Autophagy plays a pro-apoptotic role in arsenic trioxide-induced cell death of liver cancer.

OBJECTIVE: The effects of arsenic trioxide (As2O3) 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 As2O3-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 As2O3 was evaluated using flow cytometry, Hoechst 33258 staining, and TUNEL assays. The rate of autophagy among liver cancer cells treated with As2O3 was detected using immunofluorescence, Western blot assay and transmission electron microscopy. RESULTS: Upon treatment with As2O3, 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 As2O3, as shown by flow cytometry. Apoptosis in liver cancer cells treated with As2O3 was also shown by the activation of the caspase cascade and the regulation of Bcl-2/Bax expression. Furthermore, As2O3 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, As2O3 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 As2O3-induced autophagy and apoptosis. Furthermore, inhibiting autophagy with 3-methyladenine partially reversed the negative effects of As2O3 on cell viability. Serum starvation increased autophagy and amplified the effect of As2O3 on cell death. CONCLUSION: As2O3 induces apoptosis and autophagy in liver cancer cells. Autophagy induced by As2O3 may have a proapoptotic effect that helps to reduce the viability of liver cancer cells. This study provides novel insights into the effects of As2O3 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.

Diosgenin prevents high-fat diet-induced rat non-alcoholic fatty liver disease through the AMPK and LXR signaling pathways.

Non-alcoholic fatty liver disease (NAFLD) is a major public health concern worldwide. The aim of the present study was to observe the effect of diosgenin on NAFLD and investigate the underlying mechanisms. Diosgenin treatment increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in HepG2 cells. Diosgenin significantly inhibited high glucose (HG)-induced triglyceride (TG) accumulation and sterol regulatory element­binding protein-1c (SREBP-1c) mRNA increase in HepG2 cells, which were partially abolished by the AMPK inhibitor compound C. Diosgenin also significantly inhibited the increase of liver X receptor (LXR) α mRNA induced by HG or T0901317. However, T0901317­induced upregulation of LXRα and SREBP-1c mRNA was not blocked by compound C. Following a high-fat diet for 16 weeks, the body and liver weights of the experimental rats were significantly increased, but this effect was significantly suppressed by diosgenin. Diosgenin and fenofibrate ameliorated lipid deposition in the liver and reduced the increase of hepatic TG content. Diosgenin significantly decreased the alanine aminotransferase (ALT) level, whereas fenofibrate significantly increased the ALT and aspartate aminotransferase levels. Diosgenin also increased AMPK and ACC phosphorylation and suppressed LXRα in the liver. In conclusion, the results of the present study suggested that diosgenin is a potential agent for preventing the development of NAFLD through the AMPK and LXR signaling pathways.

Diosgenin induces G2/M cell cycle arrest and apoptosis in human hepatocellular carcinoma cells.

Diosgenin is a major compound of Dioscoreaceae plants such as yam, which is used as a drug in Traditional Chinese Medicine, and a common vegetable worldwide. The anticancer effect of diosgenin has been reported in various tumor cells, including leukemia, gastric, colorectal, and breast cancer. However, the activity of diosgenin on hepatocellular carcinoma (HCC) and the underlying mechanism have not been completely investigated. Therefore, we investigated the efficacy and associated mechanisms of diosgenin in HCC cells. Flow cytometric analysis was performed to determine the presence of cell cycle arrest and apopotic cells. Diosgenin significantly inhibited the growth of Bel-7402, SMMC-7721 and HepG2 HCC cells in a concentration-dependent manner. Diosgenin treatment for 24 h induced G2/M cell cycle arrest and apoptosis of hepatoma cells. Diosgenin inhibited Akt phosphorylation and upregulated p21 and p27 expression, but did not alter the expression of p53, suggesting diosgenin-induced upregulation of p21 and p57 is p53-independent in HCC cells. Diosgenin induced HCC cell apoptosis by activating caspase cascades -3, -8 and -9. However, diosgenin did not affect Bcl-2 and Bax levels. In conclusion, results of the present study suggest that diosgenin may be an active anti-HCC agent obtained from natural plants and provide new insights in understanding the mechanisms of diosgenin.

[Study on antagonistic effect of liangxue huayu recipe on endoplasmic reticulum stress-induced L02 hepatocyte apoptosis and its mechanism].

Endoplasmic reticulum stress (ERS) is a new pathway inducing cell apoptosis that has been discovered in recent years. This study focused on the protective effect of Liangxue Huayu recipe (LHR) on tumor necrosis factor-alpha (TNF-alpha) and D-GalN-induced hepatocyte apoptosis. It found that TNF-alpha and D-GalN could obviously inhibit hepatocyte proliferation, induce cell apoptosis, and significantly increase free calcium ions in cytoplasms, as well as protein expressions of ERS apoptosis-related signal molecules phosphorylated PERK, phosphorylated elF2alpha, cleaved Caspase-12, GRP78 and CHOP. After the administration of LHR of different concentrations, compared with the TNF-alpha/GalN injury group, LHR could significantly alleviated L02 hepatocyte proliferation, decreased cell apoptosis, inhibited growth of intracytoplasmic free calcium content, and gradually reduced the protein expressions of phosphorylated PERK, phosphorylated elF2alpha, cleaved Caspase-12, GRP78 and CHOP. These findings indicated that LHR has the inhibitory effect on TNF-alpha and D-GalN-induced hepatocyte apoptosis. Its mechanism may be related to down-regulation of ERS apoptosis-related signal molecules phosphorylated PERK, phosphorylated elF2alpha, cleaved Caspase-12, GRP78 and CHOP that maintain calcium homeostasis in endoplasmic reticulum.