Effects of Ascorbic Acid, Dehydroascorbic Acid and Methotrexate on Breast Cancer Cell Viability

Aims: To examine the effects of ascorbic acid (AA), dehydroascorbic acid (DHA) and methotrexate (MTX) combined treatments on (MDA-MB-231) breast cancer cell viability and intracellular reactive oxygen species (ROS).

Study Design: In-vitro method.

Place and Duration of Study: Biomedical Sciences Research Institute, University of Ulster, Coleraine, BT52 1SA, United Kingdom. September 2016-2017

Methodology: Cytotoxicity tests were performed with MTX (0.01- 1000 µmol/l) alone or in combination with AA or DHA, for 72 h. Cell viability was measured by 3-4,5 dimethylthiazol-2,5 diphenyl tetrazolium bromide (MTT) or Sulforhodamine B (SRB) assays. Intracellular ROS was measured by 2’,7’-dichlorofluroscein diacetate assay.

Results: Treatments of MDA-MB231 cells with single agents, showed dose dependent response with 50% inhibition of cell viability (IC50) of 110.5-201.4 µmol/l (MTX), 2237-5703 µmol/l (AA) or 2474 µmol/l (DHA). Combination studies showed clear synergisms for MTX (~10 µmol/l) and DHA or AA (1100 µmol/l) but weak or no interactions at other concentrations. Three days combination treatment of DHA showed decrease of ROS, which was reversed by MTX (>10 µmol/l).

Conclusions: Co-treatment of methotrexate with AA or DHA showed synergism (C1<1.0) and enhanced cytotoxicity of the anti-folate towards MDA-MB-231 breast cancer cells. Intracellular ROS decreased with AA and DHA treatment, which might be useful for reducing MTX-related oxidative stress.