Optimization of Enzymolysis Clearance Strategy To Enhance Renal Clearance of Radioligands
Optimization of Enzymolysis Clearance Strategy To Enhance Renal Clearance of Radioligands
复制标题
优化酶解清除策略以增强放射性配体的肾脏清除。
DOI：
10.1021/acs.bioconjchem.1c00392
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发表时间：
2021-09-06
影响因子：
4.7
通讯作者：
Chen, Xiaoyuan
中科院分区：
文献类型：
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作者：
Zhang, Mingru;Ye, Jiajun;Chen, Xiaoyuan
肾脏是放射性配体治疗（RLT）的主要剂量限制器官，因此迫切需要减少肾脏放射性蓄积。本研究的第一个目的是通过在可切割序列的第二个位置引入具有较大侧链的疏水氨基酸来测试是否可以提高切割效率，第二个目的是筛选最佳序列以使肾摄取最小化。合成了四种具有不同可切割序列的exendin 4（Ex 4）肽类似物，并用68 Ga标记。使用模型化合物或完整探针进行体外和体内代谢研究。在PBS和小鼠血清中评价示踪剂的体外稳定性。在INS-1肿瘤模型中在不同时间点获得microPET图像，并测定和比较肿瘤和肾脏中探针的放射性摄取。所有探针在PBS和小鼠血清中稳定至少1小时。对模型化合物和完整探针的体外切割研究显示出以下顺序的切割效率：MWK > MFK > MVK > MGK。体内代谢研究证实，对于具有MVK、MFK和MWK序列的所有类似物，在肾脏和尿液样品中均出现68 Ga-NOTA-Met-OH片段。microPET图像显示，所有修饰的探针的肿瘤摄取与对照的肿瘤摄取相当，而通过插入MWK、MFK或MVK接头，肾摄取显著降低。在0.5、1和2小时时间点的肿瘤与肾比率显示以下顺序：68 Ga-NOTA-MWK-Ex 4> 68 Ga-NOTA-MFK-Ex 4> 68 Ga-NOTA-MVK-Ex 4。本研究根据酶的选择性和清除策略，设计了不同的序列，并在体外和体内进行了比较。结果表明，第二疏水性氨基酸侧链的空间位阻越大，酶解效果越好，水解效率顺序为MWK > MFK > MVK > MGK。MWK似乎是减少毒蜥外泌肽4肽衍生物的肾放射性蓄积的最有效序列。
The kidney is the main dose-limiting organ in radioligand therapy (RLT), and there is an urgent need for reducing renal radioactivity accumulation. According to the enzymolysis clearance strategy, the first objective of this study is to test whether enzymolysis efficiency can be improved by introducing a hydrophobic amino acid with a bulkier side chain to the second position of the cleavable sequence, and the second objective is to screen an optimal sequence to minimize the renal uptake. Four exendin 4 (Ex4) peptide analogues with different cleavable sequences were synthesized and labeled with 68Ga. Both in vitro and in vivo metabolism studies were performed using either the model compounds or the complete probes. The in vitro stabilities of the tracers were evaluated in PBS and mouse serum. The microPET images were acquired in the INS-1 tumor model at different time points, and the radioactivity uptakes of the probes in tumors and kidneys were determined and compared. All the probes were stable in both PBS and mouse serum for at least 1 h. The in vitro cleavage study for both model compounds and intact probes showed enzymolysis efficiency in the following order: MWK > MFK > MVK > MGK. The in vivo metabolism study confirmed that a fragment of 68Ga-NOTA-Met-OH appeared in both kidney and urine samples for all analogues with MVK, MFK, and MWK sequences. The microPET images showed that the tumor uptakes of all the modified probes were comparable to those of the control, while the kidney uptakes were significantly reduced by inserting the MWK, MFK, or MVK linker. The tumor-to-kidney ratios at 0.5, 1, and 2 h time points showed the following order: 68Ga-NOTA-MWK-Ex4 > 68Ga-NOTA-MFK-Ex4 > 68Ga-NOTA-MVK-Ex4. In this study, based on the enzymolysis clearance strategy and the preference of the enzyme, different sequences were designed and compared both in vitro and in vivo. The results indicated that the larger the steric hindrance of the second hydrophobic amino acid side chain, the more effective the enzymatic hydrolysis, with enzymolysis efficiency in the following order: MWK > MFK > MVK > MGK. MWK appears to be the most effective sequence in reducing renal radioactivity accumulation of exendin 4 peptide derivatives.