N.N. Blokhin National Medical Research Center of Oncology of the Ministry of Public Health of the Russian Federation (N.N. Blokhin NMRCO), Kashirskoe Shosse, 23, 115478 Moscow, Russia.
N.I. Vavilov Institute of General Genetics RAS, Gubkina Street, 3, GSP-1, 119991 Moscow, Russia.
Int J Mol Sci. 2024 Sep 23;25(18):10197. doi: 10.3390/ijms251810197.
Tc is a well-known radionuclide that is widely used and readily available for SPECT/CT (Single-Photon Emission Computed Tomography) diagnosis. However, commercial isotope carriers are not specific enough to tumours, rapidly clear from the bloodstream, and are not safe. To overcome these limitations, we suggest immunologically compatible recombinant proteins containing a combination of metal binding sites as Tc chelators and several different tumour-specific ligands for early detection of tumours. E1b protein containing metal-binding centres and tumour-specific ligands targeting integrin αβ and nucleolin, as well as a short Cys-rich sequence, was artificially constructed. It was produced in , purified by metal-chelate chromatography, and used to obtain a complex with Tc. This was administered intravenously to healthy Balb/C mice at an activity dose of about 80 MBq per mouse, and the biodistribution was studied by SPECT/CT for 24 h. Free sodium Tc-pertechnetate at the same dose was used as a reference. The selectivity of Tc-E1b and the kinetics of isotope retention in tumours were then investigated in experiments in C57Bl/6 and Balb/C mice with subcutaneously transplanted lung carcinoma (LLC) or mammary adenocarcinoma (Ca755, EMT6, or 4T1). The radionuclide distribution ratio in tumour and adjacent normal tissue (T/N) steadily increased over 24 h, reaching 15.7 ± 4.2 for EMT6, 16.5 ± 3.8 for Ca755, 6.7 ± 4.2 for LLC, and 7.5 ± 3.1 for 4T1.
锝是一种广泛使用的放射性核素，可用于 SPECT/CT（单光子发射计算机断层扫描）诊断。然而，商业同位素载体对肿瘤的特异性不够强，会迅速从血液中清除，并且不够安全。为了克服这些限制，我们建议使用免疫相容性的重组蛋白，其中包含金属结合位点的组合作为锝螯合剂和几种不同的肿瘤特异性配体，以用于肿瘤的早期检测。人工构建了含有金属结合中心和针对整合素αβ和核仁素的肿瘤特异性配体的 E1b 蛋白，以及一个短的富含半胱氨酸的序列。它在大肠杆菌中表达，通过金属螯合层析进行纯化，并用于获得与 Tc 的复合物。将其以约 80 MBq/只的活度剂量静脉注射到健康的 Balb/C 小鼠中，并通过 SPECT/CT 在 24 小时内研究其生物分布。以相同剂量的游离钠 Tc-高锝酸盐作为参考。然后，在皮下移植的肺癌（LLC）或乳腺腺癌（Ca755、EMT6 或 4T1）的 C57Bl/6 和 Balb/C 小鼠实验中研究了 Tc-E1b 的选择性和同位素在肿瘤中的保留动力学。肿瘤和相邻正常组织（T/N）中的放射性核素分布比在 24 小时内稳定增加，达到 EMT6 为 15.7 ± 4.2，Ca755 为 16.5 ± 3.8，LLC 为 6.7 ± 4.2，4T1 为 7.5 ± 3.1。
