Interactions between dietary flavonoids apigenin or luteolin and chemotherapeutic drugs to potentiate anti-proliferative effect on human pancreatic cancer cells, in vitro

The objectives were to assess the potential of dietary flavonoids apigenin (Api) and luteolin (Lut) to enhance the anti-proliferative effects of chemotherapeutic drugs on BxPC-3 human pancreatic cancer cells and to investigate the potential molecular mechanism of action. Simultaneous treatment or pretreatment (0, 6, 24 and 42 h) of flavonoids and chemotherapeutic drugs at various concentrations (0–50 μM) were assessed using the MTS cell proliferation assay. Simultaneous treatment with either flavonoid (13, 25 or 50 μM) and chemotherapeutic drugs 5-fluorouracil (5-FU, 50 μM) or gemcitabine (Gem, 10 μM) for 60 h resulted in mostly less-than-additive effects (p < 0.05). Pretreatment for 24 h with 13 μM of either Api or Lut, followed by Gem for 36 h was optimal to inhibit cell proliferation. Pretreatment of cells with 11–19 μM of either flavonoid for 24 h resulted in 59–73% growth inhibition when followed by Gem (10 μM, 36 h). Lut (15 μM, 24 h) pretreatment followed by Gem (10 μM, 36 h), significantly decreased protein expression of nuclear GSK-3β and NF-κB p65 and increased pro-apoptotic cytosolic cytochrome c. Pretreatment of BxPC-3 human pancreatic cancer cells with low concentrations of Api or Lut effectively aid in the anti-proliferative activity of chemotherapeutic drugs.