基于同时靶向肿瘤细胞和CAFs策略构建特异触发式共载脂质体用于结直肠癌治疗的研究

Single chemotherapy is difficult to completely remove tumor cells, which may cause tumor recurrence. Tumor microenvironment (TME) plays a crucial role in tumor progression. Among that, cancer-associated fibroblasts (CAFs) as the main component of the TME can promote tumor invasion and metastasis, and has become the focus in current cancer research. In view of this, a combination therapy strategy for simultaneously targeting to tumor cells and CAFs is proposed in this project, and a kind of novel specific-triggered co-loaded liposomes is designed for the co-delivery and different-targeting between irinotecan hydrochloride (IRI) and sibrotuzumab (BIBH1). Both targeting factor cRGD peptide and cationic peptide R9 are firstly selected for the preparation of IRI liposomes, and then BIBH1 are connected to R9 via electrostatic interaction. BIBH1 can identify and bind to fibroblast activation protein (FAP) in CAFs, and then fall off from the surface of the liposomes, thus inhibit the proliferation of CAFs. Afterwards, it is triggered that cRGD peptide can target to the tumor cells, and R9 peptide mediate the liposomes into the cells with efficient transmembrane and intracellular lysosomal escape. Overall, This drug delivery system integrates multi-functions with co-loading of both drugs, specific different targets for drug release, efficient transmembrane and intracellular lysosomal escape, which is expected to improve the treatment effect on colorectal cancer, and provide a new idea for the clinical cancer treatment.

单一化学治疗很难彻底清除肿瘤细胞，易造成肿瘤复发。肿瘤微环境（TME）在肿瘤进展过程中起到至关重要作用，其中，肿瘤相关成纤维细胞（CAFs）作为肿瘤微环境的主要成分，可促进肿瘤侵袭和转移，已成为目前肿瘤研究关注的焦点。基于此，本课题提出同时靶向肿瘤细胞和CAFs的联合治疗策略，设计一种新型特异触发式共载脂质体用于盐酸伊立替康（IRI）与西罗珠单抗（BIBH1）的异靶点共递送。选用肿瘤细胞靶向因子cRGD肽、阳离子短肽R9首先制备载IRI脂质体，再将BIBH1与R9通过静电作用连接。BIBH1可与CAFs中纤维细胞活化蛋白（FAP）特异性结合并从脂质体表面脱落，抑制CAFs增殖；进而触发cRGD肽靶向肿瘤细胞，R9肽介导脂质体高效穿膜入胞以及胞内溶酶体逃逸。该药物递释体系集两药共载、特异性异靶点释药、高效穿膜、溶酶体逃逸等多功能集成与一体，有望提高结直肠癌治疗效果，对临床肿瘤治疗提供新思路。

肿瘤相关成纤维细胞（CAFs）是肿瘤微环境的主要组成部分，为肿瘤的侵袭转移等提供了必要的“土壤”。本研究项目提出了同时靶向肿瘤细胞和CAFs的联合治疗理念，在杀死肿瘤细胞的同时，消除肿瘤生长的土壤，从而重塑肿瘤微环境，进而达到提高抗肿瘤效果、有效降低恶性肿瘤侵袭转移的目的，对临床肿瘤治疗提供新思路。基于该治疗理念，本项目研究设计了不同纳米载药体系并进行了系统评价。首先，设计构建了一种伊立替康/scFv共载脂质体，伊立替康是治疗结直肠癌的一线化疗药物，能够有效杀伤肿瘤细胞；scFv是一种单链单抗，能够特异性靶向CAFs 上高表达的纤维细胞活化蛋白（FAP），脂质体能够实现在肿瘤微环境敏感释放scFv，两药联用能够同时杀伤肿瘤细胞和CAFs。该制剂集两药共载、异靶点作用、主动靶向、肿瘤深渗透、溶酶体逃逸等优势于一体，能够增加在肿瘤组织的蓄积，并表现出良好的抗肿瘤效果和抑制肺转移能力。此外，本项目还构建了一种伊立替康/BGJ-398共载pH敏感脂质体，BGJ-398可作用于CAFs上的成纤维细胞生长因子受体（FGFR），从而抑制CAFs增殖，该脂质体可在肿瘤微环境下响应性释放两种药物，实现同时抑制肿瘤细胞和CAFs增殖。在小鼠皮下移植瘤模型中体内抗肿瘤评价，经pH敏感脂质体治疗后小鼠瘤体积和瘤重均最小；小鼠结肠癌肺转移模型也表明pH敏感脂质体组肺转移结节数最少，具有更好的抑制肿瘤转移效果。相关研究内容发表SCI文章5篇（影响因子均在5分以上），中文核心期刊1篇，申请发明专利1项，培养硕士生4名，超额完成任务书目标。