超声激发叶酸靶向携氧载药微泡对卵巢癌的化疗增敏作用及机制研究

Lines of pre-clinical and clinical evidences suggest that tumor hypoxia is a key contributing factor for tumor resistance to various treatment modalities. Therefore, hyperoxic treatment is commonly prescribed before chemotherapy in order to boost tumor oxygenation, improve drug uptake, and enhance tumor response. However, increasing tumor oxygenation by hyperoxic methods such as oxygen respiration or hyperbaric chamber is not efficient because most of the oxygen change is at the systemic level. Therefore, it is clinically important to develop new techniques for targeted delivery of oxygen and anti-cancer drugs to the tumor site without major systemic side effects. Perfluorocarbon (PFC) has good oxygen solubility and stable chemical properties, which is suitable for fabricate drug or oxygen loaded microbubbles. However, Notargeted microbubbles that are readily aggregated in liver or spleen, leading to a low concentration at the disease site. The tumor targeted microbubbles limited penetration across the tumor vascular endothelium. We synthesized tumor and mononuclear phagocytes-specific multifunctional microbubbles by surface modification with folate for ultrasound mediated delivery of oxygen and drugs with ultrasound imaging guidance. We hypothesize that ultrasound mediated fragmentation of the activatible microbubbles will facilitate controlled delivery of oxygen and paclitaxel with improved efficiency. This hypothesis will tested experimentally in hypoxia ovarian cancer cells in vitro and ovarian cancer model in vivo by intraperitoneal delivery . This study may provide a new way to therapy hyperoxic ovarian cancer, and also provide a new mode of physical therapy that is efficiency for both tumor and tumor microenvironment.

乏氧是导致肿瘤化疗抵抗的关键因素，传统采用在肿瘤患者化疗前吸氧或高压氧疗等方法主要是提高机体整体血氧水平，而在改善肿瘤局部乏氧微环境方面效果不理想。氟碳物质不但有良好的携氧能力，同时化学性质稳定,常用来制备载药超声微泡造影剂，是氧气及药物靶向输送及定位控释的良好载体。但普通微泡造影剂对肿瘤组织缺乏靶向性，存在靶区外非特异性聚集现象。肿瘤特异性抗体介导的靶向超声微泡造影剂不易透过肿瘤血管内皮间隙与肿瘤组织结合。本项目基于叶酸对卵巢癌细胞、单核-巨噬细胞的双重靶向能力及单核-巨噬细胞吞噬游走特性，通过超声乳化法合成叶酸靶向携氧载紫杉醇微泡造影剂，并利用卵巢癌腹腔生长转移的生物学特点，采用腹腔给药方式，体内外系统研究该靶向微泡对卵巢肿瘤体内外寻靶能力以及超声激发微泡对卵巢肿瘤的化疗增敏作用，为乏氧卵巢肿瘤靶向治疗提供新思路，有望建立一种对肿瘤及肿瘤微环境共同敏感的新型物理治疗模式。

乏氧是导致肿瘤化疗抵抗的关键因素，传统采用在肿瘤患者化疗前吸氧或高压氧疗等方法主要是提高机体整体血氧水平，而在改善肿瘤局部乏氧微环境方面效果不理想。氟碳物质不但有良好的携氧能力，同时化学性质稳定,常用来制备载药超声微泡造影剂，是氧气及药物靶向输送及定位控释的良好载体。但普通微泡造影剂对肿瘤组织缺乏靶向性，存在靶区外非特异性聚集现象。肿瘤特异性抗体介导的靶向超声微泡造影剂不易透过肿瘤血管内皮间隙与肿瘤组织结合。本项目基于叶酸对卵巢癌细胞、单核-巨噬细胞的双重靶向能力及单核-巨噬细胞吞噬游走特性，采用机械振动法合成叶酸靶向携氧载紫杉醇微泡造影剂，并通过超声靶向激发控释氧气及药物对肿瘤进行靶向杀伤。荧光显微镜及流失细胞检测发现该造影剂对叶酸受体阳性的卵巢癌细胞及肿瘤相关巨噬细胞具有双重靶向能力，并可进入肿瘤小体内。超声联合该靶向造影剂可通过降低HIF-1α蛋白及P-gp的表达提高紫杉醇对卵巢癌细胞的敏感性，延长荷瘤鼠生存期，减少肿瘤组织CD68阳性细胞量及VEGF表达，降低肿瘤微血管密度。提示腹腔注射双靶向TOPLMBs联合超声辐照是一种对肿瘤及其微环境共同敏感的治疗方法， 其疗效优于传统化疗。该课题所合成的叶酸靶向携氧载紫杉醇声学造影剂在国内外尚未见报道，对卵巢癌的早期诊断及靶向治疗方面将具有重要的临床价值。