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Retrofitting an Estrogen Receptor Transactivation Assay with Metabolic Competence
Citation:
Deisenroth, C. Retrofitting an Estrogen Receptor Transactivation Assay with Metabolic Competence. EPA NAMs Conference 2020: State of the Science on Development and Use of NAMs for Chemical Safety Testing, DURHAM, North Carolina, October 19 - 20, 2020. https://doi.org/10.23645/epacomptox.13402154
Impact/Purpose:
Invited speaker at the EPA NAMs Conference 2020: State of the Science on Development and Use of NAMs for Chemical Safety Testing. The purpose of the presentation is to describe a case study for NAM development that addresses critical information needs for the use and acceptance of NAMs.
Description:
A potential limitation to the use of in vitro assay data in regulatory decision-making is the lack of coverage for xenobiotic metabolic processes. The EPA New Approach Methods (NAM) Work Plan emphasizes the need to develop NAMs that address deficiencies in metabolic competence for high-throughput screening assays. The Alginate Immobilization of Metabolic Enzymes (AIME) platform encapsulates hepatic S9 fractions in alginate microspheres attached to 96-well peg lids. Functional characterization across a panel of reference substrates for phase I cytochrome P450 enzymes revealed substrate depletion with expected metabolite accumulation. Performance of the AIME method in the VM7Luc estrogen receptor (ER) transactivation assay was evaluated across 15 reference chemicals and 48 test chemicals that yield metabolites previously identified as ER active or inactive. The results demonstrate the utility of applying the AIME method for identification of false positive and false negative target assay effects, reprioritization of hazard based on metabolism-dependent bioactivity, and enhanced in vivo concordance with the rodent uterotrophic bioassay. Integration of the AIME metabolism NAM may prove useful for future biochemical and cell-based HTS applications at the EPA.
URLs/Downloads:
DOI: Retrofitting an Estrogen Receptor Transactivation Assay with Metabolic Competence
2020-10-20_EPA NAM CON_DEISENROTH_V1.PDF (PDF, NA pp, 3870.31 KB, about PDF)