Concurrent Drug Unplugging and Permeabilization of Polyprodrug-Gated Crosslinked Vesicles for Cancer Combination Chemotherapy

Combination chemotherapy with both hydrophobic and hydrophilic therapeutic drugs is clinically vital toward the treatment of persistent cancers. Though conventional liposomes and polymeric vesicles possessing hydrophobic bilayers and aqueous interiors can serve as codelivery nanocarriers, it remains a considerable challenge to achieve synchronized release of both types of drugs due to distinct encapsulation mechanisms; premature release of water-soluble cargos from unstable liposomes and ruptured vesicles is also a major concern. Herein, the fabrication of physiologically stable polyprodrug-gated crosslinked vesicles (GCVs) via the self-assembly of camptothecin (CPT) polyprodrug amphiphiles and in situ bilayer crosslinking through traceless sol-gel reaction is reported. Polyprodrug-GCVs possess high CPT loading (>30 wt%) and minimized leakage of encapsulated hydrophilic doxorubicin (DOX) hydrochloride due to the suppressed permeability of crosslinked membrane, exhibiting extended blood circulation (t _1/2 > 13 h) with caged cytotoxicity in physiological circulation. Upon cellular uptake by cancer cells, cytosolic reductive milieu-triggered CPT unplugging from vesicle bilayers is demonstrated to generate hydrophilic mesh channels and make the membrane highly permeable. Concurrently, it will promote DOX corelease from hydrophilic lumen (≈36-fold increase). The reduction-activated combination chemotherapeutic potency based on polyprodrug-GCVs is confirmed by both in vitro and in vivo explorations.

AMPK: Mechanisms of Cellular Energy Sensing and Restoration of Metabolic Balance

AMPK is a highly conserved master regulator of metabolism, which restores energy balance during metabolic stress both at the cellular and physiological levels. The identification of numerous AMPK targets has helped explain how AMPK restores energy homeostasis. Recent advancements illustrate novel mechanisms of AMPK regulation, including changes in subcellular localization and phosphorylation by non-canonical upstream kinases. Notably, the therapeutic potential of AMPK is widely recognized and heavily pursued for treatment of metabolic diseases such as diabetes, but also obesity, inflammation, and cancer. Moreover, the recently solved crystal structure of AMPK has shed light both into how nucleotides activate AMPK and, importantly, also into the sites bound by small molecule activators, thus providing a path for improved drugs.