PI3K/AKT/Nrf2 signalling pathway is involved in the ameliorative effects of xanthohumol on amyloid β-induced oxidative damage and bone loss

Abstract

Abstract Objective Xanthohumol (XAN), a natural isoflavone from Humulus lupulus L., possesses biological activities on relieving oxidative stress and osteoporosis (OP). This study aimed to evaluate the antioxidative and osteoprotective effect of XAN on Aβ-injured osteoblasts, and explore its underlying mechanism. Methods Osteoblasts were pretreated with XAN followed by stimulation with Aβ1–42. Cell proliferation, ALP activity, bone mineralization and bone formation index were measured. Apoptosis and reactive oxygen species (ROS) were analysed with flow cytometer. PI3K inhibitor LY294002 or siRNA-Nrf2 was added and transfected in osteoblasts, to further confirm whether the pathway participated in the regulation of XAN-induced cytoprotection. Key findings XAN markedly improved the proliferation, differentiation and mineralization of Aβ-injured osteoblasts. Additionally, XAN reduced cell apoptosis rate and ROS level, and increased the expression of p-AKT, Nrf2, NQO1, HO-1 and SOD-2. More importantly, LY294002 or siNrf2 abolished the beneficial effect of XAN on osteoblasts activity and decreased the PI3K expression and inhibited its downstream proteins, indicating XAN activated PI3K/AKT/Nrf2 pathway in Aβ-injured osteoblasts. Conclusion It was the first time to reveal the antioxidative and osteoprotective effect of XAN through regulating PI3K/AKT/Nrf2 pathway in Aβ-injured osteoblasts, which provides reference for the clinical application of XAN in the prevention and treatment of OP.