Gene promoter methylation can be assayed in exhaled breath, and is increased in smokers and lung cancer patients. Respiratory research [Respir Res] Journal article | | Title | Gene promoter methylation can be assayed in exhaled breath, and is increased in smokers and lung cancer patients. | | Author(s) | Han W, Wang T, Reilly AA, Keller SM, Spivack SD | | Source | Respir Res 2009 Sep 25; 10(1):86. | | Abstract | ABSTRACT:
BACKGROUND: The high mortality for lung cancer demands the availability of new, noninvasive risk assessment and early disease detecttion tools for use in population screening and prevention programs.
METHODS: To investigate the feasibility of determining DNA methylation in exhaled breath condensate, we applied our previously-developed method for high resolution tag-adapted bisulfite genomic DNA sequencing for mapping of DNA methylation, and adapted it to exhaled breath condensate (EBC) from non-cancer controls, and from lung cancer cases. We analyzed promoter methylation patterns in DAPK, RASSF1A and PAX5-beta promoters in EBC samples from 54 individuals, comprised of 34 controls including current-smokers (n=19), former-smokers (n=10), never-smokers (n=8); and 17 lung cancer cases (five current, 11 former smokers and one never smoker)].
RESULTS: We found: (1) Wide inter-individual variability in methylation density and spatial distribution for DAPK, PAX5-beta and RASSF1A. (2) Methylation patterns from paired exhaled breath condensate and mouth rinse specimens were completely divergent. (3) For smoking status comparisons, for the methylation density of RASSF1A, there was statistical difference among smoking groups (p=0.0285); pair-wise comparisons showed that the former smokers had higher methylation density versus never smokers and current smokers (p=0.019 and p=0.031). There was no significant difference in the overall methylation densities for DAPK and PAX5-beta. (4) In case-control comparisons, CpG at -63 of DAPK promoter and +52 of PAX5-beta promoter were significantly associated with lung cancer status (p= 0.0042 and 0.0093, respectively). After adjusting for multiple testing, both loci were of borderline significance (p=0.054 and 0.031). (5) The DAPK gene had a regional methylation pattern with two blocks (1)~ -215~ -113 and (2) -84 ~+26), lung cancer cases and non-cancer controls had similar methylation density in block 1, but was significantly different in methylation density in block 2 (p=0.045); (6) the results of a second method, quantitative methylation-specific PCR applied to EBC, correlated with the corresponding sequencing map loci.
CONCLUSIONS: Our results show that DNA methylation in exhaled breath condensate is detectable and likely of lung origin. Suggested correlations with smoking and lung cancer case-control status depend on gene and individual CpG sites examined. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19781081 |
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