Prevention of Breast Cancer by Food Bioactives in Relation to Cancer Subtypes: Epigenetic Mechanisms

Breast cancer is the most common type of cancer and the leading cause of mortality among women worldwide. Aberrations in epigenetic regulation of tumor-suppressor genes contribute to hereditary and sporadic breast cancers. Accumulating evidence suggests a role for dietary compounds as epigenetic modifiers of breast cancer risk. However, given that breast cancer is a heterogeneous disease, it is important to consider variations in the epigenetic profile and potential response to food compounds across breast cancer subtypes. In this chapter, we first summarize research evidence regarding differences in epigenotype across breast tumor subtypes with emphasis on changes in DNA methylation, histone modifications, and the expression of noncoding RNA. Second, we discuss the role of epigenetic mechanisms in the silencing of breast cancer 1 (BRCA1), selected as a prototype early-onset breast cancer gene and epigenetic target by environmental and endogenous compounds that activate the aryl hydrocarbon receptor (AhR). Third, we highlight research evidence about food components (e.g., resveratrol and genistein) as dietary preventatives against epigenetic repression of BRCA1 by AhR agonists and the development of estrogen receptor-negative and triple-negative breast cancer.