A fluorescent cell-based assay for cytochrome P-450 isozyme 1A2 induction and inhibition

High throughput lead optimization requires simple, homogeneous cell-based a ssays capable of defining the drug-like properties of first-round screening hits. Induction and inhibition of the Phase I drug-metabolizing enzymes ar e central to this process. We report here an assay for induction and inhibi tion of cytochrome P-450 (CYP) isozyme 1A2 that meets these requirements. I t utilizes HepG2/C3A, a human liver cell line, and ethoxyresorufin. Using m ethylcholanthrene, CYP1A2 can be induced dramatically, and it is inhibited by furafylline, a mechanism-based inhibitor of this enzyme.