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Endolysosomal degradation of small interfering RNA (siRNA) significantly reduces the efficacy of RNA interference (RNAi) delivered by nonviral systems. Leveraging Golgi apparatus/endoplasmic reticulum (Golgi/ER) transport can help siRNA bypass the endolysosomal degradation pathway, but this approach may also result in insufficient siRNA release and an increased risk of Golgi/ER-mediated exocytosis. To address these challenges, we developed two distinct strategies using a nanocomplex of cell-penetrating poly(disulfide)s and chondroitin sulfate, which enhances targeted internalization, Golgi transport, and rapid cytoplasmic release of loaded siRNA. In the first strategy, monensin synergy was found to enhance RNAi by inhibiting both exocytosis and autophagic degradation. In the second strategy, a "directed sorting" approach based on KDEL peptide-mediated retrograde transport was introduced. By conjugation of the KDEL peptide to chondroitin sulfate, Golgi-to-ER transport was promoted, reducing "random" Golgi/ER-related exocytosis. These two strategies operate alternatively to achieve high-efficiency RNAi with a significant therapeutic potential. Notably, in a mouse melanoma model using anti-Bcl-2 siRNA, the strategies achieved tumor inhibition rates of 87.1 and 90.1%, respectively. These two strategies, based on "targeting" and "anchoring" Golgi/ER, provide potent solutions to overcome the challenges of cellular internalization, intracellular release, and exocytosis in efficient siRNA delivery.
Wang et al. (Mon,) studied this question.