Curcumin targeted signaling pathways: basis for anti-photoaging and anti-carcinogenic therapy

Photocarcinogenesis is caused by DNA damage from solar radiation in the ultraviolet range, resulting in the development of both melanoma and non-melanoma skin cancers. Although the ultraviolet B (UVB) spectrum has previously been considered the more carcinogenic of the two, recent evidence suggests that ultraviolet A (UVA) irradiation may have damaging effects that are not generally appreciated. Furthermore, it is becoming apparent that although sunscreens have been in use for many years, they are relatively ineffective in protecting against UVA-induced photoaging and UVA-induced skin cancers. More recently, attention has been directed on certain dietary phytochemicals, in particular curcumin, in the attempt to repair photodamaged skin as a means of preventing degeneration into solar-induced skin cancers. Curcumin has been shown to protect against the deleterious effects of injury by attenuating oxidative stress and suppressing inflammation. In this review, the curcumin-targeted signaling pathways directed against solar-induced injury are reviewed. The ability of curcumin to block multiple targets on these pathways serve as a basis for the potential use of this phytochemical in photoaging skin and photocarcinogenesis.