Figure 5

RLE inhibited STAT3 signaling in RA-FLS. (A) IL-6/sIL-6R time-dependently induced phosphorylation of STAT3 in RA-FLS. Synoviocytes were treated with IL-6/sIL-6R for indicated durations. (B) RLE suppressed the phosphorylation of STAT3 and JAK2 in IL-6/sIL-6R-stimulated synoviocytes. Cells were pre-treated with indicated concentrations of RLE for 1 h and then treated with or without IL-6/sIL-6R for 40 min. (C) RLE suppressed IL-6/sIL-6R-induced STAT3 nuclear localization in synoviocytes. Cells were treated as in (B). (D) RLE lowered protein levels of Bcl-2 and Mcl-1 in IL-6/sIL-6R-stimulated synoviocytes. Synoviocytes were pre-treated with indicated concentrations of RLE for 1 h and then treated with or without IL-6/sIL-6R for 24 h. In (A–D), protein levels were examined using immunoblotting. Representative blots are shown in left panels. Protein levels relative to loading controls were analyzed using ImageJ software, and are shown in right panels (n = 3). In (A,B,D), GAPDH served as the loading control. In (B), Lamin B1 and GAPDH served as loading controls of nuclear and cytoplasmic extracts, respectively. In (A), ## P < 0.01 vs. 0-min time point group. In (B–D), * P < 0.05, ** P < 0.01 vs. IL-6/IL-6R-only-treated group. #P < 0.05, ## P < 0.01 vs. vehicle-treated control group.