Bile acids increase intestinal marker expression via the FXR/SNAI2/miR-1 axis in the stomach

Intestinal metaplasia (IM) is a precancerous lesion that increases the risk of subsequent gastric cancer (GC) development. Previously, miR-1 has been shown to play an essential role in the initiation of bile acid (BA)-induced IM. The objective of the present study was to investigate the mechanism underlying miR-1 inhibition by BA in gastric cells.

Ingenuity pathway analysis (IPA) was used to identify molecules acting upstream of miR-1. The effects of deoxycholic acid (DCA), FXR and SNAI2 on the expression of intestinal markers were assessed using quantitative real-time PCR (qRT-PCR) and Western blotting. The expression level of major molecules was detected by immunohistochemistry (IHC) in tissue microarrays. The transcriptional regulation of miR-1 was verified using luciferase reporter and chromatin immunoprecipitation (ChIP) assays.

We found that BA treatment caused aberrant expression of FXR and intestinal markers in gastric cells. Augmented FXR led to transcriptional activation of SNAI2, which in turn suppressed the miR-1 promoter. Moreover, we found that compared with normal tissues, the expression levels of both FXR and SNAI2 were increased and positively correlated with each other in IM tissues. Additionally, their expression showed an inverse correlation with that of miR-1 in IM tissues.

Our findings indicate that FXR may be responsible for a series of molecular changes in gastric cells after BA treatment, and that the FXR/SNAI2/miR-1 axis exhibits a crucial role in BA-induced progression of IM. Blocking the FXR-oriented axis may provide a promising approach for IM or even GC treatment.