Abstract:

Background and purpose: Gastric cancer is the most common malignant tumor and the leading cause of death in Qinghai province. The possible chemical procarcinogens in our living environment must be activated and transformed ultimately into carcinogens by CYP2E1 of cytochrome, one of the most important Ⅰ phase metabolic enzymes in human body, and also the genetic polymorphisms of CYP2E1 are reportedly in different ethnic groups and in different regions. The aim of this study was to investigate the correlation between genetic polymorphisms of CYP2E1 DraⅠ and the susceptibility of gastric cancer in Qinghai province. Methods: A case control study was performed with the molecular epidemiological methods. A total of 120 gastric cancer cases (as the gastric cancer group) and 120 healthy people (as the control group) were randomly selected from affiliated hospital of Qinghai University from Jan. 2010 to Apr. 2012, and all of the individuals were living in Qinghai province. The genotypes and alleles of CYP2E1 DraⅠ in both of the above groups were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and then the outcome was analyzed statistically. Results: The distribution frequency of CYP2E1 DraⅠ genotypes (including C/C, C/D, D/D) was 58.33%, 35.00% and 6.67% in the patient group respectively, 58.33%, 38.34% and 3.33% in the control group respectively, which showed no significant differences between the two groups (the value of P were 1.00, 0.59 and 0.24, respectively). The distribution frequency of CYP2E1 DraⅠ alleles (including C and D) was 75.83% and 24.17% in the patient group respectively, meanwhile, 77.50% and 22.50% in the control group respectively, which also showed no significant difference between the two groups (χ²=0.19, P=0.67). Interestingly, the mutant genotypes (C/D, D/D) of CYP2E1 DraⅠ were associated with the well and well-moderately differentiated gastric adenocarcinoma in a way (χ²=4.49 and P=0.03; OR=3.5 and 95%CI: 1.04-11.80), and it was also demonstrated that the mutant genotypes (C/D, D/D) were the risk factors for the oncogenesis of well and wellmoderately differentiated gastric adenocarcinoma; The wild homozygote (C/C) of CYP2E1 DraⅠ was related to poorly differentiated gastric adenocarcinoma (χ²=3.97 and P=0.049; OR=0.54 and 95%CI: 0.29-1.00 ), and it was still revealed that the wild homozygote (C/C) of CYP2E1 DraⅠ was the risk factor for the tumorigenesis of poorly differentiated gastric adenocarcinoma. Conclusion: The genetic polymorphisms of CYP2E1 DraⅠ are to some extent associated with the susceptibility of different differentiated gastric adenocarcinoma in Qinghai province, furthermore, carriers of wild homozygote (C/C) of CYP2E1 DraⅠ are relatively prone to the risk factor to the occurrence of poorly differentiated gastric adenocarcinoma, and carriers of mutant homozygote (D/D) and mutant heterozygote (C/D) are also liable to occur the well/well-moderated differentiated gastric adenocarcinoma in Qinghai province.

Key words: Qinghai, Gastric cancer, CYP2E1 DraⅠ, Genetic polymorphisms