Mechanisms of tumor necrosis factor-alpha-induced interleukin-6 synthesis in glioma cells.

Abstract

BACKGROUND:

Interleukin (IL)-6 plays a pivotal role in a variety of CNS functions such as the induction and modulation of reactive astrogliosis, pathological inflammatory responses and neuroprotection. Tumor necrosis factor (TNF)-alpha induces IL-6 release from rat C6 glioma cells through the inhibitory kappa B (IkappaB)-nuclear factor kappa B (NFkappaB) pathway, p38 mitogen-activated protein (MAP) kinase and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK). The present study investigated the mechanism of TNF-alpha-induced IL-6 release in more detail than has previously been reported.

METHODS:

Cultured C6 cells were stimulated by TNF-alpha. IL-6 release from the cells was measured by an enzyme-linked immunosorbent assay, and the phosphorylation of IkappaB, NFkappaB, the MAP kinase superfamily, and signal transducer and activator of transcription (STAT)3 was analyzed by Western blotting. Levels of IL-6 mRNA in cells were evaluated by real-time reverse transcription-polymerase chain reaction.

RESULTS:

TNF-alpha significantly induced phosphorylation of NFkappaB at Ser 536 and Ser 468, but not at Ser 529 or Ser 276. Wedelolactone, an inhibitor of IkappaB kinase, suppressed both TNF-alpha-induced IkappaB phosphorylation and NFkappaB phosphorylation at Ser 536 and Ser 468. TNF-alpha-stimulated increases in IL-6 levels were suppressed by wedelolactone. TNF-alpha induced phosphorylation of STAT3. The Janus family of tyrosine kinase (JAK) inhibitor I, an inhibitor of JAK 1, 2 and 3, attenuated TNF-alpha-induced phosphorylation of STAT3 and significantly reduced TNF-alpha-stimulated IL-6 release. Apocynin, an inhibitor of NADPH oxidase that suppresses intracellular reactive oxygen species, significantly suppressed TNF-alpha-induced IL-6 release and mRNA expression. However, apocynin failed to affect the phosphorylation of IkappaB, NFkappaB, p38 MAP kinase, SAPK/JNK or STAT3.

CONCLUSION:

These results strongly suggest that TNF-alpha induces IL-6 synthesis through the JAK/STAT3 pathway in addition to p38 MAP kinase and SAPK/JNK in C6 glioma cells, and that phosphorylation of NFkappaB at Ser 536 and Ser 468, and NADPH oxidase are involved in TNF-alpha-stimulated IL-6 synthesis.

• Authors: Kumiko Tanabe, Rie Matsushima-Nishiwaki, Shinobu Yamaguchi, Hiroki Iida, Shuji Dohi, Osamu Kozawa
• Journal: Journal of neuroinflammation (J Neuroinflammation) Vol. 7 Pg. 16 (Mar 06 2010) ISSN: 1742-2094 [Electronic] England
• PMID: 20205746 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Acetophenones
• Coumarins
• Enzyme Inhibitors
• I kappa B beta protein
• I-kappa B Proteins
• Interleukin-6
• RNA, Messenger
• STAT3 Transcription Factor
• Tumor Necrosis Factor-alpha
• wedelolactone
• acetovanillone
• Protein Serine-Threonine Kinases
• NF-kappa B kinase

Topics

• Acetophenones (pharmacology)
• Analysis of Variance
• Animals
• Cell Line, Tumor
• Coumarins (pharmacology)
• Enzyme Inhibitors (pharmacology)
• Enzyme-Linked Immunosorbent Assay (methods)
• Gene Expression Regulation, Neoplastic (drug effects)
• Glioma (metabolism, pathology)
• I-kappa B Proteins (metabolism)
• Interleukin-6 (genetics, metabolism)
• Phosphorylation (drug effects)
• Protein Serine-Threonine Kinases (metabolism)
• RNA, Messenger (metabolism)
• Rats
• STAT3 Transcription Factor (metabolism)
• Time Factors
• Tumor Necrosis Factor-alpha (pharmacology)