Panel 1: the CD133 antibodies stained intensely at the membrane and in the cytoplasm of cancer cells.

<p>(A): weakly positive or focally positive staining in 10% of cells; (B): moderately or strongly positive-staining involving 10% or more of the cells; (C) and (D): the staining of CD133 on the luminal surface and the basal surface of cancer cells. Panel 2: (A): cytoplasmic or nuclear expression of β-catenin was absent; (B): nuclear expression of β-catenin was less than 10% of the cancer cells; (C) and (D): widespread nuclear accumulation of β-catenin.</p

STIM1 knockdown decreases Ca2+ influx, HMGB1-induced permeability and Src phosphorylation.

<p>A. STIM1 protein expression after RNA inference. EA.hy926 cells were transfected for 48 h with STIM1 siRNA-1, siRNA-2 or control (scrambled) siRNA. Cells were harvested and total protein was extracted and subjected to western blotting with anti-STIM1 antibodies, with anti-GAPDH antibodies as a loading control. STIM1 expression was quantified and analyzed statistically based on three independent experiments. Transfected cells were also stimulated with 200 ng/ml HMGB1 (B) or 1 μM TG (C), followed by the addition of 2 mM CaCl2. Intracellular calcium transients were measured using an Olympus FV1000 confocal microscope. Peak intracellular Ca2+ was quantified during intracellular release or extracellular Ca2+ influx. D. HMGB1-induced permeability was inhibited by STIM1 knockdown. EA.hy926 cells were plated in the upper part of transwell chambers until the formation of a tight monolayer, then transfected with STIM1 siRNA-1, siRNA-2 or control (scrambled) siRNA. HMGB1 200 ng/ml was added and cells were incubated for an additional 24 h. After incubation, endothelial permeability was assessed, as described above. E. Representative immunoblots showing that STIM1 knockdown inhibits Src activation. Transfected cells were treated with or without 200 ng/ml HMGB1 for 2 h. Cell lysates were analyzed by SDS-PAGE followed by western blotting using antibodies against phosphorylated Src and Src. Data are presented as mean ± SD of three independent experiments. *Indicates significant difference compared with the control group (P<0.05).</p

HMGB1 increases endothelial cell permeability.

<p>A. HMGB1-induced TEER decrease. EA.hy926 cells cultured on transwell filters were incubated for 3, 6, 12, 24, 36 and 48h, respectively, with or without 50, 100, 200 and 400 ng/ml HMGB1. The integrity of the tight junctions was assessed by measuring the TER. B. Cell viability in the cells treated by HMGB1. EA.hy926 cells were treated with 50, 100, 200, 400 and 800ng/ml HMGB1, respectively, for 24 h. The cell viability was measured by CCK-8 assay. Data are presented as mean ± SD of three independent experiments. *Indicates significant difference compared with the control group (P<0.05).</p

SKF96365 and 2-APB reduce Ca2+ influx and HMGB1-induced permeability.

<p>EA.hy926 cells were preincubated with 1, 5, 10 μM SKF96365 (A), or 10, 30, 50 μM 2-APB(B) or vehicle (DMSO), then stimulated with 200 ng/ml HMGB1, followed by the addition of 2 mM CaCl2. Intracellular calcium transients were measured using an Olympus FV1000 confocal microscope. Peak intracellular Ca2+ was quantified during intracellular release or extracellular Ca2+ influx. EA.hy926 cells were plated in the upper part of transwell chambers until the formation of a tight monolayer. The cells were preincubated with 1, 5, 10, 20 μM SKF96365 (C), or 10, 30, 50, 70 μM 2-APB (D) for 1 h, respectively. HMGB1 200 ng/ml was then added and the cells were incubated for an additional 24 h. After incubation, the integrity of the tight junctions was assessed by measuring the TER. Data are presented as mean ± SD of three independent experiments. *Indicates significant difference compared with the control group (P<0.05).</p

Disruption of VE-cadherin and intercellular gap formation in HMGB1-treated EA.hy926 cells.

<p>A. Representative immunoblots showing reduced expression of VE-cadherin protein by HMGB1. Total and cell membrane VE-cadherin protein levels were measured by western blotting in EA.hy926 cells treated with HMGB1 for 6, 12, 24 and 48 h, respectively. GAPDH and Na,K-ATPase α1 were used as loading controls for intact cells and plasma membranes, respectively. Western blots were quantified and analyzed statistically based on three independent experiments. *Indicates significant difference compared with wild-type group (P<0.05). B. HMGB1 increased intercellular gap formation. EA.hy926 cells were plated onto a Petri dish until the formation of a tight monolayer then treated with 200 ng/ml HMGB1 for 6, 12 and 24 h, respectively. The cells were fixed and distribution of VE-cadherin was detected using rabbit anti-human VE-cadherin antibody and FITC-labeled goat anti-rabbit antibody. Nuclei were stained with DAPI. Red arrows indicate intercellular gaps. A merged picture is shown for each condition. A representative field for each condition was captured using an Olympus FV1000 confocal microscope. Scale bar = 10 μm.</p

HMGB1 induces Src activation.

<p>A. Representative immunoblots showing HMGB1-induced Src activation. EA.hy926 cells were treated with 200 ng/ml HMGB1 for 1, 2, 3 and 4h, respectively. Cell lysates were analyzed by SDS-PAGE followed by western blotting using antibodies against phosphorylated Src and Src. B. PP2 and CGP77675 inhibit HMGB1-induced permeability. EA.hy926 cells were plated in the upper part of transwell chambers until the formation of a tight monolayer. The cells were preincubated with 1, 2.5, 5, 10 or 20μM PP2 (upper) or 0.5, 1, 2.5, 5 or 10 μM CGP77675 (lower) for 1 h, respectively. HMGB1 200 ng/ml was then added and the cells were incubated for an additional 24 h. After incubation, the integrity of the tight junctions was assessed by measuring the TER. Representative immunoblots showing that PP2 (C) and CGP77675 (D) decreased HMGB1-induced Src phosphorylation. Cells were preincubated with 1, 2.5, 5, or 10μM PP2 or 0.5, 1, 2.5 or 10 μM CGP77675 for 1 h, respectively. 200 ng/ml HMGB1 was then added and cells were incubated for an additional 24h. Cell lysates were analyzed by SDS-PAGE followed by western blotting using antibodies against phosphorylated Src and Src. GAPDH was used as a loading control. Western blots were quantified and analyzed statistically based on three independent experiments. Data are presented as mean ± SD of three independent experiments. *Indicates significant difference compared with the control group (P<0.05).</p