Molecular signatures of cytotoxic effects in human embryonic kidney 293 cells treated with single and mixture of ochratoxin A and citrinin

Ochratoxin A (OTA) and citrinin (CTN) are important mycotoxins, which often coexist in food and feed stuff. In this study, individual and combinative cytotoxicity of OTA and CTN were tested in human embryonic kidney (HEK) 293 cells via MTT assay, and synergistic cytotoxic effects were found following co-treatment with OTA and CTN, manifested by significant accumulation of HEK293 cells in S and G2/M stages. Transcriptomic and sRNA sequencing were performed to explore molecular signatures mediating individual or combinative cytotoxicity. A total of 378 miRNAs were identified, among which 66 miRNAs targeting thousands of genes were differentially expressed in response to different treatments, and 120 differentially expressed genes (DEGs) were regulated by either individual or combinative treatments. Correlations between two representative miRNAs (hsa-miR-1-3p and hsa-miR-122-5p), and their target genes, programmed cell death 10 (PDCD10) and cyclin G1 (CCNG1), associated with apoptotic signaling and cell cycle were analyzed by luciferase assay system. Further, their expression patterns were validated by quantitative real-time PCR and western blot analysis, suggesting that both miRNA-target interactions might account for the mycotoxin-induced cell death. Taken together, these findings provide molecular evidences for synergistic cytotoxic effects of exposure to single and mixture of OTA and CTN in HEK293 cells.