Department of Nuclear Medicine, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Binhu District, Wuxi 214062, P.R. China.
Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, 651 Dongfeng Road East, Guangzhou 510060, P.R. China.
Mol Pharm. 2023 Aug 7;20(8):4277-4284. doi: 10.1021/acs.molpharmaceut.3c00321. Epub 2023 Jul 18.
Integrin α6 has been considered a promising biomarker, is overexpressed in many tumors, and plays a vital role in tumor formation, recurrence, and metastasis. In this study, we identified a novel high-affinity integrin α6-targeted peptide named RD (Arg-Trp-Tyr-Asp-PEG4)-Lys-Lys and developed a F-radiolabeled peptide tracer ([F]-AlF-NOTA-RD) and evaluated its potential application in positron emission tomography (PET) imaging of pancreatic cancer. [F]-AlF-NOTA-RD was produced using GMP (Good Manufacturing Practice of Medical Products)-compliant automatic radiosynthesis on a single GE FASTLab2 cassette-type synthesis module. The stability of [F]-AlF-NOTA-RD was analyzed in phosphate-buffered saline (PBS) and fetal bovine serum (FBS). The cell uptake assay of the tracer was assessed using PANC-1 cells. In addition, small-animal PET imaging and biodistribution studies of [F]-AlF-NOTA-RD were performed in pancreatic cancer subcutaneous tumor-bearing mice. The PET tracer [F]-AlF-NOTA-RD was obtained with a radiochemical yield of 23.7 ± 4.7%, radiochemical purity of >99%, and molar activity of 165.7 ± 59.1 GBq/μmol. [F]-AlF-NOTA-RD exhibited good in vitro stability in PBS and FBS. LogP octanol water value for the tracer was -2.28 ± 0.05 ( = 3). The binding affinity of RD to the integrin α6 protein ( = 0.13 ± 3.65 μM, = 3) was significantly higher than that of the RWY (CRWYDENAC) ( = 6.97 ± 1.44 μM, = 3). Small-animal PET imaging and biodistribution also revealed that [F]-AlF-NOTA-RD displayed rapid and good tumor uptake and lower liver background uptake in PANC-1 tumor-bearing mice. [F]-AlF-NOTA-RD showed significant radioactivity accumulation in tumors and was successfully blocked by NOTA-RD. Compared with [F]-FDG, [F]-AlF-NOTA-RD PET imaging and biodistribution studies in PANC-1 xenograft tumor-bearing mice confirmed a good tumor-to-muscle ratio (8.69 ± 2.03 vs 1.41 ± 0.23, respectively) at 0.5 h and (2.99 ± 3.02 vs 1.43 ± 0.17, respectively) at 1 h post injection. Autoradiography of human pancreatic cancer tumor tissues further confirmed high accumulation of [F]-AlF-NOTA-RD. In summary, we developed an optimized integrin α6-targeted imaging tracer and obtained high radioactivity products with a cassette-type synthesis module; moreover, the tracer exhibited good binding affinity with integrin α6 and good target specificity for PANC-1 cells in xenograft pancreatic tumor-bearing mice, demonstrating its promising application as a noninvasive PET radiotracer of integrin α6 expression in pancreatic cancer.
整合素 α6 已被认为是一种很有前途的生物标志物,在许多肿瘤中过度表达,在肿瘤的形成、复发和转移中发挥着重要作用。在这项研究中,我们鉴定了一种新型高亲和力整合素 α6 靶向肽,命名为 RD(精氨酸-色氨酸-酪氨酸-天冬氨酸-聚乙二醇 4)-赖氨酸-赖氨酸,并开发了一种 F-放射性标记肽示踪剂([F]-AlF-NOTA-RD),并评估了其在胰腺癌正电子发射断层扫描(PET)成像中的潜在应用。[F]-AlF-NOTA-RD 是使用符合 GMP(医疗产品良好生产规范)的自动放射性合成在单个 GE FASTLab2 盒式合成模块上生产的。在磷酸盐缓冲盐水(PBS)和胎牛血清(FBS)中分析了[F]-AlF-NOTA-RD 的稳定性。使用 PANC-1 细胞评估了示踪剂的细胞摄取实验。此外,在胰腺癌皮下肿瘤荷瘤小鼠中进行了[F]-AlF-NOTA-RD 的小动物 PET 成像和生物分布研究。放射性示踪剂[F]-AlF-NOTA-RD 的放射化学产率为 23.7±4.7%,放射化学纯度>99%,摩尔活度为 165.7±59.1GBq/μmol。[F]-AlF-NOTA-RD 在 PBS 和 FBS 中表现出良好的体外稳定性。示踪剂的辛醇-水分配系数(logP)值为-2.28±0.05(n=3)。RD 与整合素 α6 蛋白的结合亲和力(=0.13±3.65μM,n=3)明显高于 RWY(CRWYDENAC)(=6.97±1.44μM,n=3)。小动物 PET 成像和生物分布也表明,[F]-AlF-NOTA-RD 在 PANC-1 肿瘤荷瘤小鼠中显示出快速良好的肿瘤摄取和较低的肝脏背景摄取。[F]-AlF-NOTA-RD 在肿瘤中有明显的放射性积聚,并用 NOTA-RD 成功阻断。与[F]-FDG 相比,[F]-AlF-NOTA-RD 在 PANC-1 异种移植肿瘤荷瘤小鼠中的 PET 成像和生物分布研究证实,在 0.5 h 时肿瘤与肌肉的比值(分别为 8.69±2.03 和 1.41±0.23)和 1 h 时(分别为 2.99±3.02 和 1.43±0.17)均较高。人胰腺癌细胞组织的放射自显影进一步证实了[F]-AlF-NOTA-RD 的高积累。总之,我们开发了一种优化的整合素 α6 靶向成像示踪剂,并使用盒式合成模块获得了高放射性产物;此外,示踪剂在异种移植胰腺癌荷瘤小鼠中与整合素 α6 具有良好的结合亲和力,对 PANC-1 细胞具有良好的靶向特异性,表明其作为一种非侵入性的正电子发射断层扫描(PET)示踪剂,可用于检测胰腺癌中整合素 α6 的表达,具有广阔的应用前景。