Abstract

BACKGROUND: This study aims to describe trinitrotoluene (TNT)-induced endoplasmic reticulum stress (ERS) and apoptosis in HePG2 cells.

MATERIAL AND METHODS: HePG2 cells were cultured in vitro with 0, 6, 12, or 24 μg/ml TNT solution for 12, 24, and 48 h. Western blotting was performed to detect intracellular ERS-related proteins, including glucose-regulated protein (GRP) 78, GRP94, Caspase 4, p-Jun N-terminal kinase (JNK), and C/EBP homologous protein (CHOP). Real-time PCR was used to measure mRNA expression from the respective genes.

RESULTS: The expressions of ERS-related proteins GRP78 and GRP94 as well as mRNA and protein expression of ERS signaling apoptotic CHOP in the TNT treatment group were significantly increased. In addition, the mRNA and protein expression levels of ERS-induced apoptotic protein Caspase-4 were significantly increased. Flow cytometry revealed that after TNT treatment, the apoptosis rate also significantly increased.

CONCLUSIONS: TNT could increase the expression levels of GRP78, GRP94, Caspase-4, and CHOP in HePG2 cells; this increase in protein expression might be involved in HePG2 apoptosis through the induction of the ERS pathway.

Keywords: Caspases, Initiator - metabolism, Dose-Response Relationship, Drug, Endoplasmic Reticulum Stress - drug effects, HSP70 Heat-Shock Proteins - metabolism, Heat-Shock Proteins - metabolism, In Situ Nick-End Labeling, Membrane Glycoproteins - metabolism, Membrane Proteins - metabolism, Mitogen-Activated Protein Kinase 8 - metabolism, RNA, Messenger - metabolism, Real-Time Polymerase Chain Reaction, Transcription Factor CHOP - metabolism, Trinitrotoluene - chemistry