Effects of proteasome inhibitor MG132 on autophagy,apoptosis and metastasis in hu-man gastric cancer cells MGC-803
Objective To investigate the effects of proteasome inhibitor MG132 on the autophagy,apoptosis and metastasis of human gastric cancer MCC-803 cells,and analyze the effects of proteasome inhibitor MG132 on the expression of proteins related to epithelial mesenchymal transformation(EMT).Methods MGC-803 cells were treated with different concentrations(0.25 μg/mL,0.50μg/mL,1.00 μg/mL and 2.00 μg/mL)of MG132,the number of autophagosomes were detected by laser confocal microscopy,the proportion of cell apoptosis was detected by flow cytometry and the effect on cell metastasis was detected by Transwell assay.The expression of apoptosis-related proteins and EMT-related proteins were detected by Western blotting assay.Results Compared with the blank control group,MG132 had toxic effects on MGC-803 cells with the increase of MG132 concentration.MG132 at 1.00 μg/mL significantly increased the number of cell auto-phagosomes in MGC-803 cells(1.00 μg/mL:t=9.459,P=0.011).With the increase of MG132 concentration,the ap-optosis percentage increased significantly(0.25 μg/mL:t=5.149,P=0.036;0.50 μg/mL:t=7.342,P=0.018;1.00 μg/mL:t=15.340,P=0.004).Western blotting suggested that after MG132 treatment of MGC-803 cells,the ex-pression of BAX expression gradually increased(0.25 μg/mL:t=4.646,P=0.043;0.50 μg/mL:t=4.610,P=0.044;1.00 µg/mL:t=10.760,P=0.009)and Bcl-2 protein expression gradually decreased(0.25 μg/mL:t=22.850,P=0.002;0.50 μg/mL:t=26.780,P=0.001;1.00 μg/mL:t=29.890,P=0.001).In addition,MG132 inhibited the number of migrating MGC-803 cells(0.25 μg/mL:t=16.730,P=0.004;0.50 µg/mL:t=27.340,P=0.001;1.00 μg/mL:t=32.800,P＜0.001);furthermore,0.50 μg/mL MG132 changed the expression level of EMT-re-lated proteins,and the expression of E-cadherin significantly increased(0.50 μg/mL:t=4.405,P=0.048;1.00 μg/mL:t=12.170,P=0.007),N-cadherin(0.50 μg/mL:t=5.163,P=0.036;1.00 μg/mL:t=6.811,P=0.021)and Vim-entin(0.50 μg/mL;t=5.628,P=0.030;1.00 μg/mL:t=12.670,P=0.006)expression gradually decreased.Con-clusion MG132 could promote autophagy and apoptosis of human gastric cancer MGC-803 cells,and may inhibit cell me-tastasis through EMT process.
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