%0 Journal Article %A Alae Yaseen %A Shuang Chen %A Stefanie Hock %A Roberto Rosato %A Paul Dent %A Yun Dai %A Steven Grant %T Resveratrol Sensitizes AML Cells to HDAC Inhibitors via ROS-Mediated Activation of the Extrinsic Apoptotic Pathway %D 2012 %R 10.1124/mol.112.079624 %J Molecular Pharmacology %P mol.112.079624 %X HDAC inhibitors (HDACIs) activate the pro-survival NF-κB pathway by hyperacetylating RelA/p65, whereas the chemopreventive agent resveratrol inhibits NF-κB by activating the class III HDAC Sirt1. Consequently, interactions between resveratrol and pan-HDACIs (vorinostat and LBH-589) were examined in human acute myelogenous leukemia (AML) cells. Pharmacologically achievable resveratrol concentrations (e.g., 25-50 μM) synergistically potentiated HDACI lethality in AML cell lines and primary AML blasts. Resveratrol antagonized RelA acetylation and NF-κB activation in HDACI-treated cells. However, shRNA Sirt1 knockdown failed to modify HDACI sensitivity, suggesting that factors other than or in addition to Sirt1 activation contribute to resveratrol/HDACI interactions. These interactions were associated with DR5 up-regulation and caspase-8 activation, while cells expressing dominant-negative caspase-8 were substantially protected from HDACI/resveratrol, arguing for a significant functional role for the extrinsic apoptotic pathway in lethality. Resveratrol/HDACI co-exposure induced sustained ROS generation accompanied by increased DNA DSBs, reflected by γH2A.X and comet assays. Significantly, the free radical scavenger MnTBAP blocked ROS generation, DR5 up-regulation, caspase-8 activation, DNA damage, and apoptosis, indicating a primary role for oxidative injury in lethality. Analyses of cell cycle and EdU incorporation by flow cytometry revealed that resveratrol induced S-phase accumulation, an effect abrogated by HDACI co-administration, suggesting that cells undergoing DNA synthesis may be particularly vulnerable to HDACI lethality. Collectively, these findings indicate that resveratrol interacts synergistically with HDACIs in AML cells via multiple ROS-dependent actions, including death receptor up-regulation, extrinsic apoptotic pathway activation, and DNA damage induction. They also raise the possibility that S-phase cells may be particularly susceptible to these actions. %U https://molpharm.aspetjournals.org/content/molpharm/early/2012/08/24/mol.112.079624.full.pdf