Quantitative determination of apoptotic death in cultured human pancreaticcancer cells by propidium iodide and digitonin

We present here the efficacy of an in vitro cytotoxicity assay which can me asure rapidly both apoptotic dead cells and cell growth rate, quantitativel y. Using a multi-well plate reader, the fluorescence intensity of propidium iodide (PI) corresponding to dead cells and to total cells after digitonin treatment were measured in cultured human pancreatic cancer cells followin g exposure to etoposide. The percentage of dead cells measured by this assa y was well correlated to that determined by Trypan blue staining. Furthermo re, the cell growth rate determined simultaneously was also correlated to t he cell number counted directly using a microscope. We demonstrate that thi s method, which was originally established for evaluating necrosis, could b e applied to measure apoptotic cell death. Taken together, this simple assa y is useful for testing the efficacy of anti-cancer agents and for investig ating the molecular mechanisms of apoptosis in the cultured cells. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.