集光动力治疗和缺氧活化的前药化疗于一体的多功能纳米药物肿瘤靶向治疗策略研究

Photodynamic therapy is a novel light-triggered therapeutic strategy that has been successfully translated into cancer clinic. In recent years, vascular-targeted photodynamic therapy (VTP) has been given more and more attention due to the central role of tumor angiogenesis in cancer development and the R&D breakthrough of antiangiogenic drugs. However, the previously reported VTP methods have encountered two bottlenecks shown in the triggering/aggravating tumor hypoxia stress and low sensitive, resistant peripheral tumor vasculature, both of which finally lead to comprised therapeutic efficacy and tumor relapse. In this proposal, a new nanomedicine, cRGDfK peptide-modified stealth graphene oxide (GO) nanoparticles co-deliverying photosensitizer verteporfin (VP) and hypoxia-activated prodrug AQ4N (cRGDfK-pGO-VP-AQ4N), is smartly engineered. This nanomedicine can exert programmed multi-modality anticancer functions of directly killing tumor vascular endothelial cells and tumor cells by the dual-targeting photodynamic therapy, inducing tumor hypoxia and necrosis through the VTP-mediated antivascular effects, and killing the remaining hypoxia-stressed tumor cells by AQ4 (a potent inhibitor of Topoisomerase Ⅱ) transformed from AQ4N under hypoxia. Our innovative investigation will provide new theoretical ideas and guidance in the development of tumor-targeted photodynamic therapy, chemotherapy with hypoxia-activated pro-drug, and their clinical translation.

光动力治疗是一种新颖的已成功转化于临床应用的光触发肿瘤治疗手段，近些年来，肿瘤血管靶向光动力治疗策略受到重点关注。然而，已有的血管靶向光动力治疗方法存在诱发和加重肿瘤组织缺氧应激、肿瘤边缘区域的血管不敏感导致肿瘤复发等瓶颈。本项目在前期工作基础上，率先构建集双靶向光动力治疗和缺氧活化的前药化疗于一体的多模式治疗纳米药物 — cRGDfK多肽修饰的共装载光敏剂维替泊芬（VP）和缺氧活化的前药AQ4N的氧化石墨烯（GO）隐形纳米粒（cRGDfK-pGO-VP-AQ4N）。该纳米药物具有程序性、多功能抗肿瘤特性：通过靶向光动力治疗直接杀伤肿瘤血管内皮细胞和肿瘤细胞，通过抗血管作用诱导肿瘤组织缺氧、坏死，继发AQ4N在缺氧环境中活化杀伤残存的缺氧应激下的肿瘤细胞，实现肿瘤靶向光动力治疗和缺氧活化的前药化疗的有机结合。这一多模式肿瘤靶向治疗策略和相关研究国内外未见报道，具有很高的创新价值。

肿瘤血管靶向光动力治疗（vascular-targeted photodynamic therapy，VTP）作为新近批准的实体瘤治疗方法，因其具有的微创性、独特的选择性和安全性而备受瞩目。然而，这一方法诱导的加重的肿瘤缺氧应激使得该单一模式治疗手段临床获益受限。在这一研究中，课题组开发了一种基于VTP的多模式治疗策略，利用VTP诱导的缺氧环境激活仅在缺氧条件下活化的化疗药物（AQ4N），选择性杀伤缺氧应激的肿瘤细胞。进一步通过研究和文献调研发现，低氧条件下AQ4N的主要活化酶CYP450的表达量却受到明显抑制。肿瘤细胞高表达的HIF-1α通过竞争性结合HIF-1β显著下调CYP450 1A1和2B6两种亚型的表达量，HIF-1α作为“隐形的刹车（hidden brake）”，严重阻碍了AQ4N在低氧环境下的高效活化。据此，课题组构建了基于氧化石墨烯载体的共递送光敏剂（Verteporfin，维替泊芬）、缺氧活化的前药（AQ4N）和HIF-1α siRNA的三模式治疗靶向纳米系统，通过VTP诱导的低氧环境活化AQ4N，通过HIF-1α siRNA增加低氧环境下CYP450活化酶的表达量，显著增强AQ4N在低氧环境下的活化效率，实现了肿瘤血管靶向光动力治疗，缺氧活化的前药化疗和HIF-1α siRNA三模式锁联协同治疗。