Folic Acid Induces Intake-Related Changes in the Mammary Tissue Transcriptome of C57BL/6 Mice

Abstract

Folic acid (FA) intake has been associated with increased breast cancer risk in some studies. Although underlying mechanisms are unknown, epigenetic modifications that persistently alter transcription have been suggested. We tested the hypothesis that high FA (HFA) intake alters the adult mammary transcriptome in a manner consistent with increased potential for carcinogenesis, detectable beyond the period of intake. C57BL/6 mice were fed control FA (CFA) (1 mg/kg diet) or HFA (5 mg/kg diet) diets for 4 weeks, followed by AIN93M maintenance diet for 4 weeks. Plasma 5-methyltetrahydrofolate, p-aminobenzoylglutamate and unmetabolised FA concentrations were greater (1.62, 1.56, 5.80-fold, respectively) in HFA compared to CFA mice. RNA sequencing of the mammary transcriptome (~20 million reads) showed 222 transcripts (191 upregulated) differentially expressed between groups. Gene Set Enrichment showed upregulated genes significantly enriched in Epithelial Mesenchymal Transition, Myogenesis and Apical Junction and downregulated genes in E2F targets, MYC targets and G2M checkpoint. Cancer was the most altered Disease and Disorder pathway, with Metastasis, Mammary Tumour and Growth of Tumour the most upregulated pathways. ChIP-seq enrichment analysis showed that targets of histone methyltransferase EZH2 were enriched in HFA mice. This study demonstrates HFA intake during adulthood induces mammary transcriptome changes, consistent with greater tumorigenic potential.

Protective Roles of Folic Acid in the Responses of Bovine Mammary Epithelial Cells to Different Virulent Staphylococcus aureus Strains

“…Here, high FA doses were found to promote apoptosis of Mac-T cells, but 5 μg/mL of FA can reduce the apoptosis of the cells induced by S. aureus challenge. This finding is in agreement with previous studies stating that FA has a “double-edge sword” effect [ 18 , 22 , 46 , 47 , 48 , 49 , 50 , 51 ]. Thus, the benefits or downsides of FA for cell apoptosis need to be considered in its future application.…”

Toxicity of methomyl insecticides to testicular cells and protective effect of folic acid

“…In mice, 1/10 median lethal dose (LD50) of methomyl was 1 mg/kg, and exposure to 1 mg/kg methomyl significantly increased lipid peroxidation in mice (El-Demerdash et al, 2013). In addition, 1 mg/kg folic acid treatment could reflect the human recommended daily allowance (RDA) of 200 μg/day and 5 mg/kg folic acid treatment could reflect approximately 5× the human RDA (∼0.8–1.2 mg/day) (Burton et al, 2020). In this study, we treated male mice with methomyl (1 mg/kg/d) and folic acid (1 and 5 mg/kg/d) for 30 days.…”