Prakash Surbhi, Hazari Puja Panwar, Meena Virendra Kumar, Jaswal Ambika, Khurana Harleen, Kukreti Shrikant, Mishra Anil Kumar
Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig SK Mazumdar Road, Delhi-110054, India.
Department of Chemistry, University of Delhi , Delhi-110007, India.
Bioconjug Chem. 2016 Nov 16;27(11):2780-2790. doi: 10.1021/acs.bioconjchem.6b00576. Epub 2016 Oct 21.
A new macrocyclic system 2,2'-(12-amino-11,13-dioxo-1,4,7,10-tetraazacyclotridecane-4,7-diyl)diacetic acid (ATRIDAT) was designed for coordinating metals in +2 and +3 oxidation states particularly Ga(III), for PET imaging. ATRIDAT was conjugated to d-biotin for pretargeting via biotin-avidin interaction. This model provides high tumor targeting efficiency and stability to biotinidase activity leading to modest signal amplification at the tumor site. Cyclization of triethylenetetramine with protected diethylamino malonate resulted in the formation of 13 membered diamide ring. d-Biotin was then anchored on the pendant amine rendering α-methyne carbon to the biotinamide bond which blocks the biotinidase enzyme activity. Biotinidase stability assay showed remarkable stability toward the action of biotinidase with ∼95% remaining intact after treatment following 4 h. Binding affinity experiments such as HABA assay, competitive displacement studies with d-biotin and CD showed high binding affinity of the molecule with avidin in nanomolar range. Biotin conjugate was successfully radiolabeled with Ga(III) with radiolabeling efficiency of ∼70% and then purified to get 99.9% radiochemical yield. IC of the compound was found to be 2.36 mM in HEK cell line and 0.82 mM in A549 as assessed in MTT assay. In biodistribution studies, the major route of excretion was found to be renal. Significant uptake of 4.15 ± 0.35% was observed in tumor in the avidin pretreated mouse at 1 h. μPET images also showed a high tumor to muscle ratio of 26.8 and tumor to kidney ratio of 1.74 at 1 h post-injection after avidin treatment.
设计了一种新的大环体系2,2'-(12-氨基-11,13-二氧代-1,4,7,10-四氮杂环十三烷-4,7-二基)二乙酸(ATRIDAT)，用于配位+2和+3氧化态的金属，特别是Ga(III)，用于正电子发射断层显像(PET)成像。ATRIDAT与d-生物素偶联，通过生物素-抗生物素蛋白相互作用进行预靶向。该模型具有较高的肿瘤靶向效率和对生物素酶活性的稳定性，导致肿瘤部位有适度的信号放大。三亚乙基四胺与受保护的二乙氨基丙二酸酯环化，形成13元二酰胺环。然后将d-生物素锚定在侧链胺上，使α-次甲基碳连接到生物素酰胺键上，从而阻断生物素酶的活性。生物素酶稳定性试验表明，该分子对生物素酶的作用具有显著的稳定性，处理4小时后约95%保持完整。结合亲和力实验，如HABA试验、与d-生物素的竞争性置换研究和圆二色性(CD)显示，该分子与抗生物素蛋白在纳摩尔范围内具有高结合亲和力。生物素偶联物成功地用Ga(III)进行放射性标记，放射性标记效率约为70%，然后纯化得到99.9%的放射化学产率。在MTT试验中评估发现，该化合物在HEK细胞系中的半数抑制浓度(IC)为2.36 mM，在A549细胞系中为0.82 mM。在生物分布研究中，发现主要排泄途径是肾脏。在抗生物素蛋白预处理的小鼠中，1小时时肿瘤的摄取量为4.15±0.35%。在抗生物素蛋白处理后注射1小时的μPET图像也显示，肿瘤与肌肉的比值为26.8，肿瘤与肾脏的比值为1.74。
