Chronic exposure to aflatoxin B1 (AFB1) has, in certain regions in the world, been strongly associated with hepatocellular carcinoma (HCC) development. AFB1 is a very potent hepatotoxic and carcinogenic mycotoxin which is frequently reported as a food contaminant. Epigenetic modifications provoked by environmental exposures, such as AFB1, may create a persistent epigenetic footprint. Deregulation of epigenetic mechanisms has actually been reported in HCC patients following AFB1 exposure; however, no attempts have yet been made to investigate early effects on the epigenome level which may be persistent on longer term, thereby possibly initiating carcinogenic events. In this study, we aim to identify methyl DNA-mRNA-interactions representative for a persistent epigenetic footprint associated with the early onset of AFB1-induced HCC. For this, primary human hepatocytes were exposed to 0.3μM of AFB1 for 5 days. Persistent epigenetic effects were measured 3 days after terminating the carcinogenic exposure. Whole genome DNA methylation changes and whole genome transcriptomic analysis were analyzed applying microarray technologies, and cross-omics interactions were evaluated. Upon combining transcriptomics data with results on DNA methylation, a range of persistent hyper- and hypo-methylated genes was identified which also appeared affected on the transcriptome level. For six of the hypo-methylated and up-regulated genes, namely TXNRD1, PCNA, CCNK, DIAPH3, RAB27A and HIST1H2BF, a clear role in carcinogenic events could be identified. This study is the first to report on a carcinogen-induced persistent impact on the epigenetic footprint in relation with the transcriptome which could be indicative for the early onset of AFB1-related development of HCC.
Keywords: Aflatoxin B1; Epigenomics; Hepatocellular carcinoma; Persistence; Wash-out.
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