靶向肿瘤相关巨噬细胞给药系统的构建和药效评价

Tumor-associated macrophages (TAMs) play an important role in promoting tumor angiogenesis, and are a novel target for anti-angiogenesis therapy. Antiangiogenic drugs can activate autophagy in cancer cells, and autophagy resists antiangiogenesis efficacy. Inhibiting TAMs proliferation results in antiangiogenesis, and inhibiting autophagy enhances efficacy of antiangiogenic drugs. In this study we will establish TAMs targeting drug delivery system, and investigate the influence of autophagy inhibitor chloroquine on efficacy of TAMs targeting drug delivery system. With zoledronic acid as model drug, mannose, activable cell-penetrating peptide (ACPP) and pH-sensitive polyethylene glycol (PEG) will be modified on the surface of nano-liposomes. We hypothesize that nano-liposomes passively target tumor, pH sensitive PEG hydrolyzes in acidic environment of tumor tissue and mannose modified on nano-liposomes is exposed, and ACPP is cleaved to cell-penetrating peptide by matrix metalloproteinase 2/9. Mannose and cell-penetrating peptide actively target TAMs, and pH-sensitive PEG decreases the influence on normal macrophages. Mannose receptor binding affinity and three-dimensional multicellular tumor spheroids experiments will be used to verify the sensitivity of TAMs targeting liposomes to pH and matrix metalloproteinase 2/9, and targeted depletion of TAMs and inhibition of tumor angiogenesis by TAMs targeting liposomes will be investigated. We will prepare chloroquine long circulating liposome and study the influence of chloroquine on efficacy of zoledronic acid. The purpose of this project is to provide new strategy for targeted depletion of TAMs and enhancement of antiangiogenic drugs’ efficacy.

肿瘤相关巨噬细胞（TAMs）在肿瘤血管新生中发挥关键作用，是抗肿瘤血管新生的新靶点。抗肿瘤血管新生药物诱导肿瘤细胞发生自噬，自噬抵抗药效。抑制TAMs可抗肿瘤血管新生，抑制自噬提高抗肿瘤血管新生药物药效。本项目构建靶向TAMs给药系统，并研究自噬抑制剂氯喹对其增效作用。以唑来膦酸为模型药物，用甘露糖、可激活的细胞穿膜肽（ACPP）和pH敏感聚乙二醇修饰纳米脂质体。脂质体被动靶向肿瘤后，pH敏感聚乙二醇水解使甘露糖暴露，ACPP被基质金属蛋白酶2/9（MMP-2/9）水解为细胞穿膜肽，二者实现主动靶向，pH敏感聚乙二醇减少对正常巨噬细胞的影响。通过甘露糖受体结合和三维多细胞肿瘤球实验，验证靶向TAMs脂质体对pH和MMP-2/9敏感性，考察靶向清除TAMs和抗肿瘤血管新生作用。制备氯喹脂质体，考察氯喹对唑来膦酸增效作用。本项目的实施可为靶向清除TAMs和提高抗肿瘤血管新生药物药效提供新策略。

巨噬细胞来源于循环血液中的单核细胞，受肿瘤微环境的影响，肿瘤组织中的单核细胞分化为替代激活的巨噬细胞（M2型），即肿瘤相关巨噬细胞。肿瘤相关巨噬细胞在肿瘤血管新生中发挥着关键作用，是抗肿瘤血管新生的新靶点。唑来膦酸可直接抑制肿瘤相关巨噬细胞增殖和诱导其凋亡，但唑来膦酸影响各种类型的巨噬细胞。为了不影响正常巨噬细胞的免疫功能和提高唑来膦酸的抗肿瘤药效，本课题构建了靶向肿瘤相关巨噬细胞的给药系统。制备纳米脂质体，用甘露糖和可激活的细胞穿膜肽修饰脂质体表面，用pH敏感的聚乙二醇包裹脂质体。本课题合成了维生素E聚乙二醇琥珀酸酯-甘露糖结合物、1,2-二硬脂酰-sn-甘油-3-磷脂酰乙醇胺-N-羧基（聚乙二醇2000）马来酰亚胺-穿膜肽结合物、1,2-二硬脂酰-sn-甘油-3-磷脂酰乙醇胺-N-羧基（聚乙二醇2000）马来酰亚胺-可激活的穿膜肽结合物和聚乙二醇5000-腙-磷脂酰乙醇胺。采用薄膜分散法制备了靶向肿瘤相关巨噬细胞的唑来膦酸脂质体，脂质体的粒径为108.8 nm，包封率为7.52%。本项目为靶向清除肿瘤相关巨噬细胞和抗肿瘤血管新生提供新的研究思路和方法。