The Antioxidant Alpha-Lipoic Acid Inhibits Proliferation and Invasion of Human Gastric Cancer Cells via Suppression of STAT3-Mediated MUC4 Gene Expression

Figure 5

The role of STAT3 in the inhibition of MUC4 by alpha-lipoic acid in gastric cancer cells. (a) The STAT3 siRNA was cotransfected with pGL3-MUC4 promoter construct into AGS cells pretreated with 2 mM ALA. After incubation with 20 ng/mL TNF-α for 4 h, luciferase activity was determined using a luminometer. (b) STAT3 overexpression construct was cotransfected with a pGL3-MUC4 promoter construct into AGS cells. The transfected cells pretreated with or without 2 mM ALA were incubated with 20 ng/mL TNF-α for 4 h, and then, MUC4 luciferase activity was determined using a luminometer. (c) When cell confluence was 60%, AGS, BGC-823, and MKN-28 cells were incubated with 0, 0.5, 1, or 2 mM ALA for 24 h in RPMI with 10% FBS. After incubation, STAT3 mRNA in the cell lysates was examined by RT-PCR. (d) AGS, BGC-823, and MKN-28 cells pretreated with 0, 0.5, 1, 2, or 2.5 mM ALA for 24 h in RPMI with 10% FBS were treated with or without 20 ng/mL TNF-α. And then, western blotting was performed to analyze p-STAT3 and STAT3 protein level. Data represent the from 3 independent experiments.

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