Cytoprotection against beta-amyloid (Aß) peptide-mediated oxidative damage and autophagy by Keap1 RNAi in human glioma U87mg cells.

Extensive oxidative stress has been considered a primary pathological factor for many neurodegenerative disorders (NDDs). We speculated that the oxidative damage to brain cells can be managed by promoting the endogenous cellular antioxidants through the RNA interference (RNAi) against Keap1 (kelch-like ECH-associated protein). Keap1 acts as a negative regulator of Nrf2 (NF-E2-related factor 2) that represses the activation of the antioxidant responsive element (ARE). Here, we investigated whether Keap1 knockdown enhances the cellular antioxidant capacity and provides the neuroprotection against oxidative stress from hydrogen peroxide and beta-amyloid (Aß) peptide in U87mg cells. We found that the Keap1 siRNA pre-treated group displayed higher expression of diverse antioxidant genes and an increased antioxidant capacity compared to the control group. Moreover, the Keap1 RNAi exerted a cytoprotective effect against H2O2 treatment. In Aß peptide treatment experiments, the Keap1 siRNA pre-treated groups maintained acceptable cell viability, relatively intact cellular morphology, and controlled oxidative damage levels while the control groups suffered from Aß peptide-mediated neurotoxicity. Keap1 RNAi also attenuated the oxidative stress-mediated autophagy as well. These findings suggest that Keap1 RNAi can serve as a therapeutic strategy for relieving oxidative stress-associated symptoms in many NDDs.