The influence of promoter polymorphism of nuclear factor-erythroid 2-related factor 2 gene on the aberrant DNA methylation in gastric epithelium

Oncol Rep. 2008 Jan;19(1):211-6.

Abstract

Aberrant promoter methylation is an important mechanism for gene silencing. Inflammation-related reactive oxygens contribute to this CpG island methylation. The nuclear factor-erythroid 2-related factor 2 gene (Nrf2) is known to regulate the expression of detoxifying and antioxidant genes. We investigated the relationship between promoter polymorphisms of Nrf2 gene and the CpG island methylation in non-cancerous gastric mucosa. The study was performed in 85 subjects (46 without gastric malignancies, non-GC group, and 39 with gastric cancer, GC group). The promoter methylation status of p14(ARF), p16(INK4a) and p21(Waf1) genes was determined by methylation-specific-polymerase chain reaction. The Nrf2 gene genotypes were determined by the PCR-SSCP method. In the 85 subjects, CpG island methylation was found in 25.9% for p14, 15.3% for p16, none for p21. The frequency of the methylated genes was significantly higher in GC group than non-GC group (OR, 2.67; 95% CI, 1.10-6.49; p=0.029). In particular, the frequency of p16 gene methylation was much higher in GC group (p=0.0023). The Nrf2 -686/-684 G/G haplotype was positively associated and A/G haplotype was inversely associated with the development of CpG island methylation, especially p14 gene methylation (OR, 3.28; 95% CI, 1.26-8.59; p=0.015, and OR, 0.38; 95% CI, 0.15-0.96; p=0.040, respectively). In Helicobacter pylori (H. pylori) infected subjects, the number of -686/-684 G/G allele was positively correlated and that of A/G allele was inversely correlated to the methylation status, especially p14 methylation, by the adjusted analysis (OR, 2.90; 95% CI, 1.14-7.36; p=0.026, and OR, 0.33; 95% CI, 0.13-0.88; p=0.027, respectively). Our results suggested that the promoter polymorphisms of Nrf2 gene may affect the methylation status of tumor-related genes, especially the p14 gene, under the influence of H. pylori-induced gastric inflammation.

MeSH terms

  • Aged
  • CpG Islands
  • DNA Methylation*
  • Female
  • Gastric Mucosa / physiology*
  • Gastritis / genetics
  • Gastritis / microbiology
  • Helicobacter Infections / complications
  • Humans
  • Male
  • Middle Aged
  • NF-E2 Transcription Factor / genetics*
  • Polymerase Chain Reaction
  • Polymorphism, Single-Stranded Conformational*
  • Promoter Regions, Genetic / genetics
  • Stomach Neoplasms / genetics*
  • Tumor Suppressor Protein p14ARF / genetics

Substances

  • NF-E2 Transcription Factor
  • Tumor Suppressor Protein p14ARF