Active and secondhand smoke exposure throughout life and DNA methylation in breast tumors
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Tobacco smoke exposure has been associated with altered DNA methylation. However, there is a paucity of information regarding tobacco smoke exposure and DNA methylation of breast tumors.
We conducted a case-only analysis using breast tumor tissue from 493 postmenopausal and 225 premenopausal cases in the Western New York Exposures and Breast Cancer (WEB) study. Methylation of nine genes (SFN, SCGB3A1, RARB, GSTP1, CDKN2A, CCND2, BRCA1, FHIT, and SYK) was measured with pyrosequencing. Participants reported their secondhand smoke (SHS) and active smoking exposure for seven time periods. Unconditional logistic regression was used to estimate odds ratios (OR) of having methylation higher than the median.
SHS exposure was associated with tumor DNA methylation among postmenopausal but not premenopausal women. Active smoking at certain ages was associated with increased methylation of GSTP1, FHIT, and CDKN2A and decreased methylation of SCGB3A1 and BRCA1 among both pre- and postmenopausal women.
Exposure to tobacco smoke may contribute to breast carcinogenesis via alterations in DNA methylation. Further studies in a larger panel of genes are warranted.
KeywordsBreast cancer DNA methylation Tobacco Secondhand smoke Epigenetics
This article was prepared while Catherine Callahan and Youjin Wang were employed at the University at Buffalo. The opinions expressed in this article are the authors’ own and do not reflect the view of the National Institutes of Health, the Department of Health and Human Services, or the United States government.
Catherine L. Callahan was supported by the National Cancer Institute (NCI) Grant R25CA113951.
Compliance with Ethical Standards
Conflict of interest
The authors declare no potential conflict of interest.
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