Figure 4

α-santalol regulates VEGF and VEGFR2 expression in a biphasic manner. (A and B) Expression of VEGF at mRNA level. α-santalol at low doses (0.5, 1, 5 uM) increased the VEGFA mRNA expression, whereas at higher levels of α-santalol (10, 20, 30, 40 uM) decreased the VEGFA mRNA expression. (A) HUVECs were treated with increasing concentration of α-santalol for 24 h. (B) HUVECs were treated with 5 μM α-santalol for different time intervals. Total RNAs were prepared, and VEGF mRNA levels were determined by Real-time PCR using VEGF-A specific primers. (C and D) Level of VEGF was determined by Western blot. (C) HUVECs were treated with increasing concentration of α-santalol for 24 h. α-santalol at low doses (0.5, 1, 5 uM) increased the VEGFA mRNA expression, whereas at higher levels of α-santalol (10, 20, 30, 40 uM) decreased the VEGFA mRNA expression. (D) HUVECs were treated with 5 μM α- santalol for different time intervals. Cell lysates were subjected to immunoblotting with antibody against VEGF, and β-actin was used as the internal control. Signal intensities were determined by densitometry. The expression level of VEGF in control was arbitrarily set to 1, and the relative expression level of α-santalol treated cells was calculated accordingly. (E) Expression of VEGFR1 at mRNA level. (F) Expression of VEGFR2 at mRNA level. The expression level in control was arbitrarily set to 1, and the relative expression level of α-santalol -treated cells was calculated accordingly. Values are mean ± SEM (n = 6) of three independent experiments. *p < 0.05; **p < 0.01; ***p < 0.001 versus vehicle control.