靶向线粒体的多功能聚合物胶束克服肿瘤耐药性的研究

Drug resistance is a main obstacle in chemotherapy, which is related to inhibition of apoptosis. As the center of the apoptosis regulation in the cell, mitochondrial targeting has attracted much more attention than before, but sequential targeting to mitochondrion is hindered by tumor tissue, cells and intracellular environment. Meanwhile, various anticancer drugs have various intracellular targets other than mitochondrion. So, A novel multifunctional mixed micelle consisit of GE11-PEG-PbAE and MPEG-PCCL(Ceramide/TPP) will be developed to sequentially target to mitochondrion. Once the mixed micelle was endocytosed in the cell, it will be dissociated in the accid conditions of the endosome/lysosome, and then release anticancer drug in the cytoplasm,and MPEG-PCCL(Ceramide/TPP) is released and target to mitochondrion by TPP, together with the release of ceramide in mitochondrion, and then apoptosis is induced to overcoming drug resistance of tumor cells. The research is significant to expand research in antitumor research, and promote the study of organelles targeting nanocarriers.

肿瘤耐药性是化疗失败的重要原因，其产生与肿瘤凋亡抑制有重要关系。而线粒体作为细胞凋亡的调控中心，其靶向给药诱导凋亡，从而克服肿瘤耐药性，成为当前研究的新趋势。作为细胞器水平的线粒体靶向，面临肿瘤组织、细胞和细胞内环境的多重障碍；而化疗药物又有其各自明确的作用靶点（细胞核、微管等）而不宜于线粒体统一释药。本课题合成聚乙二醇单甲醚-b-聚α-甲酸己内酯（神经酰胺/三苯基膦），和GE11肽-聚乙二醇-b-聚(β-胺基酯)，二者混合制得pH敏感胶束，包埋紫杉醇。以期通过GE11肽的主动靶向至肿瘤细胞，并在肿瘤细胞内酸性环境下发生解离，释放紫杉醇至细胞质并趋往其作用靶点，同时聚乙二醇单甲醚-b-聚α-甲酸己内酯（神经酰胺/三苯基膦）可在三苯基膦的介导下靶向至线粒体，释放神经酰胺，实现了其与紫杉醇分别释药，启动凋亡，克服肿瘤耐药性。该课题的开展对抗肿瘤研究和细胞器水平的纳米靶向载体研究，具有重要意义。

随着对线粒体的深入研究,人们认识到线粒体在调节肿瘤细胞凋亡方面起着至关重要的作用。线粒体靶向分子可以使药物特异性的作用于线粒体,进而诱导细胞凋亡,从而达到抗肿瘤的目的,在提高疗效的同时又降低了药物的毒副作用。因此线粒体靶向在抗肿瘤药物中有广阔的应用前景。本研究以透明质酸（HA）作为骨架成功构建了pH敏感的透明质酸-阿霉素-三苯基膦（HA-hydra-DOX-TPP）纳米给药系统，其粒径为192nm，电位为-24mV。HA-hydra-DOX-TPP在酸性条件下可以快速释放DOX-TPP，并且靶向到线粒体，增强细胞内Caspase 3的活性，诱导产生较多的ROS，从而产生较大的细胞毒性。体内实验结果显示HA-hydra-DOX-TPP可以提高肿瘤组织的药物累积量，导致肿瘤细胞产生较多的细胞色素C，更显著的诱导肿瘤细胞凋亡。同时构建谷胱甘肽刺激响应的非病毒基因载体N,N,N-三甲基胱胺修饰的透明质酸-精胺-阿霉素-三苯基膦（HSTC）共载siTwist和线粒体靶向药物，制得HSTC/siRNA复合物粒径为80nm，电位为17mV，具有规则的形态。HSTC/siRNA复合物具有谷胱甘肽响应性释放siRNA的功能，且可成功从溶酶体中逃逸，释放出的药物DOX-TPP能够靶向到线粒体，并且在细胞质中释放siRNA。HSTC/siRNA复合物可以提高细胞对siRNA的摄取，抑制肿瘤细胞内Twist mRNA和Twist蛋白的表达，同时抑制了耐药蛋白P-gp的表达，克服肿瘤的耐药性。体内抗肿瘤活性结果表明，HSTC/siRNA复合物可以提高肿瘤组织的药物累积量，诱导肿瘤细胞产生较多的细胞色素C，抑制Twist和P-gp蛋白表达，促进组织细胞凋亡提高抗肿瘤活性。对正常组织器官没有造成损伤，具有较好的安全性。