Effects of dietary folic acid on methylation status of colon non-neoplastic epithelium and dysplasia in mice with colitis

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. Overall design: 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), 2 mg/kg chow (folic acid basal level) 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.

叶酸补充（日粮添加8 mg/kg叶酸）可促进由致癌物氧化偶氮甲烷（azoxymethane, AOM）与葡聚糖硫酸钠（dextran sulfate sodium, DSS）诱导的结肠炎模型小鼠的结肠肿瘤发生。该叶酸补充诱导的结肠肿瘤发生与叶酸补充引发的DNA低甲基化显著相关。实验设计：小鼠先饲喂含2 mg/kg叶酸的基础日粮，随后注射致癌物氧化偶氮甲烷。所有小鼠均通过4轮葡聚糖硫酸钠处理诱导结肠炎。首次葡聚糖硫酸钠处理结束后，将小鼠随机分为三组，分别饲喂0 mg/kg叶酸（叶酸缺乏组）、2 mg/kg叶酸（叶酸基础水平组）或8 mg/kg叶酸（叶酸补充组）的日粮，持续干预16周。实验结束后，处死小鼠并收集结肠组织，用于基因表达分析。