Role of Doublecortin and CAM Kinase-Like-1 (DCAMKL-1) in Hepatitis C Virus-Induced Hepatocarcinogenesis

Background:Hepatitis C virus (HCV) infection is a prominent risk factor for the development of hepatocellular carcinoma (HCC). Most solid tumors, including HCC, are believed to contain a subpopulation of poorly differentiated cancer stem-like cells (CSCs) that can initiate tumor formation and are relatively insensitive to antineoplastic chemotherapy. Because the putative intestinal and pancreatic stem cell marker DCAMKL-1 possesses microtubulepolymerizing activity and because intact microtubule filaments are required for efficient HCV replication, we hypothesize that DCAMKL-1 may be involved in HCV-induced hepatocarcinogenesis. Aim: Our aim is to delineate the role(s) of DCAMKL-1 in the development of HCV-induced hepatocellular carcinoma. Methods: We investigated our hypothesis using a selectable subgenomic replicon-expressing hepatoma cell line (GS5) and a corresponding control cell line (Huh7.5), immunofluorescence, immunohistochemistry, Western blot analysis, real-time RT-PCR, fluorescence-activated cell sorting (FACS) and a mouse xenograft model. Results: We demonstrate that HCV enhances expression of DCAMKL-1 and colocalizes with the replication complex attached microtubules. The siRNA-mediated inhibition of DCAMKL-1 expression concomitantly reduced HCV replication (In Vitro). The HCV+DCAMKL-1+ cells isolated from GS5 or DCAMKL-1+ cells from Huh7.5 formed spheroid bodies in a matrigel-based culture assay. Furthermore, we demonstrate that HCV induces retrodifferentiation of the replicon-expressing cells that results in much higher expression of α-fetoprotein and cytokeratin-19 in the tumor xenografts of GS5 cells compared to the control Huh7.5 tumors. Conclusion: DCAMKL-1 may represent a novel cellular target for the treatment of HCV infection and for directly targeting CSCs in HCC. We further demonstrate that HCV exhibits intrinsic ability to induce CSC features in liver-derived cells.