Decreased expression of farnesoid X receptor may indicate poor prognosis in patients with colorectal cancer

BACKGROUND: Colorectal cancer (CRC) is one of the most common malignancies worldwide. Many studies showed that increased secretion of bile acid may contribute to the pathogenesis of CRC. Farnesoid X receptor (FXR) plays an important role in several physiological functions of bile acid metabolism and circulation, while the diagnostic and prognostic values of FXR remain unknown. METHODS: We used immunohistochemistry (IHC) to examine FXR expression in 132 formalin-fixed paraffin-embedded (FFPE) CRC samples, and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was also conducted to compare the mRNA expression of FXR between 50 fresh CRC tissues and 50 adjacent normal tissues. Immunohistochemical method has been used to compare the protein expression of FXR in FFPE samples, and the associate between FXR expression and clinical characteristics of the patients were also analyzed. Moreover, RT-qPCR has been applied to quantify the mRNA expression of FXR, and the diagnostic value and prognostic value of FXR were analyzed by receiver operating characteristics (ROC) analysis and Kaplan-Meier survival analysis, respectively. RESULTS: The expression of FXR was significantly decreased in CRC tumor samples compared with normal tissues on both protein and mRNA levels, and the expression of FXR was positively correlated with the tumor size, lymph node metathesis and distant metathesis of the patients. Moreover, the area under curve (AUC) of FXR for the diagnosis of CRC was 0.8088, and low expression of FXR was associated with low overall survival (OS) and disease-free survival (DFS) rate. CONCLUSIONS: FXR was down-regulated in CRC and may serve as potential diagnostic and prognostic biomarkers.