Emodin-induced autophagy against cell apoptosis through the PI3K/AKT/mTOR pathway in human hepatocytes

Abstract

Background

Emodin, a major component of Polygonum multiflorum (PM), has been reported to exert both protective and toxic effects in several cell types. However, the effects and underlying mechanisms of action of emodin in hepatic cells are still obscure.

Methods

The present study used the normal human liver cell line L02 to investigate the effects and mechanisms of emodin in hepatic cells. After treatment with emodin, L02 cells were examined for viability, apoptosis and autophagy with the Cell Counting Kit-8 (CCK-8), annexin V/PerCP staining and GFP-LC3 plasmid transfection. The expression of proteins including cleaved caspase-3, LC3B-I/II, p-PI3K, PI3K, p-AKT, AKT, p-mTOR, mTOR and actin was examined by using Western blot.

Results

Emodin significantly inhibited the viability of and induced apoptosis in L02 cells in a dose- and time-dependent manner. In addition, emodin increased the number of GFP-LC3 puncta in L02 cells and upregulated the expression of LC3B-II compared to those in control cells. Furthermore, emodin significantly decreased the expression of p-PI3K, p-AKT and p-mTOR in a dose-dependent manner compared to that in control cells without altering the expression of PI3K, AKT and mTOR. Notably, cotreatment with emodin and 3-methyladenine (3-MA) or rapamycin significantly increased and decreased the apoptosis rate of L02 cells, respectively, compared to that of cells treated with emodin alone.

Conclusion

 In conclusion, emodin exhibited cytotoxicity in the L02 human hepatic cell line by promoting apoptosis, and it also induced autophagy through the suppression of the PI3K/AKT/mTOR signalling pathway. The autophagy could play a protective role following emodin treatment.

Keywords:

• Polygonum multiflorum
• emodin
• hepatoprotective
• apoptosis
• hepatotoxic
• autophagy
• PI3K
• AKT
• mTOR

View correction statement:

Emodin-Induced Autophagy Against Cell Apoptosis Through the PI3K/AKT/mTOR Pathway in Human Hepatocytes [Corrigendum]

Acknowledgments

This work was partially supported by the Natural Science Foundation of Chongqing (cstc2018jscx-msyX0172), and the authors would like to thank the Central Laboratory of Xinqiao Hospital at the Army Medical University.

Abbreviation list

3-MA, 3-methyladenine; AMPK, adenosine 5ʹ-monophosphate (AMP)-activated protein kinase; DEPTOR, DEP domain-containing mTOR-interacting protein; GFP, green fluorescent protein; LC3, microtubule-associated protein 1A/1B-light chain 3; PRAS40, proline-rich AKT substrate of 40 kDa; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Author contributions

The study was conceived and designed by Shi-wen Zhou, Shi-ming Yang and Xiao-yuan Zheng. Technical support was provided by Rong Zhang, Guo-bing Li and Su-min Wang. The manuscript was drafted by Xiao-yuan Zheng and revised by Shi-wen Zhou and Shi-ming Yang. All authors contributed to data analysis, drafting or revising the article, gave final approval of the version to be published, and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.