Glutathione-activatable bola dendrimers mediate tumor-specific cytosolic siRNA delivery via dynamic thiol–disulfide exchange

Abstract

Effective delivery of small interfering RNA (siRNA) to the cytosol continues to pose a significant challenge in RNA interference (RNAi)-driven precision cancer therapy. In this study, we engineered glutathione (GSH)-responsive bola-amphiphilic peptide dendrimers (bola DS-C_n-K₄) for tumor-specific cytosolic siRNA delivery. These dendrimers incorporate a hydrophilic polylysine dendron for efficient siRNA binding and a hydrophobic disulfide-bridged bola-lipid core with varying alkyl chain lengths, facilitating thiol-mediated cellular uptake and enabling siRNA release in response to intracellular higher GSH levels. Our structure–activity relationship studies revealed that bola DS-C₆-K₄, characterized by the shortest alkyl chain, exhibited superior siRNA delivery, which was attributed to optimized thiol-mediated cellular uptake and accelerated GSH-triggered siRNA release stemming from improved disulfide accessibility. Mechanistic investigations validated thiol-mediated uptake as the predominant cellular internalization pathway, effectively bypassing endosomal entrapment. The siRNA/bola DS-C₆-K₄ complexes efficiently downregulate oncoprotein expression, thereby impeding cancer cell proliferation, migration, and invasion, and simultaneously inducing apoptosis. In A549 xenograft models, intravenous administration of siPLK1/bola DS-C₆-K₄ achieved substantial reductions in tumor growth and PLK1 expression while exhibiting minimal systemic toxicity. This study highlights a synergistic approach utilizing bola-amphiphilic peptide dendrimers for tumor-specific and cytosolic siRNA delivery, leveraging membrane–thiol interactions and intracellular GSH-triggered siRNA release.