Involvement of mitochondria and caspase-3 in ET-18-OCH(3)-induced apoptosis of human leukemic cells

Int J Cancer. 2000 Apr 15;86(2):208-18. doi: 10.1002/(sici)1097-0215(20000415)86:2<208::aid-ijc10>;2-e.


The induction of cell death in leukemic HL-60 cells by the ether lipid 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH(3); edelfosine) followed the typical apoptotic changes in ultrastructural morphology, including blebbing, chromatin condensation, nuclear membrane breakdown and extensive vacuolation. Using a cytofluorimetric approach, we found that ET-18-OCH(3) induced disruption of the mitochondrial transmembrane potential (DeltaPsi(m)) followed by production of reactive oxygen species (ROS) and DNA fragmentation in leukemic cells. ET-18-OCH(3) also induced caspase-3 activation in human leukemic cells, as assessed by cleavage of caspase-3 into the p17 active form and cleavage of the caspase-3 substrate poly(ADP-ribose) polymerase (PARP). ET-18-OCH(3) analogues unable to induce apoptosis failed to disrupt DeltaPsi(m) and to activate caspase-3. ET-18-OCH(3)-resistant Jurkat cells generated from sensitive Jurkat cells showed no caspase-3 activation and did not undergo DeltaPsi(m) disruption upon ET-18-OCH(3) incubation. Cyclosporin A partially inhibited DeltaPsi(m) dissipation, caspase activation and apoptosis in ET-18-OCH(3)-treated leukemic cells. Overexpression of bcl-2 by gene transfer prevented DeltaPsi(m) collapse, ROS generation, caspase activation and apoptosis in ET-18-OCH(3)-treated leukemic T cells. Pretreatment with the caspase inhibitor Z-Asp-2, 6-dichlorobenzoyloxymethylketone prevented ET-18-OCH(3)-induced PARP proteolysis and DNA fragmentation, but not DeltaPsi(m) dissipation. ET-18-OCH(3) did not affect the expression of caspases and bcl-2-related genes. ET-18-OCH(3)-induced apoptosis did not require protein synthesis. Our data indicate that DeltaPsi(m) dissipation and caspase-3 activation are critical events of the apoptotic cascade triggered by the antitumor ether lipid ET-18-OCH(3), and that the sequence of events in the apoptotic action of ET-18-OCH(3) on human leukemic cells is: DeltaPsi(m) disruption, caspase-3 activation and internucleosomal DNA degradation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects*
  • Caspase 3
  • Caspase Inhibitors
  • Caspases / genetics
  • Caspases / metabolism*
  • DNA Fragmentation
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Gene Expression / drug effects
  • Humans
  • Leukemia / enzymology
  • Leukemia / pathology*
  • Leukemia / physiopathology
  • Leukemia, Myeloid, Acute / pathology
  • Leukemia-Lymphoma, Adult T-Cell / pathology
  • Membrane Potentials / drug effects
  • Microscopy, Electron
  • Mitochondria / physiology*
  • Phospholipid Ethers / pharmacology*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Reactive Oxygen Species / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tumor Cells, Cultured


  • Antineoplastic Agents
  • Caspase Inhibitors
  • Enzyme Inhibitors
  • Phospholipid Ethers
  • Proto-Oncogene Proteins c-bcl-2
  • Reactive Oxygen Species
  • edelfosine
  • CASP3 protein, human
  • Caspase 3
  • Caspases