在人体中，神经肽Y（NPY）家族通过四种G蛋白偶联受体亚型发挥作用，分别是Y1、Y2、Y4和Y5。越来越多的证据表明，NPY系统参与了几种癌症，尤其是Y5亚型，因此可作为放射药物学发展中用于成像或靶向放射性核素治疗（TRT）的相关靶点。在这项研究中，使用[cPP（1-7），NPY（19-23），Ala31，Aib32，Gln34]hPP支架，简称为sY5ago，经过DOTA螯合剂修饰和68Ga和111In放射标记，然后通过MCF-7模型进行了体外和体内研究。在体内研究中，将MCF-7细胞正位移植入雌性裸鼠，并进行小动物正电子发射断层扫描/计算机断层扫描（μPET/CT）成像。成像结束后，将小鼠牺牲。同样经过DOTA螯合剂修饰的sY5ago的乱序版本作为阴性对照组（DOTA-[Nle]sY5ago_scrambled）。 sY5ago和DOTA-sY5ago对Y5具有亚纳摩尔级别的亲和力（分别为0.9 ± 0.1和0.8 ± 0.1 nM），并且在Y5上鉴定到单个结合位点。[68Ga]Ga-DOTA-sY5ago和[111In]In-DOTA-sY5ago具有亲水性，并显示出高度特异性的内化（1 h时为1.61 ± 0.75%/106个细胞）和适度的外流（45 min时将总结合物的55%外流）。在μPET/CT图像中，大部分信号显示在肾脏和肝脏中。MCF-7肿瘤清晰可见。在生物分布研究中，[68Ga]Ga-DOTA-sY5ago主要通过肾脏排泄（约60%ID/g）。肾脏摄取是Y5介导的。在肝脏（5.09 ± 1.15 %ID/g vs 1.13 ± 0.21 %ID/g，p < 0.05）、肺部（1.03 ± 0.34 %ID/g vs 0.20 %ID/g，p < 0.05）和脾脏（0.85 ± 0.09%ID/g vs 0.16 ± 0.16%ID/g，p < 0.05）中还观察到特异性摄取。在MCF-7肿瘤中，[68Ga]Ga-DOTA-sY5ago在注射后1 h的摄取量比[68Ga]Ga-DOTA-[Nle]sY5ago_scrambled高出12倍（分别为3.43 ± 2.32 vs 0.27 ± 0.15 %ID/g，p = 0.0008）。最后，在人体原癌样本上进行的组织显微成像研究显示了[111In]In-DOTA-sY5ago在前列腺原发性病灶中的弱结合和ISUP1病变中的高结合，而正常前列腺没有信号。

The neuropeptide-Y (NPY) family acts through four G protein-coupled receptor subtypes in humans, namely, Y1, Y2, Y4, and Y5. A growing body of evidence suggest the involvement of the NPY system in several cancers, notably the Y5 subtype, thus acting as a relevant target for the development of radiopharmaceuticals for imaging or targeted radionuclide therapy (TRT). Here, the [cPP(1-7),NPY(19-23),Ala31,Aib32,Gln34]hPP scaffold, further referred to as sY5ago, was modified with a DOTA chelator and radiolabeled with 68Ga and 111In and investigated in vitro and in vivo using the MCF-7 model. For in vivo studies, MCF-7 cells were orthotopically implanted in female nude mice and imaging with small animal positron emission tomography/computed tomography (μPET/CT) was performed. At the end of imaging, the mice were sacrificed. A scrambled version of sY5ago, which was also modified with a DOTA chelator, served as a negative control (DOTA-[Nle]sY5ago_scrambled). sY5ago and DOTA-sY5ago showed subnanomolar affinity toward the Y5 (0.9 ± 0.1 and 0.8 ± 0.1 nM, respectively) and a single binding site at the Y5 was identified. [68Ga]Ga-DOTA-sY5ago and [111In]In-DOTA-sY5ago were hydrophilic and showed high specific internalization (1.61 ± 0.75%/106 cells at 1 h) and moderate efflux (55% of total binding externalized at 45 min). On μPET/CT images, most of the signal was depicted in the kidneys and the liver. MCF-7 tumors were clearly visualized. On biodistribution studies, [68Ga]Ga-DOTA-sY5ago was eliminated by the kidneys (∼60 %ID/g). The kidney uptake is Y5-mediated. A specific uptake was also noted in the liver (5.09 ± 1.15 %ID/g vs 1.13 ± 0.21 %ID/g for [68Ga]Ga-DOTA-[Nle]sY5ago_scrambled, p < 0.05), the lungs (1.03 ± 0.34 %ID/g vs 0.20 %ID/g, p < 0.05), and the spleen (0.85 ± 0.09%ID/g vs 0.16 ± 0.16%ID/g, p < 0.05). In MCF-7 tumors, [68Ga]Ga-DOTA-sY5ago showed 12-fold higher uptake than [68Ga]Ga-DOTA-[Nle]sY5ago_scrambled (3.43 ± 2.32 vs 0.27 ± 0.15 %ID/g, respectively, p = 0.0008) at 1 h post-injection. Finally, a proof-of-principle tissular micro-imaging study on a human primary cancer sample showed weak binding of [111In]In-DOTA-sY5ago in prostatic intra-neoplasia and high binding in the ISUP1 lesion while normal prostate was free of signal.