title: siRNA-Loaded Polyion Complex Micelle Decorated with Charge-Conversional Polymer Tuned to Undergo Stepwise Response to Intra-Tumoral and Intra-Endosomal pHs for Exerting Enhanced RNAi Efficacy.
abstract: Small interfering RNA (siRNA) needs an efficient delivery vehicle to reach the cytoplasm of target cells for successful RNA interference (RNAi) therapy. This study aimed to develop an siRNA-loaded polyion complex (PIC) micelle equipped with a smart polymeric shell featuring tumor targetability and endosome escapability for enhanced RNAi activity in cancer cells. To this end, an acidic pH-responsive polypeptide was designed to exert a stepwise change in its charged state from negative to modestly positive and highly positive in response to slightly acidic environment of tumor (pH ∼6.7) and further lowered-pH condition of late endosomal compartments (pH ∼5.0), respectively, for selective binding to cancer cell surface and subsequent endosome disruption. This polypeptide, termed PAsp(DET-CDM/DBCO), was synthesized by introducing acid-labile carboxydimethyl maleate (CDM) and dibenzylcyclooctyne (DBCO) moieties into a polyaspartamide derivative bearing two-repeated aminoethylene side chains (PAsp(DET)). Then, PAsp(DET-CDM/DBCO) was installed on the surface of disulfide cross-linked PIC micelles prepared from cholesterol-modified siRNA (Chol-siRNA) and azide-poly(ethylene glycol)-b-poly[(3-mercaptopropylamidine)-L-lysine] (N3-PEG-b-PLys(MPA)) through the copper-free click reaction. Successful PAsp(DET-CDM/DBCO) coverage of PIC micelles was confirmed by a significant decrease in ζ-potential as well as a narrowly distributed size of 40 nm. The PAsp(DET-CDM/DBCO)-installed micelles significantly improved the gene-silencing efficiency in cultured lung cancer cells, compared with nonmodified control micelles, especially after incubation at pH 6.7. This improved silencing activity was nicely correlated with the facilitated cellular uptake of siRNA payloads at the acidic pH and the efficient endosomal escape. These results demonstrate that the acidic pH-responsive polypeptide shell is a promising design strategy for tumor-targeted siRNA delivery.
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Montira
authors.initials: M
authors.lastname: Tangsangasaksri
authors.affiliation: Polymer Chemistry Division, Chemical Resources Laboratory, Tokyo Institute of Technology , R1-11, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Takemoto
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Naito
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Maeda
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Daiki
authors.initials: D
authors.lastname: Sueyoshi
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Miura
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Jooyeon
authors.initials: J
authors.lastname: Ahn
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Azuma
authors.affiliation: Polymer Chemistry Division, Chemical Resources Laboratory, Tokyo Institute of Technology , R1-11, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.|Innovation Center of NanoMedicine, Institute of Industry Promotion-Kawasaki , 3-25-14 Tonomachi, Kawasaki-ku, Kawasaki 210-0821, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nishiyama
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.|Innovation Center of NanoMedicine, Institute of Industry Promotion-Kawasaki , 3-25-14 Tonomachi, Kawasaki-ku, Kawasaki 210-0821, Japan.
authors.forename: Kanjiro
authors.initials: K
authors.lastname: Miyata
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.|Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.|Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.|Innovation Center of NanoMedicine, Institute of Industry Promotion-Kawasaki , 3-25-14 Tonomachi, Kawasaki-ku, Kawasaki 210-0821, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D001692:Biological Transport; D045744:Cell Line, Tumor; D057930:Click Chemistry / Q000379:methods; D004705:Endocytosis / Q000502:physiology; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D008823:Micelles; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D014162:Transfection / Q000379:methods*
chemical_list: D008823:Micelles; D010455:Peptides; D011108:Polymers; D034741:RNA, Small Interfering