Effects of vitamin C-induced hydrogen peroxide (H2O2) on viability of cancer cells.
(a) Cancer cells were treated with vitamin C for 2 h, washed and cultured for an additional 46 h in DMEM in the absence of vitamin C. Cell viability was determined using MTT assays. IC50 values indicate the concentration of vitamin C that inhibited survival by 50%, as determined by MTT assays. (b) Effects of vitamin C on HO-1 expression in MCF7 cells. Cells were treated with vitamin C (1 mM), NAC (10 mM) and H2O2 (1 mM) for 24 h. Expression levels of HO-1 mRNA were measured using qPCR. (c) Suppressive effects of antioxidants NAC and GSH on vitamin C-induced cytotoxicity in MCF7 cells. Cell viability was determined using MTT assays in MCF7 cells treated without or with vitamin C and antioxidants. Data are presented as means ± SDs from triplicate experiments, **P < 0.01.