Analysis of NAT and CYP1A2 phenotypes and NAT2 genotype by capillary electrophoresis

Abstract

Susceptibility to bladder or colorectal cancer in humans exposed to arylamines or heterocyclic amines may be influenced substantially by the activities of the polymorphic enzymes cytochrome P4501A2 (CYP1A2) and N-acetyltransferase (NAT). An association between colorectal cancer and CYP1A2 and NAT activities is controversial. CYP1A2 and NAT phenotypes were determined simultaneously using micellar electrokinetic chromatography of caffeine metabolites in urine extracts following a single oral dose of approximately 120 mg caffeine. The peak area ratio of 1,7-dimethylxanthine/ 1,3,7-trimethylxanthine (caffeine) was used for CYP1A2 phenotyping. The peak area ratio of 5-acetylamino-6-formylamino-3-methyluracil/1 -methylxanthine was used for NAT phenotyping. The NAT2 * genotype was evaluated by restriction fragment length polymorphism analysis using capillary electrophoresis with a sieving buffer containing ethidium bromide. Capillary electrophoresis is a rapid and simple method that can be automated for CYP1A2 and NAT phenotyping by analysis of caffeine urinary metabolites as well as for NAT2* genotyping.