CAJ | 학술논문

Polymorphic cytochrome P4502E1 (CYP2E1) plays an important role in the metabolic activation of many carcinogens. We have previously shown that the c1/c1 genotype recognized by Rsa I in the 5′-regulatory region of the CYP2E1 may be a susceptibility factor for developing esophageal cancer and lung cancer in Chinese. The present study was to investigate the relationship between the Rsa I genotype and the expression of CYP2E1 in human livers. A total of 50 liver specimens were genotyped for CYP2E1 and assayed for CYP2E1 protein contents and functional activity by using specific antibody in immunoblot and a probe substrate, p-nitrophenol. A considerable interindividual variation in CYP2E1 protein (20-fold) and functional activity (56-fold) was observed among these liver samples. However, when they were categorized according to genotype, the mean content of CYP2E1 protein was significantly higher among individuals with the c1/c1 genotype than that among those having c1/c2 or c2/c2 genotype [124.0±83.9 pmol/mg (n = 28) versus 65.5±38.9 pmol/mg (n = 22), P＜0.01 . The mean activity of CYP2E1 towards p-nitrophenol for the c1/c1 genotype was also higher than that for the variant genotypes (198.4±27.8 pmol/min/mg versus 101.2±18.1 pmol-1·min-1·mg-1, P＜0.01 . Also, the protein levels and functional activity showed a significant correlation (r = 0.68, P＜0.01 . These results demonstrate an association between the Rsa I genotype and the phenotype of CYP2E1 in our samples, and the data are compatible with the assumption that CYP2E1 c1/c1 genotype is a susceptibility factor for certain cancers in Chinese.