Relationship between CYP1A1 and GSTM1 genetic polymorphisms and lung cancer susceptibility in population of Inner Mongolia

Abstract

Lung cancer is one of malignant tumors to hurt human health. It has been known that the development of lung cancer may be associated with genetic polymorphism of some lung cancer related genes. The aim of this study is to explore the susceptibility to lung cancer in relation to CYP1A1 and GSTM1 genetic polymorphisms in population of Inner Mongolia. CYP1A1 and GSTM1 genetic polymorphisms were determined by PCR-RFLP in 163 lung cancer cases and healthy controls respectively. The frequencies of CYP1A1 variation genotype (vt/vt) and GSTM1(-) were 36.8% and 65.0% in lung cancer cases and 19.0% and 48.9% in healthy controls respectively. Statistical tests showed significant difference in the frequencies between the two groups (Chi-Square =12.82, P=0.0001; Chi-Square = 9.78, P=0.002). The risk of lung cancer with CYP1A1 variation genotype was significantly higher than those of controls (OR= 2.48, 95% CI=1.51-4.08). The individuals who carried with GSTM1-null genotype had a high risk of lung cancer (OR=2.03, 95% CI=1.30-3.17). Combined analysis of the polymorphisms showed that percentage of CYP1A1(vt/vt)/GSTM1(-) in lung cancer and control groups was 28.8% and 8.0% respectively (Chi-Square = 23.883, P=0.0001). The people who carried with CYP1A1(vt/vt)/GSTM1(-) had a high risk of lung cancer (OR=4.90, 95% CI=2.50-9.83). Pearson Chi-Square of sex differential showed there was no significance between the homozygous variation genotype of CYP1A1/GSTM1(-) and the other genotypes of CYP1A1/GSTM1(-) neither in lung cancer group (Chi-Square=0.797, P=0.372) nor in control group (Chi-Square=0.670, P=0.761). Statistical tests showed that susceptibility to lung cancer was related to smoking (Chi-Square = 14.197, P=0.000), the risk of lung cancer in smoking individuals raised remarkably (OR=2.33, 95% CI=1.50-3.62). There may be a synergetic interaction between CYP1A1 variation genotype (vt/vt) and smoking on the elevated susceptibility to lung cancer (Chi-Square = 23.843, P=0.000), the smokers who carried with CYP1A1 (vt/vt) had a significantly higher risk of lung cancer (OR=4.44, 95% CI=2.40-8.32, Chi-Square = 23.843, P= 0.000). So did the GSTM1(-) and smoking on the elevated susceptibility to lung cancer, the significantly higher risk of lung cancer had also been found in those smokers who carried with GSTM1(-) (OR=7.32, 95% CI=3.39-15.50, Chi-Square = 36.708,P=0.000). The polymorphisms of CYP1A1 vt/vt and GSTM1(-) are the risk factors in lung cancer of Inner Mongolia. Smoking is also related to the susceptibility to lung cancer. There may be a synergetic interaction between CYP1A1 (vt/vt) and GSTM1(-) on the elevated susceptibility of lung cancer. So do the CYP1A1 (vt/vt), GSTM1(-) and smoking.