Cytochrome P450IIEI Genetic Polymorphisms, Racial Variation, and Lung Cancer Risk

Cytochrome P4501IEI is responsible for the activation of carcinogenic N-nitrosamines, benzene, urethane, and other low-molecularweight compounds. Restriction fragment length polymorphisms (Pstl and RsaI restriction enzymes) have been identified in the cytochrome P4501IE1 transcription regulatory region that may affect expression. This study describes the PstI and RsaI polymorphisms in different racial populations and in a case-control study of lung cancer. The allelic frequencies were markedly different in Japanese, African-Americans, and Caucasians: the PstI rare allele was present at a frequency of 2% in Caucasians, 5% in African-Americans, and 24% in Japanese (P < 0.05). For the RsaI rare allele, frequencies were 2% in Caucasians, 2% in African-Americans, and 27% in Japanese (P < 0.05). The assay was also applied to 128 individuals enrolled in a case-control study of lung cancer. Although limited in statistical power, the data indicate no evidence for an association in the aggregate of cytochrome P450IIEI Pstl [for which the odds ratio was 0.7 (95% confidence interval (C.I.) = 0.2-2.8)] or Rsal [for which the odds ratio was 0.9 (95% C.I. = 0.2-5.4)] restriction fragment length polymorphisms with lung cancer in this U.S. population. When analyzed by race, the lung cancer odds ratio for the PstI mutant allele in African-Americans was 0.19 (95% C.I. = 0.03-1.38), and in Caucasians it was 4.13 (95% C.I. = 0.34-48.8). For the Rsal mutant allele, the odds ratios were 0.20 (95% C.I. -: 0.02-2.43) and 4.28 (95% C.I. = 0.35-50.6), respectively. The ethnic differences of these restriction fragment length polymorphisms might be related to genetic susceptibilities for lung cancer among Caucasians and for gastric or esophageal cancer among Japanese.