|
KMID : 0982820060050020102
|
|
Journal of Lung Cancer
2006 Volume.5 No. 2 p.102 ~ p.110
|
|
|
Down-regulation of IL-1β-induced COX-2 Expression in A549 Lung Cancer Cells at Transcriptional Level by Leptomycin B Involves Inhibition of the IκB-α/NF-κB Pathway but Independent of CRM1
|
|
Park Chang-Kwon
Kim Jae-Bum
Keum Dong-Yoon
Jang Byung-Churl
|
|
|
Abstract
|
|
|
Purpose: Overexpression of COX-2, an enzyme responsible fro the synthesis of prostaglandins, is well linked to human chronic lung diseases. The mechanism by which COX-2 expression is increased or enhanced in cancer cells remains largely unknown. Any compound which can reduce COX-2 expression may be considered as an anti-cancer agent.
Materials and Methods: Leptomycin B (LMB) is a metabolite of Streptomyces and a specific inhibitor of CRM1 nuclear export receptor. A549 is a human lung cancer cell line. To evaluate the effect of LMB on COX-2 expression induced by IL-1β, a pro-inflammatory cytokine, in A549 cells, Western blot and RT-PCR assays were applied to measure COX-2 protein and mRNA expressions in response to IL-1β, respectively. Luciferase experiments were done to measure promoter activity of COX-2, NF-κB or AP-1. CRM1 siRNA trasfection experiment was performed to knock-down endogenous CRM1. Biochemical protein fractionation method was also carried out to see intracellular localization of proteins.
Results: LMB at 9 nM strongly suppressed IL-1β-induced expression of COX-2 protein that was attributable to decreased COX-2 transcript and promoter activity, but not mRNA stability. Distinctly, knock-down of CRM1 had no effect on COX-2 expression by IL-1β. Moreover, LMB did not affect IL-1β-induced phosphorylation of ERK-1/2, JNK- 1/2, and p38 MAPK or AP-1 promoter activity. In contrast, LMB blocked IL-1β- mediated cytosolic IκB-α degradation, p65 NF-κB nuclear translocation, and NF-κB promoter activity.
Conclusion: LMB potently down-regulates IL-1β- induced COX-2 at transcriptional level in A549 cells, in part, through modulation of the IκB-α/NF-κB pathway but independent of CRM1, MAPKs and AP-1.
|
|
|
KEYWORD
|
|
|
Leptomycin B, COX-2, IL-1β, CRM1, IκB-α/p65 NF-κB, A549 cells
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|
|