Abstract 3171: Overexpression of a cancer stem cell marker doublecortin-like kinase (DCLK1) leads to activation of inflammatory cascade during development of virus-induced hepatocellular carcinoma

Introduction: Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death worldwide. Chronic infections with hepatitis B or C viruses are the leading cause of HCC. The cancer stem cell (CSC) marker, doublecortin-like kinase (DCLK1), is believed to be a key factor for the development of multiple cancer types including HCC. However, its impact on signaling pathways that promote hepatocarcinogenesis is largely unknown. We have shown DCLK19s enhanced expression in HCC and its stimulatory role in hepatitis C virus (HCV) replication. Our published reports further suggest that DCLK1 positively affects tumor-related miRNAs and transcription factors that promote epithelial-mesenchymal transition (EMT). These observations prompted us to investigate DCLK1 signaling module in virus-induced liver pathogenesis and HCC. Methods: Genome-wide transcriptome analysis was carried out in total RNAs isolated from DCLK1-overexpressing and control hepatoma cells. One hundred five clinical cases representing various stages of liver diseases in patients with chronic hepatitis B or C were analyzed for an array of markers including DCLK1 by immunohistochemical staining and Western blot. Huh7 hepatoma cells were transplanted into the flanks of athymic nude mice to generate HCC-like tumor xenografts. The tumors were analyzed for proteins, mRNAs and miRNAs or treated with siRNA against DCLK1 and scrambled siRNA to monitor tumor growth arrest. Results: We found that the expression of 19 genes (14 upregulated, 5 downregulated) was specifically affected by DCLK1 overexpression in hepatoma cell lines. Among these, the level of kinase-suppressor of Ras 1 (KSR1) scaffold protein of Ras-MAPK pathway was increased significantly when recombinant DCLK1 was co-expressed with HCV replicon. Examination of liver tissues derived from patients with chronic hepatitis B/C and HCC suggests that a pro-inflammatory S100A9 protein tends to correlate with DCLK1 overexpression in cirrhosis with or without HCC. Both DCLK1 and S100A9 proteins were mainly localized in the regenerative nodules, fibrotic septa, mesenchymal cells, endothelium and areas with lymphocytes aggregates. Analysis of tumor xenografts developed by hepatoma cells suggest that overexpression of DCLK1 is accompanied by high-level expression of S100A9 and c-Myc as well as activation of NFκB. Conversely, siRNA-led inhibition of DCLK1 causes decrease in tumor volume considerably in a xenograft model. Conclusions: DCLK1 overexpression appears to be intimately related to the activation of pro-inflammatory and MAPK signaling pathways during the development of virus-induced pre-neoplastic conditions and initiation of tumors in liver. Thus, targeting DCLK1 at early stage of liver diseases may prevent virus-induced cirrhosis and HCC. Citation Format: Naushad Ali, Parthasarathy Chandrakesan, Mark Huycke, Sanam Husain, Allison F. Gillaspy, Randal May, William L. Berry, Sripathi Sureban, Dongfeng Qu, Nathaniel Weygant, Michael S. Bronze, Danny N. Dhanasekaran, Courtney W. Houchen. Overexpression of a cancer stem cell marker doublecortin-like kinase (DCLK1) leads to activation of inflammatory cascade during development of virus-induced hepatocellular carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3171. doi:10.1158/1538-7445.AM2014-3171