title: The Niemann-Pick C1 Inhibitor NP3.47 Enhances Gene Silencing Potency of Lipid Nanoparticles Containing siRNA.
abstract: The therapeutic applications of lipid nanoparticle (LNP) formulations of small interfering RNA (siRNA), are hampered by inefficient delivery of encapsulated siRNA to the cytoplasm following endocytosis. Recent work has shown that up to 70% of endocytosed LNP-siRNA particles are recycled to the extracellular medium and thus cannot contribute to gene silencing. Niemann-Pick type C1 (NPC1) is a late endosomal/lysosomal membrane protein required for efficient extracellular recycling of endosomal contents. Here we assess the influence of NP3.47, a putative small molecule inhibitor of NPC1, on the gene silencing potency of LNP-siRNA systems in vitro. Intracellular uptake and colocalization studies revealed that the presence of NP3.47 caused threefold or higher increases in accumulation of LNP-siRNA in late endosomes/lysosomes as compared with controls in a variety of cell lines. The gene silencing potency of LNP siRNA was enhanced up to fourfold in the presence of NP3.47. Mechanisms of action studies are consistent with the proposal that NP3.47 acts to inhibit NPC1. Our findings suggest that the pharmacological inhibition of NPC1 is an attractive strategy to enhance the therapeutic efficacy of LNP-siRNA by trapping LNP-siRNA in late endosomes, thereby increasing opportunities for endosomal escape.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Health Sciences Mall, Vancouver, British Columbia, Canada.
authors.forename: Haitang
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Health Sciences Mall, Vancouver, British Columbia, Canada.
authors.forename: Yuen Yi C
authors.initials: YY
authors.lastname: Tam
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Health Sciences Mall, Vancouver, British Columbia, Canada.
authors.forename: Sam
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Health Sciences Mall, Vancouver, British Columbia, Canada.|Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Josh
authors.initials: J
authors.lastname: Zaifman
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Health Sciences Mall, Vancouver, British Columbia, Canada.|Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Heidelberglaan, Utrecht, The Netherlands.
authors.forename: Roy
authors.initials: R
authors.lastname: van der Meel
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Ciufolini
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Health Sciences Mall, Vancouver, British Columbia, Canada.
authors.forename: Pieter R
authors.initials: PR
authors.lastname: Cullis
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D045744:Cell Line, Tumor; D004357:Drug Synergism; D011992:Endosomes / Q000737:chemistry*; D020868:Gene Silencing; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008055:Lipids / Q000737:chemistry*; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors*; D051379:Mice; D041681:NIH 3T3 Cells; D053758:Nanoparticles / Q000737:chemistry*; D000077296:Niemann-Pick C1 Protein; D011506:Proteins / Q000037:antagonists & inhibitors*; D000067996:RAW 264.7 Cells; D034741:RNA, Small Interfering / Q000494:pharmacology*; D054852:Small Molecule Libraries / Q000494:pharmacology*
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008055:Lipids; D008562:Membrane Glycoproteins; C106881:NPC1 protein, human; D000077296:Niemann-Pick C1 Protein; C106831:Npc1 protein, mouse; D011506:Proteins; D034741:RNA, Small Interfering; D054852:Small Molecule Libraries