ETOPOSIDE-INDUCED PC12 CELL-DEATH - APOPTOTIC MORPHOLOGY WITHOUT OLIGONUCLEOSOMAL DNA FRAGMENTATION OR DEPENDENCY UPON DE-NOVO PROTEIN-SYNTHESIS

Etoposide, a topoisomerase II inhibitor used in cancer therapy, has be en shown to induce apoptosis in vitro in a variety of cell types. In t he present study. we have characterized the effects of etoposide on un differentiated rat pheochromocytoma PC12 cells. Etoposide killed PC12 cells in a time-and concentration-dependent manner, 20-24 h incubation with 10 mu g/ml etoposide induced 25-50% cell death. Hoechst 33258 st aining revealed apoptotic morphology in dying cells, No evidence was f ound of either oligonucleosomal DNA fragmentation, as shown by agarose gel electrophoresis, or endonuclease involvement, as shown by the ina bility of aurintricarboxylic acid to prevent cell death. Cycloheximide and actinomycin-D were unable to prevent etoposide cytotoxicity indic ating that the process is not dependent upon de novo protein or mRNA s ynthesis. NGF (5 ng/ml) prevented etoposide-induced PC12, cell death, These results offer an example of how the morphological features of ap optosis are not necessarily associated with oligonucleosomal DNA fragm entation or with de novo macromolecule synthesis. (C) 1997 Elsevier Sc ience B.V.