胃癌血管新生与乏氧间动态发展过程的在体光学多模态定量监测方法研究

Tissue hypoxia and angiogenesis occur in the oncogenesis and progression of gastric cancer, and demonstrated dynamic mutual influence between each other. Exploring the procedures is helpful to reveal the progression of gastric cancer. However, the current researches mainly focused on molecule mechanisms of the interaction between the hypoxia and angiogenesis, and it was rarely reported on the dynamic imaging in vivo, lacking of a methodology including accurate monitoring and quantitative calculation. Therefore, it is valuable to establish a novel visual research method to monitor and quantitate angiogenesis and hypoxia dynamic developing process in gastric cancer. To aim at this problem, based on the hypoxic gastric orthotopic nude mice model containing HIF-1-Luc reporter gene, our proposal will utilize new radio-fluorescence imaging which have both advantages of optical and PET imaging, and construct a biomodal (radioluminescence/PET) probe through photo click and chelator-free, specific to angiogenesis in gastric cancer. We will use the probe to monitor the tumor angiogenesis dynamically and quantitatively in hypoxia mouse model of gastric cancer, as well as available hypoxic kinetic parameters as the same time point, establish a kinetics mathematics model of gastric cancer progression of angiogenesis and hypoxia, and finally perform the dynamics quantitative monitoring, to look forward to understanding the oncogenesis and progression of gastric cancer, and lay a solid foundation on precise diagnosis and treatment of tumor.

组织乏氧与血管新生在胃癌发生发展中呈现相互影响的动态关系，对该动态过程的探索将有助于揭示胃癌演进真实状态。已有技术手段均无法对其动态发展过程进行精确量化监测，因此，建立新的可精确量化监测胃癌血管新生与乏氧间动态发展过程的在体可视化方法十分必要。鉴于此，本项目拟以具有HIF-1-Luc报告基因的胃癌乏氧原位裸鼠模型为研究对象，通过光点击与Chelator-free法构建新型胃癌新生血管特异性放射荧光/PET双模分子探针，利用基于CT先验的动态生物发光断层成像技术和基于PET/CT先验的动态放射荧光断层成像技术，结合荧光素底物和新生血管特异靶向探针的动力学代谢模型，对胃癌乏氧动物模型不同时间点的乏氧动力学参数和肿瘤血管新生进行同步精确量化，并通过非线性最小二乘拟合，最终建立两者间动态发展过程的量化关系，实现对该过程的动态量化监测，以期为胃癌发生发展过程的深入认识及其精准可视化诊治奠定研究基础。

组织乏氧与血管新生在实体瘤发生发展中呈现相互影响的动态关系，对该动态过程的探索将有助于揭示癌症演进真实状态。已有技术手段均无法对其动态发展过程进行精确量化监测，因此，建立新的可精确量化监测实体瘤中血管新生与乏氧间动态发展过程的在体可视化方法十分必要。基于以上研究背景，本项目首先通过光点击化学法，将具有血管特异性的精氨酸-甘氨酸-天冬氨酸-N-ɛ丙烯赖氨酸(RGD-acrk)多肽与生物可降解介孔二氧化硅纳米颗粒(BMSN)表面结合的四唑化合物进行了光引发的环加成反应，构建了血管特异的荧光纳米探针(bmsn@T2-RGD-acrk)，其荧光发射波长为550 nm，具有低毒高稳定性的特性，可在4T1细胞和乳腺癌荷瘤小鼠高特异性成像，在体成像的STBRs数值是2.71倍，高出非靶向组探针2.4倍。其次，以DNA origami和蒽醌类药物AQ4嵌合构建了一种药物递送成像监测和协同治疗为一体的纳米载药成像系统（AQ4-TDO），并利用该系统在体的光声信号强弱和分布，表明药物的释放情况，并与去氧/携氧血红蛋白所提供的乏氧和常氧区光声信号同步对比，以反映化疗过程乏氧微环境的变化以及药物递送与化疗动态响应关系。大量研究显示乏氧诱导因子-1α（hypoxia inducible factor-1，HIF-1α）是介导细胞对乏氧微环境进行适应性反应的关键性转录调控因子，可通过与下游靶基因启动子和增强子中的缺氧反应元件（HREs）结合的方式参与肿瘤细胞的新血管形成。鉴于此，本项目构建了乏氧响应型HRE-Luciferase/Renilla luciferase（简称为HRE-Luc/Rluc）双荧光素酶报告基因瞬时表达细胞系和乏氧响应型HRE-Luc荧光素酶报告基因稳定表达细胞系，实现了细胞水平和在体水平的乏氧响应通路可视化监测。在此基础上，设计并合成IR780+ir(piq)3@GMO乏氧纳米探针，用于研究在体肿瘤物理缺氧区域与缺氧诱导因子HIF1α响应通路之间的关系，以及化疗过程中肿瘤乏氧微环境的变化。以期为癌症发生发展过程的深入认识及其精准可视化诊治奠定研究基础。