Suppression of STAT3 and HIF-1 Alpha Mediates Anti-Angiogenic Activity of Betulinic Acid in Hypoxic PC-3 Prostate Cancer Cells
Figure 5
Effect of betulinic acid (BA) on STAT3 binding on the VEGF promoter in hypoxic PC-3 cells.
(A) PC-3 cells were treated with or without BA (10 µM) under normoxia or hypoxia for 4 h. The immunoprecipitated DNA with rabbit normal IgG, HIF-1α or STAT3 antibody was amplified by PCR analysis for VEGF promoter. (B) Cells were transiently transfected with siRNA for scramble or STAT3 for 24 h and treated with or without BA (10 µM) for 18 h under hypoxia. VEGF levels in the culture supernatants were measured by using a Quantikine VEGF ELISA kit. Data represent means ± S.D. #, p<0.05 vs control, and *, p<0.05 vs control siRNA. Cell lysates were subjected to Western blotting for phospho-STAT3, STAT3 and HIF-1α.