TAZ regulates cell proliferation and sensitivity to vitamin D3 in intrahepatic cholangiocarcinoma

• TAZ is over-expressed in ICC.
• Patients with ICC with higher TAZ expression had a poorer prognosis.
• Silencing of TAZ suppressed ICC cells proliferation and increased apoptosis.
• TAZ reduction increased tumor cells' sensitivity to vitamin D.
• TAZ regulates the expression of VDR and CYP24A1 through regulating p53 transcriptional activity.

The transcriptional coactivator with PDZ binding motif (TAZ) is reported as one of the nuclear effectors of Hippo-related pathways. TAZ is found overexpressed in many primary tumors and could regulate many biological processes. However, little is known about the role of TAZ in Intrahepatic Cholangiocarcinoma (ICC). In this study, we found that TAZ is expressed more in ICC tissues than in peritumoral tissue, and a robust expression of TAZ is correlated with a lower overall survival rate of ICC patients after hepatectomy. TAZ knockdown results in an increase in cell apoptosis, a promotion of cell-cycle arrest and a decrease in tumor size and weight in vivo through an increased expression of p53. Vitamin D3 can also inhibit cell proliferation by promoting p53 expression in ICC cells. A reduction in TAZ can also enhance the sensitivity of tumor cells to vitamin D by regulating the p53/CYP24A1 pathway. In conclusion, TAZ is associated with the proliferation and drug-resistance of ICC cells, and could be a novel therapeutic target for the treatment of ICC.