Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, 48471-93698, Sari, Mazandaran, Iran.
Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran.
Ann Nucl Med. 2020 Jul;34(7):460-466. doi: 10.1007/s12149-020-01472-9. Epub 2020 May 10.
The APT is an aptide specific to the extra domain B (EDB) of fibronectin with high affinity for EDB, which is expressed in malignant tumors including brain cancer (U87MG) and colorectal cancer (HT-29). Aim of this study was to evaluate the [Tc] Tc-APT potential as an imaging probe for colorectal cancer.
Radiochemical purity was evaluated by HPLC and radio-isotope TLC scanner. Blocking study for specific binding assay and affinity calculation (K) on HT-29 cell lines were also carried out. Planar imaging and bio-distribution studies were performed in HT-29 tumor-bearing mice.
The APT was efficiently labeled with technetium-99m in high radiochemical yield (up to 97%). Cellular binding study demonstrated specific binding of the [Tc] Tc-APT in cultured HT-29 cells. The K value was found to be 40.46 ± 13.39 nM. The tumor-to-muscle ratio was ~ 1.5 in ex vivo bio-distribution study at 1 h after injection. Planar imaging study showed higher activity accumulation in EDB expressing HT-29 tumor relative to muscle (used as control) (~ 1.7) at 1 h.
Although more studies are required to find out the full potential of this radio-ligand as an imaging probe, the present results nevertheless provide useful information about [Tc] Tc-APT, which might be beneficial in design and development of new [Tc] Tc-APT for efficient targeting of tumor in vivo.
APT 是一种对纤维连接蛋白的额外结构域 B（EDB）具有高亲和力的 aptide，在包括脑癌（U87MG）和结直肠癌（HT-29）在内的恶性肿瘤中表达。本研究旨在评估 [Tc]Tc-APT 作为结直肠癌成像探针的潜力。
通过 HPLC 和放射性同位素 TLC 扫描仪评估放射化学纯度。还进行了针对 HT-29 细胞系的特异性结合测定和亲和力计算（K）的阻断研究。在 HT-29 荷瘤小鼠中进行了平面成像和生物分布研究。
APT 与锝-99m 的标记效率高，放射化学产率高达 97%。细胞结合研究表明，[Tc]Tc-APT 在培养的 HT-29 细胞中具有特异性结合。发现 K 值为 40.46±13.39 nM。在注射后 1 小时的离体生物分布研究中，肿瘤与肌肉的比值约为 1.5。平面成像研究显示，在表达 EDB 的 HT-29 肿瘤中，与肌肉（用作对照）相比，放射性配体的活性积累更高（约 1.7）。
尽管需要更多的研究来发现这种放射性配体作为成像探针的全部潜力，但目前的结果仍然提供了有关 [Tc]Tc-APT 的有用信息，这可能有助于设计和开发新的 [Tc]Tc-APT，以实现体内肿瘤的有效靶向。
