FIGURE 6.

Promoter analysis (A and B) and siRNA-mediated gene silencing (C) demonstrate that ATF4 mediates celecoxib-induced CHOP up-regulation. A and B, the given reporter constructs with different lengths of the 5′-flanking region of CHOP gene (A) or with different mutations as indicated (B) were co-transfected with pCH110 plasmid into H1792 cells for 24 h. The cells were treated with dimethyl sulfoxide (DMSO) or 50 μm celecoxib (CCB) for 12 h and then subjected to luciferase assay. Each column represents a mean ± S.D. (error bars) of triplicate determinations. C, the indicated cell lines were transfected with control (Ctrl) or ATF4 siRNA for 48 and then treated with and without 50 μm celecoxib for an additional 10 h. The cells were harvested for preparation of whole cell protein lysates and subsequent Western blot analysis for the given proteins.