Relationship between cell cycle changes and variations of the mitochondrial membrane potential induced by etoposide.
Etoposide, a clinically useful anticancer drug, is a potent inhibitor of topoisomerase II. The DNA strand breaks caused by this epipodophyllotoxin lead to apoptotic death of tumor cells. Flow cytometry was used to investigate the relationship between the effects of the drug on the cell cycle of human leukemia HL-60 cells and the variations of the mitochondrial transmembrane potential (DeltaPsi(mt)). Three cationic fluorescent probes, DiOC(6), JC-1, and TMRM, were used to measure drug-induced changes of DeltaPsi(mt). In all three cases, we found that the arrest in the G2/M phase of the cells treated with 0.5 microM etoposide is associated with an increase in the potential of mitochondrial membranes whereas treatment with a tenfold higher drug concentration trigger massive apoptosis and a collapse of DeltaPsi(mt). DNA fragmentation (TUNEL assay) and externalization of phosphatidylserine residues in the outer leaflet of the plasma membrane (annexin V binding) were measured to characterize the apoptotic cell population.
Facompré
M
M
Institut National de la Santé et de la Recherche Médicale, Unité 524 and Laboratoire de Pharmacologie Antitumorale du Centre Oscar Lambret, Place de Verdun, Lille, 59045, France.
Wattez
N
N
Kluza
J
J
Lansiaux
A
A
Bailly
C
C
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis; D002453:Cell Cycle; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology*; D005434:Flow Cytometry; D005453:Fluorescence; D005456:Fluorescent Dyes; D018922:HL-60 Cells; D006801:Humans; D020287:In Situ Nick-End Labeling; D008564:Membrane Potentials / Q000187:drug effects*; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D059005:Topoisomerase II Inhibitors
D000972:Antineoplastic Agents, Phytogenic; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D059005:Topoisomerase II Inhibitors; D005047:Etoposide