基于靶向多肽探针的循环肿瘤细胞高选择性分析探索

Highly selective and sensitive methods for the analysis of characteristic molecular events in circulating tumor cells (CTCs) are promising for the early diagnosis, metastasis prediction and therapeutic outcome assessment of cancer. However, detection and characterization of CTCs have been challenging owing to their extremely low content, dynamic nature and lacking of biomarkers. Herein, according to the cancerous and metastatic nature of CTCs, a novel strategy for the design and screening of peptide probes towards a new broad-spectrum biomarker LAPTM4B protein is proposed for CTCs analysis. Based on the degeneracy of antisense peptides, position-scanning peptide libraries are designed by choosing a metastasis-related domain as the target. A novel screening system is developed by using binding-activated fluorescence assay to obtain an optimal antisense peptide. With the high specificity and affinity, the screened peptide will be further applied in targetable bioimaging of tumor cell and real-time tracking of LAPTM4B protein. Taking advantage of the LAPTM4B-targeting peptide and the apoptosis-responsive caspase-3 substrate peptide, a multi-functional activatable nanoprobe is constructed. According to the "on-off" signals, highly selective and sensitive detection of live CTCs in the blood stream can be realized. This work can provide a foundation for the development of a clinically available method for CTCs analysis and important information for understanding the molecular mechanism of tumor metastasis.

针对循环肿瘤细胞（CTCs）的分子特征，发展高选择性、高灵敏度的分析方法，可望为肿瘤转移的早期预警和个性化治疗提供新的手段。CTCs异常低的含量、缺乏特征标志物和动态变化的特点是其准确识别检测的关键难题。本项目拟针对CTCs的肿瘤特性和转移活性，以新型肿瘤标志蛋白LAPTM4B为目标，以其促进肿瘤转移相关的结构域为靶点，发展位置扫描的组合化学反义肽库构建新方法；建立多肽亲和筛选新体系，筛选出高亲和力的反义肽；以LAPTM4B蛋白靶向多肽和细胞凋亡识别多肽为元件，构建双靶向识别、荧光响应的“开/关”型多肽纳米探针，开展肿瘤活细胞的成像分析研究；探索基于识别信号响应的CTCs高选择性、高灵敏度分析检测新方法。

循环肿瘤细胞（CTCs）含量低、缺乏特征标志物和动态变化的特点是其准确识别检测的关键难题。本项目针对CTCs的肿瘤特性和转移活性，以新型肿瘤标志蛋白LAPTM4B为目标，以其促进肿瘤转移相关的结构域为靶点，发展了位置扫描的反义肽库构建新方法；建立了多肽识别荧光响应的亲和筛选新体系，筛选出了与靶标分子具有高亲和力、高选择性的反义肽。以LAPTM4B蛋白靶向多肽和细胞凋亡识别多肽为元件，构建了靶向识别、荧光响应的“开/关”型多肽探针，开展了双靶向肿瘤活体分析和成像检测研究；制备了多肽功能化的界面纳米材料，实现了CTCs的高效、高选择性捕获和高灵敏度检测；构建了自组装纳米聚集体，通过特异性识别肿瘤细胞并氧化损伤线粒体，实现了肿瘤的高效、特异性抑制并无系统毒性；为肿瘤转移的早期发现和个性化治疗提供了新工具和新方法。本项目在Chem. Sci., Anal. Chem., Chem. Commun. 等学术期刊发表论文15篇，申请发明专利5项，获得2016年中国分析测试协会科学技术奖二等奖1项。