Abstract (EN):
Colorectal cancer (CRC) is one of the most common cancers worldwide. Epidemiological and experimental studies suggest that bile acids may play a role in CRC etiology. Our aim was to characterize the effect of the primary bile acid chenodeoxycholic acid (CDCA) upon14C-BT uptake in tumoral (Caco-2) and non-tumoral (IEC-6) intestinal epithelial cell lines. A 2-day exposure to CDCA markedly and concentration-dependently inhibited 14C-BT uptake by IEC-6 cells (IC50?=?120 mu M), and, less potently, by Caco-2 cells (IC50?=?402 mu M). The inhibitory effect of CDCA upon 14C-BT uptake did not result from a decrease in cell proliferation or viability. In IEC-6 cells: (1) uptake of 14C-BT involves both a high-affinity and a low-affinity transporter, and CDCA acted as a competitive inhibitor of the high-affinity transporter; (2) CDCA inhibited both Na+-coupled monocarboxylate cotransporter 1 (SMCT1)- and H+-coupled monocarboxylate transporter 1 (MCT1)-mediated uptake of 14C-BT; (3) CDCA significantly increased the mRNA expression level of SMCT1; (4) inhibition of 14C-BT uptake by CDCA was dependent on CaM, MAP kinase (ERK1/2 and p38 pathways), and PKC activation, and reduced by a reactive oxygen species scavenger. Finally, BT (5?mM) decreased IEC-6 cell viability and increased IEC-6 cell differentiation, and CDCA (100 mu M) reduced this effect. In conclusion, CDCA is an effective inhibitor of 14C-BT uptake in tumoral and non-tumoral intestinal epithelial cells, through inhibition of both H+-coupled MCT1- and SMCT1-mediated transport. Given the role played by BT in the intestine, this mechanism may contribute to the procarcinogenic effect of CDCA at this level. J. Cell. Biochem. 113: 29372947, 2012. (C) 2012 Wiley Periodicals, Inc.
Language:
English
Type (Professor's evaluation):
Scientific
No. of pages:
11