Activation of ET-1 promoter in response to DHEA or insulin treatment was
augmented by PI 3-kinase blockade and inhibited by MAPK blockade. BAECs
grown in 24-well plates were transfected with ET-1 promoter luciferase
reporter and renilla luciferase (internal control). One day later cells were
serum-starved overnight and then treated for 8 h with vehicle, DHEA (100
nm), or insulin (100 nm) without or with wortmannin (100
nm), PD98059 (12.5 μm). Luciferase activity in each
group was normalized to that in the group treated with DHEA alone (panel
A, mean ± S.E. of eight independent experiments in triplicate) or
insulin alone (panel B, mean ± S.E. of eight independent
experiments in triplicate). When compared with cells treated with vehicle
alone, ET-1 promoter activity was significantly increased in cells treated
with either DHEA (panel A, p < 0.001) or insulin
(panel B, p < 0.001). When compared with cells treated
with DHEA or insulin alone, ET-1 promoter activity was further increased in
cells co-treated with wortmannin (panel A, p < 0.03;
panel B, p = 0.05) and inhibited in cells co-treated with
PD98059 (panel A and B, p < 0.0001).