Ya-Wu JING, Jing YI, Yu-Ying CHEN, Qing-Shen HU, Gui-Ying SHI, Hue LI, and Xue-Ming TANG*
(Department of Cell Biology, Shanghai Second Medical University, Shanghai 200025, China)

Abstract The effects of a number of cytotoxic drugs are influenced by cellular reduction/oxidation (redox) state. In the present study, we attempt to explore if dicoumarol, an inhibitor of NADPH: quinone oxidoreductase (NQO1), alters the cellular redox state and how this alteration affects the redox-related apoptosis. Flow cytometry was used to assess the reactive oxygen species (ROS) level and apoptotic rates of HeLa cells treated with arsenic trioxide (As₂O₃) alone or in combination with natural anthraquinone emodin and dicoumarol or plus N-acetyl-cysteine. Western blot, immunofluorescence, electrophoretic mobility shift assay and luciferase assay were used to detect Nuclear Factor kappa B (NF-κB) activation. The results showed that dicoumarol synergized with emodin to sensitize HeLa cells to As₂O₃-induced apoptosis through raising the ROS level. More notably, this enhanced susceptibility was associated with a ROS-mediated inhibition of NF-κB activation in which the combinative treatment with dicoumarol prevented NF-κB from binding to target DNA. It was suggested that dicoumarol in combination with anthraquinones might be a novel strategy to expand the chemotherapeutic spectrum of As₂O₃ by means of interfering the cellular redox state.

Key words dicoumarol; arsenic trioxide; reduction/ oxidation state; apoptosis; NF-κB

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Received: November 13, 2003 Accepted: January 6, 2004
This work was supported by the grants from National Natural Science Foundation of China (No. 30170475) and Shanghai Education Committee (ZDXK2001).
*Corresponding author: Tel, 86-21-63846590-776421; E-mail, xmtang@shsmu.edu.cn