Combined etoposide (VP16) and geldanamycin (GA) treatment of HCT116 cells causes cellular death by apoptosis

Copyright information:Taken from "Inhibition of Hsp90 acts synergistically with topoisomerase II poisons to increase the apoptotic killing of cells due to an increase in topoisomerase II mediated DNA damage"Nucleic Acids Research 2006;34(4):1148-1157.Published online 16 Feb 2006PMCID:PMC1373695.© The Author 2006. Published by Oxford University Press. All rights reserved HCT116 cells were seeded at a density of 1 × 10 cells in 35 mm glass bottom microwell dishes, left to adhere for 96 h. And were treated with 2 µM etoposide (VP16), 500 nM geldanamycin (GA) or a combination of the two over a period of 48 h. Cells were imaged every 15 min in the presence of 15 µg/ml propidium iodide (PI) and 40 ng/ml annexin-V-FITC (AnnV) using a Zeiss Axiovert 200. FITC was excited at 488 nm and emitted at 540 nm. PI fluorescence was excited at 543 nm and emitted at 570 nm. Data capture and analysis was carried out using LSM510 version 3.2 software. Individual cells were scored for annexin-V and/or PI, cell percentages and were normalized to time zero. () Percentage of cells binding annexin-V and PI over time. () Cumulative total percentage of cells binding annexin-V and PI. Lines on graphs; Navy blue = viable cells; green = annexin-V; red = propidium iodide. For information, at the 5 h time point the staining of the control cells, no drug treatment was 0.6% with PI and 0.6% with annexinV.