MUC5AC靶向分子探针对胰腺癌和胰腺炎动物模型MRI成像研究

Pancreatic cancer is highly malignant and the prognosis is poor, and does great harm to human health. Early, accurate diagnosis is the key to the improvement of survival rate of the patients. Based on the low expression of MUC5AC in the normal pancreatic tissue and pancreatitis, high expression in PanINs and pancreatic cancer, we choose MUC5AC for imaging targets. Firstly, we established dual-mode targeted probe with fluorescent and magnetic Nano-MR imaging (Cy5.5-anti-MUC5AC-MNPs). The qualities and functions of the probe were tested by Elisa method, electronic diffraction, zeta potential, vibration magnetometer. Secondly, a series of experiments in vitro were performed with molecular probe and pancreatic cancer cells BxPC3, as well as in normal islet cells for comparison. Thirdly, targeted molecular contrasts were injected into animal models of pancreatic cancer and pancreatitis. Targeted MR molecular imaging was done in vivo. Finally, the two murine lesions and surrounding tissue specimens were tested by immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR), Western blotting and routine pathological and immunohistochemical methods, and the results of targeted enhancement in animal models of pancreatic cancer and pancreatitis were compared. Based on the MUC5AC targeted molecular imaging in vivo, dynamic evaluation of pancreatic cancer, the research aims to achieve early and specific diagnosis at the molecular level in pancreatic cancer.

胰腺癌恶性程度高，预后差，严重危害人类的健康。早期、准确诊断是提高生存率的关键。基于MUC5AC在正常胰腺组织及胰腺炎中低表达，在胰腺早期瘤变PanINs各期及胰腺癌中高表达，我们选择MUC5AC为成像靶点，首先构建具有荧光和磁性纳米MR成像的双模式靶向探针，采用Elisa法、电子衍射、zeta电位、振动磁强计等方法， 对该探针进行性能检测； 其次，将该探针和胰腺癌细胞BxPC3进行系列体外实验，并和正常胰岛细胞对照；然后，将靶向探针注入胰腺癌和胰腺炎小鼠动物模型体内，进行靶向活体MR分子水平显像；最后，取该两种小鼠动物病变和周围组织标本，应用免疫组化、逆转录-聚合酶链反应、Western 印迹法等进行常规病理和免疫组化检测，并与两种动物模型的靶向增强结果进行对照分析。其研究目的就是基于MUC5AC靶向分子成像，活体、动态评价胰腺癌，希望实现对胰腺癌在分子水平早期特异性诊断之目的。

胰腺癌（PDAC）是常见的恶性肿瘤之一，恶性程度高，临床进展快，易早期侵犯和转移，死亡率高，因此，胰腺癌的早期诊断对于提高可治愈率、术后预后及最终存活率具有重要意义。本项目研究合成聚乙二醇修饰的磁性纳米颗粒PEG∙SPIONs，并对该纳米颗粒性质进行性能表征，再构建基于MUC5AC磁性及荧光双模态成像探针FITC-anti-MUC5AC-PEG∙SPIONs；然后，通过 PEG∙SPIONs 与胰腺癌细胞系SW1990及小鼠成纤维细胞系3T3共同孵育的方法评价探针的毒性和体内药物代谢动力学试验，并研究探针FITC-anti- MUC5AC-PEG∙SPIONs体外成像能力及靶向能力；最后，应用双模态靶向分子探针进行人胰腺癌裸鼠原位移植瘤模型的MR成像，结合MR图像和病理结果，分析该双模态靶向分子探针对胰腺癌的靶向成像效果。结果显示该双模态靶向分子探针的粒径小、胶体稳定性佳、磁学参数理想且无毒性，体外实验结果显示普鲁士蓝染色显示孵育anti-MUC5AC-PEG∙SPIONs靶向探针的胰腺癌细胞内有大量的蓝色铁颗粒分布，荧光结果进一步显示孵育FITC-anti-MUC5AC-PEG∙SPIONs靶向探针的胰腺癌细胞内有大量荧光分布，且该探针在T2WI上为低信号，提示该分子探针可能是一个理想的MRI分子探针，该双模态靶向分子探针能有效的靶向分布到裸鼠的人胰腺癌原位移植肿瘤中，引起瘤体MR T2信号的降低，其普鲁士蓝染色结果也证实实验组48h时的肿瘤组织内布满大量的蓝色铁颗粒，说明靶向探针能够特异性靶向到达肿瘤组织，此时肿瘤组织T2WI信号较对照组明显降低。上述结果表明本项目研究制备的探针是一个理想的胰腺癌双模态靶向分子探针，有望成为在分子水平早期诊断胰腺癌的重要手段。