Bioactive Food Components for Melanoma: An Overview

Abstract

The skin being the largest organ in the body accounts for the most common cancer in humans. Skin cancer is typically of three types, basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma. Despite accounting for only 4% of all cases, melanoma is the most deadly skin cancer, resulting in over 79% of skin cancer related deaths [1, 2]. In the year 2011 in the United States melanoma is thought to cause 70,230 cases (40,010 in men and 30,220 in women) with 8,790 deaths (5,750 in men and 3,040 in women) associated with the disease [3]. The median age at diagnosis is between 45 and 55, although 25% of cases occur in individuals before age 40. It is the second most common cancer in women between the ages of 20 and 35, and the leading cause of cancer death in women ages 25 to 30. There are multiple risk factors that contribute to the escalating incidences of melanomas in humans (Table 1). Among all, ultraviolet (UV)-radiation emitted from the sun is the main contributing factor towards the development of melanomas. It is well documented that UVradiation is absorbed by the chromophores such as DNA, RNA, protein and melanin in the skin [4]. This UV absorption in the skin results in different photochemical reactions and the secondary interactions involving ROS (reactive oxygen species) result in damaging effects. UV irradiation of the skin causes erythema, edema, hyperplasia, hyperpigmentation, sunburn cells, immunosuppression, photoaging and photocarcinogenesis [5, 6]. UV irradiation to skin also has direct effects on biomolecules such as formation of cyclobutane pyrimidine dimers (CPDs), 8-hydroxy-2'-deoxyguanosine (8-OHdG), protein oxidation and generation of ROS [4, 7, 8]. Over the years, changes in lifestyle patterns have led to a significant increase in the amount of UV radiation that people receive, leading to a surge in the incidence of skin cancer and photoaging. Since these trends are likely to continue in the foreseeable future, the adverse effects of ultraviolet radiation have become a major human concern. One way of combating against the melanomas is through “chemoprevention” which is defined as the use of natural or synthetic agents to reverse, suppress or prevent premalignant lesions from progressing to