Interaction of aflatoxin B 1 and fumonisin B 1 in HepG2 cell apoptosis

Abstract

Abstract Aflatoxin B 1 (AFB 1 ) and fumonisin B 1 (FB 1 ) are mycotoxins commonly coexisted in cereal-based ingredients or foods, and their co-apoptotic activity in HepG2 cells was studied to further the understanding of their combinative toxicity. The values of IC 50 , based on sulforhodamine B (SRB) colorimetric assay, were 9.5 μM and 481.7 μM for AFB 1 and FB 1 , respectively, showing AFB 1 is more toxic to HepG2 cells than FB 1 . The cytotoxicity was also evidenced by substantially decreased contents of cellular DNA and ATP accompanying an increase of intracellular ROS upon exposure to AFB 1 (1 μM = 10% IC 50 ) , FB 1 (70 μM = 10% IC 50 ) and their combinations. After HepG2 cells were arrested in S or G0/G1 phase after exposure to mycotoxins, flow cytometry assay on the rate of apoptosis showed a synergistic interaction (p 1 and FB 1 at dosage levels with equivalent toxicity of 10% and 30% measured by SRB assay. Consistently, immunocytochemistry analysis on the expression of apoptosis related proteins showed higher expression of Bax, Caspase 3, and p53 upon exposure to combinations of AFB 1 and FB 1 than their individual treatments at the dosages with the same equivalent level of toxicity. In the meantime, it seems that the expression of capase-8 is antagonistic between AFB 1 and FB 1 , which indicates the synergetic proapoptotic activity of AFB 1 and FB 1 is likely caused by their different mechanisms in HepG2 cell apoptosis upon mycotoxin exposure.