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Biochem Biophys Res Commun. 2017 Sep 16;491(2):486-492. doi: 10.1016/j.bbrc.2017.07.016. Epub 2017 Jul 18.

γ-Oryzanol suppresses COX-2 expression by inhibiting reactive oxygen species-mediated Erk1/2 and Egr-1 signaling in LPS-stimulated RAW264.7 macrophages.

Author information

1
Department of Biological Sciences, Sanghuh College of Life Sciences, Konkuk University, Seoul 05029, Republic of Korea; Cancer and Metabolism Institute, Konkuk University, Seoul 05029, Republic of Korea.
2
Functional Food and Nutrition Division, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 55365, Republic of Korea.
3
Division of Bioscience and Biotechnology, BMIC, Konkuk University, Seoul 05029, Republic of Korea. Electronic address: yoongo@konkuk.ac.kr.
4
Department of Biological Sciences, Sanghuh College of Life Sciences, Konkuk University, Seoul 05029, Republic of Korea; Cancer and Metabolism Institute, Konkuk University, Seoul 05029, Republic of Korea. Electronic address: yhlee58@konkuk.ac.kr.

Abstract

Cyclooxygenase (COX)-2 produces prostanoids, which contribute to inflammatory responses. Nuclear factor (NF)-κB is a key transcription factor mediating COX-2 expression. γ-Oryzanol is an active component in rice bran oil, which inhibits lipopolysaccharide (LPS)-mediated COX-2 expression by inhibiting NF-κB. However, the inhibition of COX-2 expression by γ-oryzanol independently of NF-κB is poorly understood. We found that LPS upregulated Egr-1 expression at the transcriptional level. Forced expression of Egr-1 trans-activated the Cox-2 promoter independently of NF-κB. In contrast, silencing of Egr-1 abrogated LPS-mediated COX-2 expression. LPS produced reactive oxygen species (ROS), which, in turn, induced Egr-1 expression via the Erk1/2 MAPK pathway. ROS scavenging activity of γ-oryzanol suppressed Egr-1 expression by inhibiting the Erk1/2 MAPK pathway. Our results suggest that γ-oryzanol inhibits LPS-mediated COX-2 expression by suppressing Erk1/2-mediated Egr-1 expression. This study supports that γ-oryzanol may be useful for ameliorating LPS-mediated inflammatory responses.

KEYWORDS:

Cyclooxygenase-2; Egr-1; Erk1/2; Lipopolysaccharide; RAW264.7 macrophages; γ-Oryzanol

PMID:
28728842
DOI:
10.1016/j.bbrc.2017.07.016
[Indexed for MEDLINE]

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