Gene promoter methylation in plasma and sputum increases with lung cancer risk

Clin Cancer Res. 2005 Sep 15;11(18):6505-11. doi: 10.1158/1078-0432.CCR-05-0625.


Purpose: Lung cancer is the leading cause of cancer mortality in the United States, due in part to the lack of a validated and effective screening approach for early detection. The prevalence for methylation of seven and three genes was examined in DNA from sputum and plasma, respectively, from women at different risk for lung cancer.

Experimental design: Lung cancer survivors (n = 56), clinically cancer-free smokers (n = 121), and never smokers (n = 74) comprised the study population. Plasma was collected from all three groups, whereas sputum was collected from lung cancer survivors and smokers.

Results: Methylation was detected in plasma DNA from 10 of 74 women who never smoked. Prevalence for methylation of the p16 gene in plasma was highest in lung cancer survivors. Lung cancer survivors showed a significant increase in the odds of having at least one or more genes methylated in plasma (odds ratio, 3.6; 95% confidence interval, 1.9-9.1) than never smokers. The prevalence for methylation of the O(6)-methylguanine-DNA methyltransferase, ras effector homologue 1, death associated protein kinase, and PAX5alpha genes in sputum was significantly higher in lung cancer survivors compared with smokers. Lung cancer survivors had 6.2-fold greater odds (95% confidence interval, 2.1-18.5) for methylation of three or more genes in sputum compared with smokers. Methylation was more commonly detected in sputum than plasma for O(6)-methylguanine-DNA methyltransferase and ras effector homologue 1, but not p16, in lung cancer survivors.

Conclusion: Concomitant methylation of multiple gene promoters in sputum is strongly associated with lung cancer risk.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Apoptosis Regulatory Proteins
  • Calcium-Calmodulin-Dependent Protein Kinases / genetics
  • Cyclin-Dependent Kinase Inhibitor p16 / genetics*
  • DNA Methylation*
  • DNA, Neoplasm / blood
  • DNA, Neoplasm / genetics
  • DNA, Neoplasm / isolation & purification
  • DNA-Binding Proteins / genetics
  • Death-Associated Protein Kinases
  • Female
  • Humans
  • Lung Neoplasms / genetics*
  • Lung Neoplasms / pathology
  • Middle Aged
  • O(6)-Methylguanine-DNA Methyltransferase / genetics
  • PAX5 Transcription Factor
  • Promoter Regions, Genetic / genetics*
  • Risk Factors
  • Smoking
  • Sputum / chemistry
  • Sputum / cytology
  • Survivors
  • Transcription Factors / genetics
  • Tumor Suppressor Proteins / genetics


  • Apoptosis Regulatory Proteins
  • Cyclin-Dependent Kinase Inhibitor p16
  • DNA, Neoplasm
  • DNA-Binding Proteins
  • PAX5 Transcription Factor
  • PAX5 protein, human
  • RASSF1 protein, human
  • Transcription Factors
  • Tumor Suppressor Proteins
  • O(6)-Methylguanine-DNA Methyltransferase
  • Death-Associated Protein Kinases
  • Calcium-Calmodulin-Dependent Protein Kinases