树状大分子-介孔硅纳米诊疗体与UTMD联合提高分级靶向性且逆转胰腺癌化疗抵抗的实验研究

The problem of chemo-resistance of pancreatic cancer is urgently to be solved, and for a long time it is the hot direction. The applicant found that ultrasound targeted microbubble (UTMD) technology has great potential in sensitization of pancreatic cancer chemotherapy. Its advantages were of good safety, no selectivity of drugs and drug-carriers, and the specific targeting of irradiation site. On UTMD technology platform, the next problem need to addressed is reducing the chemo-resistance not only induced by pancreatic tumor cells themselves but also induced by tumor stroma abduction. The applicant has proved that the gene of Periostin was closely related to chemo-resistance inducing by tumor stroma. Our coalition partner has done a lot of research on PAMAM- mesoporous silica (MS) nanoparticles. Based on above mentioned foundations, this study intends to use multiple modified PAMAM, grafting with the antibody of Periostin, the antibody of insulin-like growth factor 1 receptor (IGF-1R), and with Gd chelate, which is in order to identify the pancreatic tumor cells and tumor stroma. The MS agent will be efficiently loaded with EGFR inhibitors, IGF-1R inhibitors and gemcitabine, and the chemical stability of the chemo-drugs and the performance of slow-release could be maintained by this nano-MS agent. UTMD could promote this "nano-theranostic agent" richly into the tumor, kill the cancer cells persistently, and reduce the drug side effects. Meanwhile this nano-agent could be used for MRI molecular imaging. Hence, this new therapeutic regime could increase the chemotherapy sensitization, and is expected to provide a new strategy for individualized precise treatment of pancreatic cancer.

化疗抵抗是胰腺癌治疗中亟待解决的也是长期研究的热点问题。申请人前期证实超声靶向破坏微泡技术(UTMD)在胰腺癌化疗增敏中极具潜力，其优势是安全性好、无药物/载体选择性及具有辐照部位靶向性；在此技术平台上，仍需解决由肿瘤细胞自身改变及间质诱导而来的抵抗作用，且选择合适的药物载体分级靶向到肿瘤组织。前期研究表明，骨膜蛋白（Periostin）是间质中特异的化疗抵抗靶点；树状大分子(PAMAM) -介孔硅(MS)纳米的多重修饰及高效负载特性允许多分子靶标显像的同时高效递送多重药物。据此，本研究拟利用PAMAM-MS枝接Periostin抗体、胰岛素样生长因子1受体抗体及钆螯合物，靶向识别肿瘤细胞及间质；荷载Erlotinib、BMS-754807来协同增效吉西他滨；UTMD促进纳米诊疗体分级靶向到细胞，持续抑制肿瘤，减少药物副作用，MRI分子成像评估疗效，为胰腺癌化疗抵抗的精准治疗提供新的策略。

化疗抵抗是胰腺癌治疗中亟待解决的也是长期研究的热点问题。课题组联合超声靶向微泡技术(UTMD)与纳米载体技术研发出增强胰腺癌化疗敏感性的新型精准诊疗一体化平台。首先，课题组制备了包载吉西他滨和微小RNA21抑制剂(miR-21i)的树状大分子纳米金聚合物（Gem-Au DENPs/miR-21i）、荷载吉西他滨及吡非尼酮的pH/GSH 响应性介孔硅控释载药系统(PFD@HMON-Gem)，利用UTMD促进了这些纳米载体在胰腺癌肿瘤细胞的聚集，突破了胰腺癌质韧间质阻碍化疗药物作用的瓶颈，实现了药物在肿瘤部位的可控性缓释，增强了吉西他滨对胰腺癌的化疗敏感性，肿瘤抑制率较对照组显著提升，达79.88%；此外，课题组进一步研发出可用于超声成像的纳米诊疗体(PDA@HMONs-PFP/DOX)，用中空介孔有机硅纳米颗粒（HMONs）为载体，内部包载阿霉素（DOX）和氟碳类超声显影剂全氟戊烷（PFP），表面包覆具有光热转换特性的有机聚合物聚多巴胺(PDA)，以PDA良好的光热转换性能使HMONs装载的PFP在外源性近红外线辐照下产生液气相变，在体内外实现超声显像，还能产生化疗与光热治疗的协同作用，为胰腺癌的化疗增敏提供了一种精准诊疗一体化的新策略；再次，课题组证实了Periostin促进胰腺癌细胞外泌体的分泌进而诱导上皮向间质转化的发生，首次明确提出Periostin/外泌体正反馈环路调控胰腺癌化疗抵抗，为胰腺癌的靶向增敏治疗提供了理论依据。