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Functional Characterization of Human CYP2C9 Allelic Variants in COS-7 Cells

Huihui Du1, Zhiyun Wei1, Yucai Yan1

  • 1Bio-X Institutes, Shanghai Jiao Tong UniversityShanghai, China; Shanghai Genome Pilot Institutes for Genomics and Human HealthShanghai, China.

Frontiers in Pharmacology
|May 21, 2016
PubMed

Insights

Cytochrome P450 2C9 (CYP2C9) genetic variations significantly impact drug metabolism and response. Specific CYP2C9 variants, particularly CYP2C9.3 and CYP2C9.11, show reduced catalytic activity, affecting drug efficacy in the Chinese Han population.

Area of Science:

  • Pharmacogenomics
  • Drug Metabolism
  • Enzyme Kinetics

Background:

  • Cytochrome P450 2C9 (CYP2C9) activity variability influences drug response, affecting about 15% of marketed therapeutics.
  • Genetic polymorphisms in CYP2C9 are key drivers of interindividual differences in drug efficacy and safety.

Purpose of the Study:

  • To functionally characterize novel CYP2C9 allelic variants identified in the Chinese Han population.
  • To assess the impact of CYP2C9(*)2, CYP2C9(*)3, CYP2C9(*)8, CYP2C9(*)11, and CYP2C9(*)31 on S-warfarin metabolism.

Main Methods:

  • Transient expression of wild-type and variant CYP2C9 enzymes in COS-7 cells.
  • Determination of kinetic parameters (Km, Vmax, Clint) for S-warfarin 7-hydroxylation.
  • Comparative analysis of enzyme activity across different CYP2C9 alleles.

Main Results:

  • All tested allelic variants exhibited significantly reduced Vmax and Clint compared to wild-type CYP2C9.1.
  • CYP2C9.3 and CYP2C9.11 showed the most substantial reduction in catalytic activity, with Clint ratios of 8.2% and 9.8%, respectively.
  • CYP2C9.3 and CYP2C9.11 displayed significantly higher Km values, indicating altered substrate binding affinity.

Conclusions:

  • The identified CYP2C9 variants, especially CYP2C9.3 and CYP2C9.11, possess significantly impaired catalytic functions.
  • These findings are crucial for predicting CYP2C9 phenotype profiles in the Chinese Han population.
  • Understanding these functional alterations will aid in optimizing pharmacotherapy and personalized drug treatment strategies.
Keywords:
Chinese HanHPLC (high-performance/pressure liquid chromatography)S-warfarincytochrome P450genetic polymorphismsin vitro modelspharmacokinetics

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