V. Helin et al., Cell cycle-dependent distribution and specific inhibitory effect of vectorized antisense oligonucleotides in cell culture, BIOCH PHARM, 58(1), 1999, pp. 95-107
Factors limiting the use of antisense phosphodiester oligodeoxynucleotides
(ODNs) as therapeutic agents are inefficient cellular uptake and intracellu
lar transport to RNA target. To overcome these obstacles, ODN carriers have
been developed, but the intracellular fate of ODNs is controversial and st
rongly depends on die means of vectorization. Polyamidoamine dendrimers are
non-linear polycationic cascade polymers that are able to bind ODNs electr
ostatically. These complexes have been demonstrated to protect phosphodiest
er ODNs from nuclease degradation and also to increase their cellular uptak
e and pharmacological effectiveness. We studied the intracellular distribut
ion of a fluorescein isothiocyanate-labeled ODN vectorized by a dendrimer v
ector and found that intracellular ODN distribution was dependent on the ph
ase of the cell cycle, with a nuclear localization predominantly in the G2/
M phase. In addition, in order to evaluate the relevance of ODN vectors in
enhancing the inhibition of the targeted genes' expression, we developed a
rapid screening system which measures the transient expression of two repor
ter genes, one used as target, the other as control and vice versa. This sy
stem was validated through investigating the effect of the dendrimer vector
on ODN biological activity. Antisense sequence-specific inhibition of more
than 70% of one reporter gene was obtained with a chimeric ODN containing
four phosphorothioate groups, two at each end. BIOCHEM PHARMACOL 58;1:95-10
7, 1999. (C) 1999 Elsevier Science Inc.