Interactions of human P-glycoprotein transport substrates and inhibitors at the drug binding domain: Functional and molecular docking analyses

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• 作者：Onat Kadioglu^a ; Mohamed E.M. Saeed^a ; Massimo Valoti^b ; Maria Frosini^b ; Giampietro Sgaragli^b ; ^{sgaragli@unisi.it" class="auth_mail" title="E-mail the corresponding author} ; Thomas Efferth^a ; ^{efferth@uni-mainz.de" class="auth_mail" title="E-mail the corresponding author}
• 关键词：CSA ; cyclosporin A ; DBD ; drug-binding domain ; DMD ; defined molecular docking ; EPI ; epirubicin ; LBE ; lowest binding energy ; MDA ; molecular docking analysis ; MDR ; multidrug resistance ; MFI ; mean fluorescence intensity ; P-gp ; P-glycoprotein ; R123 ; rhodamine 123 ; VMD ; Visual Molecular Dynamics
• 刊名：Biochemical Pharmacology
• 出版年：2016
• 出版时间：15 March 2016
• 年：2016
• 卷：104
• 期：Complete
• 页码：42-51
• 全文大小：1330 K

文摘

Rhodamine 123 (R123) transport substrate sensitizes P-glycoprotein (P-gp) to inhibition by compound 2c (cis–cis) N,N-bis(cyclohexanolamine)aryl ester isomer in a concentration-dependent manner in human MDR1-gene transfected mouse T-lymphoma L5178 cells as shown previously. By contrast, epirubicin (EPI) concentration changes left unaltered 2c IC₅₀ values of EPI efflux. To clarify this discrepancy, defined molecular docking (DMD) analyses of 12 N,N-bis(cyclohexanolamine)aryl esters, the highly flexible aryl ester analog 4, and several P-gp substrate/non-substrate inhibitors were performed on human P-gp drug- or nucleotide-binding domains (DBD or NBD). DMD measurements yielded lowest binding energy (LBE, kcal/mol) values (mean ± SD) ranging from −11.8 ± 0.54 (valspodar) to −3.98 ± 0.01 (4). Lys234, Ser952 and Tyr953 residues formed H-bonds with most of the compounds. Only 2c docked also at ATP binding site (LBE value of −6.9 ± 0.30 kcal/mol). Inhibition of P-gp-mediated R123 efflux by 12 N,N-bis(cyclohexanolamine)aryl esters and 4 significantly correlated with LBE values. DMD analysis of EPI, ³H-1EPI, ³H-2EPI, ¹⁴C-1EPI, ¹⁴C-2EPI, R123 and 2c before and after previous docking of each of them indicated that pre-docking of either 2c or EPI significantly reduced LBE of both EPI and R123, and that of both ³H-2EPI and ¹⁴C-2EPI, respectively. Since the clusters of DBD amino acid residues interacting with EPI were different, if EPI docked alone or after pre-docking of EPI or 2c, the existence of alternative secondary binding site for EPI on P-gp is credible. In conclusion, 2c may allocate the drug-binding pocket and reduce strong binding of EPI and R123 in agreement with P-gp inhibition experiments, where 2c reduced efflux of EPI and R123.