Zhao Ziming, Wang Yu, Han Jin, Wang Keli, Yang Dan, Yang Yihua, Du Qian, Song Yuanjian, Yin Xiaoxing
Department of Pharmacy, Xuzhou Medical College, Xuzhou, People's Republic of China ; Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, Xuzhou, People's Republic of China.
Department of Pharmacy, Xuzhou Medical College, Xuzhou, People's Republic of China.
Int J Nanomedicine. 2014 Dec 12;9:5849-62. doi: 10.2147/IJN.S73111. eCollection 2014.
The aim of this work was to design, synthesize, and characterize self-assembled micelles based on polypeptides as a potential antitumor drug carrier. Amphiphilic poly(L-phenylalanine)-b-poly(L-serine) (PFS) polypeptides were obtained through the polymerization of N-carboxyanhydride. As a novel hydrophilic segment, poly(L-serine) was utilized to enhance tumor targeting due to a large demand of tumors for serine. PFS could self-assemble into micelles with an average diameter of 110-240 nm and a slightly negative charge. PFS polypeptides adopted random coil in pH 7.4 phosphate-buffered saline and could partly transform to α-helix induced by trifluoroethanol. PFS micelles with a low critical micelle concentration of 4.0 μg mL(-1) were stable in pH 5-9 buffers and serum albumin solution. PFS micelles had a loading capacity of 3.8% for coumarin-6 and exhibited a sustained drug release. Coumarin-6 loaded rhodamine B isothiocyanate-labeled PFS micelles were incubated with Huh-7 tumor cells to study the correlation between drugs and carriers during endocytosis. The uptake of drugs was consistent with the micelles, illustrating that the intracellular transport of drugs highly depended on the micelles. PFS micelles diffused in whole cytoplasm while coumarin-6 assumed localized distribution, suggesting that the micelles could release the loaded drugs in particular areas. The internalization mechanism of PFS micelles was involved with clathrin-mediated endocytosis and macropinocytosis. Excess serine inhibited the uptake of PFS micelles, which demonstrated that serine receptors played a positive role in the internalization of PFS. The more interesting thing was that the uptake inhibition impacted on normal cells but not on tumor cells at the physiological concentration of serine. The difference in the uptake of PFS micelles was fourfold as high between the tumor cells and the normal cells, which indicated that PFS micelles had good tumor targeting in vitro. In conclusion, PFS micelles reported in this work were a promising drug delivery system for tumor targeting therapy.
本研究旨在设计、合成并表征基于多肽的自组装胶束，将其作为一种潜在的抗肿瘤药物载体。两亲性聚（L-苯丙氨酸）-b-聚（L-丝氨酸）（PFS）多肽通过N-羧基酸酐聚合反应制得。作为一种新型亲水性片段，聚（L-丝氨酸）因肿瘤对丝氨酸的大量需求而被用于增强肿瘤靶向性。PFS能够自组装成平均直径为110 - 240 nm且带有轻微负电荷的胶束。PFS多肽在pH 7.4的磷酸盐缓冲盐溶液中呈无规卷曲构象，在三氟乙醇诱导下可部分转变为α-螺旋构象。临界胶束浓度低至4.0 μg mL(-1)的PFS胶束在pH 5 - 9的缓冲液和血清白蛋白溶液中稳定。PFS胶束对香豆素-6的载药量为3.8%，并呈现出药物的持续释放。将载有香豆素-6的异硫氰酸罗丹明标记的PFS胶束与Huh-7肿瘤细胞共孵育，以研究内吞过程中药物与载体之间的相关性。药物的摄取与胶束一致，说明药物在细胞内的转运高度依赖于胶束。PFS胶束扩散至整个细胞质，而香豆素-6呈局部分布，这表明胶束能够在特定区域释放所载药物。PFS胶束的内化机制涉及网格蛋白介导的内吞作用和巨胞饮作用。过量的丝氨酸会抑制PFS胶束的摄取，这表明丝氨酸受体在PFS的内化过程中发挥了积极作用。更有趣的是，在生理浓度的丝氨酸条件下，摄取抑制对正常细胞有影响，但对肿瘤细胞无影响。肿瘤细胞与正常细胞对PFS胶束摄取的差异高达四倍，这表明PFS胶束在体外具有良好的肿瘤靶向性。总之，本研究报道的PFS胶束是一种用于肿瘤靶向治疗的有前景的药物递送系统。
