Tian Yaxin, Jiang Yanghongyan, Ma Ping, Ma Xiaowei, Du Liang, Wang Fengkui, Yu Xiaodong, Zhao Qian
Department of Nuclear Medicine, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China.
School of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia, China.
Front Oncol. 2024 Aug 30;14:1442601. doi: 10.3389/fonc.2024.1442601. eCollection 2024.
Fibroblast activation protein (FAP) is highly expressed in the mesenchyme of most malignant epithelial tumors, while its expression is low in normal tissues. FAP inhibitors (FAPIs) bind specifically to FAP and are used for tumor-targeted diagnosis and therapy. The aim of this study was to radiosynthesize a novel molecular probe I-FAPI and evaluate its targeting and biological characteristics.
The structurally modified FAPI was labelled with I through the chloramine-T method. The radiolabeling rate was then detected by thin-layer chromatography (TLC). The stability of I-FAPI was determined at PBS (room temperature) and serum (37°C). Its hydrophilicity was calculated by measuring its lipid-water partition coefficient. Pancreatic cancer PANC-1 cell line and glioma U87 cell line were cultured . Cell uptake assay was used to show the binding ability of I-FAPI. The CCK-8 assay was used to calculate the inhibitory effects of I-FAPI at different time points (4h, 8h, 12h, 24h, 48h) after comparing with the I and FAPI. The before-and-after-24h scratch areas of the two cells were determined in order to verify the effect of I-FAPI on the migration ability of the cells.
The radiolabeling rate was (84.9 ± 1.02) %. The radiochemical purity of I-FAPI remained over 80% in both 25°C PBS and 37°C serum. The value of the lipid-water partition coefficient was -0.869 ± 0.025, indicating the hydrophilic of the probe. The cellular uptake assay showed that U87 cells had a specific binding capacity for I-FAPI. In cell inhibition assays, the inhibitory effect of I-FAPI on U87 cells increased with time. The results of cell scratch assay showed that I-FAPI had the strongest inhibitory effect on the migratory ability of U87 cells compared with I and FAPI (<0.001).
I-FAPI was synthesized with good stability and hydrophilic properties. It can be specifically bound by U87 cells. The proliferation and migration of U87 cells can be effectively inhibited. I-FAPI is promising to become a therapeutic probe.
成纤维细胞活化蛋白（FAP）在大多数恶性上皮肿瘤的间充质中高表达，而在正常组织中表达较低。FAP抑制剂（FAPIs）特异性结合FAP，用于肿瘤靶向诊断和治疗。本研究的目的是放射性合成一种新型分子探针I-FAPI，并评估其靶向性和生物学特性。
通过氯胺-T法用碘标记结构修饰的FAPI。然后通过薄层色谱（TLC）检测放射性标记率。在PBS（室温）和血清（37°C）中测定I-FAPI的稳定性。通过测量其脂水分配系数计算其亲水性。培养胰腺癌PANC-1细胞系和胶质瘤U87细胞系。采用细胞摄取试验显示I-FAPI的结合能力。与碘和FAPI比较后，用CCK-8试验计算I-FAPI在不同时间点（4小时、8小时、12小时、24小时、48小时）的抑制作用。测定两种细胞24小时前后的划痕面积，以验证I-FAPI对细胞迁移能力的影响。
放射性标记率为（84.9±1.02）%。I-FAPI在25°C PBS和37°C血清中的放射化学纯度均保持在80%以上。脂水分配系数值为-0.869±0.025，表明该探针具有亲水性。细胞摄取试验表明，U87细胞对I-FAPI具有特异性结合能力。在细胞抑制试验中，I-FAPI对U87细胞的抑制作用随时间增加。细胞划痕试验结果表明，与碘和FAPI相比，I-FAPI对U87细胞迁移能力的抑制作用最强（<0.001）。
合成的I-FAPI具有良好的稳定性和亲水性。它能被U87细胞特异性结合。可有效抑制U87细胞的增殖和迁移。I-FAPI有望成为一种治疗探针。
