Figure 3.

Induction of p53-dependent transactivation of the PTGF-β promoter by etoposide. Subconfluent U2-OS cells were co-transfected with β-galactosidase-expressing construct and PTGF-β W/p53BS luciferase reporters, individually, or in combination with a construct expressing a dominant negative p53 mutant (p53-280T) or the vector control by the Lipofectamine method. Cells were treated with etoposide (25 μM) 24 hr after transfection for 0, 2, 6, 12, 24, and 48 hr, respectively, followed by luciferase activity measurements. Three independent transfections, each run in duplicate, were performed, and results are presented as fold activation ± standard error after normalization with β-galactosidase activity for transfection efficiency. To calculate the fold activation, the luciferase activity from PTGF-β W/p53BS construct after 0 hr of etoposide treatment was arbitrarily set as 1.