Fig. 3.

SF1126 induces apoptosis of parental and trastuzumab-resistant cells. a SK-parental, SK-HRp2, BT-parental, and BT-HRp3 cells were either untreated or treated with 40-μM SF1126 for 48 h, at which point they were fixed and stained with propidium iodide. DNA content was analyzed by flow cytometry. The percentages of cells with sub-diploid DNA content are shown, with error bars representing standard deviation between duplicates. SF1126 increased the percentage of cells in sub-G1, consistent with induction of apoptosis. b Cells were untreated or treated with 20-μM SF1126 for 48 h, at which point the drug-containing media were removed and replaced with drug-free media. Cells were maintained for an additional 6 days, then stained with methylene blue and photographed with the Odyssey Imaging System. Experiments were done in duplicate at least two times. Representative cultures are shown for each group. SF1126 inhibited colony survival. c SK-parental and SK-HRp2cells, and d BT-parental and BT-HRp2 cells were treated with 0, 10, 20, or 40-μM SF1126 for 24 h. Total protein lysates (50 µg) were immunoblotted for PARP, cleaved caspase 3, and survivin. Actin served as a loading control. SF1126 induced cleavage of PARP and caspase 3, and caused downregulation of survivin. These results indicate that SF1126 promotes growth arrest and apoptosis of HER2-over-expressing breast cancer cells