Involvement of bile acids in cholangiocarcinoma progression via the Hippo-yes-associated protein signaling pathway

Cholangiocarcinoma (CCA) is a highly aggressive malignancy with limited therapeutic options. Dysregulation of the Hippo-yes-associated protein (YAP) signaling pathway plays a key role in tumor progression, but the effects of distinct bile acids on this pathway remain unclear.

To investigate the roles of glycochenodeoxycholic acid (GDCA) and deoxycholic acid (DCA) in CCA progression through Hippo-YAP signaling and to evaluate the effects of YAP-targeted interventions.

The in vitro experiments were performed using HuCCT1 CCA cells treated with GDCA, DCA, and combinations with a YAP inhibitor (verteporfin) or agonist (GA-017). Key molecular changes in the Hippo-YAP pathway were assessed by western blot, immunofluorescence, and reverse transcription quantitative real-time polymerase chain reaction. Functional assays, including Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine, Transwell, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-nick end labelling, were conducted to evaluate cell proliferation, migration, invasion, and apoptosis. In vivo, nude mice bearing subcutaneous HuCCT1 tumors were treated with GDCA, DCA, or combined YAP modulators. Tumor growth was monitored, and molecular analyses of tumor tissues were performed using western blot.

The GDCA significantly activated YAP by reducing mammalian STE20-like protein kinase 1 and large tumor suppressor 1 phosphorylation, promoting YAP nuclear translocation, and enhancing tumor cell proliferation, migration, and invasion. In contrast, DCA inhibited YAP activation, suppressed tumor cell functions, and increased apoptosis. GDCA combined with YAP inhibitors attenuated its tumor-promoting effects, while DCA combined with YAP agonists reversed its inhibitory effects. In vivo, GDCA accelerated tumor growth, while DCA reduced tumor size and weight, with molecular changes consistent with in vitro findings.

The GDCA and DCA exert opposing effects on CCA progression through Hippo-YAP signaling. GDCA promotes tumor growth via YAP activation, while DCA inhibits these processes. YAP-targeted interventions demonstrate therapeutic potential, providing insights into new treatment strategies for CCA.