Figure 3. VE-821 sensitizes pancreatic cancer cells to gemcitabine treatment. (A) Clonogenic survival of cells treated with gemcitabine and 1 µM VE-821. Cells were treated with increasing concentrations of gemcitabine for 24 h followed by 72 h treatment of 1 µM VE-821. Colony forming ability was assessed after 10 to 21 d (see graphical representation in panel E). (B) Clonogenic survival of cells treated with gemcitabine in hypoxia. Plated cells were transferred to hypoxia (0.5% O₂) and acclimatized for 6 h. Cells were then treated with increasing concentrations of gemcitabine for 24 h followed by 72 h treatment of 1 µM VE-821. Hypoxic cells were transferred to normoxia 1 h after VE-821 addition. (C) Bar graph representation of clonogenic survival after treatment with 20 nM gemcitabine and VE-821 in oxic and hypoxic (0.5% O₂) conditions, shown in (A and B). (D) Clonogenic survival of cells treated with gemcitabine and irradiation. PSN-1 and MiaPaCa-2 cells were treated with 5 nM or 10 nM gemcitabine, respectively, for 24 h, medium was then replaced and 1 µM VE-821 was added from 1 h prior to 72 h post 4 Gy irradiation. Colony forming ability was assessed after 10 to 21 d. (n = 3). *, p < 0.05; **, p < 0.01; ***, p < 0.001 over DMSO-treated control. (E) Graphical representation for the treatment regimes used in panels [A, B, (C) and D].