<i>In vitro</i> and <i>in vivo</i> antitumor effects of lupeol-loaded galactosylated liposomes

Lupeol liposomes, modified with Gal-PEG-DSPE, were developed following a thin-film dispersion method. Then, the morphology, physicochemical properties, and <i>in vitro</i> release properties of those liposomes were investigated. The scanning electron microscopic images showed that most of the liposomes were spherical particles; they were similar in size and uniformly dispersed. Both lupeol liposomes and Gal-lupeol liposomes exhibited an average particle size of about 100 nm. The encapsulation efficiency was greater than 85%. The encapsulation efficiency of lupeol liposome and Gal-lupeol liposome, stored with 15% sucrose as glycoprotein for 6 months, was higher than 80%; although the particle size increased, they remained within 200 nm. The cell-uptake study demonstrated that the Gal-lupeol-liposome uptake efficiency was the highest in HepG2 cells. The HepG2 cells treated with the Gal-lupeol liposomes had higher apoptotic efficiency than the lupeol liposome and free lupeol. After HepG2 cells were treated with Gal-lupeol liposome, the expressions of AKT/mTOR-related proteins (p-AKT308 and p-AKT473) were also significantly reduced than the lupeol-liposome and free lupeol group. The <i>in vivo</i> targeting studies showed that Gal-NR-L exhibited liver-targeting effects on FVB mice. The pharmacodynamic study was performed by transfecting AKT and c-MET via the high-pressure tail vein of FVB mice. After Gal-lupeol-L administration, the liver index and liver weight of mice were less than those non-targeted group. The histopathological study showed that the lobular structure in the mice liver was clearer, the vacuoles were more obvious, and the cytoplasm was more abundant after Gal-lupeol-L administration. Also, the qRT-PCR study showed that AFP, GPC3, and EpCAM mRNA expression levels were significantly lower than those non-targeted lupeol-liposomes.

本研究采用薄膜分散法制备了经半乳糖-聚乙二醇-二硬脂酰磷脂酰乙醇胺（Gal-PEG-DSPE）修饰的羽扇豆醇（lupeol）脂质体。随后对该脂质体的形貌、理化性质及体外（in vitro）释放特性展开研究。扫描电子显微镜图像显示，多数脂质体呈球形，粒径均一且分散性良好。羽扇豆醇脂质体与Gal-羽扇豆醇脂质体的平均粒径均约为100 nm，包封率均高于85%。以15%蔗糖作为糖蛋白稳定剂储存6个月后，羽扇豆醇脂质体与Gal-羽扇豆醇脂质体的包封率仍高于80%；尽管粒径有所增大，但仍维持在200 nm以内。细胞摄取实验表明，在HepG2细胞中，Gal-羽扇豆醇脂质体的摄取效率最高。经Gal-羽扇豆醇脂质体处理的HepG2细胞，其凋亡效率高于羽扇豆醇脂质体组与游离羽扇豆醇组。经Gal-羽扇豆醇脂质体处理后，HepG2细胞中AKT/mTOR相关蛋白（p-AKT308与p-AKT473）的表达水平亦显著低于羽扇豆醇脂质体组与游离羽扇豆醇组。体内（in vivo）靶向实验显示，Gal-NR-L对FVB品系小鼠具有肝脏靶向作用。本研究通过高压尾静脉注射法向FVB小鼠转染AKT与c-MET基因以开展药效学实验，给予Gal-羽扇豆醇-L（Gal-lupeol-L）后，小鼠的肝脏指数与肝脏重量均低于非靶向脂质体组。组织病理学研究显示，给予Gal-lupeol-L后，小鼠肝脏的小叶结构更清晰，空泡更为明显，细胞质更为丰富。此外，实时荧光定量聚合酶链反应（qRT-PCR）结果显示，AFP、GPC3及EpCAM的mRNA表达水平均显著低于非靶向羽扇豆醇脂质体组。