Evaluation of backbone-cyclized HER2-binding 2-helix Affibody molecule for In Vivo molecular imaging
Evaluation of backbone-cyclized HER2-binding 2-helix Affibody molecule for In Vivo molecular imaging
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DOI：
10.1016/j.nucmedbio.2012.12.009
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发表时间：
2013-04-01
影响因子：
3.1
通讯作者：
Jarver, Peter
中科院分区：
文献类型：
--
作者：
Honarvar, Hadis;Jokilaakso, Nima;Jarver, Peter
引言：亲和体分子，小的支架蛋白，已被证明是一个可观的潜力，作为成像探针。亲和体分子由三个α-螺旋组成。螺旋1和2参与分子识别，而螺旋3提供稳定性。亲和体分子的大小可以通过省略第三个α-螺旋并交联剩余的两个来减小，从而提供具有更好的外渗和更快的未结合示踪剂清除的更小分子。本研究的目的是通过天然化学连接（native chemical ligation，NCL）的骨架环化作用，构建一种新型的2-螺旋Affibody分子。用In-111和（68）Ga标记DOTA-Z（HER 2：342 min）。体外评价DOTA-Z的结合亲和力（HER 2：342 min）。在SKOV-3移植瘤小鼠中评价了In-111-和（68）Ga-DOTA-Z（HER 2：342 min）的靶向性质，并与In-111-和（68）Ga-标记的PEP 09239（一种通过同型半胱氨酸二硫桥环化的DOTA缀合的2-螺旋Affibody类似物）的性质进行了比较。用In-111和（68）Ga标记DOTA-Z（HER 2：342 min）。两种缀合物均表现出与HER 2表达细胞的双相结合动力学，其中K-D1处于低纳摩尔范围。两种变体均在表达HER 2的异种移植物中表现出特异性摄取。注射后2 h的肿瘤与血液比率对于In-111-DOTA-Z为6.1 +/-1.3（HER 2：342 min），对于（68）Ga-DOTA-Z为4.6 +/-0.7（HER 2：342 min）。然而，DOTA-Z（HER 2：342 min）在肺、肝和脾中的摄取明显高于基于PEP 09239的对应物的摄取。结论：天然化学连接能够产生具有低纳摩尔靶亲和力和特异性肿瘤摄取的主链环化的HER 2结合2-螺旋亲和体分子（Z（HER 2：342 min））。(C)2013 Elsevier Inc. All rights reserved.
Introduction: Affibody molecules, small scaffold proteins, have demonstrated an appreciable potential as imaging probes. Affibody molecules are composed of three alpha-helices. Helices 1 and 2 are involved in molecular recognition, while helix 3 provides stability. The size of Affibody molecules can be reduced by omitting the third alpha-helix and cross-linking the two remaining, providing a smaller molecule with better extravasation and quicker clearance of unbound tracer. The goal of this study was to develop a novel 2-helix Affibody molecule based on backbone cyclization by native chemical ligation (NCL).Methods: The HER2-targeting NCL-cyclized Affibody molecule Z(HER2:342min) has been designed, synthesized and site-specifically conjugated with a DOTA chelator. DOTA-Z(HER2:342min) was labeled with In-111 and (68) Ga. The binding affinity of DOTA-Z(HER2:342min) was evaluated in vitro. The targeting properties of In-111- and (68) Ga-DOTA-Z(HER2:342min) were evaluated in mice bearing SKOV-3 xenografts and compared with the properties of In-111- and (68) Ga-labeled PEP09239, a DOTA-conjugated 2-helix Affibody analogue cyclized by a homocysteine disulfide bridge.Results: The dissociation constant (K-D) for DOTA-Z(HER2:342min) binding to HER2 was 18 nM according to SPR measurements. DOTA-Z(HER2:342min) was labeled with In-111 and (68) Ga. Both conjugates demonstrated bi-phasic binding kinetics to HER2-expressing cells, with K-D1 in low nanbmolar range. Both variants demonstrated specific uptake in HER2-expressing xenografts. Tumor-to-blood ratios at 2 h p.i. were 6.1 +/- 1.3 for In-111-DOTA-Z(HER2:342min) and 4.6 +/- 0.7 for (68) Ga-DOTA-Z(HER2:342min). However, the uptake of DOTA-Z(HER2:342min) in lung, liver and spleen was appreciably higher than the uptake of PEP09239-based counterparts.Conclusions: Native chemical ligation enables production of a backbone-cyclized HER2-binding 2-helix Affibody molecule (Z(HER2:342min)) with low nanomolar target affinity and specific tumor uptake. (C) 2013 Elsevier Inc. All rights reserved.