J Cancer Prev.  2016 Sep;21(3):135-143. 10.15430/JCP.2016.21.3.135.

Fraxetin Induces Heme Oxygenase-1 Expression by Activation of Akt/Nrf2 or AMP-activated Protein Kinase α/Nrf2 Pathway in HaCaT Cells

• Kundu J
• Chae IG
• Chun KS

• KMID: 2367571
• DOI: http://doi.org/10.15430/JCP.2016.21.3.135

Abstract

BACKGROUND
Fraxetin (7,8-dihydroxy-6-methoxy coumarin), a coumarin derivative, has been reported to possess antioxidative, anti-inflammatory and neuroprotective effects. A number of recent observations suggest that the induction of heme oxygenase-1 (HO-1) inhibits inflammation and tumorigenesis. In the present study, we determined the effect of fraxetin on HO-1 expression in HaCaT human keratinocytes and investigated its underlying molecular mechanisms.
METHODS
Reverse transcriptase-PCR and Western blot analysis were performed to detect HO-1 mRNA and protein expression, respectively. Cell viability was measured by the MTS test. The induction of intracellular reactive oxygen species (ROS) by fraxetin was evaluated by 2"²,7"²-dichlorofluorescin diacetate staining.
RESULTS
Fraxetin upregulated mRNA and protein expression of HO-1. Incubation with fraxetin induced the localization of nuclear factor-erythroid-2-related factor-2 (Nrf2) in the nucleus and increased the antioxidant response element-reporter gene activity. Fraxetin also induced the phosphorylation of Akt and AMP-activated protein kinase (AMPK)α and diminished the expression of phosphatase and tensin homolog, a negative regulator of Akt. Pharmacological inhibition of Akt and AMPKα abrogated fraxetin-induced expression of HO-1 and nuclear localization of Nrf2. Furthermore, fraxetin generated ROS in a concentration-dependent manner.
CONCLUSIONS
Fraxetin induces HO-1 expression through activation of Akt/Nrf2 or AMPKα/Nrf2 pathway in HaCaT cells.

Keyword

Fraxetin; Keratinocytes; Heme oxygenase-1; Nrf2

MeSH Terms

AMP-Activated Protein Kinases*
Blotting, Western
Carcinogenesis
Cell Survival
Heme Oxygenase-1*
Heme*
Humans
Inflammation
Keratinocytes
Neuroprotective Agents
Phosphorylation
Reactive Oxygen Species
RNA, Messenger
AMP-Activated Protein Kinases
Heme
Heme Oxygenase-1
Neuroprotective Agents
RNA, Messenger
Reactive Oxygen Species