FIGURE 7.

Bcl-2 is a downstream effector of the Ang2-ILK-Akt1/2 signaling that mediates Ang2-enhanced cell survival and Ang2-attenuated cell apoptosis of MCF-7 cells. A and B, a pharmacological inhibitor of Bcl-2, HA14–1, significantly inhibited Ang2-enhanced cell survival (A) and Ang2-protected cell apoptosis (B) under serum-starvation conditions. *, p < 0.001 by t test and error bars: mean ± S.D. C, IB analyses: knockdown of Bcl-2 with a control (C) or siRNA pool for Bcl-2 (B) in control GFP or Ang2#1 cells abrogated the Ang2-enhanced cell survival (D) and reversed Ang2-attenuated cell apoptosis (E) in vitro under serum starvation condition (A). *, p < 0.001 by t test. Error bars: mean ± S.D. F, knockdown of Bcl-2 with a siRNA pool (siRNA.Bcl-2) but not the control in Ang2#1 cells attenuated the Ang2-enhanced cell survival in the lung of mice (4 mice per group) in 24 h and 5 days after the tail-vein injections. Representative images of the lung of various mice at each time point are shown. Scale bars: 100 μm. G, percentage of survived breast cancer cells in the lung of mice of each group in F was analyzed by normalizing the mean numbers of the cells in 24 h or 5 days after injections with those of each group at 4 h post-injections. Difference of the percentage of cell survival at each time point was statistically analyzed using Mann-Whitney U test. *, p < 0.05 and error bars: mean ± S.D. The experiments of A–G are representative from two or three independent experiments with similar results.