Taurocholate Induces Cyclooxygenase-2 Expression via the Sphingosine 1-phosphate Receptor 2 in a Human Cholangiocarcinoma Cell Line.

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Liu R, Li X, Qiang X, Luo L, Hylemon PB, Jiang Z, Zhang L, Zhou H

Taurocholate Induces Cyclooxygenase-2 Expression via the Sphingosine 1-phosphate Receptor 2 in a Human Cholangiocarcinoma Cell Line.

J Biol Chem. 2015 Dec 25;290(52):30988-1002. doi: 10.1074/jbc.M115.668277. Epub 2015 Oct 30.

PubMed ID
26518876 [ View in PubMed
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Abstract

Cholangiocarcinoma (CCA) is a rare, but highly malignant primary hepatobiliary cancer with a very poor prognosis and limited treatment options. Our recent studies reported that conjugated bile acids (CBAs) promote the invasive growth of CCA via activation of sphingosine 1-phosphate receptor 2 (S1PR2). Cyclooxygenase-2 (COX-2)-derived prostaglandin E2 (PGE2) is the most abundant prostaglandin in various human malignancies including CCA. Previous studies have indicated that COX-2 was highly expressed in CCA tissues, and the survival rate of CCA patients was negatively associated with high COX-2 expression levels. It has also been reported that CBAs induce COX-2 expression, whereas free bile acids inhibit COX-2 expression in CCA mouse models. However, the underlying cellular mechanisms and connection between S1PR2 and COX-2 expression in CCA cells have still not been fully elucidated. In the current study, we examined the role of S1PR2 in conjugated bile acid (taurocholate, (TCA))-induced COX-2 expression in a human HuCCT1 CCA cell line and further identified the potential underlying cellular mechanisms. The results indicated that TCA-induced invasive growth of human CCA cells was correlated with S1PR2-medated up-regulation of COX-2 expression and PGE2 production. Inhibition of S1PR2 activation with chemical antagonist (JTE-013) or down-regulation of S1PR2 expression with gene-specific shRNA not only reduced COX-2 expression, but also inhibited TCA-induced activation of EGFR and the ERK1/2/Akt-NF-kappaB signaling cascade. In conclusion, S1PR2 plays a critical role in TCA-induced COX-2 expression and CCA growth and may represent a novel therapeutic target for CCA.