Abstract 4552: Trimethoxy-cis-stilbene exhibits potent anti-tumor activities via suppression of AKT signaling and cell cycle arrest in virus-induced hepatocellular carcinoma

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Background: Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world, and the incidence is likely to increase due to other health complications such as obesity and diabetes. Chronic hepatitis C virus (HCV) infection and cirrhosis are considered to be major risk factors for induction of HCC. HCV induces cirrhosis, regenerative nodules and cancer stem cell (CSC)-related proteins in the liver. Treatments for chronic hepatitis C and HCC have been challenging so far. Therefore, identification of novel therapeutic agents that target HCV and/or HCV-induced HCC is an unmet medical need. Resveratrol (RES) and its synthetic analogue, trimethoxy-cis-stilbene (TMS) have shown to possess a range of therapeutic activities against various diseases. Although RES has been extensively studied, the anti-viral and anti-tumor activities of TMS have not been fully explored. Methods: HCV subgenomic replicon-expressing hepatoma cells were treated with varying concentrations of RES, TMS or DMSO (control) for 48 hrs. The IC50 values for these drugs were determined based on HCV expression levels in the treated and untreated cultures. Effects of the drugs on cell cycle and AKT signaling pathways were investigated using flow cytometry and protein expression profiles. Cell cytotoxicity of the drugs was determined by MTS assay using normal human hepatocytes (NHH) and hepatoma cells. Magnetic levitation method was carried out to determine effects of the drugs on 3D spheroid cultures. Results: Both RES and TMS downregulated the HCV RNA and NS5B polymerase levels within 48 hr and showed IC50 values equivalent to 100 μM and 1.0 μM, respectively. However, the NHH viability was not compromised during these culture conditions as determined by cytotoxic assays. The anti-HCV effects were accompanied by cell cycle arrest at G2/M phase for TMS, whereas G1/S arrest was observed for RES. TMS-induced G2/M arrest was confirmed by a sharp reduction in phosphorylated CDK1 level in the treated cells. Further analysis showed that active serine/threonine kinase AKT (phosphorylated at Ser473) level was significantly reduced by 1.0 μM TMS. Conversely, the level of p21(Cip1/Waf1), a CDK1 inhibitor, was increased following TMS treatment. Only TMS, but not DMSO (control), successfully inhibited 3D hepatoma spheroid growth in culture. Conclusion: Trimethoxy-cis-stilbene appears to be more potent than its parent compound resveratrol as an anti-HCV and anti-tumor drug in culture conditions. Its anti-tumor effects on HCV-expressing hepatoma cells are exerted by suppression of AKT signaling pathway and cell cycle arrest. This is also supported by an increase in p21(Cip1/Waf1) levels following TMS treatment. Based on these observations, TMS appears to be a promising therapeutic agent for HCV-induced liver diseases including HCC. Citation Format: Charles Nguyen, Hari Kotturi, Sripathi Sureban, Randal J. May, Parthasarathy Chandrakesan, Nathaniel Weygant, Dongfeng Qu, Courtney Houchen, Naushad Ali. Trimethoxy-cis-stilbene exhibits potent anti-tumor activities via suppression of AKT signaling and cell cycle arrest in 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 4552. doi:10.1158/1538-7445.AM2014-4552