Activation of caspase-8 in drug-induced apoptosis of B-lymphoid cells is independent of CD95/Fas receptor-ligand interaction and occurs downstream of caspase-3

Blood ◽  
2001 ◽  
Vol 97 (5) ◽  
pp. 1378-1387 ◽  
Author(s):  
Thomas Wieder ◽  
Frank Essmann ◽  
Aram Prokop ◽  
Karin Schmelz ◽  
Klaus Schulze-Osthoff ◽  
...  

The activation of caspase-8, a crucial upstream mediator of death receptor signaling, was investigated in epirubicin- and Taxol-induced apoptosis of B-lymphoma cells. This study was performed because the CD95/Fas receptor-ligand interaction, recruitment of the Fas-associated death domain (FADD) adaptor protein, and subsequent activation of procaspase-8 have been implicated in the execution of drug-induced apoptosis in other cell types. Indeed, active caspase-8 was readily detected after treatment of mature and immature B-lymphoid cells with epirubicin or Taxol. However, neither constitutive nor drug-induced expression of the CD95/Fas ligand was detectable in B-lymphoma cells. Furthermore, overexpression of a dominant-negative FADD mutant (FADDdn) did not block caspase-8 processing and subsequent DNA fragmentation, indicating that drug-induced caspase-8 activation was mediated by a CD95/Fas-independent mechanism. Instead, caspase-8 cleavage was slightly preceded by activation of caspase-3, suggesting that drug-induced caspase-8 activation in B-lymphoma cells is a downstream event mediated by other caspases. This assumption was confirmed in 2 experimental systems—zDEVD-fmk, a cell-permeable inhibitor of caspase-3–like activity, blocked drug-induced caspase-8 cleavage, and depletion of caspase-3 from cell extracts impaired caspase-8 cleavage after in vitro activation with dATP and cytochrome c. Thus, these data indicate that drug-induced caspase-8 activation in B-lymphoma cells is independent of death receptor signaling and is mediated by postmitochondrial caspase-3 activation.

1999 ◽  
pp. 21-23 ◽  
Author(s):  
S T Taylor ◽  
J A Hickman ◽  
C Dive

The suppression of apoptosis is one mechanism by which tumours become drug resitant. Extracellular signals from the germinal centre (GC) of secondary lymphoid tissue can rescue B cells from physiological- and chemotherapy-induced apoptosis. Such survival signals include CD40 receptor ligation, interleukin-4 (IL-4) receptor stimulation and the interaction of the integrin ligand VCAM-1 with its receptor. The GC environment was modelled in vitro by providing B lymphoma cells with these survival signals. JLP119 B lymphoma cells underwent apoptosis after exposure to the topisomerase II inhibitor etoposide and this was dramatically reduced when the cells were cultured in the GC system. CD40 receptor ligation resulted in increased levels of Bcl-XL. Etoposide diminished the binding between Bax and Bcl-XL but this was restored by IL-4 and VCAM-1 triggered signals. These data demonstrate combined effects of three microenvironmental signals on the Bcl-2 family and illustrate the potential importance of such signalling pathways in drug resistance of tumour cells.


Blood ◽  
1999 ◽  
Vol 93 (9) ◽  
pp. 3053-3063 ◽  
Author(s):  
Sebastian Wesselborg ◽  
Ingo H. Engels ◽  
Evi Rossmann ◽  
Marek Los ◽  
Klaus Schulze-Osthoff

Abstract Proteases of the caspase family are the critical executioners of apoptosis. Their activation has been mainly studied upon triggering of death receptors, such as CD95 (Fas/APO-1) and tumor necrosis factor-R1, which recruit caspase-8/FLICE as the most proximal effector to the receptor complex. Because apoptosis induced by anticancer drugs has been proposed to involve CD95/CD95 ligand interaction, we investigated the mechanism of caspase activation by daunorubicin, doxorubicin, etoposide, and mitomycin C. In Jurkat leukemic T cells, all drugs induced apoptosis and the cleavage of procaspase-8 to its active p18 subunit. However, cells resistant to CD95 were equally susceptible to anticancer drugs and activated caspase-8 with a similar kinetic and dose response as CD95-sensitive cells. The broad caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone prevented apoptosis and caspase-8 activation in response to CD95 and drug treatment, whereas a neutralizing CD95 decoy as well as a dominant-negative FADD construct selectively abrogated CD95, but not drug-induced effects. A potent activation of caspase-8 was also induced by cycloheximide, indicating that it was independent of protein synthesis. Our data, therefore, show that (1) anticancer drug-induced apoptosis does not require de novo synthesis of death ligands or CD95 interaction, and (2) that caspase-8 can be activated in the absence of a death receptor signaling.


Blood ◽  
1999 ◽  
Vol 93 (9) ◽  
pp. 3053-3063 ◽  
Author(s):  
Sebastian Wesselborg ◽  
Ingo H. Engels ◽  
Evi Rossmann ◽  
Marek Los ◽  
Klaus Schulze-Osthoff

Proteases of the caspase family are the critical executioners of apoptosis. Their activation has been mainly studied upon triggering of death receptors, such as CD95 (Fas/APO-1) and tumor necrosis factor-R1, which recruit caspase-8/FLICE as the most proximal effector to the receptor complex. Because apoptosis induced by anticancer drugs has been proposed to involve CD95/CD95 ligand interaction, we investigated the mechanism of caspase activation by daunorubicin, doxorubicin, etoposide, and mitomycin C. In Jurkat leukemic T cells, all drugs induced apoptosis and the cleavage of procaspase-8 to its active p18 subunit. However, cells resistant to CD95 were equally susceptible to anticancer drugs and activated caspase-8 with a similar kinetic and dose response as CD95-sensitive cells. The broad caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone prevented apoptosis and caspase-8 activation in response to CD95 and drug treatment, whereas a neutralizing CD95 decoy as well as a dominant-negative FADD construct selectively abrogated CD95, but not drug-induced effects. A potent activation of caspase-8 was also induced by cycloheximide, indicating that it was independent of protein synthesis. Our data, therefore, show that (1) anticancer drug-induced apoptosis does not require de novo synthesis of death ligands or CD95 interaction, and (2) that caspase-8 can be activated in the absence of a death receptor signaling.


1995 ◽  
Vol 25 (5) ◽  
pp. 1352-1357 ◽  
Author(s):  
Michael S. K. Choi ◽  
Lawrence H. Boise ◽  
Alexander R. Gottschalk ◽  
José Quintans ◽  
Craig B. Thompson ◽  
...  

Oncogene ◽  
2001 ◽  
Vol 20 (41) ◽  
pp. 5865-5877 ◽  
Author(s):  
Simone Fulda ◽  
Martin U Küfer ◽  
Eric Meyer ◽  
Frans van Valen ◽  
Barbara Dockhorn-Dworniczak ◽  
...  

1999 ◽  
Vol 251 (1) ◽  
pp. 128-134 ◽  
Author(s):  
Anders Elm Pedersen ◽  
Søren Bregenholt ◽  
Britta Johansen ◽  
Søren Skov ◽  
Mogens Helweg Claesson

2001 ◽  
Vol 33 (4) ◽  
pp. 284-292 ◽  
Author(s):  
Yeo-Jin Chae ◽  
Ho-Shik Kim ◽  
Hyangshuk Rhim ◽  
Bo-Eun Kim ◽  
Seong-Whan Jeong ◽  
...  

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