Inter-laboratory comparison of a yeast bioassay for the determination of estrogenic activity in biological samples

Bovee, Toine F.H.; Bor, Gerrit; Becue, Ilse; Daamen, Frieda E.J.; Duursen, Majorie B.M. van; Lehmann, Sylvi; Vollmer, Günter; Maria, Raffaella De; Fox, Jennifer E.; Witters, Hilda; Bernhöft, Silke; Schramm, Karl‐Werner; Hoogenboom, L.A.P.; Nielen, Michel W. F.

doi:10.1016/j.aca.2008.09.064

Cited by 15 publications

(4 citation statements)

References 14 publications

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“…The deuterium-labeled internal steroid standards were from CDN isotopes (Point-Claire, Canada) and ITS+ premix and NuSerum from BD Biosciences (Bedford, MA). Chemicals to prepare the growth media for yeast were described previously (Bovee et al, 2009). Milli-Q water was obtained using a Purelab Ultra system from Elga (Bucks, UK).…”

Section: Methodsmentioning

confidence: 99%

Extending an In Vitro Panel for Estrogenicity Testing: The Added Value of Bioassays for Measuring Antiandrogenic Activities and Effects on Steroidogenesis

Wang

Rijk

Besselink

et al. 2014

Toxicological Sciences

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In the present study, a previously established integrated testing strategy (ITS) for in vitro estrogenicity testing was extended with additional in vitro assays in order to broaden its sensitivity to different modes of action resulting in apparent estrogenicity, i.e., other than estrogen receptor (ER) binding. To this end, an extra set of 10 estrogenic compounds with modes of action in part different from ER binding, were tested in the previously defined ITS, consisting of a yeast estrogen reporter gene assay, an U2OS ERα CALUX reporter gene assay and a cell-free coregulator binding assay. Two androgen reporter gene assays and the enhanced H295R steroidogenesis assay were added to that previous defined ITS. These assays had added value, as several estrogenic model compounds also elicited clear and potent antiandrogenic properties and in addition also showed effects on steroidogenesis that might potentiate their apparent estrogenic effects in vivo. Adding these assays, examining mechanisms of action for estrogenicity apart from ERα binding, gives a more complete and comprehensive assessment of the ability of test compounds to interfere with endocrine signaling. It was concluded that the extended ITS will go beyond in vivo estrogenicity testing by the uterotrophic assay, thereby contributing to the 3R-principles.

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Section: Methodsmentioning

confidence: 99%

Extending an In Vitro Panel for Estrogenicity Testing: The Added Value of Bioassays for Measuring Antiandrogenic Activities and Effects on Steroidogenesis

Wang

Rijk

Besselink

et al. 2014

Toxicological Sciences

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“…For the yeast estrogen screen (YES) assay, another ER-controlled reporter gene transactivation assay using a recombinant yeast strain, the variability observed when measuring a saturating E2 concentration (6.96 × 10 –9 M), expressed as the CV, amounted up to 7.4%. However, this relatively low CV was only achieved after sophisticated optimization of the protocol, whereas studies with other types of yeast estrogen assays reported mean CVs of 18.0% and 18.6% . A variability in the same range as for the transactivation assays was reported for classical ERα ligand binding assays, e.g., a CV of 11% in a study performed by Kase et al in 2009 .…”

Section: Discussionmentioning

confidence: 97%

Robust Array-Based Coregulator Binding Assay Predicting ERα-Agonist Potency and Generating Binding Profiles Reflecting Ligand Structure

Aarts

Wang

Beuningen

et al. 2013

Chem. Res. Toxicol.

