The Center for Alternatives to Animal Testing is an academic center affiliated with the Division of Toxicological Sciences in the Department of Environmental Health Sciences of the Johns Hopkins University Bloomberg School of Public Health.

 

Johns Hopkins School of Public Health

Research Grants 2000-2001

Evaluation of CYP3A Induction with Engineered Cell Lines

Bingfang Yan, PhD
University of Rhode Island, Kingston, Rhode Island

Nearly all drugs and other foreign compounds absorbed by the body undergo metabolism, in which extensive chemical modifications usually take place as a result of the involvement of phase I and phase II biotransformation. Cytochrome P450 (CYP) enzymes are a family of heme-containing proteins and rank first among the phase I biotransformation enzymes in terms of catalytic versatility and the number of foreign compounds they metabolize. Many foreign compounds are shown to increase the expression levels of CYP enzymes thus alter the overall drug-metabolizing capacity. Such an alteration may accelerate the inactivation of drugs thus diminish therapeutical effectiveness or increase the formation of toxic metabolites thus cause tissue damage. The Food and Drug Administration requests the new drugs be tested as CYP inducers, which is usually conducted with human hepatocytes and animals. The availability of human tissues and the use of a large number of animals, however, are presenting major obstacles in rapidly and accurately screening daily increasing number of dug candidates. The proposed project is designed to develop and optimize an in vitro screening system for CYP3A induction. The CYP3A enzymes are the most abundant of CYP enzymes and involve the metabolism of two thirds of drugs and other foreign compounds. In this system, cells will be engineered to express appropriate proteins to support CYP3A induction, and the inductive effects will be monitored by determining a reporter activity, thus increasing the detection sensitivity. This system will significantly reduce the number of animal use and ease the supply of human tissues.