PARP inhibitor, ABT-888, induces apoptosis in HP1-depleted breast cancer cells.

<p>ABT-888 (20 μM or 200 μM) was used to treat MCF7 and individually HP1-depleted MCF7 cells for 72 hours. Cells were stained with Annexin V and propidium iodide staining and cell population was analyzed by flow cytometry. <i>A</i>. Cell death percentage on Y-axis is for the double stained population using Annexin V (FITC-conjugated) and propidium iodide. <i>B</i>. Annexin V stained cell population was analyzed by flow cytometry. Y axis: cell numbers, X axis: FL1 values (Annexin V). <i>C</i>. HP1β-depleted MCF7 breast cancer cells are more prone to apoptosis by ABT-888 and carboplatin. Apoptosis of MCF7 and individually HP1-depleted MCF7 cells was determined after treatment of ABT-888 (20 μM), carboplatin (20 μM) or ABT-888/carboplatin combination (20 μM/20 μM) for 72 hours. A representative Annexin V staining of MCF7 and HP1β depleted MCF7 cells. <i>D</i>. Percentage of apoptotic MCF7 and HP1-depleted MCF7 cells were determined by double staining with Annexin V and propidium iodide followed by analysis using flow cytometry. _*: <i>p</i> < 0.05 from analysis of three independent assays, Student's t-test.