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Testing chemicals for their endocrine-disrupting potential, including interference with estrogen receptor (ER) signaling, is an important aspect of chemical safety testing. Because of the practical drawbacks of animal testing, the development of in vitro alternatives for the uterotrophic assay and other in vivo (anti)estrogenicity tests has high priority. It was previously demonstrated that an in vitro assay that profiles ligand-induced binding of ERα to a microarray of coregulator-derived peptides might be a valuable candidate for a panel of in vitro assays aiming at an ultimate replacement of the uterotrophic assay. In the present study, the reproducibility and robustness of this coregulator binding assay was determined by measuring the binding profiles of 14 model compounds that are recommended by the Office of Prevention, Pesticides and Toxic Substances for testing laboratory proficiency in estrogen receptor transactivation assays. With a median coefficient of variation of 5.0% and excellent correlation (R(2) = 0.993) between duplicate measurements, the reproducibility of the ERα-coregulator binding assay was better than the reproducibility of other commonly used in vitro ER functional assays. In addition, the coregulator binding assay is correctly predicting the estrogenicity for 13 out of 14 compounds tested. When the potency of the ER-agonists to induce ERα-coregulator binding was compared to their ER binding affinity, their ranking was similar, and the correlation between the EC50 values was excellent (R(2) = 0.96), as was the correlation with their potency in a transactivation assay (R(2) = 0.94). Moreover, when the ERα-coregulator binding profiles were hierarchically clustered using Euclidian cluster distance, the structurally related compounds were found to cluster together, whereas the steroid test compounds having an aromatic A-ring were separated from those with a cyclohexene A-ring. We concluded that this assay is capable of distinguishing ERα agonists and antagonists and that it even reflects the structural similarity of ERα agonists, indicating a potential to achieve identification and classification of ERα endocrine disruptors with high fidelity.

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“…However, such immunoassays are considered as screening assays due to the risk of false non-compliant results and subsequent confirmation with instruments such as liquid chromatography (LC) combined with mass spectrometry (MS) is compulsory [8]. Screening assays with multi-analyte reagents (group-specific antibodies [9], transport proteins [10], or receptors [11]) are of particular interest since they might pinpoint the occurrence of emerging yet unidentified food contaminants and the subsequent MS identification of the interacting compound(s) is essential. In an ideal situation, to avoid different sample preparations with different selectivities, the screening should be as close as possible to the MS confirmation or identification of unknowns, which could be achieved by using identical bioreagents in both methods.…”

Section: Introductionmentioning

confidence: 99%

Immunomagnetic microbeads for screening with flow cytometry and identification with nano-liquid chromatography mass spectrometry of ochratoxins in wheat and cereal

et al. 2011

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Multi-analyte binding assays for rapid screening of food contaminants require mass spectrometric identification of compound(s) in suspect samples. An optimal combination is obtained when the same bioreagents are used in both methods; moreover, miniaturisation is important because of the high costs of bioreagents. A concept is demonstrated using superparamagnetic microbeads coated with monoclonal antibodies (Mabs) in a novel direct inhibition flow cytometric immunoassay (FCIA) plus immunoaffinity isolation prior to identification by nano-liquid chromatography–quadrupole time-of-flight-mass spectrometry (nano-LC-Q-ToF-MS). As a model system, the mycotoxin ochratoxin A (OTA) and cross-reacting mycotoxin analogues were analysed in wheat and cereal samples, after a simple extraction, using the FCIA with anti-OTA Mabs. The limit of detection for OTA was 0.15 ng/g, which is far below the lowest maximum level of 3 ng/g established by the European Union. In the immunomagnetic isolation method, a 350-times-higher amount of beads was used to trap ochratoxins from sample extracts. Following a wash step, bound ochratoxins were dissociated from the Mabs using a small volume of acidified acetonitrile/water (2/8 v/v) prior to separation plus identification with nano-LC-Q-ToF-MS. In screened suspect naturally contaminated samples, OTA and its non-chlorinated analogue ochratoxin B were successfully identified by full scan accurate mass spectrometry as a proof of concept for identification of unknown but cross-reacting emerging mycotoxins. Due to the miniaturisation and bioaffinity isolation, this concept might be applicable for the use of other and more expensive bioreagents such as transport proteins and receptors for screening and identification of known and unknown (or masked) emerging food contaminants.FigureMicrobead coated with antibody

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Inter-laboratory comparison of a yeast bioassay for the determination of estrogenic activity in biological samples

Cited by 15 publications

References 14 publications

Extending an In Vitro Panel for Estrogenicity Testing: The Added Value of Bioassays for Measuring Antiandrogenic Activities and Effects on Steroidogenesis

Extending an In Vitro Panel for Estrogenicity Testing: The Added Value of Bioassays for Measuring Antiandrogenic Activities and Effects on Steroidogenesis

Robust Array-Based Coregulator Binding Assay Predicting ERα-Agonist Potency and Generating Binding Profiles Reflecting Ligand Structure

Immunomagnetic microbeads for screening with flow cytometry and identification with nano-liquid chromatography mass spectrometry of ochratoxins in wheat and cereal

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