Table of Contents
Journal of Allergy
Volume 2012, Article ID 307838, 6 pages
Research Article

Cyclin D1 in ASM Cells from Asthmatics Is Insensitive to Corticosteroid Inhibition

1Respiratory Research Group, Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia
2Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW 2006, Australia

Received 8 July 2011; Accepted 17 November 2011

Academic Editor: Georgia Hardavella

Copyright © 2012 Jodi C. Allen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Hyperplasia of airway smooth muscle (ASM) is a feature of the remodelled airway in asthmatics. We examined the antiproliferative effectiveness of the corticosteroid dexamethasone on expression of the key regulator of G1 cell cycle progression—cyclin D1—in ASM cells from nonasthmatics and asthmatics stimulated with the mitogen platelet-derived growth factor BB. While cyclin D1 mRNA and protein expression were repressed in cells from nonasthmatics in contrast, cyclin D1 expression in asthmatics was resistant to inhibition by dexamethasone. This was independent of a repressive effect on glucocorticoid receptor translocation. Our results corroborate evidence demonstrating that corticosteroids inhibit mitogen-induced proliferation only in ASM cells from subjects without asthma and suggest that there are corticosteroid-insensitive proliferative pathways in asthmatics.