Drug Metabolizing Enzymes In Humans And Animal Models

成就：我们已经在人类中发现了CYP家族的基因多态，它负责某些药物和环境化学品的可变新陈代谢，并改变人类对这些化学品的敏感性。通过重新测序，我们在3个种族的72名个体中发现了21个SNP，其中包括两个编码变化的等位基因：CYP2C8*2(Ile269Phe)和CYP2C8*3(Arg139Lys和Lys399Arg)。基因测试表明，CYP2C8*2在非裔美国人中发现，而CYP2C8*3主要在高加索人中发现。利用重组的cDNA表达系统，我们发现CYP2C8*3在抗癌药物紫杉醇和内源化合物花生四烯酸的代谢中存在缺陷。CYP2C8在人的心脏和血管中表达，因此具有额外的临床意义。细胞色素P450 2 C9。在一名对抗惊厥药物苯妥英表现出严重临床毒性的非裔美国人患者中，发现了一个新的零突变，该突变使苯妥英的代谢率降低了85%。该个体为新的CYP2C9缺失突变体纯合子。这是这种临床上重要的酶的第一个零多态性的例子。人口研究表明，这种突变在非裔美国人中发现，但在高加索人中缺失或罕见。新近发现了细胞色素P3A4基因的多态，它代谢了几乎一半的临床已知药物。两种氨基酸的变化会影响对有机磷杀虫剂毒死蜱和激素睾酮的催化活性。这些氨基酸变化的影响正在细菌的cdna表达系统中解决。对72名个体的CYP2C9进行了重新测序，发现了6个新的编码变化。目前正在使用定点突变和cdna表达系统来研究这些突变的后果。CYP2C19代谢抗溃疡药物奥美拉唑、抗惊厥药美苯妥英、安定、某些巴比妥酸盐，激活某些抗疟疾药物，并亚磺化杀虫剂甲拌磷。已检测到9个新的基因多态性。它们的影响将在重组的cdna表达系统中得到解决。

ACCOMPLISHMENTS: We have identified genetic polymorphisms in the CYP family in humans which are responsible for the variable metabolism of certain drugs and environmental chemicals and altered susceptibility of humans to these chemicals. By resequencing efforts we have found 21SNPs in 72 individuals from 3 racial groups resequenced for human CYP2C8 including two alleles with coding changes : CYP2C8*2( Ile269Phe) and CYP2C8*3(Arg139Lys and Lys399Arg). Genetic tests showed CYP2C8*2 is found in African-Americans, and CYP2C8*3 primarily in Caucasians. Using recombinant cDNA expression systems, we found CYP2C8*3 is defective in the metabolism of the anticancer drug taxol as well as the endogenous compound arachidonic acid. CYP2C8 is expressed in human heart and blood vessels and is therefore of additional clinical interest. CYP2C9. A new null mutation was found in CY2C9 which decreased metabolism of the phenytoin by 85% in an African-American patient exhibiting severe clinical toxicity to the anticonvulsant phenytoin. The individual was homozygous for a new deletion mutant of CYP2C9. This is the first example of a null polymorphism in this clinically important enzyme. Population studies showed that the mutation was found in African-Americans but absent or rare in Caucasians. New polymorphisms have been discovered in CYP3A4 which metabolizes almost half of all clinically known drugs. Two amino acid changes affect catalytic activity toward the organophosphorus pesticide chlorpyrifos, and the hormone testosterone. The effects of these amino acid changes are being addressed in a bacterial cDNA expression system. Resequencing of CYP2C9 in 72 individuals has uncovered six new coding changes. The consequences of these are being studied using site-directed mutagenesis and cDNA expression systems. CYP2C19 metabolizes the antiulcer drug omeprazole, the anticonvulsant mephenytoin, valium, certain barbiturates, activates certain antimalarials, and sulfoxidizes the pesticide phorate. Nine new polymorphisms have been detected in CYP2C19. Their effects will be addressed in recombinant cDNA expression systems.