Evidence for the presence of mutagenic arylamines in human breast milk and DNA adducts in exfoliated breast ductal epithelial cells

Abstract

Aromatic and heterocyclic amines are ubiquitous environmental mutagens present in combustion emissions, fried meats, and tobacco smoke, and are suspect human mammary carcinogens. To determine the presence of arylamines in breast tissue and fluid, we examined exfoliated breast ductal epithelial cells for DNA adducts and matched human milk samples for mutagenicity. Breast milk was obtained from 50 women who were 4 -6 weeks postpartum, and exfoliated epithelial-cell DNA was evaluated for bulky, nonpolar DNA adducts by 32 P-postlabeling and thin-layer chromatography. Milk was processed by acid hydrolysis, and the extracted organics were examined in the standard plate-incorporation Ames Salmonella assay using primarily strain YG1024, which detects frameshift mutations and overexpresses aryl amine N-acetyltransferase. DNA adducts were identified in 66% of the specimens, and bulky adducts migrated in a pattern similar to that of 4-aminobiphenyl standards. The distribution of adducts did not vary by NAT2 genotype status. Of whole milk samples, 88% (22/25) had mutagenic activity.Among the samples for which we had both DNA adduct and mutagenicity data, 58% (14/19) of the samples with adducts were also mutagenic, and 85% (11/13) of the mutagenic samples had adducts. Quantitatively, no correlation was observed between the levels of adducts and the levels of mutagenicity. Separation of the milk showed that mutagenic activity was found in 69% of skimmed milk samples but in only 29% of the corresponding milk fat samples, suggesting that the breast milk mutagens were moderately polar molecules. Chemical fractionation showed that mutagenic activity was found in 67% (4/6) of the basic fractions but in only 33% (2/6) of acidic samples, indicating that the mutagens were primarily basic compounds, such as arylamines. Although pilot in nature, this study corroborates previous findings of significant levels of DNA adducts in breast tissue and mutagenicity in human breast milk and indicates that breast milk mutagens may be moderately polar basic compounds, such as arylamines.

Carcinogen–DNA adducts in human breast epithelial cells

“…It was previously found [Thompson et al, 2002] that human breast milk exhibits mutagenic activity. The same study showed that most of the mutagenicity is in the basic fraction of the milk, which implies that basic compounds such as aromatic and heterocyclic amines, and polycyclic aromatic hydrocarbons contribute to the observed mutagenicity.…”

“…The study by Thompson et al [2002] showed that epithelial cells from human breast milk that had mutagenic activity contained bulky DNA adducts. The presence of DNA-carcinogen adducts was earlier demonstrated in human breast tissue [Perera et al, 1995;Li et al, 1996] and in cultured human epithelial cells [Swaminathan et al, 1994].…”

Alterations of DNA methylome in human bladder cancer

“…[92][93][94][95] However, the genotoxicity of aromatic amines is not exclusive to the target organ of tumorigenesis. 24,[94][95][96][97][98] This suggests that an alternative mode of action (epigenetics) may also exist that singly or in combination with genotoxicity can explain the bladder-specific tumorigenicity of aromatic amines. 24 The concept of a chemical carcinogen exerting its biological effects through epigenetic changes is very novel, and has never been investigated comprehensively.…”

DNA damage in human breast milk cells and its induction by early and late milk extracts

“…In five determinations the 2-Amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) (Ͼ97% pure) was cell number ranged from 3.2ϫ10 4 /ml breast milk to 1.08ϫ10 6 /ml, in line with obtained from Toronto Research Chemicals (Toronto, Canada). All other published values (14). The numbers of epithelial cells present were measured chemicals, including o-toluidine, were obtained from Sigma Chemical Co.…”

“…Donors whose untreated cells contained the most DNA damage tended to from freshly expressed milk provides a ready source, obtained yield genotoxic breast milk extracts. Cells isolated from non-invasively, of HMECs in which to study the presence of, milk activated the rodent mammary carcinogens o-toluidine and their susceptibility to, DNA damage (14,15). Analysis, in and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine tandem, of the milk from which the cells were obtained (PhIP).…”