Molecules 2014, 19, 6202-6219; doi:10.3390/molecules19056202 OPEN ACCESS molecules ISSN 1420-3049 www.mdpi.com/journal/molecules Review Ultraviolet Radiation, Aging and the Skin: Prevention of Damage by Topical cAMP Manipulation Alexandra Amaro-Ortiz 1, Betty Yan 1 and John A. D’Orazio 1,2,* 1 The Graduate Center for Toxicology, the Markey Cancer Center and the Department of Pediatrics, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY 40536, USA 2 Markey Cancer Center, University of Kentucky College of Medicine, Combs Research Building 204, 800 Rose Street, Lexington, KY 40536-0096, USA * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +1-859-323-6238; Fax: +1-859-257-8940. Received: 26 April 2014; in revised form: 8 May 2014 / Accepted: 13 May 2014 / Published: 15 May 2014 Abstract: Being the largest and most visible organ of the body and heavily influenced by environmental factors, skin is ideal to study the long-term effects of aging. Throughout our lifetime, we accumulate damage generated by UV radiation. UV causes inflammation, immune changes, physical changes, impaired wound healing and DNA damage that promotes cellular senescence and carcinogenesis. Melanoma is the deadliest form of skin cancer and among the malignancies of highest increasing incidence over the last several decades. Melanoma incidence is directly related to age, with highest rates in individuals over the age of 55 years, making it a clear age-related disease. In this review, we will focus on UV-induced carcinogenesis and photo aging along with natural protective mechanisms that reduce amount of “realized” solar radiation dose and UV-induced injury.