Epigenetics is defined as heritable changes in gene expression not associated with alterations in DNA sequence.1 DNA methylation, histone modifications, chromatin remodeling factors, and noncoding regulatory RNAs are all known to be involved in epigenetic regulation of chromatin structure and gene activity. These epigenetic regulatory processes are considered critical components of normal development in cellular differentiation, organogenesis, and aging. Additionally, there is mounting evidence that epigenetic abnormalities are causative factors in several diseases, including cancer. Evidence also continues to surface for constituents in food and dietary supplements to influence gene expression, as well as an individual's risk of developing some cancers. Since epigenetic regulatory processes may be susceptible to changes by environmental factors, they offer potential mechanistic explanations for how diet may modify cancer risk and tumor behavior.
The Division of Cancer Prevention (DCP), National Cancer Institute (NCI), and the Office of Dietary Supplements (ODS), Office of the Director, National Institutes of Health (NIH), hosted the symposium titled Diet, Epigenetic Events, and Cancer Prevention, on September 26–27, 2007. The objectives of the symposium were 1) to identify voids that are impeding progress in basic, translational, and clinical research related to the use of bioactive food components (BFCs) in cancer prevention, and 2) to provide information about new tools to facilitate epigenetic research. The 2007 symposium represented a continuation of a previous trans-Department of Health and Human Services workshop on Diet, DNA Methylation Processes and Health, held in August, 2001. That workshop gave rise to a number of publications2 as well as an NCI Funding Opportunity Announcement (as a Request for Applications) that led to the funding of 10 projects in collaboration with ODS. NCI continues to support research on diet, epigenetic events, and cancer prevention through active funding opportunities currently available in the NIH Guide to Grants and Contracts available at http://grants.nih.gov/grants/guide/index.html.
The Diet, Epigenetic Events, and Cancer Prevention symposium provided a critical synopsis of the strengths and weaknesses of the evidence linking diet and bioactive food components with epigenetic processes (including DNA methylation, histone modifications, chromatin remodeling factors, and non-coding regulatory RNAs), their implications for cancer prevention, as well as the next steps for advancing research encompassing the inter-related fields of diet, epigenetic events, and cancer prevention. Symposium topics included the following: critical windows of time for DNA methylation modifications and potential modification by dietary factors; analyzing DNA methylation patterns in human populations and intervention studies to assess relationships with diet; non-coding RNA in transcriptional gene silencing and evidence for diet and bioactive food components in modulating this gene expression regulatory mechanism; recent evidence suggesting an impact of BFCs on histone modification and gene expression; and a discussion of additional emerging issues and approaches in epigenetics research. These topics were addressed by speakers and during panel and group discussions. A brief summary of the presentations and panel discussions is provided here. The remaining articles in this supplement summarize the presentations and views of the speakers in the sequence they were given during the symposium.