A Case-Control Stuy On The Association Between Polymorphisms Of Metabolic Enzyme Genes, External Exposure Factors And Their Interaction And Hepatoma Susceptibility

Objective: To study the relationship between genetic polymorphisms of phaseⅠ(CYP2E1,CYP1A1) and phaseⅡ(GSTM1,EPHX1) metabolizing enzymes and susceptibility to primary hepatocellular carcinoma (PHC) in southwest Guangxi province, and to find out whether there is gene-gene or gene-external exposure factors interaction between them. So as to provide a new route for screening and early diagnosis and making the integrated preventive measures for PHC in Guangxi Province.Methods: A case-control study was conducted, which included 102 Patients with PHC and 102 normal controls in southwest GuangXi subjects. Genetic polymorphisms of phaseⅠ(CYP2E1, CYP1A1) and phaseⅡ(GSTM1, EPHX1) were determined by Polymerase chain reaction(PCR) and Polymerase chain reaction restriction fragment length polymorphisms (PCR-RFLP). Statistics analysis adopt SPSS16.0 statistical package. Departure from Hardy-Weinberg Equilibrium (HWE) for polymorphism genotype in controls was tested by Chi-square test. The distribution differences of polymorphisms of CYP2E1, CYP1A1, GSTM1, EPHX1 and related risk between the case group and control group were analyzed by chi-square test. Crude and adjusted odds ratio (OR) and 95% confidence interval (CI) were used to evaluate associations between polymorphism genotype and PHC risk. Based on the multiplication model of crossover analysis and Logistic regression were used to analyze the relationship of gene-gene, gene-external exposure factors interaction. All statistical tests were two-sided withαis 0.05.Results: 1. There were no statistically differences in the distribution of age, sex , nationality between cases and controls, respectively (P>0.05).2. Hepatitis B infection, drinking showed significant difference between cases and controls (P < 0.05), OR(95%CI) were 2.08(1.181～3.663), 20.833(9.882～43.922), respectively. There was no statistically differences in the distribution of smoking between two groups (P>0.05).3. The genotype frequency distribution of CYP2E1, CYP1A1, EPHX1 were in accordance with the Hardy-Weinberg Equilibrium among the controls (P>0.05).4.(1) As for CYP2E1 genotype, frequencies of c1/c1, c1/c2, c2/c2 genotype were 61.8%, 30.4%, 7.8% in case group, 55.9%, 41.2%, 2.9% in control group respectively . The difference were no significant between two groups (χ~2=4.322,P=0.115).(2) As for CYP1A1 genotype, frequencies of IIe/IIe, IIe/Val, Val/Val genotype were 34.3%, 46.1%, 19.6% in case group, 43.1%, 45.1%, 11.8% in control group respectively. The difference were no significant between two groups (χ~2=3.036,P=0.219).(3) As for GSTM1 genotype, frequencies of null, no-null genotype were 52%, 48% in case group, 41.2%, 58.8% in control group respectively. The difference were no significant between two groups (χ~2=2.384,P=0.123).(4) The frequencies of polymorphism genotype of His/His, His/Arg, Arg/Arg of EPHX1 gene in patients with PHC were 72.5%, 25.5%, 2% respectively, which in the control group were 62.7%, 37%, 1% respectively. The difference were no significant between two groups(χ~2=2.966,P=0.226).5. Gene-gene interaction analytical results:(1) When combination both of CYP2E1, CYP1A1, GSTM1, EPHX1 genotype were analyzed, combination of the GSTM1, CYP2E1 and the CYP2E1, CYP1A1 were associated with the risk of PHC.(2) When combination every three of CYP2E1, CYP1A1, GSTM1, EPHX1 genotype were analyzed, except the combination of GSTMI, CYP1A1, EPHX1 might be not associated with the susceptibility of PHC, others were associated with the susceptibility of PHC.(3) When combination of polymorphism of CYP2E1, CYP1A1, GSTM1, EPHX1 genotype was analyzed, the risk of PHC was increased. And the risk of suffering PHC in individuals with CYP2E1c1/c1, CYP1A1(IIe/Val or Val/Val), EPHX1His/His, GSTM1null was 6.876 fold increase than that without any of them (95%CI was 1.104-42.789).6. Gene-external exposure factors interaction analytical results:(1) The combination of drinking and a single gene of CYP2E1, CYP1A1, GSTM1, EPHX1 are associated with the risk of PHC.(2) There was synergistic action between smoking and EPHX1 genotype on the risk of PHC (P=0.029). Smoking combined with CYP1A1 genotype might no synergistic action on the susceptibility of PHC (P=0.227). And no obvious interaction was observed in smoking combined with other genotype.(3) Interaction existed between CYP1A1 or GSTM1 or EPHX1 genotype and hepatitis B infection. Hepatitis B infection combined with CYP2E1 genotype might no synergistic action on the susceptibility of PHC (P=0.305).Conclusions:The Polymorphism of a single gene of CYP2E1, CYP1A1, GSTM1, EPHX1 might be not associated with the susceptibility of PHC, but when they combined with each other or combined with smoking or drinking; the risks of PHC were increased. These results suggest that gene-gene or gene-external exposure factors interaction play an importance role in the susceptibility of PHC, in addition, it necessary to take targeted preventive measures for PHC in Guangxi Province.