FIGURE 6.
Knockdown of Akt1 and Akt2 diminishes Ang2-stimulated cell survival of MCF-7 cells in vitro and in the lung of mice. A, IB analyses: knockdown of Akt1+Akt2 (A1&2) blocked the Ang2-stimulated phosphorylation of Akt at Ser-473 (S473) and Ang2-induced expression of Bcl-2 proteins in Ang2#1 cells. C, control siRNAs. Total proteins of Akt and β-actin were used as loading controls. B and C in vitro cell survival assays. Knockdown of Akt1&Akt2 by siRNAs (siRNA.Akt1 + 2) abrogated the Ang2-enhanced cell survival in vitro under serum-starvation condition (B) or after the cells were exposed to CoCl2 (C). *, p < 0.001 by t test. Error bars: mean ± S.D. D, knockdown of Akt1 + Akt2 (siRNA.Akt1 + 2) in MCF-7 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. E, percentage of survived breast cancer cells in the lung of mice of each group in D 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. Data in B, C, and E, *, p < 0.05 and error bars: mean ± S.D. The results of A–G are representative from two or three independent experiments with similar results.