High-Speed Screening and Structure-Activity Relationship Analysis for the Substrate Specificity of P-Glycoprotein (ABCB1)

• Published in: Chem-Bio Informatics Journal Vol. 3; no. 4; pp. 175 - 193
• Main Authors: Onishi, Yuko, Hirano, Hiroyuki, Nakata, Kunio, Oosumi, Keisuke, Nagakura, Makoto, Tarui, Shigeki, Ishikawa, Toshihisa
• Format: Journal Article
• Language: English
• Published: Tokyo Chem-Bio Informatics Society 01.01.2003; Japan Science and Technology Agency
• Subjects: chemical fragmentation code; high-throughput screening (HTS); P-glycoprotein; structure-activity relationship (SAR)
• ISSN: 1347-6297; 1347-0442
• DOI: 10.1273/cbij.3.175

Human ABCB1 (P-glycoprotein or MDR1) mediates the elimination of a variety of drugs from cells and thereby plays a critical role in determining the pharmacokinetic profiles of drugs in our body. In the present study, we have developed a high-speed screening system to investigate the substrate specificity of ABCB1 towards a variety of drugs and compounds. The plasma membrane fraction of Sf9 insect cells overexpressing human ABCB1 was used to measure the ATPase activity. Among 41 different compounds and therapeutic drugs tested in this study, Ca2+ channel blockers, such as verapamil, bepridil, fendiline, prenylamine, and nicardipine, stimulated the ATPase activity. Doxorubicin, paclitaxel, quinidine, and FK506 also stimulated the ABCB1 ATPase activity, although to an extent relatively smaller than that of the Ca2+ channel blockers. We have measured the surface activity of those 41 different compounds. A two-dimensional plot of the air-water partition coefficient (Kaw) vs. ABCB1 ATPase activity clearly classified those compounds into two groups; namely, ABCB1 substrate and non-substrate groups. ABCB1 substrates were found to have a log Kaw value higher than 4.3. Based on the ABCB1 ATPase activity, we have analyzed structure-activity relationships (SAR) for a total of 37 different compounds. The multiple linear regression analysis delineates a clear relationship between the ABCB1 ATPase activity and the chemical fragmentation codes. Thereby, we have identified multiple sets of chemical fragmentation codes closely related with the substrate specificity of ABCB1. This approach is considered to be practical and useful for the molecular design of such new drugs that can penetrate the blood-brain-barrier or circumvent the multidrug resistance of human cancer.