Abstract 3300: Inhibition of autophagy by 3-MA enhances the effect of ursolic acid-induced apoptosis in hepatoma SK-Hep-1 cells

Abstract

Abstract Purpose The aim of this study is to investigate the autophagic effect of Ursolic Acid (UA) on hepatoma SK-Hep-1 cells. Methods The cytotoxicity of UA in hepatoma SK-Hep-1 cells was measured by MTT assay, the accumulation of acidic vesicular organelles was measured by FACS, the protein expression of LC3-II was detected by immunofluorescence staining, and the autophagic protein expression was evaluated by western blotting. Hepatoma SK-Hep-1 cells treated with a combination of autophagy inhibitor 3-Methyladenine (3-MA) and UA, then use Annexin V/PI Double Staining and western blotting to detect apoptosis and apoptotic protein levels. Statistical Analyses Data was expressed as the mean ± standard deviation and were compared using the Student’s t-test. A p value of <0.05 was considered to indicate statistical significance. All statistical analyses were performed using GraphPad Prism software, version 4.0 (GraphPad Software, Inc., La Jolla, CA, USA). Preliminary Results SK-Hep-1 cells treated with different concentrations of UA (0, 20, 40, and 60 μM). Regarding the results, the half-maximal inhibitory concentration (IC50) was 45.9 and 36.6 μM for 24 and 48 h, respectively. The FACS results showed that when increase the dose of UA could increase the percentages of autophagic populations. The anti-autophagic proteins such as Beclin, Atg-5, Atg-7, and LC3-II, in our results showed that UA decreased the protein expression of mTOR, PI3K, and p62 and PI3K/Akt/mTOR expression. Immunocytochemistry staining showed that SK-Hep-1 cells treated with UA increased the protein expression of LC3-II. The combination treatment of 3-MA and UA significantly increased the apoptotic cell death as monitored by increased protein expression of Caspase-3 and PAPR. Conclusions UA could induced autophagy in hepatoma SK-Hep-1 cells through inhibition of mTOR and PI3K signaling pathways. SK-Hep-1 cells treated with UA exhibited LC3-І/LC3-II conversion, increased protein expression levels of Beclin, Atg-7, and Atg-5 along with reduced protein expression levels of p62. UA-induced apoptosis was enhanced by the treatment of autophagy inhibitor 3-MA. Our findings may assist in the development of novel chemotherapeutic agents for the treatment of malignant types of liver cancer. Citation Format: Chuang Wan-Ling, Lin Ping-Yi, Chen Yao-Li. Inhibition of autophagy by 3-MA enhances the effect of ursolic acid-induced apoptosis in hepatoma SK-Hep-1 cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3300. doi:10.1158/1538-7445.AM2017-3300