Purpose: To explore the apoptotic effect of ubiquitin-proteasome inhibitor (PI) MG-132 on human tongue squamous cell carcinoma cell line (Tca-8113 cell) through endoplasmic reticulum stress.
Methods: Tca-8113 cells were cultured in RPMI 1640 medium supplemented with 10% fetal calf serum, the exponential cells were divided into 5 groups.The cell culture medium was added to 1640 (negative control group), thapsigargin 5 μmol/L (positive control group), and 10,20,30 μmol/L (MG-132 group). After 24 h, the following experiments were carried out: morphological change of apoptotic cells was observed by Hoechst 33258 fluorescent staining under fluorescent microscope, apoptotic rate of cells was determined with annexin V-FITC/PI double staining by flow cytometry, the GRP78 mRNA level was determined by RT-PCR, the expression of caspase-12 protein was evaluated by Western blot, the human ubiquitin-protein ligase E3 concentration was detected by ELISA. The data was analyzed using SPSS16.0 software package.
Results: Typical morphological change of apoptosis in Tca-8113 cells was observed 24 hours after treating with 10.0, 20.0, 30.0 μmol/L MG-132 and positive control group; The apoptotic rate of MG-132 groups gradually increased with MG-132 concentration; The GRP78 mRNA level was up-regulated; The expression of caspase-12 increased was demonstrated by Western blot; The expression of the human ubiquitin-protein ligase E3 in MG-132 groups was 28.75 ± 2.28, 18.16 ± 0.65 and 8.85 ± 0.72.
Conclusions: MG-132 can induce apoptosis of Tca-8113 cells through endoplasmic reticulum stress; MG-132 can inhibit the expression of human ubiquitin ligase E3.