Abstract 2239: The tumor stem cell marker doublecortin-like kinase (DCLK1) activates inflammatory and carcinogenic signals in hepatocellular carcinoma

Introduction: Hepatocellular Carcinoma (HCC) is the third most common cause of cancer-related deaths worldwide. Chronic viral hepatitis, non-alcoholic steatohepatitis and cirrhosis are considered to be major risk factors for the development of HCC. The risk of HCC increases significantly in patients with chronic hepatitis C virus (HCV) infection and metabolic diseases. Thus, HCC represents a wide-ranging public health issue worldwide. Our recent studies have revealed a positive correlation between expression of the tumor stem cell (TSC) marker, doublecortin-like kinase (DCLK1) and cancer growth in liver, colon and pancreas. However, the molecular mechanism by which its overexpression impacts key signaling pathways during hepatocarcinogenesis is largely unknown. We have previously shown a dynamic relationship between active HCV replication and expression of a few TSC markers including DCLK1. Our published reports further suggest that DCLK1 positively affects the viral replication and transcription factors that promote epithelial-mesenchymal transition. These observations prompted us to investigate a possible DCLK1-controlled signaling network in HCC. Methods: We used transcriptome analysis of DCLK1-overexpressing and HCV replicon co-expressing cell lines, RNA interference, Huh7 hepatoma cells-derived tumor xenografts, patient9s liver tissues and normal human hepatocytes-derived hepatospheroids to investigate DCLK1-regulated signaling pathways in the liver. Immunohistochemical staining, real-time PCR and Western blot were used to validate our observations. The siRNAs and shRNAs against DCLK1 were used to monitor inhibition of cell migration and tumor growth. Results: Although normal human liver lacks detectable DCLK1, extensive DCLK1 expression was observed in lymphoid aggregates, epithelial and stromal cells, lymphocytes, and bile ducts in HCV-positive patients with cirrhosis and HCC. The DCLK1 expression correlated with pro-inflammatory S100A9 levels and activation of NFκB. Normal human hepatocytes-derived spheroids acquired DCLK1 expression, and differentiated into stem/progenitor-like and neuron-like cells upon stimulation with serum. Silencing of DCLK1 inhibited S100A9 expression and hepatoma cell migration. Based on transcriptome data and validation at protein levels, we found a novel DCLK1-controlled feed-forward-like signaling network that potentially drives inflammation and tumorigenesis in the liver. DCLK1 was also found to regulate SMARCA2 (hBRM) protein that participates in the formation of tumor-associated SW1/SNF1 chromatin remodeling complexes. Conclusions: The TCS marker, DCLK1, appears to be a master regulator of inflammatory, oncogenic and chromatic remodeling networks. It is possible to target this signal regulator for preventing hepatic inflammation and liver neoplasia. Citation Format: Naushad Ali, Parthasarathy Chandrakesan, Charles B. Nguyen, Sanam Husain, Allison F. Gillaspy, Mark Huycke, William L. Berry, Randal May, Dongfeng Qu, Nathaniel Weygant, Sripathi M. Sureban, Danny N. Dhanasekaran, Courtney W. Houchen. The tumor stem cell marker doublecortin-like kinase (DCLK1) activates inflammatory and carcinogenic signals in hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2239. doi:10.1158/1538-7445.AM2015-2239