Transcriptome profiling and DNA methylation analysis of human hepatocyte cell line HHL-16 in response to aflatoxin B1

Abstract

Dietary exposure to aflatoxin B1 (AFB1) can cause acute aflatoxicosis and liver cancer, and is associated with immune suppression and growth impairment, but the molecular mechanisms of the health effects are not fully understood. A non-neoplastic human hepatocyte cell line 16 (HHL-16) was utilized to understand the effects of AFB1 on transcriptome and DNA methylation changes, identifying molecular pathways underlying toxicity and health effects. RNA sequencing and bioinformatic analysis (RNA-Seq) was applied to find the genes and pathways affected by AFB1. Bisulfite pyrosequencing was used to assess DNA methylation levels of CpG sites around promoter regions of gene of interest. RNA-sequencing revealed 280 significantly up-regulated and 296 significantly down-regulated genes in HHL-16 cells after 20 μg/ml AFB1 treatment for 24 h. KEGG pathway enrichment analysis indicated that differentially expressed genes (DEGs) were significantly enriched in the following pathways: cytokine-cytokine receptor interaction, NF-kappa B signalling pathway, TNF signalling pathway, IL-17 signalling pathway, amoebiasis, MAPK signalling pathway, and lipid and atherosclerosis. Further DNA methylation analysis found that there was significant hypomethylation at one CpG site of CCL20 after 20 μg/ml AFB1 treatment on HHL-16 cells for 24 h. In conclusion, AFB1 modulates the expression of genes related to the pathways that play important roles in inflammatory response, growth, and cancers, and demonstrates the effects of AFB1 on DNA methylation.