Apoptotic cell death induced by actinomycin D arisen at different levels and cell cycle stages according to human cultured cell species

Nine kinds of human cultured cells, including fetus cells (smooth chorion trophoblast cells, amnion epithelial cells and HE-21), adult non-carcinoma cells (HCF), and carcinoma cells (KATO-III, COLO 201, Lu-134-AH, SK-OV-3 and SKG-3a) were stimulated with Actinomycin (Act.) D for 24 h. Apoptosis induction was investigated by agarose gel electrophoresis for DNA fragmentation analysis and by flow cytometric analysis of stained cells using in situ terminal deoxynucleotidyl-transferase (TdT)-mediated dUTP nick-end labeling TUNEL) staining techniques for the quantification of apoptosis, and simultaneously using propidium iodide for the gain of some information about cell cycle. By agarose gel electrophoresis, DNA fragmentation of these cells except amnion epithelial and SKG-3a cells was detected, depending on concentration of Act. D. Using flow cytometric analysis, these cells were separated into four groups according to, the information about cell cycle. Group 1 included amnion epithelial and SKG-3a cells, which were TUNEL negative. In group 2, all cell populations at G(0)/G(1) and G(2)/M phases of HCC, KATO-III and SK-OV-3 were TUNEL staining positive. A portion of each G(0)/G(1) or G(2)/M phase cell of Lu-134-AH and COLO 201 in group 3 was TUNEL stain positive. In group 4, G(2)/M phase cells of smooth chorion trophoblast cells and HE-21 were mostly stained and a small population of G(0)/G(1) phase cells were also TUNEL stain positive. These results show that the stages of the cell cycle at which apoptosis was arisen by Act. D stimulation were significantly different depending on the cells types.