Polarized cell cultures for integrated studies of drug metabolism and transport

This chapter describes the development of polarized cellular systems coexpressing adenovirus (AdV) with CYP3A4 (Ad3A4), P450 reductase (AdRed), and the MDR1/Pgp transporter. Because the experimental approach may be adapted to study the interplay of multiple enzyme/transporting systems, it may find significant application as a screening tool for the pharmaceutical industry and as a more basic research tool to study the kinetics of intestinal drug bioavailability. The expression system must have robust CYP3A4 activity. Transduction with recombinant adenovirus (AdV) offers several advantages.6 Adenovirus infects most cell types, levels of the recombinant protein can represent 15-20% of total cellular protein, and multiple AdV can be introduced simultaneously. The multidrug resistance gene MDR1 encodes the drug efflux transporter P-glycoprotein (Pgp), and because many drugs that interact with CYP3A are Pgp substrates, this transporter can influence the magnitude of CYP3A induction 1 and CYP3A metabolism. The challenges for the future are to generate model systems in which the dynamic interplay between drug transporting proteins and drug metabolizing enzymes may be explored.