Two sesquiterpene aminoquinones protect against oxidative injury in HaCaT keratinocytes via activation of AMPKα/ERK-Nrf2/ARE/HO-1 signaling

Aims: To investigate the cytoprotective effects of two sesquiterpene aminoquinones isolated from the marine Sponge Dysidea fragilis, Dysidaminone H (DA8) and 3'-methylamino-avarone (DA14), we examined their effects against hydrogen peroxide (H₂O₂)-induced oxidative injury in human keratinocyte cell line and elucidated the underlying mechanisms.

Main methods: Cell viability was detected using a CCK-8 assay kit. Intracellular Reactive Oxygen Species (ROS) production was measured by fluorescence of 2, 7-Dichlorodi-hydrofluorescein diacetate (DCFH-DA). Messenger RNA and protein expression were measured by real-time quantitative PCR and western blotting analysis. Immunocytochemistry was performed to determine the intracellular location of nuclear factorerythroid 2 p45 related factor 2 (Nrf2). The antioxidant response element (ARE)-luciferase reporter gene assay and RNA interference were used to establish the role of ARE and Nrf2.

Key findings: DA8 and DA14 (DAs) resisted H₂O₂induced decline of cell viability by inhibiting the accumulation of ROS. Meanwhile, DAs increased HO-1 expression and ARE activity and induced Nrf2 expression, as well as the accumulation of Nrf2 in the cell nucleus. However, silencing of Nrf2 abolished DAs-induced HO-1 expression and ARE luciferase activation. In addition, DAs induced the phosphorylation of both cyclic AMP-activated protein kinase-α (AMPKα) and extracellular signal-regulated kinase (ERK), while specific inhibitors of AMPKα and ERK abrogated HO1 upregulation and Nrf2 activation.

Significance: DAs provided cytoprotective effects against H₂O₂-induced cytotoxicity by activation of the Nrf2/ARE/HO-1 pathway via phosphorylation of AMPKα and ERK. The findings suggested that DA8 and DA14 might be the candidate therapeutic agents for skin diseases caused by oxidative injury.