基于CXCR4的诊疗一体化纳米泡的构建及其用于肿瘤分子显像和治疗的实验研究

It is the key point in ultrasound molecular imaging to construct and clarify the mechanism of targeted drug-loaded nanobubbles with the integrated effect on tumor diagnosis and treatment. In our prior studies, we have successfully prepared targeted nanobubbles specific to prostate cancer, and confirmed that they can achieve specific contrast-enhanced ultrasound imaging of prostate cancer. However, the process and mechanism of targeted ultrasound imaging after they pass through tumor blood vessels are still unclear. Moreover, targeted nanobubbles that used for ultrasound molecular imaging of a variety of tumors have not been constructed. C-X-C chemokine receptor type 4 (CXCR4) is the most common high expression chemokine receptor on the tumor cellular membrane and could bind with CXCL12. CXCL12/CXCR4 axis plays a positive role in tumor growth and metastasis, blocking the axis will reverse the result. Therefore, the project aims firstly to construct targeted drug-loaded nanobubbles with dual therapeutic effects, whose surfaces link the antagonist binding with CXCR4 and lipid shells encapsulated doxorubicin, and then to clarify the processes and mechanisms including coupling with many tumor cells, targeted imaging, blocking the CXCL12/CXCR4 axis and inhibition effect of doxorubicin on tumor growth in ultrasound-irradiation nanobbubble destruction through in-vitro and in-vivo experiments, and finally to provide the new intergrated theranositic ultrasound contrast agent and drug carrier for targeted molecular diagnosis and treatment of a variety of tumor.

构建具备肿瘤诊断和治疗一体化功能的靶向载药纳米泡并阐明其作用机制是超声分子影像学研究的重点。我们前期针对前列腺癌成功制备了靶向纳米泡，证实了其能使前列腺癌组织特异性显像，但是其穿过肿瘤血管发生特异性显像的过程和机制尚不清楚，且尚未构建出能同时用于多种肿瘤超声分子显像的靶向纳米泡。CXC型趋化因子受体4（CXCR4）在大多数肿瘤细胞膜上均异常高表达，与其配体CXCL12构成CXCL12/CXCR4轴，在肿瘤生长和转移过程中发挥重要促进作用，阻断该轴可治疗肿瘤。因此，本项目拟在纳米泡上连接能与CXCR4特异性结合的拮抗剂，并在纳米泡的脂质壳内包裹阿霉素，构建一种具有双重治疗作用的靶向载药纳米泡，在体外和体内研究其与多种肿瘤细胞结合、靶向显像、阻断CXCL12/CXCR4轴以及超声辐照破坏纳米泡释放阿霉素抑制肿瘤生长的过程和机制，为多种肿瘤的靶向分子显像和治疗提供一体化的新型造影剂和药物载体。

构建具备肿瘤诊断和治疗一体化功能的靶向载药纳米泡并阐明其作用机制是目前超声分子影像学研究的重点和难点。我们前期针对前列腺癌成功制备了靶向纳米泡，证实了其能使前列腺癌组织特异性超声显像，但是其穿过肿瘤血管发生特异性显像的过程和机制尚不清楚，且尚未构建出能可用于多种肿瘤超声分子显像的靶向纳米泡。由于CXC型趋化因子受体4(CXCR4)在大多数肿瘤细胞膜上均异常高表达，与其配体基质细胞衍生因子-1（SDF-1）构成SDF-1/CXCR4轴，在肿瘤生长和转移过程中发挥了重要的促进作用，阻断该轴可有效抑制肿瘤的生长和转移。因此本项目以多种肿瘤细胞膜上高表达的CXCR4为靶点，将CXCR4小分子拮抗剂AMD070作为靶向修饰物，成功构建了携载化疗药物紫杉醇（PTX）的诊疗一体化多功能靶向脂质纳米泡（PTX-AMD070 NBs），证实其能实现多种移植瘤的靶向超声分子成像，同时PTX-AMD070 NBs联合超声辐照技术能起到靶向增效治疗肿瘤的作用。项目还成功构建了AMD070靶向修饰的、携载光声显像剂吲哚菁绿（ICG）的多模态显像纳米泡（ICG-TNBs），并进一步研究了ICG-TNBs抑制乳腺癌细胞生长的作用及其机制，特别是ICG-TNBs对SDF-1/CXCR4信号通路的影响，结果进一步证实超声辐照下ICG-TNBs通过空化效应能有效提高肿瘤细胞的细胞膜通透性，促进AMD070有效抑制和阻断SDF-1/CXCR4/Akt通路的活动，提高细胞内活性氧（ROS）水平，促进Caspase3和Cleaved-caspase3的表达，导致肿瘤细胞生长抑制和凋亡。在此基础上，本项目组针对多种肿瘤细胞表面高表达核仁蛋白，进一步构建了能与其特异性结合的核酸适配体AS1411靶向修饰的携载化疗药物阿霉素（DOX）的诊疗一体化脂质纳米泡（AS1411-DOX-NBs），通过对携载阿霉素靶向脂质纳米泡的抗肿瘤效能及心肌保护作用的评估，证实了靶向载药纳米泡在肿瘤治疗中的安全性和有效性，为肿瘤的临床诊治提供安全高效的诊疗一体化多功能纳米泡。.本项目已发表学术论著7篇，其中SCI论著5篇，CSCD论著2篇，申请国家发明专利3项，其中2项专利已获得授权。共培养博士研究生2名，硕士研究生5名，参加国际学术会议交流共计4次。