Chen Lanlan, Lai Jingjing, Dong Siqi, Liu Wenjun, Zhang Ximei, Yang Huanghao
New Cornerstone Science Laboratory, MOE Key Laboratory for Analytical Science of Food Safety and Biology, College of Chemistry, Fuzhou University, Fuzhou 350108, P. R. China.
Anal Chem. 2025 Jan 14;97(1):382-391. doi: 10.1021/acs.analchem.4c04408. Epub 2025 Jan 1.
Evaluating tumor radiosensitivity is beneficial for the prediction of treatment efficacy, customization of treatment plans, and minimization of side effects. Tracking the mitochondrial DNA (mtDNA) repair process helps to assess tumor radiosensitivity as mtDNA repair determines the fate of the cell under radiation-induced mtDNA damage. However, current probes developed to monitor levels of DNA repair enzymes suffered from complex synthesis, uncontrollable preparation, limited tumor selectivity, and poor organelle-targeting ability. Especially, the correlation between mtDNA repair activity and inherent radiosensitivity of tumors has not yet been explored. Here, we present a mitochondria-targeted DNA-based nanoprobe (TPP-Apt-tFNA) for in situ monitoring of the activity of the mtDNA repair enzyme and evaluating tumor radiosensitivity. TPP-Apt-tFNA consists of a DNA tetrahedral framework precisely modified with three functional modules on each of the three vertexes, that is, the tumor cell-targeting aptamer, the mitochondrion-targeting moiety, and the apurinic/apyrimidinic endonuclease 1 (APE1)-responsive molecule beacon. Once selectively internalized by tumor cells, the nanoprobe targeted the mitochondrion and specifically recognized APE1 to activate fluorescence, allowing the observation of mtDNA repair activity. The nanoprobe showed elevated APE1 levels in the mitochondria of tumor cells under oxidative stress. Moreover, the nanoprobe enabled the illumination of different levels of APE1-mediated mtDNA repair activity in different cell cycle phases. Furthermore, using the nanoprobe and , we found that tumor cells with high activity of mtDNA repair, which allowed them to recover from radiation-induced mtDNA lesions, had low sensitivity to radiation and an unsatisfactory radiotherapy outcome. Our work provides a new imaging tool for exploring the roles of mtDNA repair activity in diverse biological processes and for guiding tumor radiation treatment.
评估肿瘤放射敏感性有助于预测治疗效果、制定个性化治疗方案并将副作用降至最低。追踪线粒体DNA（mtDNA）修复过程有助于评估肿瘤放射敏感性，因为mtDNA修复决定了细胞在辐射诱导的mtDNA损伤下的命运。然而，目前开发的用于监测DNA修复酶水平的探针存在合成复杂、制备不可控、肿瘤选择性有限和细胞器靶向能力差等问题。特别是，mtDNA修复活性与肿瘤固有放射敏感性之间的相关性尚未得到探索。在此，我们提出了一种基于线粒体靶向DNA的纳米探针（TPP-Apt-tFNA），用于原位监测mtDNA修复酶的活性并评估肿瘤放射敏感性。TPP-Apt-tFNA由一个DNA四面体框架组成，在三个顶点上的每一个都精确修饰有三个功能模块，即肿瘤细胞靶向适体、线粒体靶向部分和脱嘌呤/脱嘧啶内切酶1（APE1）响应分子信标。一旦被肿瘤细胞选择性内化，纳米探针靶向线粒体并特异性识别APE1以激活荧光，从而可以观察mtDNA修复活性。该纳米探针显示氧化应激下肿瘤细胞线粒体中APE1水平升高。此外，该纳米探针能够照亮不同细胞周期阶段中不同水平的APE1介导的mtDNA修复活性。此外，使用该纳米探针，我们发现mtDNA修复活性高的肿瘤细胞能够从辐射诱导的mtDNA损伤中恢复，对辐射敏感性低且放疗效果不理想。我们的工作为探索mtDNA修复活性在各种生物学过程中的作用以及指导肿瘤放射治疗提供了一种新的成像工具。
