Synergistic tumor inhibition of colon cancer cells by nitazoxanide and obeticholic acid, a farnesoid X receptor ligand

The tumor-suppressive role of Farnesoid X receptor (FXR) in colorectal tumorigenesis supports restoring FXR expression as a novel therapeutic strategy. However, the complicated signaling network and tumor heterogeneity hinder the effectiveness of FXR agonists in the clinical setting. These difficulties highlight the importance of identifying drug combinations with potency and specificity to enhance the antitumor effects of FXR agonists. In this study, we found that the β-catenin level affected the antitumor effects of the FXR agonist OCA on colon cancer cells. Mechanistic studies identified a novel FXR/β-catenin complex in colon cancer cells. Furthermore, the depletion of β-catenin expedited FXR nuclear localization and enhanced its occupancy of the SHP promoter and thereby sensitized colon cancer cells to OCA. Furthermore, we utilized a drug combination study and identified that the antiparasitic drug nitazoxanide (NTZ) abrogated β-catenin expression and acted synergistically with OCA in colon cancer cells. The combination of OCA plus NTZ exerts synergistic tumor inhibition in CRC both in vitro and in vivo by cooperatively upregulating SHP expression. In conclusion, our study offers useful evidence for the clinical use of FXR agonists combined with β-catenin inhibitors in combating CRC.