Effects of dietary folic acid levles on colitis-associated tumorigenesis.

Folic acid supplementation (8 mg/kg diet) promotes colon tumor formation in mice with established colitis induced by carcinogen azoxymethane (AOM) and dextran sulfate sodium sulfate (DSS). This induction of colon tumors was associated with hypomethylation of DNA cased by folic acid supplementation. Mice were fed a diet containing folic acid 2 mg/kg chow (basal level), followed by carcinogen azoxymethane injection. Colitis was induced in all mice using 4 cycles of DSS. Immediately after the first DSS treatment, mice were randomized to receive folic acid 0 mg/kg chow (folic acid deficient) or 8 mg/kg chow (folic acid supplemented) for 16 weeks. At the end of study, mice were euthanized and colons were collected and process for gene expression analyses