title: c-Jun-NH2-terminal kinase potentiates apoptotic cell death in response to carboplatin in B lymphoma cells.
abstract: OBJECTIVE
  Exposure to carboplatin (CBDCA) has been demonstrated to result in apoptotic and/or necrotic cell death, but molecular mechanisms underlying CBDCA-induced apoptosis or necrosis remain largely unclear. Here, we examined whether activation of c-Jun NH(2)-terminal kinase (JNK) modulates the mode of cell death induced by CBDCA in CD31 B lymphoma cells.
  
  
  METHODS
  The mode of cell death (apoptosis versus necrosis) was investigated by flow cytometry using 7-amino-actinomycin D (7-AAD) and annexin-FITC probes. To evaluate the role of JNK1 in CBDCA-induced cell death, CH31 B lymphoma cells overexpressing dominant-negative form of JNK1 (dnJNK1) or constitutively active form of JNK1 (MKK7-JNK1) were established. Intracellular accumulation of superoxide anion (O(2) (-)) was determined by flow cytometry using the fluorescent probe dihydroethidium (DHE).
  
  
  RESULTS
  The CBDCA-induced primary apoptosis and secondary necrosis were abrogated in the dnJNK1-overexpressing CH31 cells, while it was somewhat enhanced in the MKK7-JNK1-overexpressing cells. In contrast, the CBDCA-induced primary necrosis was reduced by MKK7-JNK1, with a concurrent decrease in production of O(2) (-). The superoxide anion scavenger for butylated hydroxyanisol (BHA) partially reduced the CBDCA-induced O(2) (-) production and necrotic, but not apoptotic, death in both wild type and dnJNK1-overexpressing CH31 cells.
  
  
  CONCLUSIONS
  Prolonged activation of JNK1 appears to be involved in CBDCA-induced apoptosis with prevention of necrosis induction, and the induction of necrosis appears to correlate with CBDCA-induced O(2) (-) production, which is partially blocked by co-culture with BHA. These observations provide valuable information for understanding molecular mechanisms underlying CBDCA-induced cell death, and hopefully for the design of novel treatment modalities for patients with tumors.
authors.affiliation: Department of Immunology and Intractable Immunology Research Center, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan.
authors.forename: Eiko
authors.initials: E
authors.lastname: Takada
authors.forename: Kikumi
authors.initials: K
authors.lastname: Hata
authors.forename: Junichiro
authors.initials: J
authors.lastname: Mizuguchi
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002083:Butylated Hydroxyanisole / Q000494:pharmacology; D016190:Carboplatin / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004336:Drug Antagonism; D004789:Enzyme Activation / Q000187:drug effects; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016393:Lymphoma, B-Cell / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D048688:MAP Kinase Kinase 7 / Q000378:metabolism*; D051379:Mice; D009336:Necrosis / Q000139:chemically induced; D013481:Superoxides / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D013481:Superoxides; D002083:Butylated Hydroxyanisole; D016190:Carboplatin; D048031:JNK Mitogen-Activated Protein Kinases; D048688:MAP Kinase Kinase 7