Thymoquinone inhibits proliferation in gastric cancer via the STAT3 pathway in vivo and in vitro

Figure 3 Thymoquinone suppresses STAT3-dependent reporter gene expression and activates caspase activity. A: Thymoquinone (TQ) suppressed STAT3 transcriptional activity. HGC27 cells (1 × 10⁶/mL) were transfected with STAT3-luciferase (STAT3-Luc) plasmid, incubated for 24 h, and treated with 25, 50, and 75 μmol/L TQ for 24 h. Whole-cell extracts were then prepared and analyzed for luciferase activity. The results shown are representative of three independent experiments; B: TQ inhibited the expression of Cyclin D, survivin, and VEGF. HGC27 cells (1 × 10⁶/mL) were treated with the indicated concentrations of TQ for 24 h, and western blotting was performed. The same blots were stripped and reprobed with the GAPDH antibody to verify equal protein loading; C: HGC27 cells (1 × 10⁶/mL) were treated with the indicated concentrations of TQ for 24 h, and whole-cell extracts were prepared, separated by SDS-PAGE, and subjected to western blot against Bcl-2, Bax, and PARP antibody. The same blot was stripped and reprobed with GAPDH antibody to show equal protein loading; (D) TQ activates caspase activity. HGC27 cells (1 × 10⁶/mL) were treated with the indicated concentrations of TQ for 24 h, and western blotting was performed. The results shown are representative of three independent experiments. PARP: Poly(ADP-ribose)polymerase