AJP - Lung Cellular and Molecular Physiology, Vol 269, Issue 2 178-L184, Copyright © 1995 by American Physiological Society
Antisense oligonucleotides for PDGF-B and its receptor inhibit mechanical strain-induced fetal lung cell growth
M. Liu, J. Liu, S. Buch, A. K. Tanswell and M. Post
Department of Pediatrics, University of Toronto, Ontario, Canada.
An intermittent mechanical strain regimen, which simulates fetal breathing
movements, has been shown to enhance DNA synthesis and cell division of
fetal rat lung cells. The signaling mechanism through which the physical
stimulus is transduced is unknown. Herein, we report that mechanical strain
(5% elongation, 60 cycles/min) of fetal lung cells, cultured in a
three-dimensional environment provided by Gelfoam sponges, increased the
mRNA levels of platelet-derived growth factor B (PDGF-B) and beta-receptor
(PDGF-beta-R) within 5 min of the onset of strain. Both PDGF-BB and
PDGF-beta-R proteins were increased after a 24-h intermittent strain (15
min/h). Phosphorothioate antisense PDGF-B oligonucleotides (ON) at 15
microM abolished the strain-enhanced DNA synthesis and cell growth.
Scrambled PDGF-B ON had no such effect. A neutralizing PDGF-BB antibody (10
micrograms/ml) also attenuated strain-induced DNA synthesis. Furthermore,
the strain-induced stimulatory effect on DNA synthesis of fetal lung cells
was blocked by tyrphostin 9 (1 microM), a PDGF receptor-associated tyrosine
kinase inhibitor, but not by its inactive structural analogue tyrphostin 1.
Antisense but not sense PDGF-beta-R ON (10 microM) also abrogated the
strain-enhanced DNA synthesis. These results suggest that physical forces
such as fetal breathing movements regulate fetal lung cell growth by
controlling PDGF-B and PDGF-beta-R gene expression.
