title: Fumonisin B1 induces global DNA hypomethylation in HepG2 cells - An alternative mechanism of action.
abstract: Fumonisin B1 (FB1), a common mycotoxin contaminant of maize, is known to inhibit sphingolipid biosynthesis and has been implicated in cancer promoting activity in animals and humans. FB1 disrupts DNA methylation and chromatin modifications in human hepatoma (HepG2) cells. We investigated the effect of FB1 on enzymes, DNA methyltransferases and demethylases, involved in chromatin maintenance and gross changes in structural integrity of DNA in HepG2 cells. We measured: (i) the expression of 84 key genes encoding enzymes known to modify genomic DNA and histones (superarray and qPCR); (ii) protein expression of DNA methyltransferases (DNMT1, DNMT3A and DNMT3B) and the major demethylase (MBD2) (western blotting); (iii) degree of DNA methylation by FACS using anti-5-MeCyt and (iv) DNA migration (single cell gel electrophoresis). FB1 significantly decreased the methyltransferase activities of DNMT1, DNMT3A and DNMT3B, and significantly up regulated the demethylases (MBD2 expression and activity, and KDM5B and KDM5C expression). FACS data showed FB1 significantly increased DNA hypomethylation and resulted in gross changes in structural DNA as evidenced by the Comet assay. We conclude that FB1 induces global DNA hypomethylation and histone demethylation that causes chromatin instability and may lead to liver tumourigenesis.
authors.affiliation: Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Durban, South Africa. Electronic address: chutur@ukzn.ac.za.
authors.forename: Anil
authors.initials: A
authors.lastname: Chuturgoon
authors.affiliation: Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Durban, South Africa. Electronic address: Phulukdaree@ukzn.ac.za.
authors.forename: Alisa
authors.initials: A
authors.lastname: Phulukdaree
authors.affiliation: Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Durban, South Africa. Electronic address: Devan_Moodley@hms.harvard.edu.
authors.forename: Devapregasan
authors.initials: D
authors.lastname: Moodley
mesh_terms: D015153:Blotting, Western; D002274:Carcinogens, Environmental / Q000633:toxicity*; D002843:Chromatin / Q000187:drug effects; D020552:Comet Assay; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects*; D000090205:DNA Methyltransferase 3A; D037341:Fumonisins / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects*; D056945:Hep G2 Cells; D056466:Histone Demethylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D015854:Up-Regulation / Q000187:drug effects; D000097584:DNA Methyltransferase 3B
chemical_list: D002274:Carcinogens, Environmental; D002843:Chromatin; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D037341:Fumonisins; D056466:Histone Demethylases; D006657:Histones; D000097584:DNA Methyltransferase 3B; C000717967:DNMT3A protein, human; C056933:fumonisin B1; C000619380:DNMT1 protein, human
keywords: DNA hypomethylation; Demethylase; Fumonisin B(1); Histones; Liver cancer; Methyltransferase