Effect of NO and hypoxia on the expression of the VEGF reporter gene in A-172 cells.
(A) Time-course of human VEGF promoter activity in A-172 cells. The cells were exposed to normoxia (21% O2), hypoxia (1% O2), DMSO (0.1%), or SNAP (0.5 mmol/L in 0.1% DMSO) for 0, 6, 12, or 24 hours. In the result labeled 12 + 12h, a half dose of SNAP was added at 24 hours, and the remaining dose was added 12 hours before harvesting the cells. *P < 0.05, **P < 0.01 versus corresponding controls; n = 6 independent experiments. (B-D) Effect of SNAP (B), NOC5 (C), and AP (D) on human VEGF promoter activity in A-172 cells. The cells were stimulated for 12 hours under normoxic or hypoxic conditions. The final concentration of DMSO was 0.1% in (B) and (D). (NOC5 was dissolved in PBS.) (B): n = 8; *P < 0.05, **P < 0.01 versus control in normoxia, #P < 0.01 versus control in hypoxia. (C): n = 8; *P < 0.01 versus control in normoxia, #P < 0.01 versus control in hypoxia. (D): n = 6; no significant difference. Relative luc activity represents the mean ± SEM of the ratio of luciferase/β-galactosidase activity.
