Figure 5

Effect of DSS1 knockdown on apoptotic cell death in breast cancer cells. (A) To examine the stage of cell death, live cells were stained with Annexin XII, which identifies the early apoptotic stage, in combination with PI staining; cells were marked as Annexin XII⁺PI^- (green; early apoptotic), Annexin XII⁺PI⁺ (doubly merged yellow; the intermediate stage), or Annexin XII^-PI⁺ (red; late apoptotic/necrotic). Scale bar indicates 100 μm. (B) EM analysis was carried out at day 5 after treatment with siCtrl or siDSS1-(a). Arrowheads show the chromatin condensation typical of cell death, and asterisks indicate cell death with atypical chromatin accumulation and density. Scale bar indicates 500 μm. (C) An alkaline comet assay was carried out to detect the DNA damage resulting from both single-strand and double-strand breaks and evaluated as in Figure 3. Statistical significance was assessed by Student’s t-test, with **P < 0.01. Scale bar indicates 200 μm.