Effect of GenX on P-Glycoprotein, Breast Cancer Resistance Protein, and Multidrug Resistance–Associated Protein 2 at the Blood–Brain Barrier

Abstract

BACKGROUND: Ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoic acid (GenX) is a replacement for perfluorooctanoic acid in the production of fluoropolymers used in a variety of consumer products. GenX alters fetal development and antibody production and elicits toxic responses in the livers and kidneys of rodents. The GenX effect on the blood-brain barrier (BBB) is unknown. The BBB protects the brain from xenobiotic neurotoxicants and harmful endogenous metabolites. OBJECTIVES: We aimed to investigate the effects of GenX on the transport activity and expression of P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance-associated protein 2 (MRP2) at the BBB. METHODS: Transporter activities were measured in isolated rat brain capillaries by a confocal microscopy-based method. ATPase (enzymatic hydrolysis of adenosine triphosphate to inorganic phosphate) levels were measured in vitro. Western blotting determined P-gp and BCRP protein levels. Cell survival after GenX exposure was determined for two human cell lines. RESULTS: Nanomolar levels of GenX inhibited P-gp and BCRP but not MRP2 transport activities in male and female rat brain capillaries. P-gp transport activity returned to control levels after GenX removal. GenX did not reduce P-gp-or BCRP-associated ATPase activity in an in vitro transport assay system. Reductions of P-gp but not BCRP transport activity were blocked by a peroxisome proliferator-activated receptor c (PPARc) antagonist. GenX reduced P-gp and BCRP transport activity in human cells. CONCLUSION: In rats, GenX at 0:1-100 nM rapidly (in 1-2 h) inhibited P-gp and BCRP transport activities at the BBB through different mechanisms. PPARc was required for the GenX effects on P-gp but not BCRP transport activity.

Bisphenol A Inhibits the Transporter Function of the Blood-Brain Barrier by Directly Interacting with the ABC Transporter Breast Cancer Resistance Protein (BCRP)

“…For example, low concentrations of tetrabromobisphenol A (TBBPA; a commonly used brominated flame retardant) and GenX (CAS no. 62037-80-3; used as a replacement for perfluorooctanoic acid (PFOA) in consumer products, such as frying pans) have been shown to inhibit BCRP-mediated transport in rat brain capillaries [ 43 , 44 ]. In addition, many commonly used therapeutic drugs inhibit BCRP transporter activity [ 18 ].…”

A Critical Review and Meta-Analysis of Impacts of Per- and Polyfluorinated Substances on the Brain and Behavior

“…Integrity of the BBB can be compromised because of exposures to certain toxicants, such as pesticides, mixed vehicle emissions, and tobacco smoke, as well as certain health conditions including diabetes and neurological disorders reviewed in Neurotoxicity of PFAS in Sensitive Populations , through molecular alterations in barrier function ( Gupta et al, 1999 ; Weiss et al, 2009 ; Mazzone et al, 2010 ; Oppenheim et al, 2013 ; Prasad et al, 2014 , 2015 ; Erdő et al, 2017 ; Suwannasual et al, 2018 ; Martinez and Al-Ahmad, 2019 ). PFAS can disrupt BBB integrity by various mechanisms including disruption of endothelial tight junctions, actin filament remodeling induced by oxidative stress, and decreased activity of efflux transporters ( Qian et al, 2010 ; Wang X. et al, 2011 ; Reistad et al, 2013 ; Cannon et al, 2020 ). Therefore, PFAS exposure may impact access and accumulation of contaminants in the brain, by increasing permeability at the BBB.…”

“…Although lipophilicity is important for transmembrane diffusion through the BBB, some compounds that are too lipophilic can be discharged after crossing into the brain by the P-gp efflux transporter ( Abbott, 2002 ; Banks, 2009 ). Cannon et al (2020) isolated rat brain capillaries to assess the effects of Perfluoro (2-methyl-3-oxahexanoic) acid (GenX), a perfluoroether carboxylic acid that was introduced as an alternative for PFOA and PFOS, on the BBB. This study found that GenX decreases the transport activity of P-gp and breast cancer resistance protein (BCRP), two ABC transporters which actively limit endogenous ligands, xenobiotics, and drugs from reaching sensitive target tissues, including the brain.…”

Biotechnological Applications and Health-Promoting Properties of Flavonols: An Updated View

“…In enterocytes, excretion of polyphenols towards the intestinal lumen can occur through ATP-binding cassette transporters (ABCs). Other transporters, such as multidrug resistance proteins (MRPs) and monocarboxylate transporters, play a role in the transport of polyphenols to the vascular side [23]. Furthermore, it has been shown that MRP2 and p-glycoprotein play a pivotal role in the efflux of metabolized polyphenols as highlighted in a Caco-2 cell transwell model.…”