Phosphatase and tensin homolog (PTEN) expression affects the combined effect of olaparib and suberoylanilide hydroxamic acid (SAHA) in triple-negative breast cancer (TNBC) cells. (A) The expression levels of proliferative signaling pathway proteins in TNBC cells were analyzed by western blotting following drug treatment. (B) Transfection efficacy was verified by western blot analysis with anti-PTEN, anti-phosphorylated (p)-AKT, and anti-α-tubulin (as a loading control) antibodies. (C) PTEN silencing decreased cellular sensitivity to dual inhibition by the poly (ADP-ribose) polymerase (PARP) and histone deacetylase (HDAC) inhibitors. The cells were transfected with nonspecific control or PTEN-specific siRNA, and then exposed to increasing concentrations of olaparib with a fixed concentration of SAHA for 5 d. IC50 values are presented in bar graphs with error bars (n = 3); *P <0.001. CI, combination index.