靶向PARP1的智能分子探针研制及其在乳腺癌PET显像中的应用研究

Early accurate diagnosis has great significance for the efficient treatment and better prognosis of malignant tumors (e.g., breast cancer). Therefore, it has been an urgent clinical need to develop new probes. Poly(ADP-ribose) polymerase（PARP1）is a ribozyme that senses DNA damage and repairs DNA damage in vivo, and its activation and high expression in cells are closely related to cancers. In this project, based on the click reaction, we propose to design and synthesize a new molecular probe which is comprised of PARP1 inhibitor as target and 64Cu as imaging agent. The probe achieves tumor targeting by specific binding of a PARP1 inhibitor to PARP1, which is highly expressed in tumor cells. Under glutathione reduction, the probe condensed to yield cyclized dimer, and then "Smart" self-assembling into “64Cu-nanoparticles”. Since the formed nanostructures are not easily pumped by the cell membrane and continuously aggregate in the targeting cells, the concentration is much higher than that which can be achieved by the nuclide itself, thereby reducing the amount and cost of the nuclide and achieving high specificity and highly sensitive PET imaging of tumors. In this study, based on click reaction, we control the intracellular condensation self-assembly of 64Cu to form nanoprobes for the first time, and explore the imaging value of this intelligent method in breast cancer, so as to provide theoretical basis and new choice for constructing a new tumor diagnosis and treatment platform.

早期精准诊断对于恶性肿瘤如乳腺癌的治疗和预后具有重要意义。因此，发展新型分子探针成为临床迫切需求。聚腺苷二磷酸核糖聚合酶(PARP1)是生物体内感应DNA损伤并对DNA损伤进行修复的核酶，其在细胞内的激活和高度表达与癌症密切相关。本项目基于点击反应平台，构建一种以PARP1抑制剂为靶向和64Cu为显像剂的新型分子探针，该探针通过PARP1抑制剂与肿瘤细胞内高度表达的PARP1特异性结合实现靶向作用，被癌细胞内谷胱甘肽还原后发生点击反应并智能自组装成“64Cu-纳米粒子”结构，由于形成的纳米结构不易被细胞膜泵出而在细胞内不断聚集，产生远高于核素本身所能达到的浓度，从而可以降低核素的用量和成本，并实现对肿瘤的高特异性和高灵敏PET显像。本研究利用细胞内点击反应首次将64Cu控制在细胞内缩合自组装形成纳米探针，探讨这种智能的方法在乳腺癌中的显像价值，为构建新型肿瘤诊治平台提供理论依据和新选择。

早期精准诊断对于恶性肿瘤的治疗和预后具有重要意义。因此，开发新型PET分子探针成为临床迫切需求。本项目基于CBT点击反应平台，以聚腺苷二磷酸核糖聚合酶（PARP1）为靶点，构建了一种“智能”的新型PET分子探针进行乳腺癌的早期精准诊断研究。该探针能够快速靶向富集在PARP1高表达的肿瘤细胞，在谷胱甘肽的作用下发生点击反应并进一步自组装形成纳米粒子结构，有效增加了靶区正电子核素的浓度。该方法既降低了核素的用量，同时提高了PET显像的灵敏度和分辨率。已经成功合成靶向PARP1的分子探针，同时对探针进行了结构表征，进行了动物显像。在本项目的支持下，我们以GRP78蛋白为靶点，开发了靶向GRP78蛋白的正电子核素分子探针，并成功应用于肝癌的早期显像研究并获得较好的成像结果，有望于进一步用于临床；我们以肿瘤微环境为研究对象，设计了以成纤维激活蛋白酶（FAP）为靶点的PET／MR分子探针，目前已经成功合成探针前体分子并进行结构表征，用于PET／MR显像的胰腺癌模型正在构建中。这些新型PET分子探针将为肿瘤的早期精准诊断提供更好，更个性化的选择，具有非常重要的临床应用价值。在项目执行期间，发表论文两篇（SCIE收录），另外三篇工作即将完成，预计在未来三个月内会陆续投稿，培养了硕士研究生两名。