Induction of gamma-glutamylcysteine synthetase by cigarette smoke is associated with AP-1 in human alveolar epithelial cells

Increased levels of glutathione (GSH) occur in the epithelial lining fluid (ELF) of chronic cigarette smokers. Therefore we investigated the effect of cigarette smoke condensate solution (CSC) on GSH synthesis and the regulation of gamma-glutamylcysteine synthetase (gamma GCS) in human type II alveolar epithelial cells (A549). CSC exposure increased GSH levels, gamma GCS activity and gamma GCS heavy subunit (HS) mRNA, as well as increasing DNA binding of the activator protein-1 (AP-1) and the human antioxidant response element (hARE). Transfection of deletion constructs of the gamma GCS-HS promoter in a chloramphenicol acetyl transferase (CAT) reporter system revealed that an hARE, present within promoter, is not required for the CSC mediated induction. We conclude that CSC induction of gamma GCS-HS expression is associated with AP-1/AP-1-like responsive elements.