Global methylation profiles in buccal cells of long-term smokers and moist snuff consumers

Abstract

Purpose: Alternations in gene methylation and other epigenetic changes regulate normal development as well as drive disease progression. The aim of this study is to investigate global methylation changes in the buccal cells of smokers and smokeless tobacco users.

Materials and methods: Generally healthy adult male subjects were recruited into smoker (SMK), moist snuff consumer (MSC) and non-tobacco consumer (NTC) cohorts (40 subjects/cohort) (ClinicalTrials.gov Identifier: NCT01923402). Global methylation profiling was performed on Illumina 450 K methylation arrays using buccal cell DNAs.

Results: The SMK cohort exhibited larger qualitative and quantitative changes relative to MSC. Approximately half of the differentially methylated 1252 gene loci were grouped as combustible tobacco-related (CTR) signatures and a third of the changes, tobacco-related (TR) signatures, were associated with smoking. Very few (41) differentially methylated gene loci were exclusively associated with moist snuff use and were designated as moist snuff-related (MSR) signature. Pathway enrichment analyses revealed that developmental and immune response pathways, among others, were impacted due to tobacco use.

Conclusions: Chronic cigarette smoking causes hyper- and hypo-methylation of genes that could contribute to smoking-related diseases. These results help place combustible and non-combustible tobacco products along a risk continuum and provide additional insights into the effects of tobacco consumption.

Keywords:

• Buccal cells
• methylation profiles
• tobacco

Acknowledgements

The authors thank Bobbette A. Jones for managing the clinical conduct of the study and for assistance in preparing this manuscript. The authors thank Megan J. Whelen for critical review and editing of this manuscript. Drs. Borgerding and Prasad are full-time employees of RAI Services Company. RAI Services Company is a wholly owned subsidiary of Reynolds American Inc., which is a wholly owned subsidiary of British American Tobacco Plc. Dr. Jessen is a full-time employee of Laboratory Corporation of America Holdings (LabCorp).

Disclosure statement

Drs. Borgerding and Prasad are full time employees of RAI Services Company. RAI Services Company is a wholly owned subsidiary of Reynolds American Inc., which is a wholly owned subsidiary of British American Tobacco plc. Dr. Jessen is a full time employee of Laboratory Corporation of America Holdings (LabCorp).