Application and adaptation of the in vitro micronucleus assay for the assessment of nutritional requirements of cells for DNA damage prevention.

DNA damage is a fundamental cause of developmental and degenerative diseases. The in vitro cytokinesis-block micronucleus cytome (CBMN-Cyt) assay is an established comprehensive method for assessing cytostasis and chromosome stability in cells. Originally developed to study the acute effects of single environmental genotoxicants, creative applications and adaptations to the basic protocol have allowed its use in evaluating the impacts of dietary micronutrients and micronutrient combinations (nutriomes) on DNA damage. In this review, we examine some of these studies and the important findings they have generated with respect to nutrient/nutrient, nutrient/genotype and nutrient/genotoxicant interactions, as well as assessment of the carcinogenic (or protective) potential of whole dietary patterns. In addition, we outline current knowledge gaps and technical limitations and propose future adaptations to enhance the applicability of the CBMN-Cyt method for in vivo predictions.

The interactive effect of alcohol and folic acid on genome stability in human WIL2-NS cells measured using the cytokinesis-block micronucleus cytome assay.

Chromosomal mutations are commonly found in cancer cells, and can be caused by several factors including dietary insufficiency and exposure to environmental and life-style genotoxins. Folate (vitamin B9), one of the essential micronutrients, is required for DNA repair and synthesis and to maintain genome stability. Since excessive alcohol (ethanol) consumption may alter folate status and low folate might alter susceptibility to alcohol toxicity, a study was performed to investigate the individual and interactive impacts of folic acid (FA) and ethanol on genome stability in vitro. The experiments were performed using WIL2-NS cells cross-tested at three FA (20, 200 and 2000 nM) and four ethanol concentrations (0, 0.09, 0.36 and 1.34%, v/v) over a two-week culture time. Chromosomal damage and cytotoxicity were measured using the cytokinesis-block micronucleus cytome assay. The present study showed dose-related genotoxic effects of both decreasing folic acid concentration and increased ethanol on day 15 resulting in significant induction of micronuclei, nuclear buds and nucleoplasmic bridges which are biomarkers of chromosome breakage or loss, gene amplification and chromosomal rearrangement, respectively. Increased ethanol and FA deficiency interacted to further significantly increase micronuclei and nucleoplasmic bridges. However there was no evidence showing alcohol's ability to cleave FA. The findings from this study suggest a protective effect of FA against alcohol-induced DNA damage and that FA deficiency in the physiological range has a stronger impact on genome stability than exposure to cytotoxic doses of ethanol achievable in binge drinking.