title: Antitumor activity of antisense clusterin oligonucleotides is improved in vitro and in vivo by incorporation of 2'-O-(2-methoxy)ethyl chemistry.
abstract: Phosphorothioate (P=S) antisense oligonucleotides (ASO) targeting the cell survival gene clusterin synergistically enhance castration- and chemotherapy-induced apoptosis in prostate cancer xenografts. This study compares efficacy, tissue half-lives, and toxicity of P=S clusterin ASO to third-generation backbone 2'-O-(2-methoxy)ethyl (2'MOE) ribose-modified clusterin ASO. Northern analysis quantified changes in clusterin mRNA levels in human PC-3 cells and tumors. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay measured effects of combined clusterin ASO plus paclitaxel on PC-3 cell growth. Athymic mice bearing PC-3 tumors were treated with paclitaxel plus either P=S clusterin ASO, 2'-MOE clusterin ASO, or mismatch control oligonucleotides for 28 days. Weekly body weights and serum parameters were measured to assess toxicity. Tissue half-life of P=S and 2'-MOE ASO in PC-3 tumors was assessed using capillary gel electrophoresis (CGE). Both 2'-MOE and P=S ASO decreased clusterin mRNA levels in a dose-dependent and sequence-specific manner. 2'-MOE ASO more potently suppressed clusterin mRNA (80 versus 40% at 500 nM) compared with P=S ASO. IC(50) of paclitaxel was equally reduced (50--75%) by both compounds. In vivo tissue half-life was significantly longer for 2'-MOE-modified ASO than for P=S ASO (5 versus 0.5 days). Using CGE, >90% of detected 2'-MOE ASO in tumor tissue was full length. Weekly administration of 2'-MOE clusterin ASO was equivalent to daily P=S clusterin ASO in enhancing paclitaxel efficacy in vivo. 2'-MOE-modified ASO potently suppressed clusterin expression and prolonged tissue half-lives with no additional side effects. These results support the use of 2'-MOE-modified ASO over conventional P=S ASO by potentially increasing potency and allowing longer dosing intervals in clinical trials.
authors.affiliation: The Prostate Centre, Vancouver General Hospital, Vancouver, British Columbia, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Zellweger
authors.forename: H
authors.initials: H
authors.lastname: Miyake
authors.forename: S
authors.initials: S
authors.lastname: Cooper
authors.forename: K
authors.initials: K
authors.lastname: Chi
authors.forename: B S
authors.initials: BS
authors.lastname: Conklin
authors.forename: B P
authors.initials: BP
authors.lastname: Monia
authors.forename: M E
authors.initials: ME
authors.lastname: Gleave
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D015152:Blotting, Northern; D051152:Clusterin; D019075:Electrophoresis, Capillary; D006023:Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D006207:Half-Life; D006801:Humans; D008297:Male; D051379:Mice; D018832:Molecular Chaperones / Q000096:biosynthesis / Q000235:genetics*; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics*; D016376:Oligonucleotides, Antisense / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology*; D017239:Paclitaxel / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D013778:Tetrazolium Salts; D013844:Thiazoles; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D000972:Antineoplastic Agents, Phytogenic; C495242:CLU protein, human; C495243:Clu protein, mouse; D051152:Clusterin; D006023:Glycoproteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D013778:Tetrazolium Salts; D013844:Thiazoles; C022616:thiazolyl blue; D017239:Paclitaxel