Transcriptomics and flow cytometry reveals the cytotoxicity of aflatoxin B and aflatoxin M in bovine mammary epithelial cells.

Aflatoxin is a known mycotoxin that pollutes various grains widely in the environment. Aflatoxin B (AFB) and Aflatoxin M (AFM) have been shown to induce cytotoxicity in many cells, yet their effects on mammary epithelial cells remain unclear. In this study, we examined the toxicity and the effects of AFB and AFM on bovine mammary epithelial cells (BME cells). The cells were treated with AFB or AFM at a concentration of 0-10 mg/L for 24 or 48 h, followed by cytotoxicity assays, flow cytometry, and transcriptomics. Our results demonstrated that AFB and AFM induced cell proliferation inhibition, apoptosis and cell cycle arrest. However, the level of intracellular reactive oxygen species has no significant difference. The RNA-Seq results also showed that AFB and AFM changed many related gene expressions like apoptosis and oxidative stress, cycle, junction, and signaling pathway. Taken together, AFB and AFM were found to affect cytotoxicity and related gene changes in BME cells. Notably, this study reported that 2 mg/L of AFB and AFM affected the expression of methylation-related genes, and ultimately altered the rate of mA methylation in RNA. It may provide a potential direction for toxins to indirectly regulate gene expression by affecting RNA methylation modification. Our research provides some novel insights and data about AFB and AFM toxicity in BME cells.