多个负电荷对99mTc标记的二聚体环状RGD肽的血液清除率和生物分布特征的影响

Impact of multiple negative charges on blood clearance and biodistribution characteristics of 99mTc-labeled dimeric cyclic RGD peptides.

作者信息

Yang Yong, Ji Shundong, Liu Shuang

机构信息

School of Health Sciences, Purdue University , 550 Stadium Mall Drive, West Lafayette, Indiana 47907, United States.

出版信息

Bioconjug Chem. 2014 Sep 17;25(9):1720-9. doi: 10.1021/bc500309r. Epub 2014 Aug 21.

DOI:10.1021/bc500309r

PMID:25144854

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4166031/

Abstract

This study sought to evaluate the impact of multiple negative charges on blood clearance kinetics and biodistribution properties of (99m)Tc-labeled RGD peptide dimers. Bioconjugates HYNIC-P6G-RGD2 and HYNIC-P6D-RGD2 were prepared by reacting P6G-RGD2 and P6D-RGD2, respectively, with excess HYNIC-OSu in the presence of diisopropylethylamine. Their IC50 values were determined to be 31 ± 5 and 41 ± 6 nM, respectively, against (125)I-echistatin bound to U87MG glioma cells in a whole-cell displacement assay. Complexes [(99m)Tc(HYNIC-P6G-RGD2)(tricine)(TPPTS)] ((99m)Tc-P6G-RGD2) and [(99m)Tc(HYNIC-P6D-RGD2)(tricine)(TPPTS)] ((99m)Tc-P6D-RGD2) were prepared in high radiochemical purity (RCP > 95%) and specific activity (37-110 GBq/μmol). They were evaluated in athymic nude mice bearing U87MG glioma xenografts for their biodistribution. The most significant difference between (99m)Tc-P6D-RGD2 and (99m)Tc-P6G-RGD2 was their blood radioactivity levels and tumor uptake. The initial blood radioactivity level for (99m)Tc-P6D-RGD2 (4.71 ± 1.00%ID/g) was ∼5× higher than that of (99m)Tc-P6G-RGD2 (0.88 ± 0.05%ID/g), but this difference disappeared at 60 min p.i. (99m)Tc-P6D-RGD2 had much lower tumor uptake (2.20-3.11%ID/g) than (99m)Tc-P6G-RGD2 (7.82-9.27%ID/g) over a 2 h period. Since HYNIC-P6D-RGD2 and HYNIC-P6G-RGD2 shared a similar integrin αvβ3 binding affinity (41 ± 6 nM versus 31 ± 5 nM), the difference in their blood activity and tumor uptake is most likely related to the nine negative charges and high protein binding of (99m)Tc-P6D-RGD2. Despite its low uptake in U87MG tumors, the tumor uptake of (99m)Tc-P6D-RGD2 was integrin αvβ3-specific. SPECT/CT studies were performed using (99m)Tc-P6G-RGD2 in athymic nude mice bearing U87MG glioma and MDA-MB-231 breast cancer xenografts. The SPECT/CT data demonstrated the tumor-targeting capability of (99m)Tc-P6G-RGD2, and its tumor uptake depends on the integrin αvβ3 expression levels on tumor cells and neovasculature. It was concluded that the multiple negative charges have a significant impact on the blood clearance kinetics and tumor uptake of (99m)Tc-labeled dimeric cyclic RGD peptides.

摘要

本研究旨在评估多个负电荷对（99m）Tc标记的RGD肽二聚体的血液清除动力学和生物分布特性的影响。生物共轭物HYNIC-P6G-RGD2和HYNIC-P6D-RGD2分别通过使P6G-RGD2和P6D-RGD2在二异丙基乙胺存在下与过量的HYNIC-OSu反应制备。在全细胞置换试验中，它们对与U87MG胶质瘤细胞结合的（125）I-echistatin的IC50值分别测定为31±5和41±6 nM。复合物[（99m）Tc（HYNIC-P6G-RGD2）（tricine）（TPPTS）]（（99m）Tc-P6G-RGD2）和[（99m）Tc（HYNIC-P6D-RGD）（tricine）（TPPTS）]（（99m）Tc-P6D-RGD2）以高放射化学纯度（RCP>95%）和比活度（37-110 GBq/μmol）制备。在携带U87MG胶质瘤异种移植瘤的无胸腺裸鼠中评估它们的生物分布。（99m）Tc-P6D-RGD2和（99m）Tc-P6G-RGD2之间最显著的差异在于它们的血液放射性水平和肿瘤摄取。（99m）Tc-P6D-RGD2的初始血液放射性水平（4.71±1.00%ID/g）比（99m）Tc-P6G-RGD2（约为0.88±0.．05%ID/g）高约5倍，但在注射后60分钟时这种差异消失。在2小时内，（99m）Tc-P6D-RGD2的肿瘤摄取（2.20-3.11%ID/g）比（99m）Tc-P6G-RGD2（约为7.82-9.27%ID/g）低得多。由于HYNIC-P6D-RGD2和HYNIC-P6G-RGD2具有相似的整合素αvβ3结合亲和力（41±6 nM对31±5 nM），它们在血液活性和肿瘤摄取方面的差异很可能与（99m）Tc-P6D-RGD2的九个负电荷和高蛋白结合有关。尽管（99m）Tc-P6D-RGD2在U87MG肿瘤中的摄取较低，但其在肿瘤中的摄取是整合素αvβ3特异性的。使用（99m）Tc-P6G-RGD2在携带U87MG胶质瘤和MDA-MB-231乳腺癌异种移植瘤的无胸腺裸鼠中进行SPECT/CT研究。SPECT/CT数据证明了（99m）Tc-P6G-RGD2的肿瘤靶向能力，其肿瘤摄取取决于肿瘤细胞和新生血管上整合素αvβ3的表达水平。得出的结论是，多个负电荷对（99m）Tc标记的二聚体环状RGD肽的血液清除动力学和肿瘤摄取有显著影响。