Department of Chemistry, Brandeis University , 415 South Street, Waltham, Massachusetts 02453, United States.
State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Collaborative Innovation Center of Chemical Science, Nankai University , Tianjin 300071, P.R. China.
J Am Chem Soc. 2016 Dec 14;138(49):16046-16055. doi: 10.1021/jacs.6b09783. Epub 2016 Dec 1.
Targeting organelles by modulating the redox potential of mitochondria is a promising approach to kill cancer cells that minimizes acquired drug resistance. However, it lacks selectivity because mitochondria perform essential functions for (almost) all cells. We show that enzyme-instructed self-assembly (EISA), a bioinspired molecular process, selectively generates the assemblies of redox modulators (e.g., triphenyl phosphinium (TPP)) in the pericellular space of cancer cells for uptake, which allows selectively targeting the mitochondria of cancer cells. The attachment of TPP to a pair of enantiomeric, phosphorylated tetrapeptides produces the precursors (L-1P or D-1P) that form oligomers. Upon dephosphorylation catalyzed by ectophosphatases (e.g., alkaline phosphatase (ALP)) overexpressed on cancer cells (e.g., Saos2), the oligomers self-assemble to form nanoscale assemblies only on the surface of the cancer cells. The cancer cells thus uptake these assemblies of TPP via endocytosis, mainly via a caveolae/raft-dependent pathway. Inside the cells, the assemblies of TPP-peptide conjugates escape from the lysosome, induce dysfunction of mitochondria to release cytochrome c, and result in cell death, while the controls (i.e., omitting TPP motif, inhibiting ALP, or removing phosphate trigger) hardly kill the Saos2 cells. Most importantly, the repeated stimulation of the cancers by the precursors, unexpectedly, sensitizes the cancer cells to the precursors. As the first example of the integration of subcellular targeting with cell targeting, this study validates the spatial control of the assemblies of nonspecific cytotoxic agents by EISA as a promising molecular process for selectively killing cancer cells without inducing acquired drug resistance.
通过调节线粒体的氧化还原电位来靶向细胞器是一种很有前途的杀死癌细胞的方法，因为这种方法最大限度地减少了获得性耐药性。然而，它缺乏选择性，因为线粒体为（几乎）所有细胞提供了必需的功能。我们表明，酶指导的自组装（EISA）是一种受生物启发的分子过程，它选择性地在癌细胞的细胞外空间生成氧化还原调节剂（如三苯基膦（TPP））的组装体以供摄取，从而允许选择性地靶向癌细胞的线粒体。TPP 与一对对映体、磷酸化的四肽连接，产生前体（L-1P 或 D-1P），它们形成寡聚物。在癌细胞上过表达的外磷酸酶（如碱性磷酸酶（ALP））催化去磷酸化后，寡聚体自组装仅在癌细胞表面形成纳米级组装体。因此，癌细胞通过内吞作用摄取这些 TPP 组装体，主要通过网格蛋白/筏依赖途径。在细胞内，TPP-肽缀合物的组装体逃避溶酶体，诱导线粒体功能障碍以释放细胞色素 c，导致细胞死亡，而对照（即省略 TPP 基序、抑制 ALP 或去除磷酸触发）几乎不能杀死 Saos2 细胞。最重要的是，意想不到的是，这些前体反复刺激癌症，使癌细胞对前体变得敏感。作为亚细胞靶向与细胞靶向相结合的第一个例子，本研究验证了 EISA 对非特异性细胞毒性剂组装体的空间控制，作为一种有前途的分子过程，可以选择性地杀死癌细胞而不诱导获得性耐药性。
