Gene polymorphisms of folate metabolizing enzymes and susceptibility to lung adenocarcinoma in Serbia.

Abstract

e12020 Background: Methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TS) are important enzymes of the folate metabolism and are suggested as new prognostic factors for lung cancer. Cytosine to thymine transition at nucleotide 677 (C677T) leads to reduced MTHFR activity. The TS promoter has a tandem repeat polymorphism (2R, 3R) and a guanine to cytosine transition in the 3R allele related to TS protein expression. The aim of this study was to analyze the association of MTHFR and TS polymorphisms with lung adenocarcinoma in Serbia. Methods: A case-control study including 55 late-stage lung adenocarcinoma patients and 53 healthy subjects was performed. Restriction fragment length polymorphism analysis was used for MTHFR and TS genotyping. Depending on the presence of high (3RG) or low (2R, 3RC) expression alleles, TS functional groups were subclassified into HH (3RG/3RG), HL (2R/3RG, 3RG/3RC) and LL (2R/2R, 2R/3RC, 3RC/3RC) groups. Descriptive analyses included genotype and allelic frequencies; the odds ratio (OR) and 95 % confidence interval (CI) were calculated as an estimate of relative risk. Significance was considered for p < 0.05. Results: The distribution of the MTHFR variants in patients vs. controls was 61.8 % vs. 24.5 % for CC, 32.7 % vs. 62.3 % for CT and 5.5 % vs. 13.2 % for TT. A significant difference in CC vs. TT+CT MTHFR genotype distribution was observed between patients and controls (χ2 = 13.79; OR = 4.98; 95 % CI, 2.14 – 11.61). There was no significant association between the TS polymorphisms and the risk of lung adenocarcinoma occurrence, but in the CT+TT MTHFR subgroup, a nonsignificant difference in LL vs. HL+HH TS genotype distribution was observed between patients and controls (χ2 = 0.04; OR = 1.07; 95% CI, 0.31 – 3.67). Conclusions: A significant corelation between the CC MTHFR genotype and lung adenocarcinoma occurence in Serbia was found. Also, there was no significant correlation with lung adenocarcinoma occurence in the CT+TT MTHFR subgroup for carriers of the LL TS genotype. As this study was performed on a relatively small sample size further large case-control studies including analysis of gene-gene interactions with genes coding for other folate metabolism enzymes is needed.