Exp Mol Med.  2002 Nov;34(5):332-339.

Dual effect of oxidative stress on NF-kappaB activation in HeLa cells

• Byun MS
• Jeon KI
• Choi JW
• Shim JY
• Jue DM

Abstract

Reactive oxygen species (ROS) has been implicated as an inducer of NF-kappaB activity in numbers of cell types where exposure of cells to ROS such as H2O2 leads to NF-kappaB activation. In contrast, exposure to oxidative stress in certain cell types induced reduction of tumor necrosis factor (TNF)-induced NF-kappaB activation. And various thiol-modifying agents including gold compounds and cyclopentenone prostaglandins inhibit NF-kappaB activation by blocking IkappaB kinase (IKK). To understand such conflicting effect of oxidative stress on NF-kappaB activation, HeLa cells were incubated with H2O2 or diamide and TNF-induced expression of NF-kappaB reporter gene was measured. NF-kappaB activation was significantly blocked by these oxidizing agents, and the inhibition was accompanied with reduced nuclear NF-kappaB and inappropriate cytosolic IkappaB degradation. H2O2 and diamide also inhibited IKK activation in HeLa and RAW 264.7 cells stimulated with TNF and lipopolysaccharide, respectively, and directly blocked IKK activity in vitro. In cells treated with H2O2 alone, nuclear NF-kappaB was induced after 2 h without detectible degradation of cytosolic IkBa or activation of IKK. Our results suggest that ROS has a dual effect on NF-kappaB activation in the same HeLa cells: it inhibits acute IKK-mediated NF-kappaB activation induced by inflammatory signals, while longer-term exposure to ROS induces NF-kappaB activity through an IKK-independent pathway.

Keyword

NF-kappaB; oxidative stress; hydrogen peroxide; diamide; protein kinases; oxidation-reduction

MeSH Terms

Cell Nucleus/drug effects/metabolism
Cytosol/drug effects/metabolism
Diamide/pharmacology
Hela Cells/drug effects/metabolism
Human
Hydrogen Peroxide/pharmacology
I-kappa B/drug effects/metabolism
NF-kappa B/drug effects/genetics/*metabolism
Oxidants/pharmacology
*Oxidative Stress
Protein-Serine-Threonine Kinases/metabolism
Signal Transduction/drug effects
Time Factors
Transcription, Genetic
Tumor Necrosis Factor/pharmacology