Regulation of vascular smooth muscle cell insulin-like growth factor I receptors by phosphorothioate oligonucleotides. Effects on cell growth and evidence that sense targeting at the ATG site increases receptor expression.
We have recently shown that insulin-like growth factor I (IGF I) is a mediator of angiotensin II-induced mitogenesis in vascular smooth muscle cells (Delafontaine, P., and Lou H. (1993) J. Biol. Chem. 268, 16866-16870). To study the role of the IGF I receptor in vascular smooth muscle cell growth, phosphorothioate oligonucleotides were used to modulate IGF I receptors. An antisense oligonucleotide targeting the ATG site inhibited basal and serum-induced DNA synthesis in vascular smooth muscle cells. Mismatch oligonucleotide had no effect, while surprisingly sense oligonucleotide increased IGF I receptor number and basal and serum-induced DNA synthesis. A 51% reduction in IGF I receptor number following exposure to 5 microM antisense oligonucleotide markedly inhibited angiotensin II-induced mitogenesis. A 70% increase in IGF I receptor number following exposure to 5 microM sense oligonucleotide resulted in a 4-fold increase in basal [3H]thymidine incorporation, and angiotensin II (1-1000 nM) had no additive stimulatory effect. An antisense oligonucleotide targeting a sequence starting at +109 base pairs (relative to ATG) also reduced IGF I receptor number, however, the corresponding sense oligonucleotide was without effect. These findings demonstrate that alterations in vascular smooth muscle cell IGF I receptor density play a critical role in the proliferative response of vascular smooth muscle cells to serum and to angiotensin II. In addition, the surprising observation that an ATG-directed sense oligonucleotide up-regulates IGF I receptors identifies a novel effect of oligonucleotides on gene expression.
Delafontaine
P
P
Department of Medicine, Emory University Atlanta, Georgia 30322, USA.
Meng
X P
XP
Ku
L
L
Du
J
J
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D001769:Blood; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D008934:Mitogens / Q000494:pharmacology; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism*; D013873:Thionucleotides / Q000494:pharmacology*
D008934:Mitogens; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D013873:Thionucleotides; D000804:Angiotensin II; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1