DNA methylation of the cancer-related genes F2RL3 and AHRR is associated with occupational exposure to polycyclic aromatic hydrocarbons

Carcinogenesis. 2018 Jul 3;39(7):869-878. doi: 10.1093/carcin/bgy059.

Abstract

Some polycyclic aromatic hydrocarbons (PAH) are known carcinogens and workplace PAH exposure may increase the risk of cancer. Monitoring early cancer-related changes can indicate whether the exposure is carcinogenic. Here, we enrolled 151 chimney sweeps, 152 controls and 19 creosote-exposed male workers from Sweden. We measured urinary PAH metabolites using LC/MS/MS, the cancer-related markers telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) using qPCR, and DNA methylation of lung cancer-related genes F2RL3 and AHRR using pyrosequencing. The median 1-hydroxypyrene (PAH metabolite) concentrations were highest in creosote-exposed workers (8.0 μg/g creatinine) followed by chimney sweeps (0.34 μg/g creatinine) and controls (0.05 μg/g creatinine). TL and mtDNAcn did not differ between study groups. Chimney sweeps and creosote-exposed workers had significantly lower methylation of AHRR CpG site cg05575921 (88.1 and 84.9%, respectively) than controls (90%). Creosote-exposed workers (73.3%), but not chimney sweeps (76.6%) had lower methylation of F2RL3 cg03636183 than controls (76.7%). Linear regression analyses showed that chimney sweeps had lower AHRR cg05575921 methylation (B = -2.04; P < 0.057, adjusted for smoking and age) and lower average AHRR methylation (B = -2.05; P < 0.035), and non-smoking chimney sweeps had lower average F2RL3 methylation (B = -0.81; P < 0.042, adjusted for age) compared with controls. These cancer-related markers were not associated with urinary concentrations of PAH metabolites. In conclusion, although we found no associations with PAH metabolites in urine (short-term exposure), our results suggest dose-response relationship between PAH exposure and DNA hypomethylation of lung cancer-related loci. These findings indicate that further protective measures should be taken to reduce PAH exposure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Basic Helix-Loop-Helix Transcription Factors / genetics*
  • Biomarkers, Tumor / genetics
  • Carcinogens / toxicity
  • Creosote / adverse effects
  • DNA Methylation / drug effects*
  • DNA, Mitochondrial / genetics
  • Humans
  • Lung Neoplasms / chemically induced*
  • Lung Neoplasms / genetics*
  • Male
  • Middle Aged
  • Occupational Exposure / adverse effects*
  • Polycyclic Aromatic Hydrocarbons / adverse effects*
  • Receptors, Thrombin / genetics*
  • Repressor Proteins / genetics*
  • Sweden
  • Young Adult

Substances

  • AHRR protein, human
  • Basic Helix-Loop-Helix Transcription Factors
  • Biomarkers, Tumor
  • Carcinogens
  • DNA, Mitochondrial
  • Polycyclic Aromatic Hydrocarbons
  • Receptors, Thrombin
  • Repressor Proteins
  • Creosote
  • protease-activated receptor 4