胰腺癌早期诊断及基因治疗双功能磁共振分子探针构建及性能研究

Pancreatic cancer is a devastating and virtually unexceptionally lethal malignancy, partly because the cancer usually causes no symptoms early on, leading to locally advanced or metastatic disease at time of diagnosis. Combined with advanced contrast agent, MRI may allow for molecular profiling of pancreatic cancer and potentially enable the early detection of pancreatic cancer, more accurate staging, and treatment monitoring. The Mucin (MUC4) expressing in pancreatic cancer cells provides a reasonable target for early diagnosis and therapy as the human MUC4 mucin plays an important role in the pathogenesis of pancreatic cancer. In this project, we propose to screen out MUC4-targeting peptide and MUC4-specific small interfering RNA (siRNA) based on the phage display screening and the in vitro gene silence effects. Targeting peptide of MUC4 and MUC4-siRNA will be conjugated onto superparamagnetic iron oxide nanoparticles to serve as novel theranostics for pancreatic cancer diagnosis and gene therapy. We will ascertain off-target and gene silence effects of MUC4-siRNA-labeling iron oxide nanoparticles in established animal models of pancreatic cancer in order to develop a new protocol for noninvasive monitoring pancreatic cancer diagnosis and gene therapy. Thus, these finding will impact a wide range of diseases including pancreatic cancer that are amenable to treatment using theranostics based on functional iron oxide nanoparticles.

胰腺癌是一种严重威胁人类健康的恶性肿瘤，早期诊断困难，死亡率高，迫切需要建立早期诊断、治疗以及监测治疗效果的有效方法。粘蛋白MUC4对胰腺癌的生物学行为起着重要作用并为早期诊断和治疗胰腺癌提供了新的方向。本课题拟采用噬菌体展示技术筛选胰腺癌细胞粘蛋白MUC4的靶向多肽；从备选小干扰RNA(small interfering RNA, siRNA )中筛选出沉默效果最好的MUC4特异性siRNA。用靶向多肽和MUC4-siRNA修饰超顺磁性氧化铁纳米颗粒（superparamagnetic iron oxide nanoparticles, SPIO），使SPIO具有靶向胰腺癌组织并兼具基因治疗的双重功能。进一步建立胰腺癌动物模型，运用MR检测MUC4在早期胰腺癌的表达并监测MUC4-siRNA对胰腺癌的治疗效果，从而实现早期活体无创性诊断胰腺癌及监测其基因治疗疗效。

胰腺癌的分子影像研究对胰腺癌的早期诊断及治疗有着重要的意义。粘蛋白（MUC4）在胰腺肿瘤组织中特异性高表达，为胰腺癌的早期诊断和治疗提供了新的思路。本项目首先采用噬菌体展示技术筛选出了胰腺癌细胞MUC4的靶向短肽，其氨基酸序列为：VHWDFRQWWQPS。然后再通过体外实验证明了该靶向短肽具有与MUC4蛋白特异性结合的能力。同时我们还筛选出了针对胰腺癌MUC4沉默效果最好的siRNA（small interfering RNA），其碱基序列为：GGGAACAACTTCAGTCCAACT。随后利用PEI/SPIO纳米复合物复合该siRNA，并对胰腺癌细胞株进行转染实验。结果证明，该复合体进入细胞后能够自动释放siRNA并对MUC4基因产生良好的沉默效应，抑制胰腺癌细胞表面MUC4的表达。目前，该项目已培养了硕士研究生15人，培养了尼日利亚访问学者1人，发表外文文章4篇。