A Review on Epigenetic Effects of Environmental Factors Causing and Inhibiting Cancer

Epigenetic modifications refer to reversible changes in gene expression. Epigenetic changes include DNA methylation, histone modification, and non-coding RNAs that are collectively called epigenome. Various epigenetic effects account for the main impacts of environment and lifestyle on multifactorial diseases, such as cancers. The environmental impacts on cancers act as double-edged swords. While some of them are involved in cancer development, some others contribute to preventing it. In this review article, the keywords "cancer", "epigenetic", "lifestyle", "carcinogen", " cancer inhibitors" and related words were searched to finding a link between environmental factors and epigenetic mechanisms influencing cancer in ISI, PUBMED, SCOPUS, and Google Scholar databases. Based on the literature, environmental factors that are effective in cancer development or cancer prevention will be divided into physical, chemical, biological, and lifestyle types in this review. Different types of epigenetic mechanisms known for each of these agents will be addressed. Unregulated changes in epigenome play roles in tumorigenicity and cancer development. The action mechanism and genes targeted which are related to the signaling pathway for epigenetic alterations determine whether environmental agents are carcinogenic or prevent cancer. Having knowledge about the effective factors and related mechanisms such as epigenetic on cancer can help to prevent and improve cancer treatment.