Abstract LB-005: TRIP13/PCH2 is a novel regulator of EGF-mTOR signaling promoting hepatocellular carcinoma development

Abstract

Abstract Hepatocellular carcinoma (HCC) is currently the third most common cause of cancer-related mortality with limited treatment options and bleak prognosis. The main risk factors for HCC have been linked to hepatitis infection, alcoholic liver injury, non-alcoholic fatty liver disease (NAFLD) and metabolic diseases. Current therapeutic options are limited, which could be due to the lack of understanding of the key cellular players and signalling pathways in HCC. In order to find novel regulators of HCC development, we surveyed expression data of human hepatocellular carcinoma (E-GEOD-25097) and found the AAA-ATPase Thyroid Hormone Receptor Interactor 13 (TRIP13) to be upregulated in tumorous tissue compared to non-tumorous tissue. Consistently, using a mouse model for HCC by injection of Diethylnitrosamine (DEN), we observed induced expression of TRIP13 in liver tumors compared to healthy liver tissue. Additionally, in a model of liver regeneration by partial hepatectomy, induction of TRIP13 coincided with a peak in cell proliferation in the regenerating liver. Strinkingly, Adeno-associated virus (AAV)-mediated hepatocyte-specific knockdown of TRIP13 impeded liver regeneration upon partial hepatectomy, suggesting an important role of TRIP13 in liver cell proliferation. Indeed, knockdown (KD) of TRIP13 severely impaired cell growth and proliferation in different human and murine HCC cell lines in vitro. To investigate the oncogenic potential of TRIP13 in vivo, we injected lentiviral infected cells subcutaneously into mice and measured tumor growth. Remarkably, knockdown of TRIP13 in Hepa1-6 cells led to the development of smaller tumors compared to control cells, whereas TRIP13-deficient Huh7 cells did not form any tumors. Interestingly, shRNA knockdown of TRIP13 in HCC cell lines showed decreased phosphorylation of key players in the mTOR signalling pathway and reduction of the downstream Cyclin D1 levels. Concurrently, the mRNA and protein expression of EGF receptor was also downregulated in TRIP13 KD-cells. Taken together, we identified a novel role of TRIP13 during hepatocyte proliferation both in liver regeneration and HCC. Additionally, our findings also support an oncogenic function of TRIP13 through the regulation of the EGFR-mTOR signalling axis. Citation Format: Bettina Meissburger, Jessica Chan, Roldan de Guia, Stephan Herzig, Mauricio Berriel Diaz. TRIP13/PCH2 is a novel regulator of EGF-mTOR signaling promoting hepatocellular carcinoma development. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-005.