Epigenetics of skin cancer: Interventions by selected bioactive phytochemicals

The prevalence and risk of skin cancer have been increasing over past three decades. Two major types of skin cancer observed in humans are melanoma and nonmelanoma. Nonmelanoma further subdivided into basal cell carcinoma and squamous cell carcinoma. Melanoma arises from melanocyte which locates at the bottom layer of skin epidermis, which primarily protects the skin from being exposed to external factors. Melanoma is less common among all other types of skin cancers but causes higher mortality. Epigenetic regulation associated with the transcriptional activation and inactivation of genes plays a major role in various disease progression including skin cancer. The major epigenetic changes observed at cellular level include DNA methylation, histone modifications, and miRNA-mediated gene regulation. The aberrant pattern in these epigenetic processes leads to altered expression of several genes involved in cell cycle, cell proliferation, cell motility, and apoptosis. Several natural bioactive phytochemicals have been shown to exhibit epigenetic modulatory capability and act as chemopreventive as well as therapeutic agents. In this review, we mainly discuss the major epigenetic modifications observed in melanoma and the epigenetic modulatory role of selected bioactive phytochemicals against the skin cancer.