Journal Article

The bile acid deoxycholic acid (DCA) at neutral pH activates NF-κB and induces IL-8 expression in oesophageal cells <i>in vitro</i>

G.J.S. Jenkins, K. Harries, S.H. Doak, A. Wilmes, A.P. Griffiths, J.N. Baxter and J.M. Parry

in Carcinogenesis

Volume 25, issue 3, pages 317-323
Published in print March 2004 | ISSN: 0143-3334
Published online March 2004 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgh032
The bile acid deoxycholic acid (DCA) at neutral pH activates NF-κB and induces IL-8 expression in oesophageal cells in vitro

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Barrett's oesophagus patients accumulate chromosomal defects during the histological progression to cancer, one of the most prominent of which is the amplification of the whole of chromosome 4. We aimed to study the role that the transcription factor NF-κB, a candidate cancer- promoting gene, present on chromosome 4, plays in Barrett's oesophagus, using OE33 cells as a model. Specifically, we wanted to determine if NF-κB was activated by exposure to bile acid (deoxycholic acid) in oesophageal cells. We employed pathway specific cDNA microarrays and real-time PCR, to first identify bile acid induced genes and specifically to investigate the role of NF-κB. An NF-κB reporter system was used, as well as an inhibitor of NF-κB (pyrrolidine dithiocarbamate) to confirm the activation of NF-κB by bile. We show that physiological levels of DCA (100–300 μM) were capable of activating NF-κB in OE33 cells and inducing NF-κB target gene expression (particularly IκB and IL-8). Other gene expression abnormalities were also shown to be induced by DCA. Importantly, preliminary experiments showed that NF-κB activation by bile occurred at neutral pH, but not at acid pH. Acidic bile did however cause over-expression of the c-myc oncogene, as reported previously. Hence, we present data showing that NF-κB may be a key mediator of carcinogenesis in bile exposed Barrett's tissues. In addition, neutral bile acids appear to play a significant part in reflux induced gene expression changes. We postulate that the activation of the survival factor NF-κB by bile may be linked to the previous cytogenetic data from our laboratory showing the amplification of NF-κB's chromosome (chromosome 4), during Barrett's cancer progression. Hence chromosome 4 amplification may provide a survival mechanism for bile exposed oesophageal tissues via NF-κB.

Keywords: DCA, deoxycholic acid

Journal Article.  5376 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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