Differential effects of the oncogenic BRAF inhibitor PLX4032 (vemurafenib) and its progenitor PLX4720 on ABCB1 function

Michaelis, M, Rothweiler, F, Nerreter, T, Van Rikxoort, M, Sharifi, M, Wiese, M, Ghafourian, T and Cinatl Jr., J (2014) Differential effects of the oncogenic BRAF inhibitor PLX4032 (vemurafenib) and its progenitor PLX4720 on ABCB1 function. Journal of Pharmacy and Pharmaceutical Sciences, 17 (1). pp. 154-168. ISSN 1482-1826

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Abstract

PURPOSE: The clinically approved oncogenic BRAF inhibitor PLX4032 (vemurafenib) was shown to be a substrate of the ATP-binding cassette (ABC) transporter ABCB1. Here, we compared PLX4032 and its structurally closely related precursor compound PLX4720 for their interference with ABCB1 and the ABCB1-mediated compound transport using docking and cell culture experiments. METHODS: For the docking study of PLX4032 and PLX4720 with ABCB1, we analysed binding of both compounds to mouse Abcb1a and to human ABCB1 using a homology model of human ABCB1 based on the 3D structure of Abcb1a. Naturally ABCB1 expressing cells including V600E BRAF-mutated and BRAF wild-type melanoma cells and cells transduced with a lentiviral vector encoding for ABCB1 were used as cell culture models. ABCB1 expression and function were studied by the use of fluorescent and cytotoxic ABCB1 substrates in combination with ABCB1 inhibitors. RESULTS: Docking experiments predicted PLX4032 to interact stronger with ABCB1 than PLX4720. Experimental studies using different cellular models and structurally different ABCB1 substrates confirmed that PLX4032 interfered stronger with ABCB1 function than PLX4720. For example, PLX4032 (20μM) induced a 4-fold enhanced rhodamine 123 accumulation compared to PLX4720 (20μM) in ABCB1-transduced UKF-NB-3 cells and reduced the IC50 for the cytotoxic ABCB1 substrate vincristine in this model by 21-fold in contrast to a 9-fold decrease induced by PLX4720. CONCLUSIONS: PLX4032 exerted stronger effects on ABCB1-mediated drug transport than PLX4720. This indicates that small changes in a molecule can substantially modify its interaction with ABCB1, a promiscuous transporter that transports structurally different compounds.

Item Type: Article
Keywords: multidrug resistance protein 1; n 3 (5 chloro 1h pyrrolo2,3 b]pyridine 3 carbonyl) 2,4 difluorophenyl]propanesulfonamide; rhodamine 123; vemurafenib; vincristine; ABCB1 protein, human; adenosine triphosphatase; antineoplastic agent; B Raf kinase; indole derivative; multidrug resistance protein; n 3 (5 chloro 1h pyrrolo2,3 b]pyridine 3 carbonyl) 2,4 difluorophenyl]propanesulfonamide; sulfonamide; vemurafenib; vincristine, article; binding affinity; cell culture; controlled study; drug cytotoxicity; drug effect; drug protein binding; drug structure; human; human cell; melanoma cell; molecular docking; mouse; nonhuman; protein expression; protein function; protein transport; animal; antagonists and inhibitors; cell line; dose response; drug combination; drug effects; flow cytometry; melanoma; metabolism; tumor cell line, Adenosine Triphosphatases; Animals; Antineoplastic Agents; Cell Line; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Therapy, Combination; Flow Cytometry; Humans; Indoles; Melanoma; Mice; Molecular Docking Simulation; P-Glycoproteins; Proto-Oncogene Proteins B-raf; Sulfonamides; Vincristine
Schools and Departments: School of Life Sciences > Biochemistry
Depositing User: Taravat Ghafourian
Date Deposited: 01 Dec 2017 08:31
Last Modified: 01 Dec 2017 08:31
URI: http://sro.sussex.ac.uk/id/eprint/64128

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