基于标签离子修饰探针的体内抗癌药物靶点EGFR及其信号通路的DESI质谱成像分析方法研究

质谱成像作为一种基于原位电离的高特异性分子影像技术，可同时获取药物、代谢物在体内的空间分布信息，在探究药物分子机制方面有重要应用价值，但在分析药物靶点与信号通路因子方面存在技术局限，而这些靶点及信号通路因子的表达水平与分布，与药物作用分子机制有更直接联系，且对调控下游代谢水平起关键媒介作用。本项目选取抗癌药物靶点EGFR及其信号通路为研究对象，建立一种基于报告离子修饰探针的DESI质谱成像分析方法，对上述生物分子在荷瘤动物体内的表达水平进行多重可视化分析。当探针完成目标生物分子定位后，通过离线原位裂解或在线实时裂解，将探针上修饰的报告离子释放、解吸并引入质谱仪进行信号读取，从而高灵敏、多指标地完成靶点及其通路分子的空间分布表征。本方法的建立为精准探究候选药物作用的分子靶向性，深入评价候选药物的药效或潜在毒性的分子机制，发现上市药物全新临床适应症等药物研发关键问题具有重要的应用价值。

Mass spectrometry imaging (MSI) has already proved its great advantage in drug’s molecular mechanism research. Due to its high chemical specificity, it can simultaneously provide spatial information both in xenogenous drug and endogenous metabolites. However, MSI is still currently limited in mapping drug target and its correspondent signaling factors, which are not only in close relation with drug action, but also in regulating downstream metabolomics phenotype. In this research project, a tagged ion-modified probe based desorption electrospray ionization (tip-DESI) MSI method will be developed aiming at multiplex analysis of drug target and signaling factors in body. The key technical issue is to design and synthesize a mass tags-modified MSI probe which is bifunctional in specific molecular recognition and ion signal amplification. The probe employs antibody as the recognition unit to localize the drug target by specific interaction. Dendrimer is introduced as the amplification unit by modifying mass tag which has high ionization efficiency. Finally, by off-line or on-line real time cleavage, the dendrimer-bonded mass tags are released, desorbed and ionized into the MS for ion signal readout. Thus, the in situ distribution pattern of the target can be indirectly characterized. It is believed that this tip-DESI MSI must have great application potential in precisely investigating the drug candidate’s molecular targeting effect, evaluating the in-depth pharmacological/toxicological mechanism, and discovering the new indication of clinical drugs.