两链肝细胞生长因子（tcHGF），成熟的HGF形式，与恶性肿瘤和抗癌药物抗性相关，其定量是癌症诊断的重要指标。 在肿瘤中，活化的tcHGF几乎不排出到全身循环中，表明tcHGF是分子成像使用正电子发射断层扫描（PET）的优秀靶点。 我们最近发现HGF抑制肽-8（HiP-8），它与人类tcHGF具有纳摩尔亲和力。 本研究旨在调查基于HiP-8的PET探针在人类HGF基因敲入人性化小鼠中的有用性。 使用交叉桥环状磺酰胺螯合物CB-TE1K1P合成了64Cu标记的HiP-8分子。 基于放射高性能液相色谱法的代谢稳定性分析显示，至少在15分钟内，超过90％的探针以完整形式存在于血液中。 在PET研究中，双肿瘤小鼠中，hHGF过表达肿瘤与hHGF阴性肿瘤相比，显著选择性显示了。 标记的HiP-8累积到过表达hHGF的肿瘤中，被竞争性抑制显著降低。 此外，磷酸化的MET / HGF受体的放射性和分布与组织中的HiP-8共定位。 这些结果表明，64Cu标记的HiP-8探针适用于体内tcHGF成像，分泌蛋白如tcHGF可以成为PET成像的靶点。

Two-chain hepatocyte growth factor (tcHGF), the mature form of HGF, is associated with malignancy and anticancer drug resistance; therefore, its quantification is an important indicator for cancer diagnosis. In tumors, activated tcHGF hardly discharges into the systemic circulation, indicating that tcHGF is an excellent target for molecular imaging using positron emission tomography (PET). We recently discovered HGF-inhibitory peptide-8 (HiP-8) that binds specifically to human tcHGF with nanomolar affinity. The purpose of this study was to investigate the usefulness of HiP-8-based PET probes in human HGF knock-in humanized mice. 64Cu-labeled HiP-8 molecules were synthesized using a cross-bridged cyclam chelator, CB-TE1K1P. Radio-high-performance liquid chromatography-based metabolic stability analyses showed that more than 90% of the probes existed in intact form in blood at least for 15 min. In PET studies, significantly selective visualization of hHGF-overexpressing tumors versus hHGF-negative tumors was observed in double-tumor-bearing mice. The accumulation of labeled HiP-8 into the hHGF-overexpressing tumors was significantly reduced by competitive inhibition. In addition, the radioactivity and distribution of phosphorylated MET/HGF receptor were colocalized in tissues. These results demonstrate that the 64Cu-labeled HiP-8 probes are suitable for tcHGF imaging in vivo, and secretory proteins like tcHGF can be a target for PET imaging.