title: Systemic administration of optimized aptamer-siRNA chimeras promotes regression of PSMA-expressing tumors.
abstract: Prostate cancer cells expressing prostate-specific membrane antigen (PSMA) have been targeted with RNA aptamer-small interfering (si)RNA chimeras, but therapeutic efficacy in vivo was demonstrated only with intratumoral injection. Clinical translation of this approach will require chimeras that are effective when administered systemically and are amenable to chemical synthesis. To these ends, we enhanced the silencing activity and specificity of aptamer-siRNA chimeras by incorporating modifications that enable more efficient processing of the siRNA by the cellular machinery. These included adding 2-nucleotide 3'-overhangs and optimizing the thermodynamic profile and structure of the duplex to favor processing of the siRNA guide strand. We also truncated the aptamer portion of the chimeras to facilitate large-scale chemical synthesis. The optimized chimeras resulted in pronounced regression of PSMA-expressing tumors in athymic mice after systemic administration. Anti-tumor activity was further enhanced by appending a polyethylene glycol moiety, which increased the chimeras' circulating half-life.
authors.affiliation: Department of Internal Medicine, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Justin P
authors.initials: JP
authors.lastname: Dassie
authors.forename: Xiu-Ying
authors.initials: XY
authors.lastname: Liu
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Thomas
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Whitaker
authors.forename: Kristina W
authors.initials: KW
authors.lastname: Thiel
authors.forename: Katie R
authors.initials: KR
authors.lastname: Stockdale
authors.forename: David K
authors.initials: DK
authors.lastname: Meyerholz
authors.forename: Anton P
authors.initials: AP
authors.lastname: McCaffrey
authors.forename: James O
authors.initials: JO
authors.lastname: McNamara
authors.forename: Paloma H
authors.initials: PH
authors.lastname: Giangrande
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000097:blood*; D052157:Aptamers, Nucleotide / Q000008:administration & dosage* / Q000235:genetics; D018797:Cell Cycle Proteins / Q000378:metabolism; D048708:Cell Growth Processes / Q000235:genetics; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000235:genetics; D043425:Glutamate Carboxypeptidase II / Q000097:blood*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009690:Nucleic Acid Conformation; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics; D023041:Xenograft Model Antitumor Assays; D000097869:Polo-Like Kinase 1
chemical_list: D000954:Antigens, Surface; D052157:Aptamers, Nucleotide; D018797:Cell Cycle Proteins; D043425:Glutamate Carboxypeptidase II; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D000097869:Polo-Like Kinase 1; C473848:FOLH1 protein, human
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