Inhibition of JNK signaling diminishes early but not late cellular stress-induced apoptosis.
The human leukemic T-cell line Jurkat was used to define the role of the cellular stress pathway with its key player kinase JNK in cancer therapy-induced apoptosis. JNK activity was inhibited by stable transfection with a dominant negative mutant of the upstream kinase JNKK/MKK4 or with the novel, potent and selective JNK1, -2 and -3 inhibitor SP600125. Inhibition of JNK activity delayed the onset of apoptosis induced by cisplatin, doxorubicin, gamma-irradiation and CD95-L but did not prevent apoptosis per se. Early events during apoptosis such as induction of CD95-L, activation of caspase-8 and exposure of phosphatidylserine on the cell surface were strongly inhibited. Also, at early time points of apoptosis, loss of the mitochondrial membrane potential and release of cytochrome c were markedly impaired. However, late signaling events during apoptosis such as cleavage of PARP and DNA fragmentation apoptosis were only marginally affected. These findings are in accordance with the activity of initiator and effector caspases. Whereas activity of the initiator caspase-8 was strongly inhibited early and late after induction, an inhibition of caspase-3 activity was only observed early after induction of apoptosis. We therefore suggest that cellular stress signaling contributes to the initiation of apoptosis, whereas it might be dispensable for the progression of apoptosis. Dysfunction of this pathway under pathological conditions might contribute to therapy resistance of cancer cells.
Krilleke
Dominik
D
Division of Molecular Oncology, German Cancer Research Center, Heidelberg, Germany.
Ucur
Esat
E
Pulte
Dianne
D
Schulze-Osthoff
Klaus
K
Debatin
Klaus-Michael
KM
Herr
Ingrid
I
D000873:Anthracenes / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D045304:Cytochromes c; D004317:Doxorubicin / Q000494:pharmacology; D004789:Enzyme Activation; D053222:Fas Ligand Protein; D005799:Genes, Dominant; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D019169:Jurkat Cells / Q000187:drug effects / Q000528:radiation effects; D048670:MAP Kinase Kinase 4; D008562:Membrane Glycoproteins / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000528:radiation effects; D008928:Mitochondria / Q000187:drug effects / Q000528:radiation effects; D048055:Mitogen-Activated Protein Kinase 8; D048056:Mitogen-Activated Protein Kinase 9; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors*; D018384:Oxidative Stress; D010718:Phosphatidylserines / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases; D015398:Signal Transduction / Q000187:drug effects*; D019014:fas Receptor / Q000494:pharmacology
D000873:Anthracenes; D000970:Antineoplastic Agents; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D010718:Phosphatidylserines; D019014:fas Receptor; C432165:pyrazolanthrone; D004317:Doxorubicin; D045304:Cytochromes c; D011065:Poly(ADP-ribose) Polymerases; D048056:Mitogen-Activated Protein Kinase 9; D048031:JNK Mitogen-Activated Protein Kinases; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; C482559:MAP2K4 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D020169:Caspases; D002945:Cisplatin