Background: Cytochrome P450 2E1 (CYP2E1) has an important role in the metabolic activation of precarcinogens such as N-nitrosoamines and other low relative molecular mass, organic compounds. This study examined whether CYP2E1 RsaI and DraI polymorphism are associated with susceptibility to esophageal squamous cell carcinoma and the correlation between the genotypes and expression levels of CYP2E1 mRNA.
Methods: Seventy-seven patients with newly diagnosed, untreated esophageal squamous cell carcinoma and 79 healthy controls matched in age, gender and residence were recruited for the control study. An RsaI polymorphism in the 5'-flanking region and a DraI polymorphism in the sixth intron of the CYP2E1 gene, which could possibly affect its transcription, were determined in this study by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and mRNA level of CYP2E1 was measured by quantitative real-time reverse transcription PCR.
Results: No significant association of RsaI or DraI polymorphism of CYP2E1 with susceptibility of esophageal squamous cell carcinoma were demonstrated (OR = 1.67, 95% CI: 0.89 - 3.15, P = 0.11; OR = 1.11, 95% CI: 0.59 - 2.09, P = 0.74, respectively). With SHEsis software, no linkage disequilibrium was detected between RsaI and DraI polymorphism (D' = 0.528, r(2) = 0.27). When combined RsaI polymorphism with DraI polymorphism, the association between that carrying c2 allele and DD genotype and the risk for esophageal squamous cell carcinoma were found (OR = 5.77, 95% CI: 1.65 - 20.22). Compared with the normal controls, the mRNA levels with RsaI polymorphism, DraI polymorphism, or any combined genotypes in cases showed no statistical difference.
Conclusions: This study suggests that carrying c2 allele and DD genotype conferreded an elevated risk for esophageal squamous cell carcinoma. There was no significant statistical relationship between the genotypes c1/c2, D/C, or the combined allele and mRNA expression.