Department of Pharmaceutics, School of Pharmacy, Qingdao University, Qingdao 266021, China.
Department of Pharmaceutical Sciences, School of Pharmacy, Southwest Medical University, Luzhou 646000, China.
Nanoscale. 2020 Mar 5;12(9):5380-5396. doi: 10.1039/c9nr10574c.
9-Nitro-20(S)-camptothecin (9-NC) is a broad-spectrum antitumor drug used in tumor treatments, but its clinical applications and antitumor efficacy are limited by its structural instability, poor solubility, and extremely low drug utilization in tumor tissues. In this study, enzyme-sensitive nuclear-targeted dual-functional polymeric micelles were developed for 9-NC delivery with a high drug loading content (12.93 ± 0.88%), steady-state circulation, and a rapid attack at the "heart" of tumor cells. Briefly, chrysin (CHR) as a π-conjugated moiety was immobilized on the PCL terminal in the TAT-PCL amphiphiles and combined with the ALAL peptide as a linker on HA chains to yield the ultimate CHR-PCL-TAT-ALAL-HA (HATPC) amphiphiles. Spherical 9-NC-loaded micelles were obtained from the self-assembly of the dual-functional amphiphiles comprising HATPC and 9-NC with uniform nanosize (121.6 ± 5.79 nm), well-distributed morphology (PDI: 0.256), and negative surface charge (-23.2 ± 0.5 mV), yielding high stability during blood circulation. In this drug delivery system, HA acts as an active tumor-targeting instrument via CD44-receptor-mediated endocytosis; further, the ALAL peptide could be cutoff in the lysosomes of the tumor cells due to the high expression of cathepsin B, leading to lysosomal escape, while the secondary polymeric micelles targeted the tumor cell nucleus via the exposed TAT peptide. The enzyme sensitivity and nuclei targetability of the 9-NC/HATPC micelles were confirmed by dynamic light scattering and confocal laser scanning microscopy analyses. As compared to free 9-NC and traditional mPEG2k-PCL2k polymeric micelles, 9-NC/HATPC micelles were the most concentrated in the tumor cell nucleus; therefore, they exhibited the highest cytotoxicity against SKOV3 tumor cells both in vitro (IC50 = 0.03 μg mL-1) and in vivo. This enzyme-sensitive nuclear-targeted dual-functional drug delivery system involving HATPC provided a new and promising strategy for enhanced 9-NC delivery and antitumor efficacy.
9-硝基-20(S)-喜树碱（9-NC）是一种广谱抗肿瘤药物，用于肿瘤治疗，但由于其结构不稳定、溶解度差以及在肿瘤组织中药物利用率极低，其临床应用和抗肿瘤疗效受到限制。在本研究中，开发了酶敏感核靶向的双重功能聚合物胶束用于 9-NC 递送，具有高载药含量（12.93±0.88%）、稳态循环和快速攻击肿瘤细胞“心脏”的能力。简而言之，白杨素（CHR）作为一个π共轭部分被固定在 TAT-PCL 两亲物的 PCL 末端，并与 ALAL 肽作为连接子结合在 HA 链上，得到最终的 CHR-PCL-TAT-ALAL-HA（HATPC）两亲物。由包含 HATPC 和 9-NC 的双重功能两亲物自组装得到的球形 9-NC 载药胶束，具有均匀的纳米尺寸（121.6±5.79nm）、良好的分散形态（PDI：0.256）和负表面电荷（-23.2±0.5mV），在血液循环中具有高稳定性。在这个药物递送系统中，HA 通过 CD44 受体介导的内吞作用作为主动肿瘤靶向工具；此外，由于组织蛋白酶 B 的高表达，ALAL 肽可以在肿瘤细胞的溶酶体中被切断，导致溶酶体逃逸，而二级聚合物胶束通过暴露的 TAT 肽靶向肿瘤细胞核。通过动态光散射和共聚焦激光扫描显微镜分析证实了 9-NC/HATPC 胶束的酶敏感性和核靶向性。与游离 9-NC 和传统的 mPEG2k-PCL2k 聚合物胶束相比，9-NC/HATPC 胶束在肿瘤细胞核中最集中；因此，它们对 SKOV3 肿瘤细胞的体外（IC50=0.03μgmL-1）和体内的细胞毒性最高。这种涉及 HATPC 的酶敏感核靶向双重功能药物递送系统为增强 9-NC 递送和抗肿瘤疗效提供了一种新的有前途的策略。
