Effect of nano-sized iron overload with ascorbic acid on the formation of colonic pre-neoplastic lesions in mice

Iron-overload can cause harmful effects such as cancer and aging via promoting the production of free radicals. The effect of orally administered nano-Fe overload with ascorbic acid on colon carcinogenesis was investigated in male ICR mice. After a 1-week acclimation, 5-week-old mice received three intraperitoneal injections (experimental week 0-2) of azoxymethane (AOM, 10 mg/kg body weight) weekly, followed by 2% dextran sodium sulfate (DSS) in drinking water for the next 1 week to induce aberrant crypt foci (ACF). Animals were divided into four groups; carboxymethylcellulose (CMC) alone (control), CMC + ascorbic acid (AA), CMC + nano-Fe (NFe), and CMC + NFe + AA groups. Animals were fed an AIN-76A purified rodent diet and daily administrated oral doses of 450 ppm each of nano-Fe and AA combination for 6 weeks. The colonic mucosa was stained with 0.5% methylene blue, and then the ACF and polyps were counted. Lipid peroxidation in the serum and liver was evaluated using the thiobarbituric acid-reactive substances (TBARS) assay. Iron concentration in the liver was measured using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Iron concentration in the liver of the NFe-overloaded groups was higher than that of the control (p less than 0.05). AA treatment increased the iron concentration in the liver. The number of ACF was not significantly different among all the groups. The number of polyps in all the NFe-treated groups was slightly higher than that in the control group and AA only-treated group. The serum TBARS was not significantly different among all the groups, but that in the liver was higher in all the NFe-treated groups than it was in the control group (p less than 0.05). These results indicate that the additional NFe treatment did not affect the experimental colon carcinogenesis in mice regardless of the presence of ascorbic acid.