Details

Autor(en) / Beteiligte

• Ziesché, Elisabeth
• Bachmann, Malte
• Kleinert, Hartmut
• Pfeilschifter, Josef
• Mühl, Heiko

Titel

The Interleukin-22/STAT3 Pathway Potentiates Expression of Inducible Nitric-oxide Synthase in Human Colon Carcinoma Cells

Ist Teil von

• The Journal of biological chemistry, 2007-06, Vol.282 (22), p.16006-16015

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2007

Quelle

MEDLINE

Beschreibungen/Notizen

• Inducible nitric-oxide synthase (iNOS) has been identified as a marker and mediator of disease in human colonic inflammation and carcinogenesis. Accordingly, identification of mediators that trigger iNOS in colon carcinoma/epithelial cells is an important topic of current research. Here we demonstrate that interleukin (IL)-22, a newly described member of the IL-10 cytokine family, potently synergizes with interferon (IFN)-γ for iNOS expression in human DLD-1 colon carcinoma cells. Detection of both IL-22 receptor chains and STAT3 phosphorylation proved robust IL-22 responsiveness of these cells. Short interfering RNA technology identified STAT3 as being crucial for up-regulation of iNOS. Compared with IFNγ, STAT1 phosphorylation by IL-22 was insufficient. IL-22 did not stabilize IL-1β/tumor necrosis factor-α/IFNγ-induced iNOS mRNA. IL-22 also failed to amplify expression of the prototypic IFNγ-inducible parameters IL-18-binding protein and CXCL-10, indicating that IL-22 is not a general amplifier of IFNγ functions. This assumption is furthermore supported by the observation that IL-22 was unable to enhance cellular activation of the pro-inflammatory transcription factor nuclear factor-κB. In contrast, IL-22 increased iNOS promoter activation as detected by using DLD-1 cells stably transfected with a corresponding 16-kb promoter construct (pNOS2(16)-Luc). IL-22 likewise enhanced iNOS in Caco-2 colon carcinoma cells. With IL-22 we introduce a novel potent determinant of iNOS expression in human colon carcinoma/epithelial cells. Considering the eminent functions of STAT3 and iNOS in inflammation and carcinogenesis, IL-22 may represent a novel target for immunotherapeutic intervention.