A novel variant of ileal bile acid binding protein is up-regulated through nuclear factor-kappaB activation in colorectal adenocarcinoma.
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Fang C, Dean J, Smith JW
A novel variant of ileal bile acid binding protein is up-regulated through nuclear factor-kappaB activation in colorectal adenocarcinoma.
Cancer Res. 2007 Oct 1;67(19):9039-46.
- PubMed ID
- 17909007 [ View in PubMed]
- Abstract
Ileal bile acid binding protein (IBABP) is the only cytosolic protein known to bind and transport bile acids. Because IBABP is reportedly up-regulated in colorectal cancer, it has been suggested as a link between bile acids and the risk of colorectal cancer. However, in this study, we show that IBABP is not up-regulated. Rather, a novel transcript of the IBABP gene, which encodes an additional 49 NH(2)-terminal amino acid residues, is up-regulated in colorectal cancer (P < 0.001). The novel transcript, called IBABP-L, is also distinct from IBABP because its transcription is controlled by nuclear factor-kappaB (NF-kappaB) rather than by the farnesoid X receptor. Most significantly, IBABP-L is necessary for the survival of HCT116 colon cancer cells in the presence of physiologic levels of the secondary bile acid deoxycholate. Collectively, the studies point toward a unique bile acid response pathway involving NF-kappaB and IBABP-L that could be useful for diagnosis and could potentially be targeted for therapeutic benefit.