Figure 5.

Egr1 directly regulates the Id1 expression in prostate cancer. LNCaP and PC3 cells were first incubated in phenol-red free RPMI-1640 medium containing 10% FBS for 48 h. The cells were then treated with indicated concentrations of bombesin for another 72 h before mRNA levels were measured using qRT-PCR. Bombesin induced a dose-dependent upregulation of Egr1 both in LNCaP (A) and PC3 (B) cells. Id1 was also upregulated in the same pattern in LNCaP (C) and PC3 (D) cells. When specific siRNA targeting at Egr1, or the control siRNA were used before 1 nM of bombesin was supplemented, the upregulation of Id1 became withdrawn following the silencing of Egr1 in both cells (E, F, *P < 0.01).