Background/Objectives
Epidemiological evidence suggests maternal folate status influences childhood leukaemia risk; however, the underlying mechanisms remains unclear. Genetic aberrations are considered leukaemia-initiating events; however, they are insufficient on their own to cause disease, necessitating additional “hits”. Epigenetic alteration, specifically DNA methylation, represents a potential mechanism by which maternal folate is likely to contribute to disease development. Because controlled folate depletion during pregnancy is not feasible in humans, we employed a murine model to investigate the relationship between folate depletion and DNA methylation in tissues relevant to childhood leukaemia.
Methods
Female mice were allocated low or normal folate diets for 4 weeks before mating and onwards. Offspring were sampled at embryonic day 17.5 and at weaning. DNA was isolated from fetal liver and bone marrow of weaned mice, the key haematopoietic sites involved in leukemogenesis. Epigenome-wide DNA methylation was profiled using Infinium® Mouse Methylation BeadChip Array. Differentially methylated probes (DMP) and regions (DMRs) were identified and annotated to genes using R/Bioconductor packages, applying regression models and dimensionality reduction approaches. Gene enrichment analysis was conducted by Enrichr.
Results
In response to folate depletion, 737 genes were differentially methylated in fetal liver (FDR<0.05), encompassing 598 DMPs and 313 DMRs, compared with 1,339 genes in bone marrow (FDR<0.05), encompassing 1,206 DMPs and 515 DMRs. The limited overlap of 83 genes between tissues suggests that folate depletion elicits distinct, tissue-specific methylation changes, while partially targeting common genes. Enrichment analysis of differentially methylated genes exhibited significant enrichment (FDR<0.05) in bone marrow across leukaemia, cancer, immune, neurological, developmental, and syndrome-related datasets, whereas fetal liver showed enrichment primarily in leukaemia, cancer and immune-related datasets. Notably, both tissues revealed significant enrichment in datasets associated with leukemia, other cancers, and immune function.
Conclusion
Overall, folate depletion induces tissue-specific DNA methylation changes, affecting genes in both tissues relevant to leukaemia and immune function. These findings support potential epigenetic mechanisms linking maternal folate status to childhood leukaemia development and highlighting the importance of maternal nutrition as a modifiable factor in public health policy.