Response of intestinal HT-29 cells to the trichothecene mycotoxin deoxynivalenol and its sulfated conjugates.

The sulfated forms of the Fusarium toxin deoxynivalenol (DON), deoxynivalenol-3-sulfate (DON-3-Sulf) and deoxynivalenol-15-sulfate (DON-15-Sulf) were recently described, however little is known about their mechanism of action in mammalian cells. DON-3-Sulf and DON-15-Sulf were taken up by HT-29 colon carcinoma cells, although to a lesser extent compared to DON. All three compounds were found to enhance the intracellular ROS level in the dichlorofluorescein assay (≥ 1μM), even though substantial differences were observed in their cytotoxic potential. In silico modelling highlighted that DON-sulfates do not share the classical mechanism of action of DON, being unable to fit into the ribosomal pocket and trigger the classical ribotoxic stress response. However, DON-3-Sulf and DON-15-Sulf sustained a distinctive proliferative stimulus in HT-29 and activated autophagy. The mechanisms of action of DON-3-Sulf and DON-15-Sulf suggest a potential interplay between the onset of ribosomal inhibition and autophagy activation as an alternative and/or complementary mode of action for DON and its sulfated analogues.