A functional trinucleotide repeat polymorphism in the 5'-untranslated region of the glutathione biosynthetic gene GCLC is associated with increased risk for lung and aerodigestive tract cancers

Mol Carcinog. 2013 Oct;52(10):791-9. doi: 10.1002/mc.21923. Epub 2012 May 18.

Abstract

Glutathione (GSH), the major intracellular antioxidant, protects against cancer development by detoxifying carcinogens and free radicals and strengthening the immune system. Recently, a GAG-trinucleotide repeat polymorphism in the 5'-untranslated region of the gene for the rate-limiting enzyme for GSH biosynthesis, γ-glutamine cysteine ligase (GCL), was shown to be associated with lowered GCL activity and GSH levels in vitro and in vivo. We tested the hypothesis that this functional polymorphism in GCL is associated with the risk for lung and aerodigestive tract cancers. To this end, we conducted a case-control study that included 375 lung cancer cases, 200 aerodigestive tract cancer cases, and 537 controls. GAG repeat genotype (4, 7, 8, 9, and 10 repeat alleles) was determined by capillary electrophoresis of PCR products from the repeat region of the GCL catalytic subunit (GCLC). Odds ratios (OR) were calculated by logistic regression and adjusted for risk factors, including age, sex, body mass index, and smoking history. The GAG-7/7 genotype was associated with a 1.9-fold increased risk of lung cancer and 2.6-fold increased risk of aerodigestive tract cancer compared to the wild-type GAG-9/9 (P < 0.05). Similarly, the GAG-7 allele was associated with an increased risk of lung cancer (OR = 1.5, P = 0.01) and aerodigestive tract cancer (OR = 2.3, P < 0.001) compared to subjects without GAG-7 allele. These findings suggest that GSH synthesis affects the risk of lung and aerodigestive tract cancers, and further implicates a role for oxidative stress in the development of these cancers.

Keywords: GAG-repeat polymorphism; aerodigestive tract cancer; glutathione; lung cancer; γ-glutamine cysteine ligase.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • 5' Untranslated Regions / genetics*
  • Adenocarcinoma / etiology
  • Adenocarcinoma / pathology
  • Adult
  • Aged
  • Aged, 80 and over
  • Carcinoma, Large Cell / etiology
  • Carcinoma, Large Cell / pathology
  • Carcinoma, Non-Small-Cell Lung / etiology
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Carcinoma, Squamous Cell / etiology
  • Carcinoma, Squamous Cell / pathology
  • Case-Control Studies
  • Digestive System Neoplasms / etiology*
  • Digestive System Neoplasms / pathology
  • Female
  • Genotype
  • Glutamate-Cysteine Ligase / genetics*
  • Humans
  • Lung / metabolism
  • Lung / pathology
  • Lung Neoplasms / etiology*
  • Lung Neoplasms / pathology
  • Male
  • Middle Aged
  • Polymerase Chain Reaction
  • Polymorphism, Genetic / genetics*
  • Prognosis
  • Risk Factors
  • Small Cell Lung Carcinoma / etiology
  • Small Cell Lung Carcinoma / pathology
  • Trinucleotide Repeats / genetics*

Substances

  • 5' Untranslated Regions
  • Glutamate-Cysteine Ligase