Toxicity and apoptosis induced by the mycotoxins nivalenol, deoxynivalenol and fumonisin B1 in a human erythroleukemia cell line

The toxicity of the mycotoxins nivalenol (NIV), deoxynivalenol (DON) and fumonisin B1 (FB1) were studied in the K562human erythroleukemia cell line using the Trypan Blue, MTT and BrdU uptake analyses of cytotoxicity, cell metabolism and cell proliferation, respectively. Nuclear staining with propidium iodide and DNA analysis by flow cytometry were used to identify apoptosis and cell cycle distribution. By the MTT and BrdU tests, both NIV and DON were significantly more toxic than FB1 by at least one order of magnitude, with ID50s ranging from 0.5 mM for NIV to 70 mM for FB1. The MTT test indicated that NIV was significantly (approximately four times) more toxic than DON. In contrast, the Trypan Blue test did not reveal any effects of mycotoxin exposure suggesting that, at the concentrations tested, NIV, DON and FB1 did not induce cytotoxicity through plasma membrane damage. Cell cycle analysis suggested apoptotic cytotoxicity, revealing 100% cellular debris at the highest concentrations of NIV and DON and approximately 2.9 times more debris than control at the highest FB1 concentration. Morphological evidence of apoptosis was related to the toxicity of the substances, such that the more toxic NIV and DON resulted in more late stage apoptotic events than FB1. This study suggests that human blood cells are sensitive to mycotoxin exposure, that NIV is more toxic than DON which is more toxic than FB1, and that DNA damage and apoptosis rather than plasma membrane damage and necrosis may be responsible for the observed cytotoxicity.