The drug transporters P-gp and MRP2 significantly affect the absorption, distribution and excretion of many drugs. The FDA has recommended that pharmaceutical companies test all drugs for their interactions with these drug transporters. P-gp and MRP2 protein biosensors are being developed for the purpose of profiling drug libraries and other natural small molecule libraries for interaction with these drug transporter proteins to support drug discovery and improve the developmental process, the efficacy and to reduce the toxicity of many important drugs. However, P-gp and MRP2 drug transporters have multiple drug binding pockets. Currently available transport activity based assays utilize fluorescent substrates which have limited reporting spectrums as they cannot report interactions at multiple distinct drug binding pockets.
SDSU researchers have developed a P-gp and MRP2 biosensor with the ability to identify substrates, inhibitors and/or activators for P-gp and MRP2 proteins in live cells regardless of which binding pocket the test compound interacts. The biosensors can be used in a stable cell line with unlimited scalability and at low cost. Florescence plate readers can be utilized to create high-throughput screening of drug candidate libraries.
The biosensor is potentially sensitive to both allosteric regulators and transportable substrates. The biosensor screening approach has unique advantages over the standard Caco-2 or MDCK monolayer assays that require long culturing period and involve laborious steps. The biosensor may provide for a cost efficient approach for comprehensive profiling of drug interactions with P-gp and MRP2. Furthermore, standard fluorescent substrate efflux assays cannot detect substrate drugs that interact with the transporter but do not compete with fluorescent substrate binding site. In contrast, biosensor approach is capable of detecting all substrate drug interactions regardless of the binding site. Finally, biosensor can be used for in vivo studies in animals for drug bioavailability and toxicity.