多水平靶向的pH响应纳米药物对肝门部胆管癌的光动力联合阻断HIF-1a信号通路的协同治疗及其机制

Photodynamic therapy (PDT) is a novel palliative treatment for hilar cholangiocarcinoma. However, the efficacy of traditional photosensitizer (PSs) is reduced when they accumulate, and there is no targeting to tumor foci. Our previous study demonstrated the nano-drug loaded PSs with aggregation-induced emission characteristics (AIE PSs) could overcome the above-mentioned drawbacks, but the level of hypoxia-inducible factor-1a (HIF-1a) was up-regulated after PDT, which resulted in risk of the recurrence and metastasis of tumor. Therefore, we hypothesize that combination PDT with inhibition of HIF-1a signal pathway perhaps is a high efficient synergetic treatment, through carrying mitochondria-specific AIE-Mito PSs and HIF-1a inhibitor LW6 into cholangiocarcinoma cells mediated by targeting nanocarrier. . In this research, the nano-drug system will be carried by pH-responsive vector, accumulated into tumor foci (targeting in tissue level), internalized nano-drug into targeted cells mediated by cRGD (targeting in cell level), triggered to disintegration of nanostructures by acid lysosome, and release the AIE-Mito PSs and LW6. Then, the AIE-Mito PSs specifically bind to mitochondria (targeting in organelle level) and play a role in PDT effect. Meanwhile, the LW6 inhibit the HIF-1a signal pathway caused by PDT (targeting in molecular level). Thus this research aim at provide a novel treatment strategy for hilar cholangiocarcinoma via multi-level targeting of tissue, cell, organelle and molecule.

光动力治疗(PDT)是肝门部胆管癌的姑息治疗新手段，但传统光敏剂(PSs)在聚集时效率下降且对肿瘤灶无靶向性。我们研究证实负载AIE PSs的纳米药物弥补上述缺陷且疗效明确，但也致HIF-1a表达上调，为肿瘤的复发转移埋下隐患。为此，我们设想：以靶向纳米载体为工具，运载线粒体靶向的AIE-Mito PSs和HIF-1a抑制剂LW6，PDT杀灭癌细胞同时阻断HIF-1a信号通路可能是一种高效的协同治疗方案。. 本项目拟采用对pH响应的纳米载体，借助EPR效应进入肿瘤灶(组织靶向)，cRGD介导纳米药物靶向进入癌细胞内(细胞靶向)，溶酶体酸性环境促发纳米结构解体，释放出AIE-Mito PSs特异结合于线粒体(细胞器靶向)，光照下发挥PDT作用，且LW6阻断PDT所致的HIF-1a信号通路激活(分子靶向)，从组织、细胞、细胞器和分子的多水平靶向治疗肝门部胆管癌，为其提供新的治疗策略。

肝门部胆管癌（pCCA）因其起病隐匿，大多数患者就诊时已经丧失根治性切除机会，并且pCCA对放化疗均不敏感。因此，探寻新的治疗手段对这些患者至关重要。光动力治疗(PDT)是通过光将能量转移到光敏剂（PS），进而发生光化学反应，产生活性氧物质（ROS），最终破坏生物大分子的结构和功能，从而杀灭肿瘤细胞。大量临床研究证实PDT可显著抑制pCCA患者的肿瘤进展和延长生存时间。其中，PS是核心因素，但传统的PSs因聚集诱导淬灭效应在分子富集时光动力效应反而下降，并且因对肿瘤无靶向作用而无法高效富集于肿瘤灶导致杀瘤效率低。本项目中，课题组构建了负载聚集诱导发光（AIE）特性的线粒体靶向PS（即AIE-Mito PS，在聚集时荧光强度和ROS产生效率反而增强）和缺氧诱导因子-1a抑制剂的对低pH响应的靶向纳米载体系统，可协同杀灭胆管癌细胞并阻断肿瘤复发。在此基础上，该纳米载体系统可靶向进入胆管癌细胞内，发挥光动力活性并阻断HIF-1a/VEGF信号通路，从而杀灭肿瘤并细胞再增殖。同时，建立小鼠胆管癌移植瘤模型，尾静脉注射该纳米载体系统，检测癌灶靶向富集效应并经光照处理后可显著抑制瘤灶生长并防止肿瘤复发，以及阐述了其分子机制。研究结果表明：（1）AIE-Mito PS经该纳米载体系统靶向结合并进入胆管癌细胞，低pH响应促进其释放至胞浆中进而选择性富集于线粒体，光照后能更高效地杀灭胆管癌细胞，抑制肿瘤生长。（2）光动力效应后引起癌灶缺氧环境会激活HIF-1a/VEGF信号通路，但共载的缺氧诱导因子-1a抑制剂可有效阻断该信号通路激活，从而防止肿瘤复发。（3）该纳米载体系统可实现组织靶向（EPR效应）、细胞靶向（受体介导的细胞吞噬作用）、细胞器靶向（线粒体）和分子靶向（HIF-1a阻断）的多水平靶向作用，达到光动力治疗和抗肿瘤复发的协同治疗目的，为pCCA的姑息治疗提供了一种新的策略。