Comparative in vivo and in vitro analysis of possible estrogenic effects of perfluorooctanoic acid Pei-Li Yao a , David J. Ehresman b , Jessica M. Caverly Rae c , Shu-Ching Chang b , Steven R. Frame c , John L. Butenhoff b , Gerald L. Kennedy d , Jeffrey M. Peters a, * a Department of Veterinary and Biomedical Sciences and The Center of Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, PA 16802, USA b Medical Department, 3 M Company, St. Paul, MN 55144, USA c Haskell Global Centers for Health and Environmental Sciences, Newark, DE 19701, USA d Consultant to DuPont Company, Wilmington, DE 19805, USA A R T I C L E I N F O Article history: Received 22 August 2014 Received in revised form 9 October 2014 Accepted 17 October 2014 Available online 18 October 2014 Keywords: Perfluorooctanoate Uterus Estrogen receptor A B S T R A C T Previous studies suggested that perfluorooctanoate (PFOA) could activate the estrogen receptor (ER). The present study examined the hypothesis that PFOA can activate ER using an in vivo uterotrophic assay in CD-1 mice and an in vitro reporter assay. Pre-pubertal female CD-1 mice fed an estrogen-free diet from postnatal day (PND)14 through weaning on PND18 were administered 0, 0.005, 0.01, 0.02, 0.05, 0.1, or 1 mg/kg PFOA or 17b-estradiol (E 2 , 0.5 mg/kg) from PND18–20. In contrast to E 2 , PFOA caused no changes in the relative uterine weight, the expression of ER target genes, or the morphology of the uterus/cervix and/or vagina on PND21. Treatment of a stable human cell line containing an ER-dependent luciferase reporter construct with a broad concentration range of PFOA caused no change in ER-dependent luciferase activity; whereas E 2 caused a marked increase of ER-dependent luciferase activity. These data indicate that PFOA does not activate mouse or human ER. ã 2014 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Perfluoroalkyl acids (PFAAs) are compounds containing fluorine atoms on a carbon backbone with unique surfactant properties and are widely used for manufacturing and industrial applications (Andersen et al., 2008; Betts, 2007). Perfluorooctanoic acid (PFOA) is a PFAA that is reported to cause adverse effects in animal models. Humans can be exposed to PFOA because of its persistence in the environment (Post et al., 2012; Steenland et al., 2013) and its relatively long serum half-life (Olsen et al., 2007). PFOA is detectable in the blood of 99.9% of the general human population in the United States with an average serum PFOA concentration 4–5 ng/mL (10–13 nM) (Kato et al., 2011). PFOA exposure has been associated with adverse effects in the liver and reproductive systems of animal models (Lau et al., 2007). The mechanism(s) that mediate(s) PFOA-induced adverse effects may exhibit species differences (Lau et al., 2007). For example, PFOA is a relatively weak agonist for peroxisome proliferator-activated receptor (PPAR)-a, and can alter cell proliferation and lipid metabolism in rodent liver (Cheng and Klaassen, 2008; Takacs and Abbott, 2007; Wolf et al., 2008; Wolf et al., 2010). However, PPARa-mediated effects of PFOA in liver and other tissues are typically greater in rodent models as compared to human models (Albrecht et al., 2013; Bjork et al., 2011; Bjork and Wallace, 2009; Nakamura et al., 2009). These differences may be due to variation in binding affinity of PPARa agonists to human PPARa as compared to rodent PPARa. Developmental exposure of rodents to PFOA is reported to cause early pregnancy loss, reduced postnatal survival, defects in growth, and delays in developmental process (Lau et al., 2006; Wolf et al., 2010). Some of these developmental effects due to PFOA exposure are mediated by PPARa (Abbott et al., 2007), but evidence also exists that there is a species difference for these PPARa-dependent effects (Albrecht et al., 2013; Bjork et al., 2011; Bjork and Wallace, 2009; Nakamura et al., 2009) and that PFOA does not cause reduced postnatal survival by activation of human PPARa (Albrecht et al., 2013). Moreover, associations between PFOA exposure and alterations in development are not consistently observed in human studies (Fei et al., 2008; Olsen et al., 2009; Savitz et al., 2012a,b; Steenland et al., 2013). It has been suggested that PFOA may cause endocrine disruption through effects on the function of growth and sex hormones, including activation of the Abbreviations: ER, estrogen receptor; ERE, estrogen response element; PPAR, peroxisome proliferator-activated receptor; PFAA, perfluoroalkyl acid; PFOA, perfluorooctanoate; PR, progesterone receptor; TFF, trefoil factor. * Corresponding author. Tel.: +1 814 863 1387; fax: +1 814 863 1696. E-mail address: jmp21@psu.edu (J.M. Peters). http://dx.doi.org/10.1016/j.tox.2014.10.008 0300-483X/ ã 2014 Elsevier Ireland Ltd. All rights reserved. Toxicology 326 (2014) 62–73 Contents lists available at ScienceDirect Toxicology journal homepa ge: www.elsev ier.com/locate /toxicol