[STAT3 inhibitor Stattic induced IL-8 production and cell apotosis in THP-1 cells by activating ERK pathway].

Objective To observe the effect of selectively inhibiting STAT3 on the production of IL-8 and cell apoptosis of THP-1 cells by Stattic, and explore the underlying mechanism. Methods THP-1 cells were treated with different concentrations of Stattic ( 0, 1, 5, 10, 15, 20 μmol/L) for 0, 1, 3, 6, 12, 24 hours. Reverse transcription PCR or real-time PCR was performed to detect the mRNA expression of IL-8, IL-6, IL-1β and tumor necrosis factor-α (TNF-α); ELISA was used to detect the protein expression of IL-8; flow cytometry was applied to evaluate the apoptosis of THP-1 cells; and Western blot analysis was performed to detect the phosphorylation of STAT3 and extracellular signal-regulated kinase (ERK). Reverse transcription PCR was used to test the effect of U0126 at different concentrations (0, 1, 5, 10 μmol/L) on the mRNA expression of IL-8 induced by Stattic in THP-1 cells. Results Stattic significantly up-regulated the mRNA and protein expression of IL-8 in THP-1 cells in a concentration range of 10~20 μmol/L, and induced cell apoptosis only at high concentration (15, 20 μmol/L). Treated with Stattic for 0, 1, 3, 6, 12, 24 hours, IL-8 mRNA was significantly up-regulated, and after 6 hours, the expression of IL-8 protein and apoptosis of THP-1 cells were up-regulated in a time-dependent manner. STAT3 phosphorylation was inhibited in a time- and dose-dependent manner by Stattic. ERK phosphorylation was induced by different concentrations of Stattic in a time-dependent manner. In addition, U0126, a selective inhibitor of ERK pathway, inhibited Stattic-induced IL-8 expression in a concentration-dependent manner. Conclusion Stattic, a selective STAT3 inhibitor, can induce the apoptosis and IL-8 production by activating ERK signaling pathway in THP-1 cells.