Previously, we have shown that the release of AIF from mitochondria is required for As2O3-induced cell death in human
cervical cancer cells, and that
reactive oxygen species (ROS) is necessary for AIF release from mitochondria. In this study, we further investigated the role of MAPKs in ROS-mediated mitochondrial apoptotic cell death triggered by
As2O3. As2O3-induced apoptotic cell death in HeLa cells was associated with activation and mitochondrial translocation of Bax, a marked phosphorylation of Bcl-2, reduction of Bcl-2 and Bax interaction, dissipation of mitochondrial membrane potential. Using
small interfering RNA, reduced Bax expression effectively attenuated As2O3-induced mitochondrial membrane potential loss and apoptotic cell death. Moreover, the phosphorylation of Bcl-2 induced by
As2O3 diminished its ability to bind to Bax. Treatment of cells with
As2O3 activated both the
p38 MAPK and JNK pathways. Mitochondrial translocation of Bax was completely suppressed in the presence of
p38 MAPK inhibitor
PD169316 or si-p38 MAPK. The As2O3-induced Bcl-2 phosphorylation was attenuated largely by JNK inhibition using
SP600125 or si-JNK and to some extent by
p38 MAPK inhibition with
PD169316 or si-p38 MAPK. In addition, N-acetyl-L-cystein (NAC), a
thiol-containing
anti-oxidant, completely blocked As2O3-induced
p38 MAPK and JNK activations, mitochondria translocation of Bax, and phosphorylation of Bcl-2. These results support a notion that ROS-mediated activations of
p38 MAPK and JNK in response to
As2O3 treatment signals activation of Bax and phosphorylation of Bcl-2, resulting in mitochondrial apoptotic cell death in human
cervical cancer cells.