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Inter-individual differences in the ability of human milk-fat extracts to enhance the genotoxic potential of the procarcinogen benzo[a]pyrene in MCF-7 breast cells.

Kalantzi, Olga I. and Hewitt, Rebecca and Ford, Kirstie J. and Alcock, Ruth E. and Thomas, Gareth O. and Morris, James A. and Hewer, Alan and Phillips, David H. and Jones, Kevin C. and Martin, Francis L. (2004) Inter-individual differences in the ability of human milk-fat extracts to enhance the genotoxic potential of the procarcinogen benzo[a]pyrene in MCF-7 breast cells. Environmental Science & Technology, 38 (13). pp. 3614-3622. ISSN 0013-936X

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Abstract

Environmental factors are believed to play an important role in cancer aetiology. Whether environmental pollutants act in isolation or in combination within mixtures remains unclear. Four human milk-fat extracts (from resident U.K. women) were screened for levels of organochlorinated and brominated compounds prior to being tested (1−50 mg-equiv) for micronucleus (MN)-forming activity in MCF-7 cells. Using the cytokinesis-block micronucleus assay, micronuclei (MNi) were scored in 1000 binucleate cells per treatment. Cell viability (% plating efficiency) and immunohistochemical detection of p53 induction were also measured. The effects of treatment with 1 mg-equiv of extract in combination with benzo[a]pyrene (BP) were also examined. BP−DNA adducts were detected and quantified by 32P-postlabeling analysis. Dose-related increases in MNi independent of pollutant concentrations were induced by milk-fat extracts. All four extracts elevated the percentage of p53 positive cells, although not always in a dose-related fashion. Some combinations resulted in profound low-dose-induced increases in MNi and significant elevations in the percentage of p53 positive cells, which occurred without further reduction in cell viability or mitotic rate. When one particular extract was combined with BP, a 100-fold increase in BP−DNA adducts was detected as compared with the levels induced by BP alone; an effect not induced by other extracts. This adduct-enhancing extract was fractionated into 14 fractions that were subsequently tested (1 mg-equiv of original extract) in combination with 0.01 μM BP. Fraction 1, into which nonpolar pollutants mostly eluted, enhanced MN-forming activity with BP. Surprisingly, the more polar and less likely to contain fat-soluble pollutants fractions 5 and 8 also enhanced MN-forming activity. No identifiable pollutants were present in these fractions. The results suggest that different environmental pollutants present in human tissue may influence the susceptibility of target cells to initiating events.

Item Type: Article
Journal or Publication Title: Environmental Science & Technology
Subjects: Q Science > QH Natural history > QH301 Biology
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 9186
Deposited By: Dr Francis L Martin
Deposited On: 30 May 2008 13:54
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 18:33
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/9186

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