Fig. 3. Iron is involved in FMD + vitamin C toxicity selectively in KRAS mutated cancer cells.

a Intracellular free iron (Fe²⁺) measurement, relative to CTR cells, of HCT116 treated with STS with or without vitamin C (n = 5). P values were determined by two-sided unpaired t-test. Exact P value= 0.00002 (CTR vs STS + Vit C). b Detection of ferritin (FTH) protein expression by western blot in HCT116 (n = 6, n = 5 in STS), CT26 cells (n = 3) and c HCT116-derived tumor masses (n = 3). VINCULIN as loading control. P values were determined by two-sided unpaired t-test. HCT116 exact P value = 0.000002 (CTR vs STS + Vit C); CT26 exact P value = 0.00002 (CTR vs STS + Vit C). d Three-year (left panel) and 5-year (right panel) overall survival of patient bearing KRAS-mutant (left) and KRAS-wild-type (right) tumors collected from The Cancer Genome Atlas Database (TCGA) and stratified according to intratumor FTH1 mRNA expression levels. P values were determined by Wilcoxon matched-pairs signed rank test. e Viability of HCT116, DLD1 and CT26 cells in response to STS, vitamin C, or their combination with or without desferrioxamine (DFO) (n = 4, n = 3 in DLD1- CTR + DFO + Vit C and CT26- CTR + Vit C). P values were determined by two-sided unpaired t-test. HCT116: exact P value = 0.000003 (STS + Vit C vs STS + DFO + Vit C); DLD1: exact P value = 0.00003 (STS + Vit C vs STS + DFO + Vit C). All data are represented as mean ± SEM, n = independent experiments.