title: Modulation of P-glycoprotein activity by cannabinoid molecules in HK-2 renal cells.
abstract: 1. Endogenous and synthetic cannabinoid molecules have been investigated as possible MDR-1/P-glycoprotein (P-gp) modulators in HK-2-immortalized renal cells, using calcein acetoxymethylester (calcein-AM) as a P-gp substrate. 2. Among the endocannabinoid molecules tested, anandamide (AEA), but not 2-arachidonoyl-glycerol (2-AG) or palmitoyl-ethanolamide (PEA), increased the intracellular fluorescence emitted by calcein, a metabolic derivative of the P-gp substrate calcein-AM, indicative of a reduction in transport capacity. 3. All the three synthetic cannabimimetics tested, that is, R-(+)-methanandamide (R(+)-MET), AM 251 and CP55,940 significantly increased calcein accumulation in the cytosol. 4. RT-PCR demonstrated that HK-2 cells do not express CB1 or CB2 cannabinoid receptors. 5. R(+)-MET, AM251 and CP55,940 were also evaluated as modulators of P-gp expression, by Western blot analysis. Only AM251 weakly enhanced the protein levels (by 1.2-fold) after a 4-day-long incubation with the noncytotoxic drug concentration 2 microM. 6. The present data provide the first evidence that the endocannabinoid AEA and different synthetic cannabinoids may inhibit the P-gp activity in vitro via a cannabinoid receptor-independent mechanism.
authors.affiliation: Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, Via Bonanno, 6, Pisa 56126, Pisa, Italia. paola.nieri@farm.unipi.it
authors.forename: Paola
authors.initials: P
authors.lastname: Nieri
authors.forename: Nadia
authors.initials: N
authors.lastname: Romiti
authors.forename: Barbara
authors.initials: B
authors.lastname: Adinolfi
authors.forename: Andrea
authors.initials: A
authors.lastname: Chicca
authors.forename: Ilaria
authors.initials: I
authors.lastname: Massarelli
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Chieli
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D063385:Cannabinoid Receptor Modulators / Q000494:pharmacology; D002186:Cannabinoids / Q000494:pharmacology*; D002460:Cell Line; D020869:Gene Expression Profiling; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D015151:Immunoblotting / Q000379:methods; D007668:Kidney / Q000166:cytology* / Q000187:drug effects*; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2