Biomedical Program, University of Alaska, Anchorage, Alaska 99508, USA.
J Drug Target. 2010 May;18(4):313-20. doi: 10.3109/10611861003663549.
To enhance cytoplasmic delivery of liposomal contents to breast cancer cells, the authors have attached the pore-forming protein, listeriolysin O (LLO), to thermosensitive liposomes. The antibody trastuzumab (Herceptin) was also conjugated with the outer surface of the liposomes, resulting in highly specific binding and internalization into mammary epithelial cells that overexpress the human epidermal growth factor receptor 2 (Her-2). The liposomes were preloaded with a marker fluorescent dye, and the effect of LLO on the distribution of dye within the cells was monitored using fluorescence microscopy. Owing to the thermosensitive nature of the liposomes, hyperthermia at 42 degrees C triggered the release of the encapsulated fluorescent calcein from the endocytosed liposomes into the interior of the endosomes. LLO, when conjugated to these liposomes, subsequently formed pores in the endosomal membrane, allowing calcein to flow out of the endosomal compartment into the cytoplasm. Her-2-targeted liposomes bearing LLO delivered a 22-fold greater concentration of calcein to mammary epithelial cells that overexpress Her-2 compared to cells with normal Her-2 expression. Thus, the addition of LLO to preformed liposomes offers a method for significantly enhancing delivery of liposomal contents to the cytoplasm of targeted cells.
为了增强脂质体内容物向乳腺癌细胞的细胞质传递，作者将成孔蛋白李斯特菌溶血素 O（LLO）连接到热敏脂质体上。抗体曲妥珠单抗（赫赛汀）也与脂质体的外表面结合，导致高度特异性结合，并内化到过度表达人表皮生长因子受体 2（Her-2）的乳腺上皮细胞中。脂质体预先装载有标记荧光染料，并使用荧光显微镜监测 LLO 对细胞内染料分布的影响。由于脂质体的热敏性质，在 42°C 下的热疗会触发被内吞的脂质体中包裹的荧光钙黄绿素从内体中释放到内体内部。LLO 与这些脂质体连接后，随后在内体膜上形成孔，使钙黄绿素从内体隔室流出到细胞质中。与正常 Her-2 表达的细胞相比，LLO 连接到 Her-2 靶向脂质体上，将钙黄绿素的浓度提高了 22 倍，递送到过度表达 Her-2 的乳腺上皮细胞中。因此，将 LLO 添加到预先形成的脂质体中为显著增强靶向细胞的细胞质内脂质体内容物的传递提供了一种方法。
