ID3 Promotes Stem Cell Features and Predicts Chemotherapeutic Response of Intrahepatic Cholangiocarcinoma

Cancer stem cells contribute to a high rate of recurrence and chemotherapeutic resistance in many types of cancer, including intrahepatic cholangiocarcinoma (ICC). Inhibitor of differentiation 3 (ID3) has been reported to promote cancer stem cells, but its role in ICC is obscure. In this study, we identified that ID3 is highly expressed in human ICC tissues compared with matched normal tissues and correlates with poor prognosis. Functional studies demonstrate that ID3 is required for stemness maintenance in cholangiocarcinoma both in vitro and in vivo. Consistent with the regulation of cancer stem cell features by ID3, transgenic expression of ID3 enhances chemoresistance of cholangiocarcinoma cells. Moreover, we found that ICC patients with low ID3 levels benefited from postoperative transarterial chemoembolization, whereas patients with high ID3 levels did not, indicating the significance of ID3 in individualized ICC therapy. Mechanistically, ID3 could interact with E47 and block E47 recruitment to the promoter of β-catenin, which leads to activation of Wnt/β-catenin signaling. Conclusion: Our results show that ID3 could promote the stemness of ICC by increasing the transcriptional activity of β-catenin and could serve as a biomarker in predicting ICC patients' response to adjuvant chemotherapeutics.