Analogues of exendin-4 have been radiolabeled for imaging the glucagon-like peptide type 1 receptors (GLP-1R) which are overexpressed in insulinoma. The aim of this research was to synthesize an 18F–labeled silicon containing exendin-4 peptide (18F-2) and to evaluate its in vitro and in vivo behavior in CHL-GLP-1 receptor positive tumor-bearing mice. 18F–labeled silicon containing exendin-4 peptide (18F-2) was prepared via one-step nucleophilic substitution of a silane precursor with 18F–fluoride in the presence of acetic acid and K222. 18F-2 was then administered to tumor-bearing mice for PET imaging and ex vivo biodistribution experiments. 18F-2 was produced in a radiochemical yield (decay corrected) of 1.5% and a molar activity of max. 16 GBq/μmol. The GLP-1R positive tumors were clearly visualized by PET imaging. Biodistribution studies showed reduced uptake of 18F-2 in the kidneys compared to radiometal labeled exendin-4 derivatives. The radiotracer showed specific tumour uptake which remained steady over 2 h. This exendin-4 analogue, 18F-2, is a potential probe for imaging GLP-1R positive tumors.

中文翻译：

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含 18F 标记硅的 exendin-4 肽作为 PET 探针用于胰岛素瘤成像的放射合成和评估。

exendin-4 的类似物已被放射性标记，用于对在胰岛素瘤中过度表达的胰高血糖素样肽 1 型受体 (GLP-1R) 进行成像。本研究的目的是合成 18F 标记的含硅 exendin-4 肽 (18F-2) 并评估其在 CHL-GLP-1 受体阳性荷瘤小鼠中的体外和体内行为。在乙酸和 K222 存在下，通过用 18F-氟化物一步亲核取代硅烷前体制备 18F 标记的含硅 exendin-4 肽 (18F-2)。然后将 18F-2 施用于荷瘤小鼠进行 PET 成像和离体生物分布实验。18F-2 以 1.5% 的放射化学产率（衰减校正）和最大摩尔活性产生。16 GBq/μmol。GLP-1R 阳性肿瘤通过 PET 成像清晰可见。生物分布研究表明，与放射性金属标记的 exendin-4 衍生物相比，肾脏对 18F-2 的摄取减少。放射性示踪剂显示特定的肿瘤摄取，在 2 小时内保持稳定。这种 exendin-4 类似物 18F-2 是 GLP-1R 阳性肿瘤成像的潜在探针。