Copper induces apoptosis in BA/F3 beta cells: Bax, reactive oxygen species, and NF kappa B are involved

Copper, an essential trace element, can be toxic to some cells when present in excess. But thorough investigations into the cytotoxicity of copper and subsequent molecular mechanisms are rare, although the cytotoxicity of cop per has been applied to cancer chemotherapy. The present study demonstrates that Cu2+ inhibits [H-3] thymidine incorporation in mouse pro-B cell line BA/F3 beta and induces apoptosis. Apoptosis was mainly judged by morphology of cells, quantification of subdiploid DNA contents by flow cytometry, and detection of DNA fragmentation by gel electrophoresis. The apoptotic effec t is dose and time dependent. Western blotting shows Bax is upregulated by Cu2+. Bcl-2 overexpression can partially inhibit this apoptosis. Moreover, Cu2+ increases the production of reactive oxygen species (ROS) in a dose-de pendent manner. The antioxidant N-acetylcysteine (NAC) not only significant ly inhibited copper-induced apoptosis but also totally blocked generation o f ROS, while Bcl-2 overexpression has no effect on the generation of ROS. F urthermore, our results show that NF kappa B is downregulated by Cu2+. Bcl- 2 overexpression or NAC can sustain the activity of NF kappa B. These data indicate that Cu2+ might induce apoptosis in BA/F3 beta cells via upregulat ion of Bax and ROS and subsequent inactivation of NF kappa B. J. Cell. Phys iol. 184:161-170, 2000. (C) 2000 Wiley-Liss, Inc.