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This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Senchenkov, A. Articles by Cabot, M. C. Search for Related Content PubMed PubMed Citation Articles by Senchenkov, A. Articles by Cabot, M. C. Related Collections Neoplasia Apoptosis Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  Blood, 15 September 2001, Vol. 98, No. 6, pp. 1927-1934 NEOPLASIA Enhanced ceramide generation and induction of apoptosis in human leukemia cells exposed to DT388-granulocyte-macrophage colony-stimulating factor (GM-CSF), a truncated diphtheria toxin fused to human GM-CSF Alex Senchenkov, Tie-Yan Han, Hongtao Wang, Arthur E. Frankel, Timothy J. Kottke, Scott H. Kaufmann, and Myles C. Cabot From the John Wayne Cancer Institute at Saint John's Health Center, Santa Monica, CA; Departments of Cancer Biology and Medicine, Wake Forest University, School of Medicine, Winston-Salem, NC; and Mayo Clinic, Division of Oncology Research, Rochester, MN. DT388-GM-CSF, a targeted fusion toxin constructed by conjugation of human granulocyte-macrophage colony-stimulating factor (GM-CSF) with the catalytic and translocation domains of diphtheria toxin, is presently in phase I trials for patients with resistant acute myeloid leukemia. HL-60/VCR, a multidrug-resistant human myeloid leukemia cell line, and wild-type HL-60 cells were used to study the impact of DT388-GM-CSF on metabolism of ceramide, a modulator of apoptosis. After 48 hours with DT388-GM-CSF (10 nM), ceramide levels in HL-60/VCR cells rose 6-fold and viability fell to 10%, whereas GM-CSF alone was without influence. Similar results were obtained in HL-60 cells. Examination of the time course revealed that protein synthesis decreased by about 50% and cellular ceramide levels increased by about 80% between 4 and 6 hours after addition of DT388-GM-CSF. By 6 hours this was accompanied by activation of caspase-9, followed by activation of caspase-3, cleavage of caspase substrates, and chromatin fragmentation. Hygromycin B and emetine failed to elevate ceramide levels or induce apoptosis at concentrations that inhibited protein synthesis by 50%. Exposure to C6-ceramide inhibited protein synthesis (EC50 ~5 µM) and decreased viability (EC50 ~6 µM). Sphingomyelinase treatment depleted sphingomyelin by about 10%, while increasing ceramide levels and inhibiting protein synthesis. Diphtheria toxin increased ceramide and decreased sphingomyelin in U-937 cells, a cell line extremely sensitive to diphtheria toxin; exposure to DT388-GM-CSF showed sensitivity at less than 1.0 pM. Diphtheria toxin and conjugate trigger ceramide formation that contributes to apoptosis in human leukemia cells through caspase activation and inhibition of protein synthesis. © 2001 by The American Society of Hematology.   CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: J. M. Carton, D. J. Uhlinger, A. D. Batheja, C. Derian, G. Ho, D. Argenteri, and M. R. D'Andrea Enhanced Serine Palmitoyltransferase Expression in Proliferating Fibroblasts, Transformed Cell Lines, and Human Tumors J. Histochem. Cytochem., June 1, 2003; 51(6): 715 - 726. [Abstract] [Full Text] [PDF]

	Copyright © 2001 by American Society of Hematology         Online ISSN: 1528-0020