Functional CD95 ligand and CD95 death-inducing signaling complex in activation-induced cell death and doxorubicin-induced apoptosis in leukemic T cells.
Activation-induced cell death (AICD) in T cells is mediated by CD95 ligand (CD95L)/receptor interaction, which has also been implicated in apoptosis induction by some anticancer agents. In this article we show that both anti-CD3-triggering (AICD) and doxorubicin treatment led to the production of a functionally active CD95L in the CD3+/T-cell receptor-positive (TCR+) T leukemia cell line H9. CD95L-expressing H9 cells killed CD95-sensitive J16 or CEM target cells, but not CD95-resistant CEM or J16 cells overexpressing dominant negative FADD (J16/FADD-DN). By immunoprecipitation, CD95L was physically bound to CD95, suggesting that AICD and doxorubicin-induced apoptosis involve CD95L-mediated CD95 aggregation, thereby triggering the CD95 death pathway. CD95 aggregation was associated with the recruitment of FADD and caspase-8 to the CD95 receptor to form the CD95 death-inducing signaling complex (DISC), resulting in caspase-8 activation and cleavage of the effector caspase-3 and PARP. Blocking of the CD95L/receptor interaction by antagonistic antibodies to CD95 or to CD95L also blocked AICD and inhibited the early phase of doxorubicin-induced apoptosis, though cell death induced by doxorubicin eventually proceeded in a CD95-independent manner. These findings may explain some conflicting data on the role of death receptor systems in drug-induced apoptosis. Thus, in cells with an inducible CD95 receptor/ligand system, drug-induced apoptosis may be mediated by CD95L-initiated DISC formation and activation of downstream effector programs similar to AICD in T cells. (Blood. 2000;95:301-308)
Fulda
S
S
University Children's Hospital, Ulm, Germany.
Strauss
G
G
Meyer
E
E
Debatin
K M
KM
D017209:Apoptosis / Q000187:drug effects* / Q000276:immunology; D004317:Doxorubicin / Q000633:toxicity*; D053222:Fas Ligand Protein; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007700:Kinetics; D015458:Leukemia, T-Cell / Q000473:pathology / Q000503:physiopathology*; D008562:Membrane Glycoproteins / Q000235:genetics*; D016853:Muromonab-CD3 / Q000633:toxicity; D012333:RNA, Messenger / Q000235:genetics; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000502:physiology*
C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D016853:Muromonab-CD3; D012333:RNA, Messenger; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D019014:fas Receptor; D004317:Doxorubicin