Abstract 762: Disrupting the glucose-influx induced β-catenin activation for the treatment of hepatocellular carcinoma

Abstract

Abstract Background: Reprogramming of glucose metabolism is a critical hallmark in hepatocellular carcinoma (HCC), and alteration of WNT/β-catenin signaling is one of the most common molecular alterations observed in patients with HCC. Interestingly, some studies reported that high glucose exposure leaded to activation of WNT/β-catenin signaling. But, for HCC, whether the accelerated glucose metabolism affects β-catenin, and whether this singling pathway reserves potential for the development of novel anti-cancer treatment have not yet been explored. Method: HCC cells were exposed to different glucose conditions and various glucose transporter inhibitors, including Phloretin, WZB117, Canagliflozin, Dapagliflozin and Empagliflozin. Cells were examined for cell viability and molecular signaling after treatments. Huh7 xenografted tumor model was used for in vivo testing. Clinical HCC tumor tissues were examined by immunohistochemical stain. Result: HCC cells exposed to high glucose environment showed higher proliferation rate and upregulated β-catenin as comparing to those cultured in lower glucose-median. Notably, a similar association was observed in the clinical samples; HCC patients with higher glycemic level had stronger expressions of β-catenin in their tumors (p=0.034). Above data suggested that high glucose condition induced activation of β-catenin. Next, we asked whether blocking glucose influx attenuates this glucose-influx-mediated β-catenin activation and inhibits HCC cell growth. By treating HCC cells with various glucose transporter inhibitors, we found that canagliflozin, Phloretin and WZB117 attenuated glucose influx of HCC cells, but only canagliflozin showed potent growth inhibition against HCC. Furthermore, treatment of canagliflozin leaded to a dose-dependent downregulation of β-catenin in HCC cells. Using cycloheximide and MG-132, we proved that canagliflozin treatment promoted the proteasome-mediated degradation of β-catenin protein. Since the phosphorylation of β-catenin is the initial step for its degradation, we examined the expression of p-β-catenin and found that canagliflozin treatment increased the expressions of p-Ser33/Ser37/Thr41-β-catenin and p-Ser45-β-catenin. Furthermore, the activity of protein phosphatase 2A (PP2A) was decreased in canagliflozin-treated HCC cells. The roles of glucose-influx and PP2A/p-β-catenin mediating the anti-HCC effects of canagliflozin were validated. Moreover, in vivo tumor growth inhibition of canagliflozin treatment was shown. Conclusion: Our results showed that high glucose upregulated beta-catenin signaling in HCC. Canagliflozin, by direct promoting the degradation of β-catenin protein and attenuating glucose-influx, inhibits the glucose-influx-mediated β-catenin activation and produces anti-HCC effects in vitro and in vivo. Citation Format: Man-Hsin Hung, Li-Ju Chen, Pei-Yi Chu, Yao-Li Chen, Ming-Hsien Tsai, Feng-Shu Hsieh, Kuen-Feng Chen. Disrupting the glucose-influx induced β-catenin activation for the treatment of hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 762.