Rakesh Sirvastava – In last two decades, the study of epigenetic modification emerged as one of the major areas of cancer treatment targeted by dietary phytochemicals. Recent studies with various types of cancers revealed that the epigenetic modifications are associated with the food source corresponds to dietary phytochemicals. The dietary phytochemicals have been used in Asian countries for thousands of years to cure several diseases including cancer. They have been reported to modulate the several biological processes including histone modification, DNA methylation and non-coding microRNA expression. These events play a vital role in carcinogenesis. Various studies suggest that a number of dietary compounds present in vegetables, spices and other herbal products have epigenetic targets in cancer cells. Dietary phytochemicals have been reported to repair DNA damage by enhancing histone acetylation that helps to restrain cell death, and also alter DNA methylation. These phytochemicals are able to modulate epigenetic modifications and their targets to cure several cancers. Epigenetic aberrations dynamically contribute to cancer pathogenesis. Given the individualized traits of epigenetic biomarkers, the personalized nutrition will help us to prevent various types of cancer. In this review, we will discuss the effect of dietary phytochemicals on genetic and epigenetic modifications and how these modifications help to prevent various types of cancers and improve health outcomes.
Keywords: Epigenetics, Phytochemicals, DNA-methylation, Histone-modification, miRNA, Carcinogenesis.
1. Introduction
Dietary intervention experiments and epidemiological studies in humans using laboratory animals have provided evidence to suggest that lifestyle and environmental factors play a critical role in the development of a wide variety of neoplasms. Environmental factors including chemical carcinogens, environmental pollutants, dietary contaminants and physical carcinogens play important role in the etiology of human cancer (Kupchella CE 1986). Additionally, lifestyle factors, such as alcohol consumption, smoking, exposure to sunlight, increased fat consumption and chronic stress can also promote the development and progression of cancer (Stein CJ and Colditz GA 2004). It has further been demonstrated that maternal nutrition imbalance and metabolic disturbances during embryonic development have a persistent effect on the health of the offspring and may be passed down to the next generation (Attig L et al 2010). These studies provide evidence that cancer is a complex disease and manifestation of both genetic and epigenetic modifications (Macaluso M, Paggi MG et al. 2003). Cancer initiation and progression are primarily driven by acquired genetic alterations however microenvironment-mediated epigenetic perturbations play an important role in neoplastic development (Cho HS, Park JH et al. 2007). “Epigenetics” is defined as heritable changes in gene activity and expression that occur without alteration in DNA sequences and are sufficiently powerful to regulate the dynamics of gene expression (Goldberg AD, Allis CD et al. 2007; Stefanska B, Karlic H et al. 2012). Epigenetic modifications are potentially reversible, which makes them attractive and promising avenues for catering cancer preventive and therapeutic strategies. The key processes responsible for epigenetic regulation are DNA methylation, modifications in chromatin [covalent modification of core histones], and post-transcriptional gene regulation by non-coding RNA [micro-RNAs] (Dehan P, Kustermans G et al. 2009; Lim U and Song MA 2012). Additionally, some examples of genetic modifiers that alter epigenetic modifications are discussed in.
