Increased expression of p21(waf) cyclin-dependent kinase inhibitor in asthmatic bronchial epithelium.
Because the asthmatic bronchial epithelium is characterized by widespread damage, we postulated that this is associated with expression of cell cycle inhibitors that control proliferation. Using bronchial biopsies, the epithelium was the major site of expression of the cyclin-dependent kinase inhibitor, p21(waf). Immunostaining usually occurred in the cytoplasm of columnar cells; however, in severe asthma, nuclear staining was also evident in the proliferative, basal cell compartment. p21(waf) expression was significantly higher in asthmatic versus nonasthmatic epithelium and was unaffected by corticosteroid treatment; proliferating cell nuclear antigen was not significantly different in any group. p21(waf), but not p27(kip1), mRNA and protein were induced by treatment of bronchial epithelial cells in vitro with transforming growth factor (TGF)-beta or H2O2, but not by dexamethasone, which induced p57(kip2). TGF-beta and dexamethasone inhibited epidermal growth factor (EGF)-induced DNA synthesis, whereas low concentrations of H2O2 synergized with EGF; at higher doses, growth inhibition and induction of apoptosis occurred. TGF-beta caused p21(waf) to become nuclear, suggesting interaction with the replicative machinery; however, in oxidant-stressed cells, p21(waf) was predominantly cytoplasmic, where it has been linked to cell survival. We conclude that p21(waf) overexpression in asthma influences cell proliferation and survival. This may cause abnormal repair responses that contribute to airway inflammation and remodeling.
Puddicombe
Sarah M
SM
The Brooke Laboratory, Division of Infection, Inflammation and Repair, School of Medicine, Southampton General Hospital, Southampton, United Kingdom. smp2@soton.ac.uk
Torres-Lozano
Carlos
C
Richter
Audrey
A
Bucchieri
Fabio
F
Lordan
James L
JL
Howarth
Peter H
PH
Vrugt
Bart
B
Albers
Rene
R
Djukanovic
Ratko
R
Holgate
Stephen T
ST
Wilson
Susan J
SJ
Davies
Donna E
DE
D001249:Asthma / Q000378:metabolism*; D015153:Blotting, Western; D001980:Bronchi / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007150:Immunohistochemistry; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000494:pharmacology
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D004815:Epidermal Growth Factor; D003907:Dexamethasone; D006861:Hydrogen Peroxide