Regulational role of AP-1 to COX-2 transcriptional activity induced by exogenous zinc in bronchial epithelial cells

Objective To examine cycloxygenase 2(COX-2) transcriptional activity induced by exogenous zinc in bronchial epithelial cells and the regulatory role of activator protein-1(AP-1).Methods Human bronchial epithelial cells (BEAS-2B) were employed as the in vitro model.Expression of COX-2 mRNA was determined by real-time reverse transcription PCR (RT-PCR).Chromatin immunoprecipitation assay (ChIP) was used to investigate whether AP-1(c-Jun) could bind to the COX-2 gene promoter in BEAS-2B cells incubated with 50.0 μmol/L Zn²⁺ for 8 hours.Transcriptional activity of COX-2 promoter in Zn²⁺-treated BEAS-2B cells was measured using transient gene transfection luciferase reporter construct which was wild type or mutated at AP-1 binding site in the COX-2 promoter.Results Exposure of BEAS-2B cells to 50.0 μmol/L Zn²⁺ induced significantly high expression of COX-2 mRNA which was 7.68 folds over the control group of 0 μmol/L Zn²⁺. Zn²⁺ stimulation resulted in a marked increase in the binding of AP-1(c-Jun) to the COX-2 gene promoter.Mutation of the AP-1 site significantly reduced Zn²⁺-induced COX-2 promoter activity.Conclusion AP-1 regulates COX-2 expression in BEAS-2B cells exposed to exogenous Zn²⁺.