Fluorescence Detection-Based High-Throughput Functional Screening for the Identification of Inhibitors of Human ABCB1 and ABCG2 Proteins

A major cause of death in cancer is due to metastasis that are resistant to conventional therapy. Multidrug resistance (MDR) caused by the overexpression of ATP-Binding Cassette (ABC) drug transporters is a major obstacle in clinical cancer chemotherapy. Currently, two of the most important research areas in studying ABC transporter-associated MDR in cancer chemotherapy is : (1) to develop a systematic method or platform that can rapidly identify ABCB1 and/ or ABCG2 drug substrates rapidly. This is especially important for new FDA-approved chemotherapeutic drugs and drugs that are still in clinical development that has limited information on the overall pharmacokinetics and pharmacodynamics. (2) To identify and develop candidate compounds that can directly inhibit the function of ABCB1 and/or ABCG2 and/or modulate their expression levels, thus restore drug sensitivity and improve clinical outcome in ABC transporter-positive MDR cancers. We have recently developed a fluorescent cell-based high-throughput drug screening platform that can quickly identify compounds or clinically active therapeutic agents that interact directly with either human ABCB1 or ABCG2 drug transporters. This platform can rapidly provide us with information on direct drug-protein binding, as well as relative affinities of all other interactions. During our optimization and assessment stages, we tested our system by screening a small compound library consists of 5,500 compounds, as well as a collection of 40 chemotherapeutics that are either still in clinical trials or recently approved by the FDA. From them, we have identified many novel compounds and new chemotherapeutics that bind competitively to the substrate binding site(s) of ABCB1 and/ or ABCG2. Among them, we have already published studies on vemurafenib, a recently FDA-approved BRAF inhibitor for the treatment of melanoma, as well as BI 2536, the first selective polo-like kinase 1 (Plk1) inhibitor tested in clinical trials for cancer chemotherapy. The remainder of the positive hits will be reported in the near future. The objective of this proposal is to continue systematically identifying new drug substrates and novel inhibitors of ABCB1 and ABCG2 by performing high-throughput drug screening of various commercially available compound libraries, as well as new FDA-approved chemotherapeutics that are still in clinical development. Moreover, we will characterize the positive hits fully and determine the impact of ABC drug transporters on the effectiveness of these drugs, as well as provide solutions to circumvent ABC transporter-mediated drug resistance in cancer chemotherapy.

Project ID:PC10308-0668
External Project ID:MOST103-2320-B182-011