Figure 6.

DU145 and LNCaP cells are arrested exclusively in mitosis after BI 2536 and BI 6727 treatment, while PC3 cells accumulate both in G₂ and M phase. A) Western blot analysis of p21 after treatment of PCa cells with BI 2536 or BI 6727 for 24 h revealed a marked increase in p21 expression in PC3 cells, while DU145 and LNCaP cells only had a marginal increase in p21 expression. B) Real-time RT-PCRs performed after 6 and 24 h of BI treatment of DU145 and PC3 cells revealed increased mRNA levels of p21 in PC3 cells, but not in DU145 cells. Error bars represent sd of averaged fold values of 3 independent experiments. Fold changes are compared to untreated control levels using Student t test. *P < 0.01. C) Analysis of flow cytometry data acquired from PCa cell lines after treatment with BI 2536 and BI 6727 for 24 h revealed the percentage of cells at a respective cell cycle stage. With increasing concentration of the BI compounds, higher percentages of DU145 and LNCaP cells were in mitosis. While the percentage of PC3 cells in mitosis increased with increasing concentrations of the BI compounds, there was a concomitant increase in the percentage of PC3 cells in G₂ phase. Concentrations are nanomolar. Flow cytometry data represent 3 independent experiments.