Effect of euphorbia factor L1 on oxidative stress, apoptosis, and autophagy in human gastric epithelial cells.

BACKGROUND

Euphorbia factor L1 (EFL1), a lathyrane-type diterpenoid from the medicinal herb Euphorbia lathyris L. (Euphorbiaceae), has been reported for many decades to induce gastric irritation, but the underlying mechanisms remain unclear.

PURPOSE

The objective of this study was to investigate EFL1-induced cytotoxicity and the potential mechanisms of action on the human normal gastric epithelial cell GES-1.

METHODS

GES-1 cells were treated with EFL1 (12.5-200 μM) for different time intervals, and cell survival, LDH release, intracellular reactive oxygen species (ROS), malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity were detected. Mitochondrial membrane potential (MMP) assay, DAPI staining, DNA fragment assay, and annexin V-FITC/PI staining were performed. The interaction between EFL1 and Bcl-2, cytochrome c, caspase-9, caspase-3, PI3K, AKT, and mTOR proteins was simulated by molecular docking. The mRNA and protein expression of apoptosis and autophagy factors were detected by RT-qPCR and Western blotting.

RESULTS

EFL1 decreased survival, increased LDH leakage, and induced abnormal production of ROS, MDA and SOD in GES-1 cells. Mitochondria-mediated apoptosis was characterized by decreased MMP, condensed nuclei, fragmented DNA, and increased apoptosis rate. EFL1 interacted with proteins via hydrogen bonding. The mRNA, total or phosphorylated protein expression of Bcl-2, mitochondrial cytochrome c, PI3K, AKT, mTOR and p62 were downregulated; in contrast, those of cytoplasmic cytochrome c, cleaved caspase-9, cleaved caspase-3, LC3-ll and Beclin-1 were upregulated.

CONCLUSION

These findings indicated that EFL1 decreased the survival of GES-1 cells through EFL1-induced oxidative stress, activation of the mitochondria-mediated apoptosis as well as autophagy via inhibition of the PI3K/AKT/mTOR pathway.