Inhibition of c-Jun N-terminal kinase enhances temozolomide-induced cytotoxicity in human glioma cells.
Previous studies have revealed that p38, a member of the family of stress-activated protein kinases (SAPKs), cooperates with the Chk1-pathway to bring about temozolomide (TMZ)-induced G2 arrest, and that the inhibition of either pathway alone is sufficient to sensitize U87MG glioma cells to TMZ-induced cytotoxicity. c-Jun N-terminal kinase (JNK), another SAPK, has been reported to have several roles of cell survival, oncogenesis, growth, differentiation and cell death. To elucidate the functions of JNK in glioma cells treated with TMZ, we analyzed alterations in JNK and the effect of modification of JNK in U87MG human glioma cells treated with TMZ. We found that JNK was phosphorylated 1-2 days after TMZ treatment and that pretreatment (for 24 h) and post-treatment (for 72 h) with a JNK inhibitor SP600125 at a concentration of 200 nM or higher remarkably reduced clonogenicity in the TMZ-treated cells. The phosphorylation of the JNK target protein c-Jun, but not of ATF-2, was inhibited by this concentration of SP600125. Therefore JNK was proved to have a role of survival in glioma cells treated with TMZ, and c-Jun-related responses were suggested to be more important in the JNK-mediated survival of glioma cells with DNA damage. SP600125 amplified the percentage of senescence-like cells and of mitotic catastrophe cells in TMZ-treated U87MG and U87MG-E6 cells, respectively, suggesting that the enhancement of TMZ-induced cytotoxicity by a JNK inhibitor in glioma cells is induced (at least in part) by the potentiation of cell death pathways induced by TMZ alone. Further investigation based on the present data may provide a viable approach for enhancing TMZ-induced cytotoxicity in human gliomas.
Ohba
Shigeo
S
Department of Neurosurgery, Keio University, Tokyo, Japan.
Hirose
Yuichi
Y
Department of Neurosurgery, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan. yhirose@fujita-hu.ac.jp.
Kawase
Takeshi
T
Department of Neurosurgery, Keio University, Tokyo, Japan.
Sano
Hirotoshi
H
Department of Neurosurgery, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
D051698:Activating Transcription Factor 2 / Q000378:metabolism; D000873:Anthracenes / Q000494:pharmacology*; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000473:pathology; D016923:Cell Death / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D016195:G2 Phase / Q000187:drug effects; D005910:Glioma / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D000077204:Temozolomide; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
C497105:ATF2 protein, human; D051698:Activating Transcription Factor 2; D000873:Anthracenes; D018906:Antineoplastic Agents, Alkylating; D047428:Protein Kinase Inhibitors; D016159:Tumor Suppressor Protein p53; C432165:pyrazolanthrone; D003606:Dacarbazine; D048031:JNK Mitogen-Activated Protein Kinases; D001616:beta-Galactosidase; D000077204:Temozolomide