Nicotine induces platelet-derived growth factor release and cytoskeletal alteration in aortic smooth muscle cells

Abstract

Background: Cigarette smoking is implicated in atherosclerotic plaque formation, but the role of nicotine in this process is not completely understood. The release of platelet-derived growth factor (PDGF) by the bovine aortic smooth muscle cell (SMC) after nicotine administration at a concentration similar to that ingested by active and passive smokers and the role of PDGF in SMC cytoskeletal modification were studied.

Methods: SMC, harvested with enzymatic digestion from calf aorta, were stimulated in a serum-free medium for 72 hours with (-)-nicotine (from 6 x 10(-4) mol/L to 6 x 10(-8) mol/L). The release of PDGF was assessed by inhibition antibody-binding assay and confirmed by Western blotting. Mitogenic activity of nicotine on SMCs was also determined. The SMC cytoskeleton was studied with specific antibodies anti-alpha-actin fibers, anti-vimentin, and anti-beta-tubulin, and the modification induced by PDGF was assessed by blocking PDGF activity with specific antibodies.

Results: The greatest PDGF release (1.24 +/- 0.14 ng/10(4) cells vs control 0.43 +/- 0.07 ng/10(4) cells) was noted at a (-)-nicotine concentration of 6 x 10(-7) mol/L (P < .001). The addition of monoclonal antibody anti-PDGF decreased the tritiated thymidine uptake of SMCs exposed to (-)-nicotine compared with the control (29% vs 5%-P < .001). SMCs exposed to (-)-nicotine concentration of 6 x 10(-7) mol/L and 6 x 10(-8) mol/L had a significant alteration in the expression of alpha-actin fibers, vimentin, and beta-tubulin compared with control. The administration of antibody anti-PDGF in the culture medium reversed cytoskeletal alteration.

Conclusions: Nicotine enhanced the release of platelet-derived growth, which in turn caused an alteration in cytoskeletal organization.