title: Systemic delivery of siRNA by aminated poly(α)glutamate for the treatment of solid tumors.
abstract: Small interfering RNA (siRNA) can silence the expression of a targeted gene in a process known as RNA interference (RNAi). As a consequence, RNAi has immense potential as a novel therapeutic approach in cancer targeted therapy. However, successful application of siRNA for therapeutic purposes is challenging due to its rapid renal clearance, degradation by RNases in the bloodstream, poor cellular penetration, immunogenicity and aggregation in the blood. In addition, the few oligonucleotide-based nanomedicines that reached clinical trials either go to the liver following systemic administration or are applied topically. Treatment of solid tumors requires selective distribution of siRNA to the target tissue, hence there is an unmet medical need for an efficacious and safe nano-sized delivery system for their clinical use. To overcome these hurdles, we have designed, synthesized and physico-chemically characterized a novel nanocarrier based on aminated poly(α)glutamate (PGAamine). This cathepsin B-biodegradable polymer interacts electrostatically with the siRNA to form a nano-sized polyplex stable in plasma. Treatment with PGAamine-Rac1 siRNA polyplex (siRac1-polyplex) caused specific gene silencing by 80% in HeLa and SKOV-3 human ovarian adenocarcinoma cells as opposed to PGAamine-control non-targeting siRNA polyplex (siCtrl-polyplex) leading to inhibition of cell migration and wound healing abilities. A stepwise dose escalation was performed in order to determine the in vivo maximum tolerated dose (MTD). This was followed by intraperitoneal administration of siRac1-polyplex to mCherry-labeled ovarian adenocarcinoma-bearing mice leading to preferred tumor accumulation of siRac1 (8-fold) which resulted in 38% Rac1 knockdown. Furthermore, the polyplex was administered intravenously to lung carcinoma-bearing mice in which it caused 33% Rac1 knockdown. These promising results led to efficacy studies administering systemic treatment with an anticancer siRNA, siPlk1-polyplex, which inhibited tumor growth by 73% and 87% compared with siCtrl-polyplex or saline-treated mice, respectively, leading to prolonged overall survival. These findings represent the first time that a polyaminated poly(α)glutamate polymer is used for an efficacious and safe tumor delivery of RNAi following systemic administration.
authors.affiliation: Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Room 607, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Dina
authors.initials: D
authors.lastname: Polyak
authors.affiliation: Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Room 607, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Adva
authors.initials: A
authors.lastname: Krivitsky
authors.affiliation: Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Room 607, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Anna
authors.initials: A
authors.lastname: Scomparin
authors.affiliation: Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Room 607, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Shay
authors.initials: S
authors.lastname: Eliyahu
authors.affiliation: QBI Enterprises, Ltd., Ness-Ziona 70400, Israel.
authors.forename: Hagar
authors.initials: H
authors.lastname: Kalinski
authors.affiliation: QBI Enterprises, Ltd., Ness-Ziona 70400, Israel.
authors.forename: Sharon
authors.initials: S
authors.lastname: Avkin-Nachum
authors.affiliation: Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Room 607, Tel Aviv University, Tel Aviv 69978, Israel. Electronic address: ronitsf@post.tau.ac.il.
authors.forename: Ronit
authors.initials: R
authors.lastname: Satchi-Fainaro
mesh_terms: D000586:Amination; D000818:Animals; D045744:Cell Line, Tumor; D018014:Gene Transfer Techniques; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009369:Neoplasms / Q000235:genetics / Q000628:therapy*; D011099:Polyglutamic Acid / Q000737:chemistry*; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics / Q000627:therapeutic use; D000067492:RNAi Therapeutics; D020830:rac1 GTP-Binding Protein / Q000235:genetics
chemical_list: D034741:RNA, Small Interfering; D011099:Polyglutamic Acid; D020830:rac1 GTP-Binding Protein
keywords: Aminated poly(α)glutamate; Anticancer therapy; Cationic polymer; Polyplexes; siRNA systemic delivery