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A Versatile Method to Determine the Cellular Bioavailability of Small-Molecule Inhibitors
Kevin B Teuscher1,2, Min Zhang1, Haitao Ji1,3,2
1Drug Discovery Department, H. Lee Moffitt Cancer Center and Research Institute , 12902 Magnolia Drive, Tampa, Florida 33612-9416, United States.
A new HPLC-MS protocol accurately measures small-molecule inhibitor bioavailability in cells. This method characterizes intracellular concentrations, stability, and binding, aiding drug development for cancer cells.
Area of Science:
- Pharmacology
- Analytical Chemistry
- Biochemistry
Background:
- Cellular bioavailability of small-molecule inhibitors is crucial for interpreting cell-based assays and optimizing drug candidates.
- Accurate intracellular concentration data is essential for understanding drug efficacy and mechanism of action.
Purpose of the Study:
- To develop and validate a generalizable HPLC-MS based protocol for determining cellular bioavailability of small-molecule inhibitors.
- To characterize key pharmacokinetic properties of inhibitors within cancer cells.
Main Methods:
- Development of a High-Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS) protocol.
- Quantification of intracellular inhibitor concentrations.
- Assessment of inhibitor stability (extra- and intracellular), dose- and time-dependence, cell permeability, and nonspecific binding.
Main Results:
- The protocol successfully determined cellular bioavailability for inhibitors targeting protein-protein interactions, bromodomains, and the β-catenin/BCL9 interaction.
- Two bromodomain inhibitors showed high nonspecific binding and low cellular uptake.
- Two β-catenin/BCL9 inhibitors exhibited low nonspecific binding but varied cellular uptake and stability kinetics.
Conclusions:
- The developed HPLC-MS protocol provides accurate intracellular concentrations and characterizes critical properties of small-molecule inhibitors.
- This method is valuable for interpreting cell-based data and guiding the optimization of inhibitors for cancer therapy.
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