und Radiochemie
Torsten Kuwert
Lehrstuhl für Klinische Nuklearmedizin
Olaf Prante
Professur für Molekulare Bildgebung und Radiochemie
Involved external institutions
Germany (DE)How to cite
APA:
Hofmann, S., Maschauer, S., Kuwert, T., Beck-Sickinger, A.G., & Prante, O. (2015). Synthesis and in vitro and in vivo evaluation of an (18)F-labeled neuropeptide Y analogue for imaging of breast cancer by PET. Molecular Pharmaceutics, 12(4), 1121-30. https://doi.org/10.1021/mp500601z
MLA:
Hofmann, Sven, et al. "Synthesis and in vitro and in vivo evaluation of an (18)F-labeled neuropeptide Y analogue for imaging of breast cancer by PET." Molecular Pharmaceutics 12.4 (2015): 1121-30.
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