Abstract 1039: Metabolic hormones FGF19/15 promote hepatocellular carcinoma through activation of CSCs in fatty liver

Abstract

Abstract Background: Fibroblast growth factor 19 (FGF19), a member of the fibroblast growth factor (FGF) family, is a hormone that regulate glucose, lipid, and energy homeostasis in human. It has been shown that FGF19 and its specific receptor FGFR4 play an important role in non-alcoholic steatohepatitis (NASH) which is closely related hepatocellular carcinoma (HCC). Recently, we found FGF19 overexpressed in the HCC tissue and serum in patients. The high level of FGF19 was positively related to cancer stem cells (CSCs) specific surface markers such as CD133 and EpCAM. The aim of this study is to identify potential mechanism in which FGF15 (the FGF19's orthologous protein in mouse)/FGFR4 associated abnormal lipid metabolism initiates HCC progression in a NASH-HCC mouse Model. Methods: In vivo study, male C57L/J mice were injected intraperitoneally with N-nitrosodiethylamine(DEN) when 2 weeks old. Both the DEN and control mice were divided into two groups based on receiving high fat diet (HFD) or control diet (CD). Tumor nodules in the liver were monitored by ultrasound. Body weight, glucose tolerance test (GTT) and insulin tolerance test (ITT) were recorded during the experimental period. The liver weights, tumor volume, histology, alanine transaminase (ALT), alpha fetoprotein (AFP), and triglyceride (TG) were determined at 8, 20 and 32weeks. In vitro study, human HCC cell lines (Hep3B and Huh7) as well as mouse HCC cell lines (Hepa1-6 and FL83B,) were exposed to a long-chain mixture of free fatty acid(FFA) at different concentrations (UT, 0.5mM and 1mM FFA) for 24 and 48 hours, respectively. EpCAM and CD133 were determined by flow cytometery in the isolated tumor cells from HCC tissues. FGF19/15, FGFR4, CSCs surface markers and Wnt signaling pathway (β-catenin, GSK3β) were analyzed by RT-PCR and Western blot. FGFR4 signal was blocked to elucidate the role of FGF19/15 during the CSCs activation in vitro. In addition, FGF19, FGFR4 and EpCAM were also analyzed in human HCC samples. Results: Metabolic disorders were observed when DEN mice fed with HFD. HCC incidence and tumor volume were significantly increased in DEN+HFD group compared to that in DEN+CD group. DEN mice fed with HFD showed increased levels of FGF15/FGFR4 and β-catenin as well as the CSCs surface makers. Increased expression of CSCs surface makers were also found in the HCC cell lines when exposure to FFA in vitro. Blockage the FGF19 signal can abolish Wnt/β-catenin pathway and cell stemness features in the FFA environment. Increased levels of FGF19, FGFR4 and EpCAM were found in human HCC samples. Conclusion: Up-regulated FGF19/15 and FGFR4 promoted the development of HCC by active CSCs signaling in metabolic disorder microenvironment. FFA enhanced the CSCs activation was partially dependent on Wnt/β-catenin signaling. FGF19/FGFR4 could be a potential therapeutic target in HCC patients. Citation Format: Guozhen Cui, Xingkai Liu, Harshul Pandit, Yingbin Yang, Suping Li, Lu Cai, Robert C Martin, Hengjun Zhao, Wei Li, Yan Li. Metabolic hormones FGF19/15 promote hepatocellular carcinoma through activation of CSCs in fatty liver. [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 1039.