Epidermal stem cells and progenitor cells as targets in skin carcinogenesis

Sunlight has many beneficial effects. However, from a biological point of view, solar UV radiation has also detrimental effects, especially at high doses of exposure. Because of its genotoxic properties, UV radiation plays an important role in the induction of skin cancer. In the last decennia, the incidence of skin cancer is rapidly increasing. This can partly be explained by an ageing population. However, the rise in skin cancer incidence appears to be primarily due to a change in human lifestyle in which sunbathing has become very popular. Our skin is continuously challenged by UV radiation, which may lead to irreversible damage. In order to withstand sustained physical, chemical and biological damage from the environment, among which UV radiation, the skin is continuously renewed. The regenerative capacity of skin is conferred by stem cells, which persist throughout the organism__s lifetime. Because of their long residency and unlimited capacity to replicate, stem cells might accumulate DNA damage and generate the multiple genetic lesions necessary for tumour development, despite efficient cellular defence mechanisms against DNA damage. Thus, stem cells may play an important role in carcinogenesis. The aim of this study is to investigate the role of stem cells in skin carcinogenesis.