Regulation of deoxycholate induction of CXCL8 by the adenomatous polyposis coli gene in colorectal cancer

Authors

  • Nathaniel S. Rial,

    1. Cancer Biology Graduate Interdisciplinary Program, Arizona Cancer Center, University of Arizona, Tucson, AZ
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  • Gwendal Lazennec,

    1. INSERM, U844, Site Saint Eloi – Batiment INM – 80 rue Augustin Fliche, Montpellier, F-34091, France
    2. Institut National de la Santé et de la Recherche Médicale, University of Montpellier I, F-34090, France
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  • Anil R. Prasad,

    1. Southern Arizona Veterans Affairs Health Care Systems, University of Arizona College of Medicine, Tucson, AZ
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  • Robert S. Krouse,

    1. Southern Arizona Veterans Affairs Health Care Systems, University of Arizona College of Medicine, Tucson, AZ
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  • Peter Lance,

    1. Department of Medicine, University of Arizona, Tucson, AZ
    2. Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ
    3. Department of Public Health, University of Arizona, Tucson, AZ
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  • Eugene W. Gerner

    Corresponding author
    1. Department of Cell Biology and Anatomy, University of Arizona, Tucson, AZ
    2. Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, AZ
    • Arizona Cancer Center, University of Arizona, 1515 N. Campbell Avenue, Tucson, Arizona 85724, USA
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    • Fax: +520-626-4480


Abstract

Elevated deoxycholic acid (DCA), mutations in the adenomatous polyposis coli (APC) gene and chronic inflammation are associated with increased risk of colorectal cancer. APC status was manipulated to determine whether DCA mediates inflammatory molecules in normal or initiated colonic mucosa. DCA increased steady state mRNA and protein levels of CXCL8 in cells which do not express wild-type APC. Steady-state CXCL8 mRNA and protein were suppressed when cells with conditional expression of wild-type APC were exposed to DCA. Immunostaining did not detect CXCL8 in normal human colonic mucosa. CXCL8 was expressed in adenomatous polyps and adenocarcinomas. CXCL8 expression correlated with nuclear β-catenin localization in epithelial cells of adenomas, but was associated with endothelial cells and neutrophils in the adenocarcinomas. DCA-mediated CXCL8 promoter–reporter activity was elevated in a mutant APC background. Wild-type APC suppressed this effect. Mutation of activator protein-1 (AP-1) or nuclear factor kappa B (NF-κB) sites suppressed the activation of the CXCL8 promoter–reporter by DCA. Chromatin immunoprecipitation revealed that AP-1 and NF-κB binding to the 5′-promoter of CXCL8 was induced by DCA. The β-catenin transcription factor was bound to the 5′-promoter of CXCL8 in the absence or presence of DCA. Phenotypic assays determined that DCA-mediated invasion was blocked by antibody-directed against CXCL8 or wild-type APC. CXCL8 exposure led to matrix metalloproteinase-2 production and increased invasion on laminin-coated filters. These data suggest that DCA-mediated CXCL8 occurs in initiated colonic epithelium and neutralizing CXCL8 could reduce the invasive potential of tumors. © 2008 Wiley-Liss, Inc.

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