Association of the variable number of tandem repeats polymorphism in the promoter region of the SMYD3 gene with risk of esophageal squamous cell carcinoma in relation to tobacco smoking

The etiology of esophageal squamous cell carcinoma (ESCC) has been shown to be multifactorial, including genetic, epigenetic, and environmental factors, such as tobacco smoking. A variable number of tandem repeats (VNTR) polymorphism in the promoter region of SMYD3, a recently characterized histone lysine methyltransferase gene that is implicated in cell proliferation and carcinogenesis, has been shown to be functional, but its association with cancer risk has not been well established because of apparently discrepant results in different populations. In this case-control study, we genotyped 567 patients with newly diagnosed ESCC and 567 healthy controls and found an increased ESCC risk (odds ratio [OR]=1.42, 95% confidence interval [CI]=1.05-1.91) associated with the common SMYD3 VNTR genotype. Stratification analysis revealed that the increased risk was limited to smokers (OR=1.99; 95% CI=1.27-3.12). Furthermore, compared with the reference group of non-smokers carrying the homozygous or heterozygous genotype, ORs (95% CI) of the wild genotype for non-smokers, smokers who smoked <25, and ≥25 pack-years were 1.03 (0.70-1.53), 2.80 (1.66-4.70), and 4.76 (2.67-8.46), respectively (P<0.001 for trend test), suggesting an interaction between this genetic polymorphism and smoking status. These findings provide additional evidence that the common VNTR polymorphism in the promoter region of SMYD3 gene may be a susceptibility factor for human cancers such as ESCC by interacting with tobacco carcinogens.