Toxicological Mechanisms and Potencies of Organophosphate Esters in KGN Human Ovarian Granulosa Cells as Revealed by High-throughput Transcriptomics

Xiaotong Wang; Andrea Rowan-Carroll; Matthew J Meier; Andrew Williams; Carole L Yauk; Barbara F Hales; Bernard Robaire

doi:10.1093/toxsci/kfad114

Toxicological Mechanisms and Potencies of Organophosphate Esters in KGN Human Ovarian Granulosa Cells as Revealed by High-throughput Transcriptomics

Toxicol Sci. 2023 Nov 6;197(2):170-185. doi: 10.1093/toxsci/kfad114. Online ahead of print.

Authors

Xiaotong Wang¹, Andrea Rowan-Carroll², Matthew J Meier², Andrew Williams², Carole L Yauk³, Barbara F Hales¹, Bernard Robaire^{1

4}

Affiliations

¹ Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada.
² Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada.
³ Department of Biology, University of Ottawa, Ottawa, ON, Canada.
⁴ Department of Obstetrics and Gynecology, McGill University, Montréal, QC, Canada.

PMID: 37941476
PMCID: PMC10823774 (available on 2024-11-06)
DOI: 10.1093/toxsci/kfad114

Abstract

Despite the growing number of studies reporting potential risks associated with exposure to organophosphate esters (OPEs), their molecular mechanisms of action remain poorly defined. We used the high-throughput TempO-Seq™ platform to investigate the effects of frequently detected OPEs on the expression of ∼3000 environmentally responsive genes in KGN human ovarian granulosa cells. Cells were exposed for 48 h to one of five OPEs (0.1 to 50 μM): tris(methylphenyl) phosphate (TMPP), isopropylated triphenyl phosphate (IPPP), tert-butylphenyl diphenyl phosphate (BPDP), triphenyl phosphate (TPHP), or tris(2-butoxyethyl) phosphate (TBOEP). The sequencing data indicate that four OPEs induced transcriptional changes, whereas TBOEP had no effect within the concentration range tested. Multiple pathway databases were used to predict alterations in biological processes based on differentially expressed genes. At lower concentrations, inhibition of the cholesterol biosynthetic pathway was the predominant effect of OPEs; this was likely a consequence of intracellular cholesterol accumulation. At higher concentrations, BPDP and TPHP had distinct effects, primarily affecting pathways involved in cell cycle progression and other stress responses. Benchmark concentration (BMC) modelling revealed that BPDP had the lowest transcriptomic point of departure. However, in vitro to in vivo extrapolation modeling indicated that TMPP was bioactive at lower concentrations than the other OPEs. We conclude that these new approach methodologies provide information on the mechanism(s) underlying the effects of data-poor compounds and assist in the derivation of protective points of departure for use in chemical read-across and decision-making.

Keywords: in vitro to in vivo extrapolation (IVIVE); benchmark concentration (BMC); cholesterol; high-throughput transcriptomics; organophosphate esters.