Phosphatase and tensin homolog (PTEN) expression increases the synergistic effect of olaparib with suberoylanilide hydroxamic acid (SAHA) due to the induction of autophagic cell death. (A) The cells were treated with olaparib and SAHA alone or in combination for 5 d. The expression levels of apoptosis and autophagy mediators were then examined by western blotting. (B) Induction of autophagy was confirmed by monitoring GFP-tagged LC3 expression in MDA-MB-231 (left) and MDA-MB-468 (right) cells following exposure to olaparib, SAHA, or both inhibitors. (C) MDA-MB-468 cells were transfected with siRNA targeting PTEN or the negative control. Additionally, the cells were transfected with an empty vector or one encoding PTEN. After 2 d the expression of autophagy markers was evaluated using immunoblotting. (D) Translocation of GFP-tagged LC3 in MDA-MB-231 cells transfected with control or PTEN-specific siRNA was examined by confocal microscopy (top). siRNA-mediated reduction of PTEN expression was confirmed by western blotting (bottom). CI, combination index.