Maternal high-methyl diet suppresses mammary carcinogenesis in female rat offspring

Maternal nutrition during pregnancy influences the development and metabolism of the fetus. Recent studies suggest that the cancer risk of offspring later in life is associated with maternal diet, but little is known about the effect of a maternal diet high in methyl nutrients on breast cancer risk. Lipotropes are methyl group-containing essential nutrients (methionine, choline, folate and vitamin B(12)) that play key roles in one-carbon metabolism. In this study, we investigated the long-term effects of maternal dietary high-dose lipotropes (five times higher than in the control diet) on the development and progression of mammary tumors in rat offspring using two separate experiments (in utero exposure with and without postnatal supplementation). In both experiments, the female offspring were injected intraperitoneally with a single dose (50 mg/kg body wt) of N-nitroso-N-methylurea during puberty to induce mammary tumors. Tumor growth and development were recorded, and at the end of the study, tissues were collected for analysis. For both experiments, the offspring from dams fed a high-dose lipotropes showed significantly decreased tumor incidence, tumor multiplicity and tumor volume, while also displaying a significant increase in survival rate and tumor latency. Gene transcription analysis, as measured by quantitative real-time PCR, revealed a significant decrease of histone deacetylase 1 (Hdac1) messenger RNA in mammary tumors in both experiments. Our findings provide evidence that maternal dietary high-dose lipotropes reduce mammary carcinogenesis in offspring in association with long-term alterations in gene expression and may be useful in developing maternal dietary strategies to prevent breast cancer.