We developed a thyroid testing panel to assess endocrine disrupting chemicals (EDCs)
capacities to bind either the thyroid receptor beta (TR beta) or the thyroid hormones
transporter transthyretin (TTR). We first stably transfected a human U2OS cell line
with TR beta and a luciferase reporter construct to develop the TR beta CALUX (R)
reporter gene assay to assess chemicals' potential to interact with TR beta. Secondly,
we combined a TTR-binding assay with the TR beta CALUX (TTR-TR beta CALUX) and optimized
the system to evaluate the competitive properties of EDCs towards T4 for TTR binding.
Both systems were evaluated with a range of known thyroid-disrupting compounds. The
agonistic/antagonistic TR beta CALUX successfully predicted 9/9 and 9/12 test compounds,
respectively. The TTR-TR beta CALUX predicted 9/9 compounds and demonstrated competitive
activities when analyzing waste water samples. We concluded that the proposed test
battery is a promising screening method able to efficiently generate data on thyroid
hormone interferences by chemicals.