beta-Lapachone increases phase II antioxidant enzyme expression via NQO1-AMPK/PI3K-Nrf2/ARE signaling in rat primary astrocytes

Abstract

beta-Lapachone (beta-LAP) is a naturally occurring quinine that exerts a number of pharmacological actions including antibacterial, antifungal, antimalarial, and antitumor activities. In the present study, we investigated whether beta-LAP has an antioxidant effect in rat primary astrocytes. beta-LAP suppressed intracellular reactive oxygen species (ROS) production induced by hydrogen peroxide and inhibited astroglial cell death. It also increased astrocytic expression of phase II antioxidant enzymes such as heme oxygenase-1 (H0-1), NAD(P)H:quinone oxidoreductase 1 (NQO1), manganese superoxide dismutase (MnSOD), and catalase. Further mechanistic studies revealed that beta-LAP activated AMPK and Akt, and pretreatment of cells with an AMPK inhibitor (compound C) or PI3K/Akt inhibitor (LY294002) suppressed beta-LAP-induced antioxidant enzyme expression by inhibiting Nrf2/antioxidant response element (ARE) signaling. Compound C also decreased Akt phosphorylation, suggesting that AMPK is upstream of PI3K/ Akt. Furthermore, the AMPK activator 5-aminoimidazole-4-carboxamide 1-beta-D ribo furanoside mimicked the effect of beta-LAP by increasing Akt phosphorylation and ARE-mediated transcription, suggesting that AMPK plays a pivotal role in beta-LAP-mediated antioxidant enzyme expression. Because beta-LAP effects are usually associated with NQ01 activity, we examined the effect of NQ01 knockdown on antioxidant enzyme expression. Small interfering RNA (siRNA) specific for NQ01 inhibited beta-LAP-induced AMPK/Akt phosphorylation and downstream antioxidant enzyme expression. Collectively, the results suggest that beta-LAP increases antioxidant enzyme gene expression in astrocytes by modulating NQ01-AMPK/PI3KNrf2/ARE signaling. (C) 2016 Elsevier Inc. All rights reserved.