title: Chemically defined polyethylene glycol siRNA conjugates with enhanced gene silencing effect.
abstract: The therapeutic application of siRNA suffers from poor bioavailability caused by rapid degradation and elimination. The covalent attachment of PEG is a universal concept to increase molecular size and enhance the pharmacokinetic properties of biomacromolecules. We devised a facile approach for attachment of PEG molecules with a defined molecular weight, and successful purification of the resulting conjugates. We directly conjugated structurally defined PEG chains with twelve ethylene glycol units to the 3'-terminal hydroxyl group of both sense and antisense strands via an aminoalkyl linker. The conjugates were easily purified by HPLC and successful PEGylation and molecule integrity were confirmed by ESI-MS. The evaluation of in vitro gene knockdown of two different targets in MCF-7 breast cancer cells showed stable pharmacologic activity when combined with a standard transfection reagent. Sense strand PEGylation even increased the silencing potency of a CRCX4-siRNA which had modest activity in its wild-type form. The results indicate that PEG chains at the 3'-terminus of both strands of siRNA are well tolerated by the RNAi effector. The attachment of short, chemically defined PEG chains is a feasible approach to improve the pharmacokinetic properties of siRNA, and can be combined with other targeted and untargeted delivery vehicles.
authors.affiliation: University of Vienna, Department of Medicinal Chemistry, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Gaziova
authors.affiliation: University of Vienna, Department of Medicinal Chemistry, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: Volker
authors.initials: V
authors.lastname: Baumann
authors.affiliation: University of Vienna, Department of Medicinal Chemistry, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: Anna-Maria
authors.initials: AM
authors.lastname: Winkler
authors.affiliation: University of Vienna, Department of Medicinal Chemistry, Althanstraße 14, 1090 Vienna, Austria. Electronic address: johannes.winkler@univie.ac.at.
authors.forename: Johannes
authors.initials: J
authors.lastname: Winkler
mesh_terms: D020868:Gene Silencing / Q000187:drug effects*; D017930:Genes, Reporter / Q000187:drug effects*; D006801:Humans; D008156:Luciferases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D061986:MCF-7 Cells; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors* / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D034741:RNA, Small Interfering / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors* / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D019718:Receptors, CXCR4; D011092:Polyethylene Glycols; D008156:Luciferases
keywords: Gene silencing; Oligonucleotide conjugates; PEGylation; RNA interference; Synthetic oligonucleotides