靶向肿瘤细胞与新生血管MR/NIRF双模态分子探针制备及其用于食管鳞癌早期检测的实验研究

Esophageal squamous cell carcinoma (ESCC) is a common malignant tumor in the world. If this malignancy is detected as early as possible, the 5-year survival rate can arrive at more than 90%. Molecular imaging can depict small tumor and reach the goal of early diagnosis of this malignancy. RALAHPRDHPDL polypeptide has high binding affinities to the human ESCC cell line Eca-109, and the arginine-glycine-aspartic acid (RGD) peptide can bind to the integrin αvβ3. This program will aim at the development of two magnetic resonance/near-infrared fluorescence dual-modality molecular probes targeted respectively to the cell line Eca-109 or the integrin αvβ3, and labeled by both magnetic resonance contrast agent Mn(II) dendrimer and near-infrared agent Cy5.5. The effects of probe concentration on MR signal intensity, and the relaxivities of both molecular probes will be investigated. The vitro study will be performed to determine whether both probes have favorable biocompatibility and targeting specificity, and to evaluate the effect of MR targeting imaging in ESCC cell and in tumor angiogenesis. In the vivo study of ESCC xenograft mode in nude mice, the effect of MR targeting imaging in the nude mouse transplanted tumor will be investigated, and volume of the detectable minimum tumor will be measured on the contrast magnetic resonance images when single or both probes are used as contrast medium. This animal experimental study will aim at demonstrating the targeting specificity of both probes in vivo, and clarifying which probe is more conducive than the other probe for the early detection of this tumor when single target imaging is performed to the ESCC cell or to the tumor neovascularization, and feasibility of early detection of ESCC will also be determined when both-targets imaging for the ESCC cell and the tumor neovascularization is performed. Biological distribution of both probes in vivo will also be investigated when both or single probes are used to image this tumor to clarify the metabolism situation of the probes. This study will establish a foundation for the relevant research in clinical settings.

食管鳞癌是常见恶性肿瘤，早期发现，术后5年生存率超过90%。分子影像可早期检测肿瘤。RALAHPRDHPDL肽能特异结合人食管鳞癌细胞株Eca-109，RGD肽能特异结合整合素αvβ3。本项目分别以Eca-109和αvβ3为靶点，均以新型Mn(II)树状多价示踪剂为磁共振(MR)信号组件、Cy5.5为近红外光(NIRF)信号组件，构建两种MR/NIRF双模态分子探针，评价探针浓度对MR信号强度的影响及其弛豫度。用体外细胞实验研究两种探针的生物相容性及靶向特异性，以及分别对食管鳞癌细胞、新生血管的MR靶向显像效果。用裸鼠食管鳞癌移植瘤模型研究两种探针联合与单用对肿瘤的显像效果及能检测到的最小肿瘤体积，阐明探针在体内的靶向特异性，阐明肿瘤细胞与新生血管单靶点显像哪种探针更有利于肿瘤早期检测，以及双靶点显像对肿瘤早期检测的可行性；研究两种探针联合及单用时在体内的代谢。相关成果为临床研究打下基础。

基于碳酸酐酶Ⅸ（carbonic anhydrase IX，CA IX）在乏氧实体肿瘤中的关键作用，抑制CA IX同工酶作用已成为乏氧肿瘤治疗中抗肿瘤细胞增殖和转移、抑制肿瘤组织血管生成的重要手段。本课题研究实施是以均三嗪环（Triazine）为分子骨架核心，利用本课题组研发的[Mn(Ty-EDTA)]2-为磁共振信号探针，以CA IX抑制剂乙酰唑胺（5-氨基-1,3,4-噻二唑-2-磺酰胺）作为肿瘤靶向分子，在均三嗪环骨架上同时共价修饰影像信号探针和靶向分子，合成具有乏氧实体瘤靶向性的磁共振分子影像探针（CAⅨ-Mn）。用Q-PCR技术研究食管癌患者癌组织及其癌旁组织中CAⅨ的含量，用裸鼠食管鳞癌移植瘤研究靶向碳酸酐酶Ⅸ新型锰造影剂在食管癌成像的靶向性。开展了食管鳞癌磁共振外科可切除性形态学研究，用血氧水平依赖性磁共振功能成像对食管鳞癌的血氧代谢特征研究，用磁共振体素不相干运动扩散加权成像对食管鳞癌水分子布朗运动及微循环特征进行了定量研究，用动态增强磁共振对食管鳞癌的微循环特征进行了定量研究，用磁共振多模式成像对食管鳞癌体积测量及其与肿瘤分期的相关性进行了定量研究，用磁共振电影成像对食管鳞癌运动规律进行了定量研究，并用影像组学的手段对食管鳞癌的综合影像学特征进行了初步系统性研究，成果为食管鳞癌早期检测研究奠定了基础。

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