Gene expression network related to DNA methylation and miRNA regulation during the process of aflatoxin B1‐induced malignant transformation of L02 cells

Aflatoxin is a secondary metabolite secreted by Aspergillus flavus, parasitic Aspergillus, and other fungi through the polyketone pathway, and it can be detected in many foods. Aflatoxin has strong toxicity and carcinogenicity, and many studies have shown that aflatoxin is highly associated with liver cancer. In the present study, malignant transformation of L02 cells was induced by aflatoxin B1 (AFB1), and the gene expression, miRNA expression, and methylation level were detected by high-throughput sequencing. The gene and miRNA expression results showed that 2547 genes and 315 miRNAs were changed in the AFB1-treated group compared with the DMSO group. Among them, RSAD2 and SCIN were significantly upregulated, whereas TRAPPC3L and UBE2L6 were significantly downregulated. Has-miR-33b-3p was significantly upregulated, whereas Has-miR-3613-5p was significantly downregulated. The methylation results showed that 2832 CpG sites were methylated on the promoter or coding DNA sequence (CDS) of the gene, whereas the expression of DNMT3a and DNMT3b was significantly upregulated. Moreover, hypermethylation occurred in TRAPPC3L, CDH13, and SPINK13. The results of GO and KEGG pathway analyses showed that significantly changed genes and miRNAs were mainly involved in tumor formation, proliferation, invasion, and migration. The results of network map analysis showed that Hsa-miR-3613-5p, Hsa-miR-615-5p, Hsa-miR-615-3p, and Hsa-miR-3158-3p were the key miRNAs for malignant transformation of L02 cells induced by AFB1. In addition, the expression of ONECUT2, RAP1GAP2, and FSTL4 was regulated by DNA methylation and miRNAs. These results suggested that the gene expression network regulated by DNA methylation and miRNAs may play a vital role in AFB1-induced hepatocellular carcinoma.