Figure 6

Reversal of STAT3-decoy ODN-mediated inhibition of STAT3 nuclear translocation and cell death by IL-6 activation or overexpression of STAT3. A: Nuclear STAT3 in IL-6- and STAT3-decoy ODN-treated cells. Non-treated (1, 2, 3 and 4), IL-6 treated (50 ng/ml, 16 h) (5, 6, 7 and 8) cells, non-transfected (1, 2, 5 and 6), STAT3-decoy ODN-transfected (2 μg/ml) (3, 4, 7 and 8) cells. B: nuclear STAT3 in STAT3-overexpressing cells transfected with STAT3-decoy ODN. Non-transfected (1, 3 and 7) and STAT3 plasmid (PLZst3α) (2, 4, 5 and 6) transfected cells. Stattic (6 and 7), STAT3-decoy ODN (lanes 3 and 5), or IL-6 (4 and 7) -treated cells. Diminished nuclear STAT3 in STAT3-overexpressing cells, treated with STAT3-decoy ODN or Stattic (5 μM) (compare 2, 5 and 6) (short exposure). (nuclear extracts are shown). C: Increased STAT3-decoy ODN prevents overexpressed STAT3 nuclear entry. ST3-PLZst3α plasmid-transfected cells transfected with 2 μg (2, 5), 4 μg (3, 6) or no (1, 4) decoy ODN. D: Nuclear accumulation of overexpressed DBD mutated STAT3: control (1 and 4), mutated STAT3-decoy ODN- (2 μg/ml) (2 and 5) or STAT3-decoy ODN- (2 μg/ml) (3 and 6) transfected cells. E: Cell death (trypan blue exclusion) in control (black histograms) and STAT3-overexpressing cells (white histograms). Non-treated or Stattic- (5 μM), STAT3-decoy ODN- (2 μg/ml, 48 h) (ST3dODN), Stattic (5 μM) and IL-6- (50 ng/ml), mutated STAT3-decoy ODN- (2 μg/ml, 48 h) (mtdODN), or mutated STAT3-decoy ODN (2 μg/ml, 48 h) (mtdODN) and IL-6- (50 ng/ml, 48 h) treated cells (data in % of dead cells). F: Summary plot for A, B and C showing inverse nuclear STAT3/dead cells correlation (a.u.: arbitrary units).