Figure 6

Id4 expression in prostate cancer cell lines LNCaP and DU145 is associated with NKX3.1, Sox9 and PTEN expression. Panel A: Id4 was silenced in LNCaP (L) cells with gene specific shRNA (L-Id4). Panel B: NKX3.1 and Sox9 expression in LNCaP cells in which Id4 was silenced (Panel A) or in DU45 cells (D) in which Id4 was ectopically expressed (D + Id4). Panel C: Chromatin immuno-precipitation to demonstrate occupancy of androgen receptor (AR) at the androgen response element on NKX3.1 promoter in LNCaP (L) and LNCaP-Id4 (L-Id4) cells. Polymerase A (PolA) enrichment on GAPDH promoter was used as an internal control. The data represented as mean ± SEM of three different experiments is normalized IgG (CS: Charcoal stripped FBS, a* and b*: p < 0.001 as compared to a and b respectively). Note that PolA enrichment is shown on the right y-axis and IgG and ARE on the left y-axis. Panel D: PTEN protein is undetectable in LNCaP cells due to frame shift mutation. Increased PTEN expression is observed in DU145 cells in which Id4 is constitutively expressed (D + Id4). PTEN null prostate cancer cell line PC3 was used as a negative control for PTEN expression. Representative of three different experiments is shown.