Substrates and screening methods for transport proteins

Abstract

A variety of methods for assaying libraries of test compounds as ligands and / or substrates of transport proteins, including both carrier-type and receptor-type transport proteins, are provided. Both in vitro and in vivo screening methods are disclosed. Also provided are methods for screening DNA libraries to identify members that encode transport proteins. Pharmaceutical compositions including compounds identified via the screening methods are also provided.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This application is a continuation of allowed U.S. application Ser. No. 09 / 661,927, filed Sep. 14, 2000, which claims the benefit of U.S. Provisional Application No. 60 / 154,071, filed Sep. 14, 1999, the disclosure of each is incorporated herein by reference in their entirety.FIELD OF INVENTION[0002]This invention relates to the fields of combinatorial chemistry and pharmaceutical agent delivery.BACKGROUND OF THE INVENTION[0003]Recent advances in biotechnology and chemistry have made available an increasing number of potential therapeutic agents. However, many agents fail at the preclinical or early clinical stage due to poor pharmacokinetics. Other potential targets for pharmaceutical agents are largely ignored due to anticipated problems of pharmaceutical agent delivery. Oral delivery of compounds is advantageous for reducing treatment costs and increasing patient acceptance. However, formulating compounds for efficient oral bioavailabi...

AI Technical Summary

Benefits of technology

[0009]Disclosed herein are a variety of methods for screening individual or test complexes for activity as ligands for various transport proteins. Certain methods can be performed to distinguish compounds that are substrates and internalized within a cell from compounds that simply bind to a cell surface. Because the methods are amenable to high throughput screening formats and can be used to screen large libraries of complexes, one can accumulate data on structural and electronic features of those compounds that are substrates, thus allowing structure-activity relationships to be discerned. Such information in turn can be utilized in the design of pharmaceutical agents having improved cellular uptake.

[0010]By screening complexes that include a reporter, compounds that are substrates for various transport proteins can be readily detected. Use of a reporter has the additional advantage in that it can serve as a surrogate for a pharmaceutical agent. Thus, certain methods involve initially screening a library of complexes to identify a substrate and then replacing the reporter with a pharmaceutical agent and rescreening to determine whether the substrate-drug conjugate is able to be taken up by the cell. Thus, the methods can be used to develop complexes for use in drug delivery.

Problems solved by technology

However, many agents fail at the preclinical or early clinical stage due to poor pharmacokinetics.

Other potential targets for pharmaceutical agents are largely ignored due to anticipated problems of pharmaceutical agent delivery.

However, formulating compounds for efficient oral bioavailability has proven particularly difficult because of problems associated with uptake and susceptibility to metabolic enzymes in the intestinal tract.

Likewise, delivery of compounds across the blood brain barrier or targeting compounds to specific tissues has proven problematic.

Following internalization, the clathrin coat is lost and the pH in the endosome is lowered, thus resulting in the dissociation of the receptor-substrate complex.

However, existing assays are tedious, low throughput, and the delivery of many pharmaceutical agents and potential pharmaceutical agents remains to be improved.

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