Combination of FOXM1/Proteasome inhibitors and DNA-damaging agents sensitizes human cancer cells to programmed cell death.

<p>(<b>A</b>) Pancreatic cancer cells MIA PaCa-2 were treated with the indicated concentrations of doxorubicin and bortezomib (Bor) alone or in combination. 24 hours after treatment cell lysates were analyzed by immunoblotting with cleaved caspase-3, PARP and β-actin antibodies. (<b>B</b>) MIA PaCa-2 pancreatic cancer cells were treated with doxorubicin and thiostrepton (Thio) alone or in combination with the indicated concentrations for 24 hours. Immunoblotting was performed with antibodies specific for cleaved caspase-3 and β-actin as the loading control. (<b>C</b>) Pancreatic cancer cell line MIA PaCa-2 was exposed to γ-irradiation and treated in combination with thiostrepton or bortezomib for 24 hours. Immunoblotting was carried out for cleaved caspase-3 and β-actin as the loading control. (<b>D</b>) MDA-MB-231 breast cancer cells were treated with doxorubicin in combination with thiostrepton or bortezomib as indicated for 24 hours. Cell lysates were analyzed by immunoblotting with antibodies specific for cleaved caspase-3 and β-actin as the loading control. (<b>E</b>) Hep3B liver cancer cells were treated with doxorubicin and thiostrepton alone or in combination as indicated for 24 hours. Immunoblotting was performed with antibodies specific for cleaved caspase-3 and β-actin as the loading control. (<b>F</b>) Breast cancer cell line MDA-MB-231 was subjected to γ-irradiation and treated in combination with thiostrepton or bortezomib for 24 hours. Immunoblot analysis was performed with cleaved caspase-3 and β-actin antibodies. (<b>G–H</b>) 1×10⁵ MIA PaCa-2 (G) or MDA-MB-231 (H) human cancer cells were plated and treated as indicated for 24 hours. 10 days after treatment cells were stained with crystal violet and representative plates are shown. Graph shows the quantification ±SD of duplicate experiments (*, <i>P</i><0.05; **, <i>P</i><0.01; ***, <i>P</i><0.001).