Maternal B vitamin supplementation from preconception through weaning suppresses intestinal tumorigenesis in Apc ^1638N mouse offspring

Objective: Variations in the intake of folate are capable of modulating colorectal tumorigenesis; however, the outcome appears to be dependent on timing. This study sought to determine the effect of altering folate (and related B vitamin) availability during in-utero development and the suckling period on intestinal tumorigenesis. Design: Female wildtype mice were fed diets either mildly deficient, replete or supplemented with vitamins B ₂, B ₆, B ₁₂ and folate for 4 weeks before mating to Apc ^1638N males. Females remained on their diet throughout pregnancy and until weaning. After weaning, all Apc ^1638N offspring were maintained on replete diets for 29 weeks. Results: At 8 months of age tumour incidence was markedly lower among offspring of supplemented mothers (21%) compared with those of replete (59%) and deficient (55%) mothers (p=0.03). Furthermore, tumours in pups born to deficient dams were most likely to be invasive (p=0.03). The expression of Apc, Sfrp1, Wif1 and Wnt5a - all of which are negative regulatory elements of the Wnt signalling cascade - in the normal small intestinal mucosa of pups decreased with decreasing maternal B vitamin intake, and for Sfrp1 this was inversely related to promoter methylation. β-Catenin protein was elevated in offspring of deficient dams. Conclusions: These changes indicate a de-repression of the Wnt pathway in pups of deficient dams and form a plausible mechanism by which maternal B vitamin intake modulates tumorigenesis in offspring. These data indicate that maternal B vitamin supplementation suppresses, while deficiency promotes, intestinal tumorigenesis in Apc ^1638N offspring.