G‐quadruplex‐Based Artificial Transmembrane Channels Induce Cancer Cell Apoptosis by Perturbing Potassium Ion Homeostasis

Abstract

Transmembrane ion transport modality has received a widespread attention due to its apoptotic activation toward anticancer cell activities. In this study, G‐quadruplex‐based potassium‐specific transmembrane channels have been developed to facilitate the intracellular K+ efflux, which perturbs the cellular ion homeostasis thereby inducing cancer cell apoptosis. Cholesterol‐tag, a lipophilic anchor moiety, serves as a rudiment for the G‐quadruplex immobilization onto the membrane, while G‐quadruplex channel structure as a transport module permits ion binding and migration along the channels. A c‐Myc sequence tagged with two‐cholesterol is designed as a representative lipophilic G‐quadruplex, which forms intramolecular parallel G‐quadruplex with three stacks of G‐quartets (Ch2‐Para3). Fluorescence transport assay demonstrates Ch2‐Para3 a high transport activity (EC50 = 10.9 × 10−6 m) and an ion selectivity (K+/Na+ selectivity ratio of 84). Ch2‐Para3 mediated K+ efflux in cancer cells is revealed to purge cancer cells through K+ efflux‐mediated cell apoptosis, which is confirmed by monitoring the changes in membrane potential of mitochondria, leakage of cytochrome c, reactive oxygen species yield, as well as activation of a family of caspases. The lipophilic G‐quadruplex exhibits obvious antitumor activity in vivo without systemic toxicity. This study provides a functional scheme aimed at generating DNA‐based selective artificial membrane channels for the purpose of regulating cellular processes and inducing cell apoptosis, which shows a great promising for anticancer therapy in the future.