DCLK1 Expression and its Functional Significance in Intrahepatic Cholangiocarcinoma and Bil-IN Stage

Background/Aim: Although several studies in some neoplasms have reported correlation between the expression levels of Doublecortin-like kinase1(DCLK1) and carcinogenesis, its role in cholangiocarcinoma remains unknown. Materials and Methods: DCLK1 expression in normal epithelium (NE), biliary intraepithelial neoplasia (BilIN)1 similar to 3, and intrahepatic cholangiocarcinoma (ICC) were investigated immunohistochemically. The molecular effects of DCLK1 were investigated by gene silencing using RNAi [DCLK1-tagrgeting (siDCLK1)]. The human ICC cell lines HuCCT1 and HuH28 were transfected with these siRNAs, and used for assays in the presence or absence of DCLK1 inhibitors. Results: The positive ratio of DCLK1 expression in ICC was higher than that in NE, and equally distributed among BilIN1 similar to 3 (NE: BilIN1: BilIN2: BilIN3: ICC=62%: 91%: 97%: 100%: 95%, p<0.05). In the wound healing assay, the migration of the siDCLK1-treated cells was significantly inhibited compared to the NT -treated cells (p<0.05). In the cell invasion assay, the invasion of the siDCLK1-treated cells was significantly inhibited compared to the NT -treated cells (p<0.05). In the presence of the DCLK1 inhibitor, cell proliferative capacity at 24 hours was decreased in a concentration -dependent manner. Conclusion: DCLK1 was highly expressed in the early stage of ICC carcinogenesis. Human ICC cell growth was suppressed in vitro by siRNA silencing of DCLK1 or after treatment with the DCLK1 inhibitor, indicating DCLK1 may be molecular target for ICC therapy.