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Trichothecenes are a large family of chemically related mycotoxins. Deoxynivalenol (DON), T-2 and HT-2
toxins belong to this family and are produced by various species of Fusarium. The H295R steroidogenesis
assay, regulation of steroidogenic gene expression and reporter gene assays (RGAs) for the detection of
androgen, estrogen, progestagen and glucocorticoid (ant)agonist responses, have been used to assess the
endocrine disrupting activity of DON, T-2 and HT-2 toxins.
H295R cells were used as a model for steroidogenesis and gene expression studies and exposed with
either DON (0.1–1000 ng/ml), T-2 toxin (0.0005–5 ng/ml) or HT-2 toxin (0.005–50 ng/ml) for 48 h. We
observed a reduction in hormone levels in media of exposed cells following radioimmunoassay. Cell via-
bility was determined by four colorimetric assays and we observed reduced cell viability with increasing
toxin concentrations partly explaining the significant reduction in hormone levels at the highest toxin
concentration of all three trichothecenes.
Thirteen of the 16 steroidogenic genes analyzed by quantitative real time PCR (RT-qPCR) were signifi-
cantly regulated (P < 0.05) by DON (100 ng/ml), T-2 toxin (0.5 ng/ml) and HT-2 toxin (5 ng/ml) compared
to the control, with reference genes (B2M, ATP5B and ACTB). Whereas HMGR and CYP19 were down-
regulated, CYP1A1 and CYP21 were up-regulated by all three trichothecenes. DON further up-regulated
CYP17, HSD3B2, CYP11B2 and CYP11B1 and down-regulated NR5A1. T-2 toxin caused down-regulation of
NR0B1 and NR5A1 whereas HT-2 toxin induced up-regulation of EPHX and HSD17B1 and down-regulation
of CYP11A and CYP17. The expressions of MC2R, StAR and HSD17B4 genes were not significantly affected
by any of the trichothecenes in the present study.
Although the results indicate that there is no evidence to suggest that DON, T-2 and HT-2 toxins directly
interact with the steroid hormone receptors to cause endocrine disruption, the present findings indicate
that exposure to DON, T-2 toxin and HT-2 toxin have effects on cell viability, steroidogenesis and alteration
in gene expression indicating their potential as endocrine disruptors. |
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