A regulatory variant in CYP2E1 affects the risk of lung squamous cell carcinoma

Cytochrome P450 2E1 (CYP2E1), an ethanol-inducible enzyme, has been shown to metabolically activate various carcinogens, which is critical for the development of cancers. It has been demonstrated that CYP2E1 polymorphisms alter the transcriptional activity. However, studies on the association between CYP2E1 −1239G>C polymorphism and non-small cell lung cancer have reported conflicting results. Thus, the gain of the present study was to investigate whether CYP2E1 −1239G>C polymorphism is associated with the development of non-small cell lung cancer in Chinese population. A case–control study was conducted in which CYP2E1 −1239G>C polymorphism was analyzed in 526 Chinese patients with non-small cell lung cancer and 526 age-matched healthy controls by polymerase chain reaction–restriction fragment length polymorphism. Odds ratios were estimated by multivariate logistic regression. A meta-analysis was conducted to evaluate the association of CYP2E1 −1239G>C polymorphism with the risk of lung cancer in Chinese population by calculating pooled odds ratio (OR). For CYP2E1 −1239G>C polymorphism, −1239C allele carriers (OR = 0.67; 95 % confidence interval (CI) = 0.51–0.87; P = 0.002) were associated with a decreased risk of non-small cell lung cancer when compared with −1239GG homozygotes. In the group analyses by pathological types, for lung squamous cell carcinoma and other types, the ORs of the C allele carriers were 0.60 (95 % CI = 0.41–0.88; P = 0.009) and 0.54 (95 % CI = 0.30–0.99; P = 0.045). In the group analysis of smoking status, the OR for the −1239C allele-containing genotype was higher than that for −1239GG genotype (OR = 0.57; 95 % CI = 0.40–0.81; P = 0.002) among smokers, but not among nonsmokers. Moreover, when the risk associated with CYP2E1 polymorphism was further evaluated within strata of <25 and ≥25 pack-years smoked, this effect between susceptible genotypes and smoking was mostly evident among light smokers (<25 pack-years) with OR of 0.42 (95 % CI 0.23–0.79), but not among heavy smokers with OR of 0.87 (95 % CI 0.53−1.43). In the group analyses by TNM stage, there was no significant difference between CYP2E1 −1239G>C polymorphism and the risk of non-small cell lung cancer. Meta-analysis data also showed that the carriers of CYP2E1 −1239C allele had a protect effect on the risk of lung cancer in Chinese with overall OR of 0.77 (95 % CI 0.66–0.90). CYP2E1 −1239G>C polymorphism was associated with a decreased risk of development of non-small cell lung cancer in Chinese patients. The association displays a manner of gene–environment interaction between this polymorphism and smoking status.