“深渗透”级联响应脂质囊纳米粒介导雷公藤甲素靶向胰腺癌－基质互作的研究

Triptolide, an active ingredient from traditional chinese medicine Tripterygium wilfordii Hook, has demonstrated potential anti-pancreatic cancer efficacy probably through the interruption of pancreatic carcinoma-storma interaction. However, the difficulty of breaking through carcinoma mass barrier, the failure of intratumoral penetration as well as high toxicity and narrow therapeutic window have largely limited its clinical application. To solve this issue, our project aims to employ a pulsed magnetic field guide technology and environmental responsive technology to engineer a liposome-magnetic nanoparticle drug delivery system, which characterizes deep intratumoral penetration and multistage responses. By use of the multistage responsive characteristic through multi-channel, multi-mechanism way, The capability of pancreatic carcinoma targeting， intratumoral penetration and active targeting pancreatic cancer cells and tumor-associated fibroblasts are embedded together on the drug delivery to mediated triptolide targeting pancreatic carcinoma-storma interactions. Its targeting characteristics，pharmacokinetic profiles, intratumoral penetration mechanisms and transport mechanism of targeting pancreatic carcinoma cells and tumor-associated fibroblasts will be investigated comprehensively through the whole animal, cellular and molecular level by of the integrated use of BXPC3/hPSC co-cultured 3D cellular model, BXPC3/hPSC co-transplantation orthotropic xenograft model, MRI imaging, IMPM imaging, micro-dialysis technology. Our project will provide initial ideas and experimental proofs for the development of novel drug delivery systems mediating traditional Chinese medicine targeting tumor - stromal interactions.

针对中药抗肿瘤有效成分雷公藤甲素毒性大、治疗窗窄，且难以突破胰腺癌组织渗透屏障，达到肿瘤深部实现靶向胰腺癌－基质相互作用的问题。本项目拟利用脉冲磁场诱导及环境自响应技术，构建具有肿瘤组织深渗透特性的级联响应型脂质囊磁性纳米粒递药系统，表征其结构。通过多途径、多机制级联响应方式实现胰腺癌组织靶向、组织深部渗透与主动靶向胰腺癌细胞与肿瘤相关成纤维细胞三者有机结合，从而达到介导雷公藤甲素靶向胰腺癌－基质相互作用的目的。通过综合运用BXPC3/hPSC共培养3D细胞模型、原位BXPC3/hPSC共移植荷瘤裸鼠模型、MRI成像、IMPM成像、组合微透析等技术从整体动物、细胞与分子三个水平综合评价其靶向特性及药动学过程，并探讨其胰腺癌组织深渗透机制以及主动靶向胰腺癌细胞、肿瘤相关成纤维细胞的转运机制。本课题的顺利实施，将为中药靶向肿瘤－基质相互作用递药系统的构建提供新的思路与实验依据。

药理学实验及临床研究表明雷公藤甲素具有较好的抗胰腺癌疗效；然而由于雷公藤甲素存在体内半衰期短、在胰腺癌肿瘤组织内分布不具有特异性、体内肝肾毒性较强等缺点，限制了其临床抗肿瘤应用。本课题通过二硫键将雷公藤甲素链接于氧化铁纳米粒表面（粒径约25nm），并将该载药纳米粒包裹于PDGFR 识别肽 pPB（Cys-Ser -Arg-Asn-Leu-Ile-Asp-Cys）靶头修饰的脂质纳米囊（粒径约140nm）中成功构建具有核-壳结构的脂质囊氧化铁纳米粒递药系统（pPB-LP-NP-TPL）。综合运用核磁共振技术、SEM显微技术、XRD技术、DSL技术等表征纳米载体及其相关中间产物的结果和特征。体外药物释放度研究表明pPB-LP-NP-TPL具有明显的缓释特性，2h内的药物积累释放量仅19.22±2.30%。细胞水平研究表明具有还原响应性的氧化铁纳米粒可以有效携带雷公藤甲素的胰腺癌细胞摄取，提高雷公藤甲素在胞内的含量，细胞摄取机理研究表明载体主要通过anti-PDFGβ受体介导的细胞内吞作用进入胰腺癌细胞内；但该氧化铁纳米粒在血浆中容易积聚，大鼠体内消除较快。经pPB靶头修饰的脂质纳米囊包裹后不仅进一步提高了携带雷公藤甲素的氧化铁纳米粒对胰腺癌细胞的靶向性，且极大改善了纳米粒在血浆中的稳定性和延长了其大鼠循环系统中的滞留时间和在肿瘤组织中的药物浓度，从而增强雷公藤甲素对胰腺癌细胞诱导细胞周期G2/M期阻滞、抑制细胞增殖的能力，以及对BxPC3荷瘤裸鼠肿瘤组织的靶向性和抗肿瘤药效。本研究显示采用具有核-壳结构的脂质囊磁性纳米粒递药系统可有效提高雷公藤甲素在胰腺癌组织内分布，降低其在肝肾等主要脏器的药物浓度，使雷公藤甲素增效减毒，从而有助于扩大雷公藤甲素抗肿瘤临床应用。本项目的实施为中药靶向胰腺癌肿瘤递药系统的构建提供新的思路与实验依据。