Activatable aptamer probe for contrast-enhanced in vivo cancer imaging based on cell membrane protein-triggered conformation alteration
Activatable aptamer probe for contrast-enhanced in vivo cancer imaging based on cell membrane protein-triggered conformation alteration
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DOI：
10.1073/pnas.1016197108
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发表时间：
2011-03-08
影响因子：
11.1
通讯作者：
Zhou, Bing
中科院分区：
文献类型：
--
作者：
Shi, Hui;He, Xiaoxiao;Zhou, Bing
适配体已成为用于体内癌症成像的有前景的分子探针，但所报道的“永远在线”适配体探针由于高背景和有限的对比度仍然存在问题。为了解决这个问题，我们设计了一种针对活癌细胞膜蛋白的可激活适体探针（AAP），并在小鼠体内实现了对比增强的癌症可视化。 AAP 在游离状态下显示出淬灭的荧光，并在与具有激活荧光的目标癌细胞结合后发生构象变化。作为概念验证，使用特定适体 sgc8 进行 CCRF-CEM 癌细胞的体外分析和体内成像作为演示。证实AAP可以被靶癌细胞特异性激活，荧光显着增强，并且对CCRF-CEM细胞分析表现出更高的灵敏度，在200μl结合缓冲液中检测到的细胞数为118。体内研究表明，在小鼠的 CCRF-CEM 肿瘤部位明显获得了激活的荧光信号。与始终在线的适体探针相比，AAP 可以大大减少源自非目标组织的背景信号，从而显着增强图像对比度，并将诊断时间缩短至 15 分钟。此外，由于 sgc8 对靶癌细胞的特异性亲和力，AAP 在区分 CCRF-CEM 肿瘤与 Ramos 肿瘤和非肿瘤区域方面也表现出理想的特异性。该设计理念可以广泛应用于其他癌细胞特异性适体探针，用于癌症的体内分子成像。
Aptamers have emerged as promising molecular probes for in vivo cancer imaging, but the reported "always-on" aptamer probes remain problematic because of high background and limited contrast. To address this problem, we designed an activatable aptamer probe (AAP) targeting membrane proteins of living cancer cells and achieved contrast-enhanced cancer visualization inside mice. The AAP displayed a quenched fluorescence in its free state and underwent a conformational alteration upon binding to target cancer cells with an activated fluorescence. As proof of concept, in vitro analysis and in vivo imaging of CCRF-CEM cancer cells were performed by using the specific aptamer, sgc8, as a demonstration. It was confirmed that the AAP could be specifically activated by target cancer cells with a dramatic fluorescence enhancement and exhibit improved sensitivity for CCRF-CEM cell analysis with the cell number of 118 detected in 200 mu l binding buffer. In vivo studies demonstrated that activated fluorescence signals were obviously achieved in the CCRF-CEM tumor sites in mice. Compared to always-on aptamer probes, the AAP could substantially minimize the background signal originating from nontarget tissues, thus resulting in significantly enhanced image contrast and shortened diagnosis time to 15 min. Furthermore, because of the specific affinity of sgc8 to target cancer cells, the AAP also showed desirable specificity in differentiating CCRF-CEM tumors from Ramos tumors and nontumor areas. The design concept can be widely adapted to other cancer cell-specific aptamer probes for in vivo molecular imaging of cancer.