Oxidative stress response results in increased p21WAF1/CIP1 degradation in cystic fibrosis lung epithelial cells

• Published in: Free radical biology & medicine Vol. 40; no. 1; pp. 75 - 86
• Main Authors: Boncoeur, Emilie, Tabary, Olivier, Bonvin, Elise, Muselet, Celine, Fritah, Asmaa, Lefait, Emilie, Redeuilh, Gerard, Clement, Annick, Jacquot, Jacky, Henrion-Caude, Alexandra
• Format: Journal Article
• Language: English
• Published: United States 01-01-2006
• Subjects: Acetylcysteine - analogs & derivatives; Acetylcysteine - pharmacology; Annexin A5 - metabolism; Apoptosis; Caspase 3; Caspases - metabolism; Cells, Cultured; Cyclin-Dependent Kinase Inhibitor p21 - genetics; Cyclin-Dependent Kinase Inhibitor p21 - metabolism; Cysteine Proteinase Inhibitors - pharmacology; Cystic Fibrosis - enzymology; Cystic Fibrosis - pathology; Epithelial Cells - enzymology; Epithelial Cells - pathology; Humans; Hyperoxia - enzymology; Leupeptins - pharmacology; Lung - enzymology; Lung - pathology; Oxidative Stress; Oxygen - metabolism; Reactive Oxygen Species - metabolism; S Phase
• ISSN: 0891-5849
• DOI: 10.1016/j.freeradbiomed.2005.08.017

Lung epithelium in cystic fibrosis (CF) patients is characterized by structural damage and altered repair due to oxidative stress. To gain insight into the oxidative stress-related damage in CF, we studied the effects of hyperoxia in CF and normal lung epithelial cell lines. In response to a 95% O2 exposure, both cell lines exhibited increased reactive oxygen species. Unexpectedly, the cyclin-dependent kinase inhibitor p21WAF1/CIP1 protein was undetectable in CF cells under hyperoxia, contrasting with increased levels of p21WAF1/CIP1 in normal cells. In both cell lines, exposure to hyperoxia led to S-phase arrest. Apoptotic features including nuclear condensation, DNA laddering, Annexin V incorporation, and elevated caspase-3 activity were not readily observed in CF cells in contrast to normal cells. Interestingly, treatment of hyperoxia-exposed CF cells with two proteasome inhibitors, MG132 and lactacystin, restored p21WAF1/CIP1 protein and was associated with an increase of caspase-3 activity. Moreover, transfection of p21WAF1/CIP1 protein in CF cells led to increased caspase-3 activity and was associated with increased apoptotic cell death, specifically under hyperoxia. Taken together, our data suggest that modulating p21WAF1/CIP1 degradation may have the therapeutic potential of reducing lung epithelial damage related to oxidative stress in CF patients.