68Ga-DOTA-NGR as a novel molecular probe for APN-positive tumor imaging using MicroPET
68Ga-DOTA-NGR as a novel molecular probe for APN-positive tumor imaging using MicroPET
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DOI：
10.1016/j.nucmedbio.2013.12.008
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发表时间：
2014-03-01
影响因子：
3.1
通讯作者：
Wang, Feng
中科院分区：
文献类型：
--
作者：
Zhang, Jun;Lu, Xiaoli;Wang, Feng
氨基肽酶N(APN)选择性表达于多种肿瘤和肿瘤新生血管内皮细胞，有望成为肿瘤诊断和治疗的靶点。天冬酰胺甘氨酸-精氨酸(NGR)多肽已被证明能与APN受体特异性结合，并在以前的研究中用作各种治疗药物的载体。本研究的目的是合成并评价一种新型的与APN结合的分子探针--Ga-68标记的NGR多肽。方法：将NCR多肽与1，4，7，10-四氮杂环十二烷-N，N‘，N’‘，N’-四乙酸(DOTA)偶联，在95℃下用Ga-68标记10min。对A549和MDA-MB231细胞进行体外摄取和结合分析。采用解剖法测定Ga-68-DOTA-NGR在正常小鼠体内的生物分布。对A549和MDA-MB231移植瘤进行GA-68-DOTA-NGR PET检查，包括动态和静态成像。免疫组织化学方法检测APN在肿瘤和新生血管中的表达。结果：Ga-68-DOTA-NGR的放化纯度为98.0%+/-1.4%，比活度约为17.49MBq/nmol。A549细胞对Ga-68-DOTA-NGR的摄取随孵育时间的延长而增加，冷DOTA-NGR可阻断其摄取，而对MDA-MB231细胞则无特异性摄取。体内生物分布研究表明，Ga-68-DOTA-NGR主要从肾脏排泄，并从血液和非特异性器官中迅速清除。MicroPET显像显示，A549肿瘤移植瘤注射后1h(Pi)，肿瘤部位有较高的灶性聚集。与阻断剂量的DOTA-NGR共注射后，肿瘤摄取显著减少，而在MDA-MB231肿瘤移植瘤中仅发现轻微摄取。肿瘤摄取(以肿瘤/肺比率衡量)随时间增加，在1.5hpi时达到峰值12.58+/-1.26。免疫组织化学染色证实APN在A549细胞和新生血管上呈高表达。结论：GA-68-DOTA-NGR合成简单，具有良好的生物分布和动力学特性。(68)GaDOTA-NGR在体内外也能与APN受体特异性结合，有望成为非侵入性检测APN阳性肿瘤和新生血管的分子探针。(C)2014 Elsevier Inc.保留所有权利。
Aminopeptidase N (APN) is selectively expressed on many tumors and the endothelium of tumor neovasculature, and may serve as a promising target for cancer diagnosis and therapy. Asparagineglycine-arginine (NGR) peptides have been shown to bind specifically to the APN receptor and have served as vehicles for the delivery of various therapeutic drugs in previous studies. The purpose of this study was to synthesize and evaluate the efficacy of a Ga-68-labeled NGR peptide as a new molecular probe that binds to APN.Methods: NCR peptide was conjugated with 1,4,7,10-tetraazacyclododecane-N,N ',N '',N '''-tetraacetic acid (DOTA) and labeled with Ga-68 at 95 degrees C for 10 min. In vitro uptake and binding analysis was performed with A549 and MDA-MB231 cells. Biodistribution of Ga-68-DOTA-NGR was determined in normal mice by dissection method. Ga-68-DOTA-NGR PET was performed in A549 and MDA-MB231 xenografts, and included dynamic and static imaging. APN expression in tumors and new vasculatures was analyzed by immunohistochemistry. Results: The radiochemical purity of Ga-68-DOTA-NGR was 98.0%+/- 1.4% with a specific activity of about 17.49 MBq/nmol. The uptake of Ga-68-DOTA-NGR in A549 cells increased with longer incubation times, and could be blocked by cold DOTA-NGR, while no specific uptake was found in MDA-MB231 cells. In vivo biodistribution studies showed that Ga-68-DOTA-NGR was mainly excreted from the kidney, and rapidly cleared from blood and nonspecific organs. MicroPET imaging showed that high focal accumulation had occurred in the tumor site at 1 h post-injection (pi) in A549 tumor xenografts. A significant reduction of tumor uptake was observed following coinjection with a blocking dose of DOTA-NGR, whereas only mild uptake was found in MDA-MB231 tumor xenografts. Tumor uptake, measured as the tumor/lung ratio, increased with time peaking at 12.58 +/- 1.26 at 1.5 h pi. Immunohistochemical staining confirmed that APN was overexpressed on A549 cells and neovasculature.Conclusions: Ga-68-DOTA-NGR was easily synthesized and showed favorable biodistribution and kinetics. (68)GaDOTA-NGR could also specifically bind to the APN receptor in vitro and in vivo, and might be a potential molecular probe for the noninvasive detection of APN-positive tumors and neovasculature. (C) 2014 Elsevier Inc. All rights reserved.