a Strathclyde Institute of Pharmacy and Biomedical Sciences , University of Strathclyde , Glasgow , UK.
b Leibniz Institute of Polymer Research Dresden , Max Bergmann Center of Biomaterials Dresden , Dresden , Germany.
J Drug Target. 2017 Nov-Dec;25(9-10):865-872. doi: 10.1080/1061186X.2017.1363212. Epub 2017 Aug 16.
Silk nanoparticles are expected to improve chemotherapeutic drug targeting to solid tumours by exploiting tumour pathophysiology, modifying the cellular pharmacokinetics of the payload and ultimately resulting in trafficking to lysosomes and triggering drug release. However, experimental proof for lysosomotropic drug delivery by silk nanoparticles in live cells is lacking and the importance of lysosomal pH and enzymes controlling drug release is currently unknown. Here, we demonstrate, in live single human breast cancer cells, the role of the lysosomal environment in determining silk nanoparticle-mediated drug release. MCF-7 human breast cancer cells endocytosed and trafficked drug-loaded native and PEGylated silk nanoparticles (∼100 nm in diameter) to lysosomes, with subsequent drug release from the respective carriers and nuclear translocation within 5 h of dosing. A combination of low pH and enzymatic degradation facilitated drug release from the silk nanoparticles; perturbation of the acidic lysosomal pH and inhibition of serine, cysteine and threonine proteases resulted in a 42% ± 2.2% and 33% ± 3% reduction in nuclear-associated drug accumulation for native and PEGylated silk nanoparticles, respectively. Overall, this study demonstrates the importance of lysosomal activity for anticancer drug release from silk nanoparticles, thereby providing direct evidence for lysosomotropic drug delivery in live cells.
丝纳米颗粒有望通过利用肿瘤病理生理学、改变有效载荷的细胞药代动力学，最终导致溶酶体运输和触发药物释放，从而改善针对实体瘤的化疗药物靶向。然而，缺乏丝纳米颗粒在活细胞中通过溶酶体靶向递药的实验证据，且目前尚不清楚控制药物释放的溶酶体 pH 和酶的重要性。在这里，我们在活的单个人类乳腺癌细胞中证明了溶酶体环境在决定丝纳米颗粒介导的药物释放中的作用。MCF-7 人乳腺癌细胞内吞并转运载药的天然和 PEG 化丝纳米颗粒（直径约 100nm）至溶酶体，随后在给药后 5 小时内从各自的载体中释放药物并向核内转位。低 pH 和酶降解的组合促进了丝纳米颗粒的药物释放；酸性溶酶体 pH 的扰乱和丝氨酸、半胱氨酸和苏氨酸蛋白酶的抑制分别导致天然和 PEG 化丝纳米颗粒的核相关药物积累减少 42%±2.2%和 33%±3%。总的来说，这项研究证明了溶酶体活性对丝纳米颗粒中抗癌药物释放的重要性，从而为活细胞中溶酶体靶向递药提供了直接证据。
