Vitamin B12 and Methionine Deficiencies Induce Genome Damage Measured Using the Cytokinesis-Block Micronucleus Cytome Assay in Human B Lymphoblastoid Cell Lines

Abstract

One-carbon metabolism is a network of interrelated biochemical reactions that has 2 major functions: DNA methylation and DNA synthesis. Methionine (Met), an essential amino acid, is converted to S-adenosyl-methionine (SAM), the body's main methyl group donor, which is converted to S-adenosylhomocysteine during methylation reactions. Vitamin B12 (B12) acts as a coenzyme of methionine synthase, which is required for the synthesis of Met and SAM. To determine the effects of Met and B12, we used the cytokinesis-block micronucleus assay in GM13705 and GM12593 cell line cultures exposed to 13 unique combinations of B12 and Met concentrations over 9 days. The nutrient levels chosen span the normal physiological ranges in humans. The Met-B12 concentration significantly and negatively correlated with all markers of genotoxicity in the 2 cell lines tested. In both cell lines, all markers of genotoxicity were significantly higher when treated with 15 μM Met than when treated with 50 μM Met, regardless of the B12 treatment level. Genotoxicity was significantly reduced in the group treated with 50 μM Met and 600 pM B12. Concentrations of 50 μM Met and 600 pM B12 are an optimal combination for stabilizing the genome. It is advisable to acquire adequate amounts of Met and B12 for maintaining genome stability.

Epigenetic Regulation of Centromere Chromatin Stability by Dietary and Environmental Factors

“…Similar scenarios have also been observed for deficiencies in vitamin B-12, riboflavin, vitamin A, and minerals such as calcium and zinc (99). Conversely, supplementation with folic acid (97, 100-108), riboflavin, pantothenic acid, biotin (4), cobalamin (93,103), vitamin C (109)(110)(111)(112)(113)(114)(115), vitamin E (114), and vitamin A and its derivatives (107,112) was associated with decreased genotoxic damage and micronucleus reduction (4). Much research has been conducted to show the effects of folic acid supplementation and folate status on reduced micronucleus frequency.…”

The Role of Genetic Polymorphisms as Related to One-Carbon Metabolism, Vitamin B6, and Gene–Nutrient Interactions in Maintaining Genomic Stability and Cell Viability in Chinese Breast Cancer Patients

“…We hypothesized that decline in the MNBN frequencies with increasing B6 concentration may be due to a slowdown of the cell proliferation speed or to the wear of strongly damaged cells [ 22 , 23 , 24 ]. Anyhow, the cells will not arrive at the mitotic telophase when MNBNs are marked in BN cells.…”

“…In spite of its significance in the one-carbon metabolism and the elimination of oxidative stress, there is limited basic experimental proof of an association of B6 and the above-mentioned enzymes with susceptibility to cancer, especially breast cancer [ 19 , 20 , 21 ]. We previously reported associations among two polymorphisms in the MTHFR gene (677 and 1298 loci), folate (or folic acid), B12 deficiency, genome instability, and increased cell death with breast cancer risk in the Chinese Yunnan population [ 14 , 22 , 23 , 24 ]. Based on previous work, we utilized the cytokinesis-block micronucleus assay (CBMN) and PCR-restriction fragment length polymorphism (PCR-RFLP) techniques to determine the relationships between B6 deficiency, the other above-mentioned genetic polymorphisms in the folate pathway, gene-nutrient interactions and genomic stability and cell viability (GSACV) in vitro.…”