Apoptosis inducing novel anti-leukemic agent, bis(4,7-dimethyl-1,10 phenanthroline) sulfatooxovanadium(IV) [VO(SO4)(Me-2-Phen)(2)] depolarizes mitochondrial membranes

Bis(4,7-dimethyl-1,10 phenanthroline) sulfatooxovanadium(IV) [VO(SO4)(Me-2- Phen)(2)] induces apoptosis in human NALM-6 leukemia cells. In the present report, we demonstrate that VO(SO4)(Me-2-Phen)(2)-induced apoptosis is medi ated through the generation of reactive oxygen species (ROS), depletion of glutathione and depolarization of mitochondrial membrane potential (Delta P sim). Using multilaser flow cytometry methods, we further mapped out the de ath sequence that occurs in VO(SO4)(Me-2-Phen)(2)-treated leukemic cells. T riple labeling method to measure ROS, Delta Psim and glutathione coupled wi th multilaser excitation flow cytometry showed that induction of ROS took p lace before the loss of mitochondrial permeability transition and depletion of glutathione, Correlated two parameter plots of glutathione content vers us Delta Psim showed that loss of Delta Psim and depletion of glutathione. closely follows each other. Translocation of phosphatidylserine to the oute r leaflet of the cell membrane was the final step in the process before the cells became apoptotic. These results demonstrate that the mitochondrial p ermeability transition takes place during VO(SO4)(Me-2-Phen)(2)-induced apo ptosis and is mediated through induction of ROS and depletion of glutathion e.