T. Zellweger et al., Antitumor activity of antisense clusterin oligonucleotides is improved in vitro and in vivo by incorporation of 2 '-O-(2-methoxy)ethyl chemistry, J PHARM EXP, 298(3), 2001, pp. 934-940
Citations number
29
Categorie Soggetti
Pharmacology & Toxicology
Journal title
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS
Phosphorothioate (P=S) antisense oligonucleotides (ASO) targeting the cell
survival gene clusterin synergistically enhance castration- and chemotherap
y-induced apoptosis in prostate cancer xenografts. This study compares effi
cacy, tissue half-lives, and toxicity of P=S clusterin ASO to third-generat
ion backbone 2'-O-(2-methoxy)ethyl (2'MOE) ribose-modified clusterin ASO. N
orthern 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 pacli
taxel plus either P=S clusterin ASO, 2'-MOE clusterin ASO, or mismatch cont
rol oligonuclectides 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 s
equence-specific manner. 2'-MOE ASO more potently suppressed clusterin mRNA
(80 versus 40% at 500 nM) compared with P=S ASO. IC50 of paclitaxel was eq
ually reduced (50-75%) by both compounds. In vivo tissue half-life was sign
ificantly longer for 2'-MOE-modified ASO than for P=S ASO (5 versus 0.5 day
s). 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 w
ith no additional side effects. These results support the use of 2'-MOE-mod
ified ASO over conventional P=S ASO by potentially increasing potency and a
llowing longer dosing intervals in clinical trials.