c-Jun-NH sub(2)-terminal kinase potentiates apoptotic cell death in response to carboplatin in B lymphoma cells

• Published in: Cancer chemotherapy and pharmacology 2008-09, Vol.62 (4), p.569-576
• Main Authors: Takada, Eiko, Hata, Kikumi, Mizuguchi, Junichiro
• Format: Article
• Language: English
• ISSN: 0344-5704; 1432-0843
• DOI: 10.1007/s00280-007-0638-x

Purpose: 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 sub(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 sub(2) super(-)) 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 sub(2) super(-). The superoxide anion scavenger for butylated hydroxyanisol (BHA) partially reduced the CBDCA-induced O sub(2) super(-) 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 sub(2) super(-) 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.