Persistent microRNA-gene networks in primary human hepatocytes upon withdrawal of aflatoxin B1 exposure are related to hepatocellular carcinoma [miRNA]

Hepatocellular carcinoma (HCC), one of the most common cancer types, is a multi-factorial disease. One strongly associated factor is oral exposure to the food-contaminant aflatoxin B1 (AFB1). A clear link between AFB1-induced p53 mutations and HCC exists, however less is known about the association with microRNA expression changes. In particular, irreversible adverse effects that may occur at the transcriptomic level following repetitive exposure have not been investigated yet. Therefore, in this study, we aimed to dissect persistent changes in expression of microRNA-directed regulatory networks from transient transcriptome modifications contributing to AFB1-induced HCC. Primary human hepatocytes were exposed to 1 µM of AFB1 for 5 days followed by a 3 day wash-out period. Whole genome transcriptomic analysis and microRNA expressions were analyzed applying microarray technologies. By evaluating genes which remain significantly expressed into the same direction after the 3-day wash-out period persistent AFB1-induced and HCC-related biological processes could be identified. Persistent genes could be linked with "Drug and energy metabolism" and "Pre-, post- and transcriptional regulation of gene expression" related processes. Especially, two HCC-related microRNAs, hsa-miR-34b-5p and hsa-miR-222-3p, which are persistently expressed, seem to regulate genes involved in these very characteristic AFB1-induced processes referring to cancer-associated metabolism changes and regulation of gene expression. Moreover, hsa-miR-34a-5p, hsa-miR-96-5p and hsa-miR-30a-3p which become differentially expressed only upon terminating AFB1 exposure, seem to regulate persistently expressed genes. The findings within this study therefore contribute to a better understanding of the AFB1-induced onset of HCC by causing persistent effects on microRNA and gene expression. The study investigated differential gene expression and microRNA expression changes in a pool of primary human hepatocyte RNA after 3 days of wash out following 5 days of repetative exposure to 1uM of aflatoxin B1 or DMSO. Three biological replicates per compound/solvent. In total 6 arrays.