Fig. 7
Knockdown of ACE2 reverses resistance to Epirubicin but promotes the proliferation of drug-resistant breast cancer cells. A Western blot and B qRT-PCR assays verified that ACE2 was successfully knocked down by three independent shRNA targeting ACE2 in 468/EPR cells. C Silencing ACE2 in 468/EPR cells significantly increased the sensitivity to EPI compared with shControl and wild-type cells. The IC50 assay was performed by using the CCK-8 based method. D Silencing ACE2 in 468/EPR cells significantly increased cell proliferative activity compared with shControl cells (****P < 0.0001). E Knockdown of ACE2 in 468/EPR cells remarkably increased the formation of cell colonies compared with shControl cells (****P < 0.0001). F EdU cell proliferation assay displayed that knockdown of ACE2 expression resulted in a significant increase in EdU positive rate, indicating higher cell proliferation ability. G Intracellular ROS levels were remarkably increased in ACE2 knockdown 468/EPR cells than in shControl cells. H Intracellular ROS levels were increased approximately 4-fold in 468/EPR-shACE2 cells treated with 0.05 µM EPI for 72 h compared to control cells. I Knockdown of ACE2 significantly increased the rate of EPI-induced apoptosis in 468/EPR cells compared with the control group. All data are shown as mean ± SD; *P < 0.05, *P < 0.01, ***P < 0.001, ****P < 0.0001, and ns P > 0.05 versus control