Chemical sensitization and regulation of TRAIL-induced apoptosis in a panel of B-lymphocytic leukaemia cell lines.
Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) effectively kills tumour cells but not normal cells. We investigated TRAIL sensitivity and the TRAIL-induced apoptosis signalling pathway in a panel of B-lymphocytic leukaemia cell lines. Depending upon TRAIL sensitivity, leukaemia cells could be divided into three groups: highly sensitive, moderately sensitive and resistant. TRAIL receptor-2 (DR5) plays an important role in transducing apoptosis signals. DR5 was internalized into the cytoplasm where it recruited FAS-associated death domain protein (FADD) under TRAIL stimulation in both sensitive and resistant cells. However, the active form of caspase-8 was recruited to FADD and only sensitive cells showed increased caspase-8 activity upon TRAIL stimulation. The caspase-8 specific inhibitor, Z-IETD, impaired caspase-8 activation and completely abrogated TRAIL-induced apoptosis. These results suggest that TRAIL resistance in B-lymphocytic leukaemia cells is due to negative regulation at the level of caspase-8 activation and that caspase-8 activation is an indispensable process in TRAIL-induced apoptosis. However, FADD-like interleukin-1 beta-converting enzyme inhibitory protein (c-FLIPL) was similarly expressed and down-regulated after TRAIL stimulation in both sensitive and resistant cells. Interestingly, in some cell lines, TRAIL sensitivity and caspase-8 activity was enhanced or restored with the treatment of cycloheximide (CHX). In addition, X-linked inhibitor of apoptosis (XIAP) levels decreased significantly and rapidly following treatment with CHX. Down-regulation of XIAP may be responsible for enhancement or restoration of TRAIL sensitivity after CHX treatment in B-lymphocytic leukaemia cells.
Kang
Jian
J
Department of Pediatrics, Mie University School of Medicine, Tsu, Mie, Japan.
Kisenge
Rodrick R
RR
Toyoda
Hidemi
H
Tanaka
Shigeki
S
Bu
Jun
J
Azuma
Eiichi
E
Komada
Yoshihiro
Y
D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D029681:Arabidopsis Proteins / Q000378:metabolism; D015153:Blotting, Western / Q000379:methods; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000494:pharmacology; D053181:Caspase 8; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation / Q000187:drug effects; D044943:Fatty Acid Desaturases / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D015448:Leukemia, B-Cell / Q000378:metabolism / Q000473:pathology*; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D009842:Oligopeptides / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D015398:Signal Transduction; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D051636:X-Linked Inhibitor of Apoptosis Protein
D051017:Apoptosis Regulatory Proteins; D029681:Arabidopsis Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009842:Oligopeptides; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; C403753:benzyloxycarbonyl-isoleucyl-glutamyl-threonyl-aspartic acid fluoromethyl ketone; D003513:Cycloheximide; D044943:Fatty Acid Desaturases; C084083:Fad7 protein, Arabidopsis; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases