title: Thymoquinone induces heme oxygenase-1 expression in HaCaT cells via Nrf2/ARE activation: Akt and AMPKα as upstream targets.
abstract: Thymoquinone (TQ), an active constituent of Nigella sativa, possesses anti-inflammatory and anticancer properties. Multiple lines of evidence suggest that the induction of heme oxygenase-1 (HO-1) suppresses inflammation and carcinogenesis. In the present study, we examined the effect of TQ on HO-1 expression in human keratinocytes (HaCaT) and elucidated its underlying molecular mechanisms. TQ induced the expression of HO-1 in HaCaT cells in a concentration- and time-dependent manner. Treatment with TQ increased the localization of nuclear factor (NF)-erythroid2-(E2)-related factor-2 (Nrf2) in the nucleus and elevated the antioxidant response element (ARE)-reporter gene activity. Knockdown of Nrf2 abrogated TQ-induced HO-1 expression and the ARE luciferase activity. TQ induced the phosphorylation of extracellular signal-regulated kinase (ERK), Akt and cyclic AMP-activated protein kinase-α (AMPKα). Pharmacological inhibition of Akt or AMPKα, but not that of ERK, abrogated TQ-induced nuclear localization of Nrf2, the ARE-luciferase activity and the expression of HO-1. TQ also generated reactive oxygen species (ROS) and pretreatment with N-acetyl cysteine (NAC) abrogated TQ-induced ROS accumulation, Akt and AMPKα activation, Nrf2 nuclear localization, the ARE-luciferase activity, and HO-1 expression in HaCaT cells. Taken together, TQ induces HO-1 expression in HaCaT cells by activating Nrf2 through ROS-mediated phosphorylation of Akt and AMPKα.
authors.affiliation: College of Pharmacy, Keimyung University, Daegu 704-701, South Korea.
authors.forename: Juthika
authors.initials: J
authors.lastname: Kundu
authors.affiliation: Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea.
authors.forename: Do-Hee
authors.initials: DH
authors.lastname: Kim
authors.affiliation: College of Pharmacy, Keimyung University, Daegu 704-701, South Korea.
authors.forename: Joydeb Kumar
authors.initials: JK
authors.lastname: Kundu
authors.affiliation: College of Pharmacy, Keimyung University, Daegu 704-701, South Korea. Electronic address: chunks@kmu.ac.kr.
authors.forename: Kyung-Soo
authors.initials: KS
authors.lastname: Chun
mesh_terms: D000263:Adenylate Kinase / Q000378:metabolism*; D001483:Base Sequence; D016227:Benzoquinones / Q000494:pharmacology*; D002460:Cell Line; D017931:DNA Primers; D004789:Enzyme Activation; D051547:Heme Oxygenase-1 / Q000378:metabolism*; D006801:Humans; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: D016227:Benzoquinones; D017931:DNA Primers; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D051547:Heme Oxygenase-1; D051057:Proto-Oncogene Proteins c-akt; D000263:Adenylate Kinase; C003466:thymoquinone
keywords: AMPKα; Akt; HaCaT cells; Heme oxygenase-1; Nrf2; Thymoquinone