Departments of Chemistry, Molecular Biosciences, Neurobiology, and Radiology , Northwestern University , Evanston , Illinois 60208 , United States.
Department of Chemistry and Magnetic Resonance Center (CERM) , University of Florence, and Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (CIRMMP) , Via L. Sacconi 6 , 50019 Sesto Fiorentino , Italy.
J Am Chem Soc. 2019 Apr 17;141(15):6224-6233. doi: 10.1021/jacs.8b13376. Epub 2019 Apr 4.
Effective cancer therapy largely depends on inducing apoptosis in cancer cells via chemotherapy and/or radiation. Monitoring apoptosis in real-time provides invaluable information for evaluating cancer therapy response and screening preclinical anticancer drugs. In this work, we describe the design, synthesis, characterization, and in vitro evaluation of caspase probe 1 (CP1), a bimodal fluorescence-magnetic resonance (FL-MR) probe that exhibits simultaneous FL-MR turn-on response to caspase-3/7. Both caspases exist as inactive zymogens in normal cells but are activated during apoptosis and are unique biomarkers for this process. CP1 has three distinct components: a DOTA-Gd(III) chelate that provides the MR signal enhancement, tetraphenylethylene as the aggregation induced emission luminogen (AIEgen), and DEVD peptide which is a substrate for caspase-3/7. In response to caspase-3/7, the water-soluble peptide DEVD is cleaved and the remaining Gd(III)-AIEgen (Gad-AIE) conjugate aggregates leading to increased FL-MR signals. CP1 exhibited sensitive and selective dual FL-MR turn-on response to caspase-3/7 in vitro and was successfully tested by fluorescence imaging of apoptotic cells. Remarkably, we were able to use the FL response of CP1 to quantify the exact concentrations of inactive and active agents and accurately predict the MR signal in vitro. We have demonstrated that the aggregation-driven FL-MR probe design is a unique method for MR signal quantification. This probe design platform can be adapted for a variety of different imaging targets, opening new and exciting avenues for multimodal molecular imaging.
有效的癌症治疗在很大程度上依赖于通过化疗和/或放疗诱导癌细胞凋亡。实时监测细胞凋亡为评估癌症治疗反应和筛选临床前抗癌药物提供了宝贵的信息。在这项工作中，我们描述了 caspase 探针 1（CP1）的设计、合成、表征和体外评价，CP1 是一种双模式荧光-磁共振（FL-MR）探针，对 caspase-3/7 表现出同时的 FL-MR 开启响应。两种半胱天冬酶在正常细胞中均以无活性的酶原形式存在，但在细胞凋亡过程中被激活，是该过程的独特生物标志物。CP1 有三个不同的组成部分：DOTA-Gd（III）螯合物提供磁共振信号增强，四苯乙烯作为聚集诱导发射发光体（AIEgen），以及 DEVD 肽，它是 caspase-3/7 的底物。响应 caspase-3/7，水溶性肽 DEVD 被切割，剩余的 Gd（III）-AIEgen（Gad-AIE）缀合物聚集导致 FL-MR 信号增加。CP1 在体外对 caspase-3/7 表现出敏感和选择性的双 FL-MR 开启响应，并通过对凋亡细胞的荧光成像成功进行了测试。值得注意的是，我们能够使用 CP1 的 FL 响应来定量测定无活性和活性试剂的确切浓度，并准确预测体外的 MR 信号。我们已经证明，聚集驱动的 FL-MR 探针设计是一种用于 MR 信号定量的独特方法。这种探针设计平台可以适应各种不同的成像靶点，为多模态分子成像开辟了新的令人兴奋的途径。
