Autophagy plays a pro-apoptotic role in arsenic trioxide-induced cell death of liver cancer
Zhengting Deng, Shufang Liang, Guo-kai Huang, Yuqian Wang, Xiao-yu Tu, Yani Zhang, Shu Li, Tao Liu, Bin-bin Cheng
Abstract
Objective The effects of arsenic trioxide (As 2 O 3 ) on hepatocellular carcinoma have been documented widely. Autophagy plays dual roles in the survival and death of cancer cells. Therefore, we investigated the exact role of autophagy in As 2 O 3 -induced apoptosis in liver cancer cells. Methods The viability of hepatoma cells was determined using the MTT assay with or without fetal bovine serum. The rate of apoptosis in liver cancer cells treated with As 2 O 3 was evaluated using flow cytometry, Hoechst 33258 staining, and TUNEL assays. The rate of autophagy among liver cancer cells treated with As 2 O 3 was detected using immunofluorescence, Western blot assay and transmission electron microscopy . Results Upon treatment with As 2 O 3 , the viability of HepG2 and SMMC-7721 cells was decreased in a time- and dose-dependent manner. The apoptosis rates of both liver cancer cell lines increased with the concentration of As 2 O 3 , as shown by flow cytometry. Apoptosis in liver cancer cells treated with As 2 O 3 was also shown by the activation of the caspase cascade and the regulation of Bcl-2/Bax expression. Furthermore, As 2 O 3 treatment induced autophagy in liver cancer cells; this finding was supported by Western blot , immunofluorescence of LC3-II and beclin 1 , and transmission electron microscopy . In liver cancer cells, As 2 O 3 inhibited the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin ( PI3K/AKT/mTOR) signal pathway that plays a vital role in both apoptosis and autophagy. The PI3K activator SC-79 partially reversed As 2 O 3 - induced autophagy and apoptosis. Furthermore, inhibiting autophagy with 3-methyladenine partially reversed the negative effects of As 2 O 3 on cell viability . Serum starvation increased autophagy and amplified the effect of As 2 O 3 on cell death. Conclusion As 2 O 3 induces apoptosis and autophagy in liver cancer cells. Autophagy induced by As 2 O 3 may have a proapoptotic effect that helps to reduce the viability of liver cancer cells. This study provides novel insights into the effects of As 2 O 3 against liver cancer. Please cite this article as: Deng ZT, Liang SF, Huang GK, Wang YQ, Tu XY, Zhang YN, Li S, Liu T, Cheng BB. Autophagy plays a pro-apoptotic role in arsenic trioxide-induced cell death of liver cancer. J Integr Med . 2024; 22(3): 295–302.