• Journal of Medicine and Life Science
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• v.17 no.2
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• pp.41-46
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• 2020

Metformin, a predominantly prescribed anti-diabetic drug for decades, has gained new insights for its anti-tumor activity in a variety of cancer cells. Our previous studies also showed the obvious pro-apoptotic activity of metformin and the underlying action mechanisms in hepatocellular carcinoma cells. Together with apoptosis, autophagy is a crucial intracellular process to determine the survival or death of cells under some stressful environments. The present study aimed to determine the role of autophagy in metformin-induced death of H4IIE hepatocellular carcinoma cells. Metformin blocked the formation of autophagosome and the expression of LC3A, generally described as a biomarker of autophagy. Inhibition of AMPK reversed the metformin-induced blockade of autophagy. Antioxidant (NAC) suppressed the metformin-induced cell death but not affected LC3A. The inhibition of protein kinase C totally restored the metformin-suppressed expression of LC3A. In summary, our present study suggests that autophagy is an anti-apoptotic player in metformin-induced apoptosis in H4IIE cells.

• Development and Reproduction
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• v.27 no.2
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• pp.77-89
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• 2023

Metformin is the most widely used anti-diabetic drug that helps maintain normal blood glucose levels primarily by suppressing hepatic gluconeogenesis in type II diabetic patients. We previously found that metformin induces apoptotic death in H4IIE rat hepatocellular carcinoma cells. Despite its anti-diabetic roles, the effect of metformin on hepatic de novo lipogenesis (DNL) remains unclear. We investigated the effect of metformin on hepatic DNL and apoptotic cell death in H4IIE cells. Metformin treatment stimulated glucose consumption, lactate production, intracellular fat accumulation, and the expressions of lipogenic proteins. It also stimulated apoptosis but reduced autophagic responses. These metformin-induced changes were clearly reversed by compound C, an inhibitor of AMP-activated protein kinase (AMPK). Interestingly, metformin massively increased the production of reactive oxygen species (ROS), which was completely blocked by compound C. Metformin also stimulated the phosphorylation of p38 mitogen-activated protein kinase (p38MAPK). Finally, inhibition of p38MAPK mimicked the effects of compound C, and suppressed the metformin-induced fat accumulation and apoptosis. Taken together, metformin stimulates dysregulated glucose metabolism, intracellular fat accumulation, and apoptosis. Our findings suggest that metformin induces excessive glucose-induced DNL, oxidative stress by ROS generation, activation of AMPK and p38MAPK, suppression of autophagy, and ultimately apoptosis.