Ursodeoxycholic Acid Suppresses The Malignant Progression of Colorectal Cancer Through TGR5-YAP Axis

Abstract

Background: The Hippo/YAP pathway plays an important role in the development of cancers. Previous studies have reported that bile acids can activate YAP (Yes Associated Protein) to promote tumorigenesis and tumor progression. Ursodeoxycholic acid (UDCA) is a long-established old drug used for cholestasis treatment. So far, the effect of UDCA on YAP signaling in colorectal cancer (CRC) is not well defined. The study means to explore relationship of UDCA and YAP in CRC.Methods: The effect of UDCA on CRC cells proliferation was examined by MTT and clonogenic assay, western blotting (WB), real-time PCR, seperation of nucleoprotein and cytoplasmic protein and immunofluorescence (IF) assays were used to detect expression of YAP, WB, real-time PCR, GST-pull down assay and rhodamine-labeled phalloidin staining assays were used to detect activity of RhoA. After transfection of YAP5SA plasmids and RhoAV14 plasmids respectively, MTT, clonogenic assay, EdU incorporation assays and WB were performed. WB and ELISA were used to detect activity of cAMP/PKA axis, after blocking cAMP/PKA axis with siRNA and inhibitors, MTT, WB, IF and clonogenic assay were performed to test effect of UDCA on CRC cells. WB, IF and real-time PCR assays were used to detect expression of TGR5 in CRC cells after UDCA treatment, and then TGR5 agonist, TGR5 antagonist and siRNA were used to detect effect of UDCA on CRC cells. AOM/DSS-induced primary model was used to detect effect of UDCA, WB and Immunohistochemistry (IHC) were used to detect expression of related proteins.Results: UDCA suppressed YAP signaling by activating the membrane G‐protein‐coupled bile acid receptor (TGR5). TGR5 mainly regulated cAMP/PKA signaling pathway to inhibit RhoA activity, thereby suppressing YAP signaling. Moreover, the restoration of YAP expression alleviated the inhibitory effect of UDCA on CRC cell proliferation. In AOM/DSS-induced CRC model, UDCA inhibited tumor growth in a concentration-dependent manner and decreased expression of YAP and Ki67.Conclusion: UDCA plays a distinguished role in regulating YAP signaling and CRC growth from the primary bile acids and partial secondary bile acids, demonstrating the importance of maintaining normal intestinal bile acid metabolism in cancer patients. It also presents a potential therapeutic intervention for CRC.

Bile acids, bile pigments and colorectal cancer risk

“…In addition, it was demonstrated that DCA delayed wound healing in murine colonic epithelial YAMC cells via a mechanism involving TGR5 [53]. And Zhang et al [54 ▪ ] demonstrated that UDCA suppressed YAP signalling via TGR5 activation and thereby decreased colonic proliferation as well as colonic tumorigenesis in an AOM/DSS mouse model. Together, these data indicate that bile acids may influence colonic tumorigenesis or inflammatory conditions of the intestinal epithelium via YAP signalling, which is partly mediated via TGR5.…”