The
endoplasmic reticulum (ER) primarily guides protein synthesis,
folding, transport, and lipid biosynthesis inside the cells. As a
result, dysregulation in those cellular functions leading to ER stress
has recently emerged as one of the hallmarks of cancer. Yet, precise
navigation in the ER in cancer cells has continued to be a formidable
task. Herein, we engineered a lipid nanoparticle (17AAG-ER-NP) containing
(a) ER targeting moiety (Tosyl), (b) fluorescent tag with DNA damaging
capability (1,8-naphthalimide), and (c) ER stress inducer (17AAG,
Hsp90 inhibitor). These lipidic nanoparticles were confined in the
ER of HeLa cells over 6 h through caveolin-controlled endocytosis
confirmed by confocal microscopy. Western blot analysis, fluorescent
microscopy, and flow cytometry studies confirmed that 17AAG-ER-NPs
can concurrently activate ER stress and nuclear DNA impairment for
arresting the cell cycle in the G2-M phase to elicit late apoptosis,
followed by cell death, in a greatly augmented manner compared to
free drugs. Interestingly, this nanoparticle-mediated ER stress activated
autophagy, which was suppressed through a cocktail treatment with
17AAG-ER-NPs and chloroquine (autophagy inhibitor), prompted remarkable
HeLa cell killing at submicromolar concentration. This nanoplatform
can support new tools to impair multiple targets in the ER for future
cancer therapy.
Chalcone and boronic acids are important privileged structures in myriads of natural and synthetic products having diverse biological activities. However, their therapeutic window is highly narrow due to their hydrophobic nature affecting unpredictable biodistribution. To address this, we herein have synthesized a novel hybrid glycosylated chalcone−boronic acid library. Cell viability, flow cytometry, confocal microscopy, and gel electrophoresis assays demonstrated that one of the library members induces cell cycle arrest in the G2/M phase through the activation of p21 and decrease levels of cyclin B1 and CDK1. In addition, it also induces apoptosis, primarily due to the inhibition of Bcl-2/ Bcl-xl and the augmentation of BAX to prompt mitochondrial damage and reactive oxygen species generation. Most interestingly, the lead cytotoxic glycosylated chalcone−boronic acid selfassembled in water into a spherical nanodrug that can further entrap another anticancer drug (doxorubicin) to show remarkably improved efficacy in breast cancer cells. This novel lead compound has prospective as a vector-free nanodrug for combination cancer therapy.
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