title: Structural determinants of peripheral O-arylcarbamate FAAH inhibitors render them dual substrates for Abcb1 and Abcg2 and restrict their access to the brain.
abstract: The blood-brain barrier (BBB) is the main entry route for chemicals into the mammalian central nervous system (CNS). Two transmembrane transporters of the ATP-binding cassette (ABC) family - breast cancer resistance protein (ABCG2 in humans, Abcg2 in rodents) and P-glycoprotein (ABCB1 in humans, Abcb1 in rodents) - play a key role in mediating this process. Pharmacological and genetic evidence suggests that Abcg2 prevents CNS access to a group of highly potent and selective O-arylcarbamate fatty-acid amidohydrolase (FAAH) inhibitors, which include the compound URB937 (cyclohexylcarbamic acid 3'-carbamoyl-6-hydroxybiphenyl-3-yl ester). To define structure-activity relationships of the interaction of these molecules with Abcg2, in the present study we tested various peripherally restricted and non-restricted O-arylcarbamate FAAH inhibitors for their ability to serve as transport substrates in monolayer cultures of Madin-Darby Canine Kidney-II (MDCKII) cells over-expressing Abcg2. Surprisingly, we found that the majority of compounds tested - even those able to enter the CNS in vivo - were substrates for Abcg2 in vitro. Additional experiments in MDCKII cells overexpressing ABCB1 revealed that only those compounds that were dual substrates for ABCB1 and Abcg2 in vitro were also peripherally restricted in vivo. The extent of such restriction seems to depend upon other physicochemical features of the compounds, in particular the polar surface area. Consistent with these in vitro results, we found that URB937 readily enters the brain in dual knockout mice lacking both Abcg2 and Abcb1, whereas it is either partially or completely excluded from the brain of mice lacking either transporter alone. The results suggest that Abcg2 and Abcb1 act together to restrict the access of URB937 to the CNS.
authors.affiliation: Department of Anatomy and Neurobiology, University of California, Irvine 92697-4621, USA.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Moreno-Sanz
authors.affiliation: INDEGSAL, Campus Vegazana s/n, University of Leon, 24071 Leon, Spain; Department of Biomedical Sciences - Physiology, Veterinary Faculty, Campus Vegazana s/n, University of Leon, 24071 Leon, Spain.
authors.forename: Borja
authors.initials: B
authors.lastname: Barrera
authors.affiliation: Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Armirotti
authors.affiliation: Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy.
authors.forename: Sine M
authors.initials: SM
authors.lastname: Bertozzi
authors.affiliation: Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Scarpelli
authors.affiliation: Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy.
authors.forename: Tiziano
authors.initials: T
authors.lastname: Bandiera
authors.affiliation: Department of Biomedical Sciences - Physiology, Veterinary Faculty, Campus Vegazana s/n, University of Leon, 24071 Leon, Spain.
authors.forename: Julio G
authors.initials: JG
authors.lastname: Prieto
authors.affiliation: Dipartimento di Scienze Biomolecolari, University of Urbino "Carlo Bo", Piazza del Rinascimento 6, I-61029 Urbino, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Duranti
authors.affiliation: Dipartimento di Scienze Biomolecolari, University of Urbino "Carlo Bo", Piazza del Rinascimento 6, I-61029 Urbino, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Tarzia
authors.affiliation: INDEGSAL, Campus Vegazana s/n, University of Leon, 24071 Leon, Spain; Department of Biomedical Sciences - Physiology, Veterinary Faculty, Campus Vegazana s/n, University of Leon, 24071 Leon, Spain.
authors.forename: Gracia
authors.initials: G
authors.lastname: Merino
authors.affiliation: Department of Anatomy and Neurobiology, University of California, Irvine 92697-4621, USA; Drug Discovery and Development, Fondazione Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova, Italy. Electronic address: piomelli@uci.edu.
authors.forename: Daniele
authors.initials: D
authors.lastname: Piomelli
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000581:Amidohydrolases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002186:Cannabinoids / Q000737:chemistry / Q000494:pharmacology*; D002219:Carbamates / Q000737:chemistry / Q000494:pharmacology*; D004285:Dogs; D061985:Madin Darby Canine Kidney Cells; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D013329:Structure-Activity Relationship; D000099252:Fatty Acid Amide Hydrolases
chemical_list: D018528:ATP-Binding Cassette Transporters; D000581:Amidohydrolases; D002186:Cannabinoids; D002219:Carbamates; D000099252:Fatty Acid Amide Hydrolases; C552918:URB937
keywords: ATP-binding cassette transporters; Abcb1/P-gp; Abcg2/Bcrp; Blood–brain barrier; FAAH inhibitor; Fatty-acid amidohydrolase (FAAH); HEPES (PubChem CID: 23831); Ko143 (PubChem CID: 10322450); PSC833 (PubChem CID: 5281884); Polyethylene glycol (PubChem CID: 24762); Tween-80 (PubChem CID: 6364656); URB937 (PubChem CID: 53394762)