Activation of MST/Krs and c-Jun N-terminal kinases by different signaling pathways during cytotrienin A-induced apoptosis.
We found that antitumor drugs such as cytotrienin A, camptothecin, taxol, and 5-fluorouracil induced the activation of a 36-kDa protein kinase (p36 myelin basic protein (MBP) kinase) during apoptosis in human promyelocytic leukemia HL-60 cells. This p36 MBP kinase, which phosphorylates MBP in an in-gel kinase assay, results from the caspase-3-mediated proteolytic cleavage of MST/Krs protein, a mammalian Ste20-like serine/threonine kinase. Herein the correlation between cytotrienin A-induced apoptosis and the activation of MST/Krs proteins was examined in human tumor cell lines, including leukemia-, lung-, epidermoid-, cervix-, stomach-, and brain-derived cell lines. In cytotrienin A-sensitive cell lines, we observed a strong activation of p36 MBP kinase by cleavage of the C-terminal regulatory domain of full-length MST/Krs proteins by caspase-3. When the kinase-inactive mutant form of MST/Krs protein was overexpressed in cytotrienin A-sensitive HL-60 cells, the cytotrienin A-induced apoptosis was partially inhibited. Because cytotrienin A also activated c-Jun N-terminal kinase, we examined the effect of the expression of dominant negative c-Jun on cytotrienin A-induced apoptosis. The expression of dominant negative c-Jun also partially inhibited cytotrienin A-induced apoptosis. Furthermore, coexpression of kinase-inactive MST/Krs protein and dominant negative c-Jun completely suppressed cytotrienin A-induced apoptosis. These findings suggest that the proteolytic activation of MST/Krs and c-Jun N-terminal kinase activation are involved in cytotrienin A-induced apoptosis in human tumor cell lines.
Watabe
M
M
Antibiotics Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
Kakeya
H
H
Onose
R
R
Osada
H
H
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012294:Rifamycins / Q000494:pharmacology*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured / Q000187:drug effects; D051028:bcl-2-Associated X Protein
D000903:Antibiotics, Antineoplastic; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016755:Proto-Oncogene Proteins c-jun; D012294:Rifamycins; D051028:bcl-2-Associated X Protein; C106761:cytotrienin A; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C093290:MAP3K10 protein, human; D038362:Glycogen Synthase Kinase 3; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases