Ochratoxin A and fumonisin B1 exhibit synergistic cytotoxic effects by inducing apoptosis on rat liver cells

Aflatoxin G1 (AFG1), ochratoxin A (OTA), fumonisin B1 (FB1) and sterigmatocystin (ST) are very common toxic fungal metabolites with high detection rate and toxicity. The co-existence of many mycotoxins in animal feed has been reported worldwide, thus it is important to evaluate the combined cytotoxic effects among these mycotoxins. This study analysed the combined cytotoxic effects of the four mycotoxins in rat liver cells (BRL) and preliminary investigate their molecular mechanism. Cell viability assays were performed in accordance with the central composite design, and the combined index was analysed to estimate the combined effects. 4,6-Diamidino-2-phenylindole staining and flow cytometry analysis were performed, and Western blot analysis and quantitative real-time PCR were used to determine the molecular mechanism. The cytotoxicity of the mycotoxins on BRL was dose-dependent, following the order: ST > OTA > FB1> AFG1. OTA and FB1 presented synergetic cytotoxic effect on BRL by inducing apoptosis. Caspase-3 and Bax expression were induced, whereas Bcl-2 was inhibited by treating with different concentrations of OTA and FB1. In addition, the Bax/Bcl-2 values were gradually increased, which indicated an increased degree of apoptosis. These results suggested that co-exposure of OTA and FB1 in agricultural products may be more hepatotoxic than OTA or FB1separately.