Quantitative Structure−Activity Relationship Analysis and Molecular Dynamics Simulation To Functionally Validate Nonsynonymous Polymorphisms of Human ABC Transporter ABCB1 (P-Glycoprotein/MDR1)

Abstract

Several preclinical and clinical studies suggest the importance of naturally occurring polymorphisms of drug transporters in the individual difference of drug response. To functionally validate the nonsynonymous polymorphisms of ABCB1 (P-glycoprotein/MDR1) in vitro, we generated SNP variant forms (i.e., S400N, R492C, R669C, I849M, A893P, A893S, A893T, M986V, A999T, P1051A, and G1063A) and expressed them in Sf9 cells. The kinetic properties (Km and Vmax) of those variants were analyzed by measuring the ATPase activity to obtain the ATPase profile for each variant toward structurally unrelated substrates. On the basis of the experimental data, we determined the substrate specificity of ABCB1 WT and its variants by the quantitative structure-activity relationship (QSAR) analysis method. While several SNP variants appeared to influence the substrate specificity of ABCB1, the nonsynonymous polymorphisms of 2677G > T, A, or C at amino acid position 893 (Ala > Ser, Thr, or Pro) have great impacts on both the activity and the substrate specificity of ABCB1. The A893P variant (2677G > C), a rare mutation, exhibited markedly high activity of ATPase toward different test compounds. Molecular dynamics (MD) simulation based on a three-dimensional structural model of human ABCB1 revealed that multiple kinks are formed in the intracellular loop between transmembrane domains 10 and 11 of the A893P variant (2677G > C) protein. The polymorphisms of 2677G, 2677T, and 2677A exhibit wide ethnic differences in the allele frequency, and these nonsynonymous polymorphisms are suggested to be clinically important because of their altered ATPase activity and substrate specificity toward different drugs.

IDENTIFICATION OF FUNCTIONAL SNPs OF MDR1 GENE AMONG NEPHROTIC SYNDROME CHILDREN IN SOUTH INDIA

“…Whereas in the genotype frequencies data, the frequency was observed in patients were CC=15%, CT=59%, and TT=26% and controls were CC=26%, CT=48.5%, TT=25.5% observed, respectively. The silent 3435T>C polymorphism may have some effects on DNA structure, RNA stability, and P-gp function, or it is in linkage disequilibrium with other functional MDR-1 polymorphisms [29]. Our data showed that there was no such significant role of SNP G2677T/C among these study children.…”

CYP3A5*3 and POR*28 Genetic Variants Influence the Required Dose of Tacrolimus in Heart Transplant Recipients

“…27 CYP3A5 expressors had lower doseadjusted TAC-C 0 concentrations at all studied time points (P # 0.002; Fig. 1; Table 4) and required 2.2-to 2.6-fold higher drug dose to reach the targeted concentration compared with CYP3A5 nonexpressors (Table 4).…”

Gefitinib Enhances the Antitumor Activity of CPT-11 in vitro and in vivo by Inhibiting ABCG2 but Not ABCB1: A New Clue to Circumvent Gastrointestinal Toxicity Risk

“…The number of viable cells was determined from counts made in a hemocytometer with Trypan blue dye exclusion. Flp-In-293 cells were transfected with the ABCB1-pcDNA5/FRT [26] or ABCG2-pcDNA5/FRT vector [24] (fig. 1a), the Flp recombinase expression plasmid pOG44 and LipofectAmine™-2000 (Invitrogen), as described previously.…”