Vol. 62, Issue 6, 1409-1417, December 2002

Enhancement of Metabolic Oxidative Stress-Induced Cytotoxicity by the Thioredoxin Inhibitor 1-Methylpropyl 2-Imidazolyl Disulfide Is Mediated through the ASK1-SEK1-JNK1 Pathway

Yong J. Lee, Jin H. Kim, Jun Chen, and Jae J. Song

Department of Surgery, Pharmacology and Cancer Institute, School of Medicine (Y.J.L., J.H.K., J.J.S.), and Department of Neurology (J.C.), University of Pittsburgh, Pittsburgh, Pennsylvania

We observed previously that glucose deprivation induces cytotoxicity, increases the intracellular levels of hydroperoxide, and activates the stress-activated protein kinase (SEK) pathway. In this study, we hypothesized that 1-methylpropyl 2-imidazolyl disulfide (IV-2), a thioredoxin (TRX) inhibitor, augments glucose deprivation-induced cytotoxicity by promoting c-Jun N-terminal kinase (JNK) activation. Human prostatic carcinoma DU-145 cells were exposed to glucose-free medium containing various concentrations of IV-2 (10-50 µM). Glucose deprivation alone or IV-2 alone induced minimal cytotoxicity within 7 h. However, the combination of glucose deprivation and IV-2 increased cell death in a dose-dependent manner. The cytotoxicity was suppressed by treatment with an antioxidant, N-acetyl-L-cysteine or overexpressing TRX. The combined glucose deprivation and IV-2 treatment also promoted glucose deprivation-induced JNK1 activation by disrupting the interaction between TRX and apoptosis signal-regulating kinase 1 (ASK1). Overexpression of the JNK1 dominant-negative mutant inhibited the activation of the SEK pathway and protected cells from glucose deprivation and IV-2-induced cytotoxicity. Therefore, IV-2 enhances glucose deprivation-induced cytotoxicity by promoting glucose deprivation-induced activation of the ASK1-SEK1-JNK1 pathway.